Patchwork [3/7] Emit macro expansion related diagnostics

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Submitter Dodji Seketeli
Date Sept. 27, 2011, 5:52 p.m.
Message ID <m3sjnhan4s.fsf@redhat.com>
Download mbox | patch
Permalink /patch/116646/
State New
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Comments

Dodji Seketeli - Sept. 27, 2011, 5:52 p.m.
I am replying to several emails in one go here, as the discussion was a
bit long on this particular patch.

Jason Merrill <jason@redhat.com> writes:

> It seems that this function steps out until we hit the spelling
> location, and then we have a real source location and stop, which is
> why the loop in maybe_unwind_expanded_macro_loc needs to use
> linemap_macro_map_loc_to_exp_point as well.  Right?  In the example,
> once we hit << in SHIFTL unwinding needs to switch to the expansion
> point.
>
> It seems to me that we should encapsulate all of this in a function
> that expresses this unwinding operation, say
> "linemap_macro_map_loc_unwind_once".  So the loop would look like
>
> +  do
> +    {
> +      loc.where = where;
> +      loc.map = map;
> +
> +      VEC_safe_push (loc_t, heap, loc_vec, &loc);
> +
> +      /* WHERE is the location of a token inside the expansion of a
> +         macro.  MAP is the map holding the locations of that macro
> +         expansion.  Let's get the location of the token in the
> +         context that triggered the expansion of this macro.
> +         This is basically how we go "down" in the trace of macro
> +         expansions that led to WHERE.  */
> +      where = linemap_unwind_once (where, &map);
> +    } while (linemap_macro_expansion_map_p (map));
>

I have done this.  Though I have called the function
linemap_step_out_once to avoid confusion with
linemap_macro_map_loc_unwind_once above.

> I think that linemap_macro_loc_to_def_point when called with false
> returns the unwound spelling location of the token (and thus is used
> for LRK_SPELLING_LOCATION), or when called with true returns the
> (not-unwound) location in the expanded macro (and so I think
> LRK_MACRO_PARM_REPLACEMENT_POINT should be renamed to
> LRK_MACRO_EXPANDED_LOCATION or something similar).

>> Would LRK_MACRO_DEFINITION_LOCATION be better then?  :-)
>
> Yes.  :)

Done.  Note that I had to mechanically update two other patches that
were OKed previously.

>
> I'm having trouble thinking of a less misleading name for
> linemap_macro_map_loc_to_def_point, since the two locations serve
> completely different purposes.  Maybe something vague like
> linemap_macro_map_loc_get_stored_loc.  Or split it into two functions
> like linemap_virtual_loc_unwind_once_toward_spelling and
> linemap_virtual_loc_get_expanded_location or something like that.

>> So would a function named linemap_macro_map_loc_to_def_point that
>> returns the second location (yI) only, and a second function
>> linemap_macro_map_loc_unwind_once be less confusing to you?
>
> Yes, that sounds good.

I have done this.

> It seems to me that either we should split those functions apart in to
> two functions with clearer names, or bundle them and
> linemap_macro_loc_to_exp_point into linemap_resolve_location; if
> linemap_location_in_system_header_p used linemap_resolve_location it
> would be more readable anyway.

I have essentially made this too.  linemap_macro_loc_to_exp_point,
linemap_macro_map_loc_unwind_once and linemap_macro_map_loc_to_def_point
are now static functions that are only subroutines of
linemap_resolve_location.  They are not part of the public line map API
anymore. linemap_location_in_system_header_p uses
linemap_resolve_location now, and I have updated the other parts of the
compiler that were using those to use linemap_resolve_location instead.

> What do you think?

It's should be less confusing now, hopefully.  :)

Now I am re-posting the two additional patches that I had to
mechanically update due to this changes.  I have bootstrapped and tested
each patch one by one, while having its dependent patches installed.
This was done on x86_64-unknown-linux-gnu against trunk for all
languages including Ada.

From: Dodji Seketeli <dodji@redhat.com>
Date: Sat, 4 Dec 2010 16:31:35 +0100
Subject: [PATCH 3/7] Emit macro expansion related diagnostics

In this third instalment the diagnostic machinery -- when faced with
the virtual location of a token resulting from macro expansion -- uses
the new linemap APIs to unwind the stack of macro expansions that led
to that token and emits a [hopefully] more useful message than what we
have today.

diagnostic_report_current_module has been slightly changed to use the
location given by client code instead of the global input_location
variable.  This results in more precise diagnostic locations in
general but then the patch adjusts some C++ tests which output changed
as a result of this.

Three new regression tests have been added.

The mandatory screenshot goes like this:

[dodji@adjoa gcc]$ cat -n test.c
     1    #define OPERATE(OPRD1, OPRT, OPRD2) \
     2      OPRD1 OPRT OPRD2;
     3
     4    #define SHIFTL(A,B) \
     5      OPERATE (A,<<,B)
     6
     7    #define MULT(A) \
     8      SHIFTL (A,1)
     9
    10    void
    11    g ()
    12    {
    13      MULT (1.0);/* 1.0 << 1; <-- so this is an error.  */
    14    }

[dodji@adjoa gcc]$ ./cc1 -quiet -ftrack-macro-expansion test.c
test.c: In function 'g':
test.c:5:14: erreur: invalid operands to binary << (have 'double' and 'int')
test.c:2:9: note: in expansion of macro 'OPERATE'
test.c:5:3: note: expanded from here
test.c:5:14: note: in expansion of macro 'SHIFTL'
test.c:8:3: note: expanded from here
test.c:8:3: note: in expansion of macro 'MULT2'
test.c:13:3: note: expanded from here

The combination of this patch and the previous ones boostrapped with
--enable-languages=all,ada and passed regression tests on
x86_64-unknown-linux-gnu.

gcc/
	* gcc/diagnostic.h (diagnostic_report_current_module): Add a
	location parameter.
	* diagnostic.c (diagnostic_report_current_module): Add a location
	parameter to the function definition.  Use it instead of
	input_location.  Resolve the virtual location rather than just
	looking up its map and risking to touch a resulting macro map.
	(default_diagnostic_starter): Pass the relevant diagnostic
	location to diagnostic_report_current_module.
	* tree-diagnostic.c (maybe_unwind_expanded_macro_loc): New.
	(virt_loc_aware_diagnostic_finalizer): Likewise.
	(diagnostic_report_current_function): Pass the
	relevant location to diagnostic_report_current_module.
	* tree-diagnostic.h (virt_loc_aware_diagnostic_finalizer): Declare
	new function.
	* toplev.c (general_init): By default, use the new
	virt_loc_aware_diagnostic_finalizer as diagnostic finalizer.
	* Makefile.in: Add vec.h dependency to tree-diagnostic.c.

gcc/cp/

	* error.c (cp_diagnostic_starter): Pass the relevant location to
	diagnostic_report_current_module.
	(cp_diagnostic_finalizer): Call virt_loc_aware_diagnostic_finalizer.

gcc/testsuite/

	* lib/prune.exp (prune_gcc_output):  Prune output referring to
	included files.
	* gcc.dg/cpp/macro-exp-tracking-1.c: New test.
	* gcc.dg/cpp/macro-exp-tracking-2.c: Likewise.
	* gcc.dg/cpp/macro-exp-tracking-3.c: Likewise.
	* gcc.dg/cpp/pragma-diagnostic-2.c: Likewise.

Addendum patch 0003

gcc/

	* diagnostic.c (diagnostic_report_current_module): Adjust for the
	renaming of LRK_MACRO_PARM_REPLACEMENT_POINT into
	LRK_MACRO_DEFINITION_LOCATION.
	* tree-diagnostic.c (maybe_unwind_expanded_macro_loc): Use the new
	linemap_step_out_once.  Adjust like above.
---
 gcc/Makefile.in                                 |    3 +-
 gcc/cp/error.c                                  |    5 +-
 gcc/diagnostic.c                                |   13 +-
 gcc/diagnostic.h                                |    2 +-
 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-1.c |   21 +++
 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-2.c |   21 +++
 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-3.c |   14 ++
 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-4.c |   14 ++
 gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-2.c  |   34 +++++
 gcc/testsuite/lib/prune.exp                     |    1 +
 gcc/toplev.c                                    |    3 +
 gcc/tree-diagnostic.c                           |  182 ++++++++++++++++++++++-
 gcc/tree-diagnostic.h                           |    3 +-
 13 files changed, 305 insertions(+), 11 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-1.c
 create mode 100644 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-2.c
 create mode 100644 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-3.c
 create mode 100644 gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-4.c
 create mode 100644 gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-2.c
Jason Merrill - Sept. 29, 2011, 12:07 a.m.
On 09/27/2011 01:52 PM, Dodji Seketeli wrote:
> +     Remember we are at the expansion point of MACRO.  Each xI is the
> +     location of the Ith token of the replacement-list. Now it gets
> +     confusing. the xI is the location of the Ith token of the
> +     replacement-list at the macro *definition* point. Not at the
> +     macro replacement point. Okay, let's try to explain this below.

This should be yI.

> +     The token '+' has two locations, so to speak. One in the context
> +     of the macro *expansion* of PLUS in #2 and one in the context of
> +     the macro *definition* of PLUS in #1. These two locations are
> +     encoded in the the latter context, somehow in the xI we are
> +     talking about.

The location of '+' in #2 is not encoded in xI or yI, we reach it 
through the expansion point location of the macro.  The location in #1 
is yI (and xI, in this case).

> +     xI is roughly the index of the token inside the replacement-list
> +     at the expansion point. So for '+', it's index would then be 1

"its"

> +     [The index of token '1' would be 0 and the index of token 2 would
> +     be 1]. So if '+' is our current xI, it is actualy an x1.

Are we still talking about #1 here?  It looks to me like the index of 
"1" would be 2, the index of "+" would be 4, and the index of token "2" 
would be 6.  I bet PLUS used to just be "A + B", and this section of 
comment didn't get updated when it changed.

Keep changing xI to yI.

> +     Now what's the y1 then? Remember, we said macro_locations is an
> +     array of pairs (xI,yI). We now know what the xI is, now let's
> +     look at the yI.

xI allows us to find where the token was actually written.  If the 
current macro context is also the spelling location of the token (e.g. 
#1 for "+"), then xI is the same as yI, i.e. the source location of that 
token.

If the current macro context is not the spelling location of the token 
(e.g. #0 or #1 for "1"), then xI is the location outside the current 
macro context.  For "1" in #0, this the location of "1" in #1, which is 
a virtual location.  For "1" in #1, this is the location of "1" in #2, 
which is a source location.

> +   * If LRK is set to LRK_MACRO_EXPANSION_POINT
> +   -------------------------------
> +
> +   The virtual location is resolved to the location to the locus of
> +   the expansion point of the macro.

The first macro expansion point that led to this macro expansion.

> +   * If LRK is set to LRK_MACRO_DEFINITION_LOCATION
> +   --------------------------------------

The virtual location is resolved to the locus of the token in the 
context of the macro definition.

> +   If LOC is the locus of a token that is an argument of a
> +   function-like macro [replacing a parameter in the replacement list
> +   of the macro] the virtual location is resolved to the locus of the
> +   parameter that is replaced, in the context of the definition of the
> +   macro.
> +
> +   If LOC is the locus of a token that is not an argument of a
> +   function-like macro, then the function behaves as if LRK was set to
> +   LRK_SPELLING_LOCATION.

(and then keep these two paragraphs)

> +   Finally, if SPELLING_LOC is not NULL, *RESULTING_LOC is set to the
> +   location to which LOC was resolved

SPELLING_LOC doesn't exist anymore.

> +   ORIG_LOC is the orginal location of the token at the definition
> +   point of the macro. If you read the extensive comments of struct
> +   line_map_macro in line-map.h, this is the xI.
> +
> +   If the token is part of a macro argument, ORIG_PARM_REPLACEMENT_LOC
> +   is the location of the point at wich the token (the argument)
> +   replaces the macro parameter in the context of the relevant macro
> +   definition. If you read the comments of struct line_map_macro in
> +   line-map.h, this is the yI.  */
> +
> +source_location
> +linemap_add_macro_token (const struct line_map *map,

ORIG_LOC is the location of the token outside this macro expansion.  If 
the token comes originally from the macro definition, it is the locus in 
the macro definition; otherwise it is a location in the caller of this 
macro expansion (which is a virtual location or a source location if the 
caller is itself a macro expansion or not).

MACRO_DEFINITION_LOC is the location in the macro definition, either of 
the token itself or of a macro parameter that it replaces.

> +/* If LOCATION is the locus of a token that is an argument of a
> +   function-like macro M and appears in the expansion of M, return the
> +   locus of that argument in the context of the caller of M.  Note
> +   that the caller of M is necessarily another macro.

Why is the caller of M necessarily another macro?  In the PLUS example 
above, if we have the location for "1" in #1, won't it give us the 
location of "1" in #2?

>   The context of M is a macro definition.

What does this mean?

> +/* Return the source line number corresponding to source location
> +   LOCATION.  SET is the line map set LOCATION comes from.  If
> +   LOCATION is the source location of token that is part of the
> +   replacement-list of a macro expansion return the line number of the
> +   macro expansion point.  */
> +
> +int
> +linemap_get_source_line (struct line_maps *set,
> +                        source_location location)

Let's call this linemap_get_expansion_line.

> +linemap_get_source_column (struct line_maps *set,

This seems unused.

> +linemap_get_file_path (struct line_maps *set,

Shouldn't we use this for BT_FILE in _cpp_builtin_macro_text?  And call 
it linemap_get_expansion_filename.

> +   Note that this function returns 0 if LOCATION belongs to a token
> +   that is part of a macro replacement-list defined in a system
> +   header, but expanded in a non-system file.  */
> +
> +int
> +linemap_location_in_system_header_p (struct line_maps *set,
> +                                    source_location location)
> +{
> +  const struct line_map *map = NULL;
> +
> +  if (location < RESERVED_LOCATION_COUNT)
> +    return false;
> +
> +  location =
> +    linemap_resolve_location (set, location, LRK_SPELLING_LOCATION, &map);

The comment seems incorrect here.  If the location passed in corresponds 
to a non-parameter token in a macro in a system header, we'll end up 
with the source location of that token, not the expansion location. 
What behavior do we want here?

> +linemap_macro_loc_unwind (struct line_maps *set,

Let's call this linemap_macro_loc_to_spelling_point.

> +/* If LOCATION is the locus of a token that is an argument of a
> +   function-like macro M, return the location of that token in the
> +   context of the definition of the first macro P which expansion
> +   triggered the expansion of M.  Note that the token must be actually
> +   present in the source of the definition of P.  If LOCATION is the
> +   locus of a token that belongs to a macro replacement-list but is
> +   not an argument to a function-like macro, return the same thing as
> +   what linemap_macor_loc_to_def_point would have returned.

This seems unnecessarily complex.  This function returns the spelling 
location of the token wherever it comes from, whether part of a macro 
definition or not.

> linemap_macro_loc_to_exp_point,
> linemap_macro_map_loc_unwind_once and linemap_macro_map_loc_to_def_point
> are now static functions that are only subroutines of
> linemap_resolve_location.  They are not part of the public line map API
> anymore.

I still see them in line-map.h.

Let's rename linemap_macro_map_loc_unwind_once to 
"linemap_macro_map_loc_unwind_toward_spelling", and 
linemap_step_out_once to "linemap_macro_map_loc_unwind_toward_expansion".

Jason

Patch

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 92016f2..d26c682 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -2796,7 +2796,8 @@  tree-pretty-print.o : tree-pretty-print.c $(CONFIG_H) $(SYSTEM_H) \
    $(TM_H) coretypes.h tree-iterator.h $(SCEV_H) langhooks.h \
    $(TREE_PASS_H) value-prof.h output.h tree-pretty-print.h
 tree-diagnostic.o : tree-diagnostic.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
-   $(TREE_H) $(DIAGNOSTIC_H) tree-diagnostic.h langhooks.h $(LANGHOOKS_DEF_H)
+   $(TREE_H) $(DIAGNOSTIC_H) tree-diagnostic.h langhooks.h $(LANGHOOKS_DEF_H) \
+   $(VEC_H)
 fold-const.o : fold-const.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(TREE_H) $(FLAGS_H) $(DIAGNOSTIC_CORE_H) $(HASHTAB_H) $(EXPR_H) $(RTL_H) \
    $(GGC_H) $(TM_P_H) langhooks.h $(MD5_H) intl.h $(TARGET_H) \
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 598ddf1..8fa163f 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -2767,7 +2767,7 @@  static void
 cp_diagnostic_starter (diagnostic_context *context,
 		       diagnostic_info *diagnostic)
 {
-  diagnostic_report_current_module (context);
+  diagnostic_report_current_module (context, diagnostic->location);
   cp_print_error_function (context, diagnostic);
   maybe_print_instantiation_context (context);
   maybe_print_constexpr_context (context);
@@ -2777,8 +2777,9 @@  cp_diagnostic_starter (diagnostic_context *context,
 
 static void
 cp_diagnostic_finalizer (diagnostic_context *context,
-			 diagnostic_info *diagnostic ATTRIBUTE_UNUSED)
+			 diagnostic_info *diagnostic)
 {
+  virt_loc_aware_diagnostic_finalizer (context, diagnostic);
   pp_base_destroy_prefix (context->printer);
 }
 
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index b46eb35..a8c0e66 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -255,9 +255,9 @@  diagnostic_action_after_output (diagnostic_context *context,
 }
 
 void
-diagnostic_report_current_module (diagnostic_context *context)
+diagnostic_report_current_module (diagnostic_context *context, location_t where)
 {
-  const struct line_map *map;
+  const struct line_map *map = NULL;
 
   if (pp_needs_newline (context->printer))
     {
@@ -265,10 +265,13 @@  diagnostic_report_current_module (diagnostic_context *context)
       pp_needs_newline (context->printer) = false;
     }
 
-  if (input_location <= BUILTINS_LOCATION)
+  if (where <= BUILTINS_LOCATION)
     return;
 
-  map = linemap_lookup (line_table, input_location);
+  linemap_resolve_location (line_table, where,
+			    LRK_MACRO_DEFINITION_LOCATION,
+			    &map);
+
   if (map && diagnostic_last_module_changed (context, map))
     {
       diagnostic_set_last_module (context, map);
@@ -301,7 +304,7 @@  void
 default_diagnostic_starter (diagnostic_context *context,
 			    diagnostic_info *diagnostic)
 {
-  diagnostic_report_current_module (context);
+  diagnostic_report_current_module (context, diagnostic->location);
   pp_set_prefix (context->printer, diagnostic_build_prefix (context,
 							    diagnostic));
 }
diff --git a/gcc/diagnostic.h b/gcc/diagnostic.h
index 8074354..4b1265b 100644
--- a/gcc/diagnostic.h
+++ b/gcc/diagnostic.h
@@ -253,7 +253,7 @@  extern diagnostic_context *global_dc;
 /* Diagnostic related functions.  */
 extern void diagnostic_initialize (diagnostic_context *, int);
 extern void diagnostic_finish (diagnostic_context *);
-extern void diagnostic_report_current_module (diagnostic_context *);
+extern void diagnostic_report_current_module (diagnostic_context *, location_t);
 
 /* Force diagnostics controlled by OPTIDX to be kind KIND.  */
 extern diagnostic_t diagnostic_classify_diagnostic (diagnostic_context *,
diff --git a/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-1.c b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-1.c
new file mode 100644
index 0000000..d975c8c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-1.c
@@ -0,0 +1,21 @@ 
+/*
+   { dg-options "-ftrack-macro-expansion=1" }
+   { dg-do compile }
+*/
+
+#define OPERATE(OPRD1, OPRT, OPRD2) \
+do \
+{ \
+  OPRD1 OPRT OPRD2; /* { dg-message "expansion" }*/ 	   \
+} while (0)
+
+#define SHIFTL(A,B) \
+  OPERATE (A,<<,B) /* { dg-message "expanded|expansion" } */
+
+void
+foo ()
+{
+  SHIFTL (0.1,0.2); /* { dg-message "expanded" } */
+}
+
+/* { dg-error "invalid operands" "" { target *-*-* } 13 } */
diff --git a/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-2.c b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-2.c
new file mode 100644
index 0000000..684af4c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-2.c
@@ -0,0 +1,21 @@ 
+/* 
+   { dg-options "-ftrack-macro-expansion=1" }
+   { dg-do compile }
+*/
+
+#define OPERATE(OPRD1, OPRT, OPRD2) \
+ OPRD1 OPRT OPRD2;		/* { dg-message "expansion" } */
+
+#define SHIFTL(A,B) \
+  OPERATE (A,<<,B) /* { dg-message "expanded|expansion" } */
+
+#define MULT(A) \
+  SHIFTL (A,1)			/* { dg-message "expanded|expansion" } */
+
+void
+foo ()
+{
+  MULT (1.0);			/* { dg-message "expanded" } */
+}
+
+/* { dg-error "invalid operands to binary <<" "" { target *-*-* } { 10 } } */
diff --git a/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-3.c b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-3.c
new file mode 100644
index 0000000..119053e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-3.c
@@ -0,0 +1,14 @@ 
+/*
+  { dg-options "-fshow-column -ftrack-macro-expansion=1" }
+  { dg-do compile }
+ */
+
+#define SQUARE(A) A * A		/* { dg-message "expansion" } */
+
+void
+foo()
+{
+  SQUARE (1 << 0.1);		/* { dg-message "expanded" } */
+}
+
+/* { dg-error "16:invalid operands to binary <<" "" {target *-*-* } { 11 } } */
diff --git a/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-4.c b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-4.c
new file mode 100644
index 0000000..1f9fe6a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/macro-exp-tracking-4.c
@@ -0,0 +1,14 @@ 
+/*
+  { dg-options "-fshow-column -ftrack-macro-expansion=2" }
+  { dg-do compile }
+ */
+
+#define SQUARE(A) A * A		/* { dg-message "expansion" } */
+
+void
+foo()
+{
+  SQUARE (1 << 0.1);		/* { dg-message "expanded" } */
+}
+
+/* { dg-error "13:invalid operands to binary <<" "" { target *-*-* } { 11 } } */
diff --git a/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-2.c b/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-2.c
new file mode 100644
index 0000000..7ab95b0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-2.c
@@ -0,0 +1,34 @@ 
+/*
+  { dg-options "-Wuninitialized -ftrack-macro-expansion=2" }
+  { dg-do compile }
+*/
+
+void f (unsigned);
+
+#define CODE_WITH_WARNING \
+  int a; /* { dg-message "expansion|declared here" } */  \
+  f (a)	 /* { dg-message "expansion" } */
+
+#pragma GCC diagnostic ignored "-Wuninitialized"
+
+void
+g (void)
+{
+  CODE_WITH_WARNING;
+}
+
+#pragma GCC diagnostic push
+
+#pragma GCC diagnostic error "-Wuninitialized"
+
+void
+h (void)
+{
+  CODE_WITH_WARNING;		/* { dg-message "expanded" } */
+}
+
+/*
+  { dg-message "some warnings being treated as errors" "" {target *-*-*} 0 }
+*/
+
+/* { dg-error "uninitialized" "" { target *-*-* } { 10 } } */
diff --git a/gcc/testsuite/lib/prune.exp b/gcc/testsuite/lib/prune.exp
index 4683f93..09d2581 100644
--- a/gcc/testsuite/lib/prune.exp
+++ b/gcc/testsuite/lib/prune.exp
@@ -29,6 +29,7 @@  proc prune_gcc_output { text } {
     regsub -all "(^|\n)collect: re(compiling|linking)\[^\n\]*" $text "" text
     regsub -all "(^|\n)Please submit.*instructions\[^\n\]*" $text "" text
     regsub -all "(^|\n)\[0-9\]\[0-9\]* errors\." $text "" text
+    regsub -all "(^|\n)(In file included|\[ \]+from)\[^\n\]*" $text "" text
 
     # Ignore informational notes.
     regsub -all "(^|\n)\[^\n\]*: note: \[^\n\]*" $text "" text
diff --git a/gcc/toplev.c b/gcc/toplev.c
index de0a58a..5f63b69 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1132,6 +1132,9 @@  general_init (const char *argv0)
      can give warnings and errors.  */
   diagnostic_initialize (global_dc, N_OPTS);
   diagnostic_starter (global_dc) = default_tree_diagnostic_starter;
+  /* By default print macro expansion contexts in the diagnostic
+     finalizer -- for tokens resulting from macro macro expansion.  */
+  diagnostic_finalizer (global_dc) = virt_loc_aware_diagnostic_finalizer;
   /* Set a default printer.  Language specific initializations will
      override it later.  */
   pp_format_decoder (global_dc->printer) = &default_tree_printer;
diff --git a/gcc/tree-diagnostic.c b/gcc/tree-diagnostic.c
index b456a2a..c8416c9 100644
--- a/gcc/tree-diagnostic.c
+++ b/gcc/tree-diagnostic.c
@@ -28,6 +28,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "tree-diagnostic.h"
 #include "langhooks.h"
 #include "langhooks-def.h"
+#include "vec.h"
 
 /* Prints out, if necessary, the name of the current function
    that caused an error.  Called from all error and warning functions.  */
@@ -35,7 +36,7 @@  void
 diagnostic_report_current_function (diagnostic_context *context,
 				    diagnostic_info *diagnostic)
 {
-  diagnostic_report_current_module (context);
+  diagnostic_report_current_module (context, diagnostic->location);
   lang_hooks.print_error_function (context, input_filename, diagnostic);
 }
 
@@ -47,3 +48,182 @@  default_tree_diagnostic_starter (diagnostic_context *context,
   pp_set_prefix (context->printer, diagnostic_build_prefix (context,
 							    diagnostic));
 }
+
+/* This is a pair made of a location and the line map it originated
+   from.  It's used in the maybe_unwind_expanded_macro_loc function
+   below.  */
+typedef struct
+{
+  const struct line_map *map;
+  source_location where;
+} loc_t;
+
+DEF_VEC_O (loc_t);
+DEF_VEC_ALLOC_O (loc_t, heap);
+
+/* Unwind the different macro expansions that lead to the token which
+   location is WHERE and emit diagnostics showing the resulting
+   unwound macro expansion trace.  Let's look at an example to see how
+   the trace looks like.  Suppose we have this piece of code,
+   artificially annotated with the line numbers to increase
+   legibility:
+
+    $ cat -n test.c
+      1    #define OPERATE(OPRD1, OPRT, OPRD2) \
+      2      OPRD1 OPRT OPRD2;
+      3
+      4    #define SHIFTL(A,B) \
+      5      OPERATE (A,<<,B)
+      6
+      7    #define MULT(A) \
+      8      SHIFTL (A,1)
+      9
+     10    void
+     11    g ()
+     12    {
+     13      MULT (1.0);// 1.0 << 1; <-- so this is an error.
+     14    }
+
+   Here is the diagnostic that we want the compiler to generate:
+
+    test.c: In function 'g':
+    test.c:5:14: error: invalid operands to binary << (have 'double' and 'int')
+    test.c:2:9: note: in expansion of macro 'OPERATE'
+    test.c:5:3: note: expanded from here
+    test.c:5:14: note: in expansion of macro 'SHIFTL'
+    test.c:8:3: note: expanded from here
+    test.c:8:3: note: in expansion of macro 'MULT2'
+    test.c:13:3: note: expanded from here
+
+   The part that goes from the third to the eighth line of this
+   diagnostic (the lines containing the 'note:' string) is called the
+   unwound macro expansion trace.  That's the part generated by this
+   function.
+
+   If FIRST_EXP_POINT_MAP is non-null, *FIRST_EXP_POINT_MAP is set to
+   the map of the location in the source that first triggered the
+   macro expansion.  This must be an ordinary map.  */
+
+static void
+maybe_unwind_expanded_macro_loc (diagnostic_context *context,
+                                 diagnostic_info *diagnostic,
+                                 source_location where,
+                                 const struct line_map **first_exp_point_map)
+{
+  const struct line_map *map;
+  VEC(loc_t,heap) *loc_vec = NULL;
+  unsigned ix;
+  loc_t loc, *iter;
+
+  map = linemap_lookup (line_table, where);
+  if (!linemap_macro_expansion_map_p (map))
+    return;
+
+  /* Let's unwind the macros that got expanded and led to the token
+     which location is WHERE.  We are going to store these macros into
+     LOC_VEC, so that we can later walk it at our convenience to
+     display a somewhat meaningful trace of the macro expansion
+     history to the user.  Note that the first macro of the trace
+     (which is OPERATE in the example above) is going to be stored at
+     the beginning of LOC_VEC.  */
+
+  do
+    {
+      loc.where = where;
+      loc.map = map;
+
+      VEC_safe_push (loc_t, heap, loc_vec, &loc);
+
+      /* WHERE is the location of a token inside the expansion of a
+         macro.  MAP is the map holding the locations of that macro
+         expansion.  Let's get the location of the token inside the
+         context that triggered the expansion of this macro.
+         This is basically how we go "down" in the trace of macro
+         expansions that led to WHERE.  */
+      where = linemap_step_out_once (line_table, where, &map);
+    } while (linemap_macro_expansion_map_p (map));
+
+  if (first_exp_point_map)
+    *first_exp_point_map = map;
+
+  /* Walk LOC_VEC and print the macro expansion trace, unless the
+     first macro which expansion triggered this trace was expanded
+     inside a system header.  */
+  if (!LINEMAP_SYSP (map))
+    FOR_EACH_VEC_ELT (loc_t, loc_vec, ix, iter)
+      {
+        source_location resolved_def_loc = 0, resolved_exp_loc = 0;
+        diagnostic_t saved_kind;
+        const char *saved_prefix;
+        source_location saved_location;
+
+        /* Okay, now here is what we want.  For each token resulting
+           from macro expansion we want to show: 1/ where in the
+           definition of the macro the token comes from; 2/ where the
+           macro got expanded.  */
+
+        /* Resolve the location iter->where into the locus 1/ of the
+           comment above.  */
+        resolved_def_loc =
+          linemap_resolve_location (line_table, iter->where,
+                                    LRK_MACRO_DEFINITION_LOCATION, NULL);
+
+        /* Resolve the location of the expansion point of the macro
+           which expansion gave the token represented by def_loc.
+           This is the locus 2/ of the earlier comment.  */
+        resolved_exp_loc =
+          linemap_resolve_location (line_table,
+                                    MACRO_MAP_EXPANSION_POINT_LOCATION (iter->map),
+                                    LRK_MACRO_DEFINITION_LOCATION, NULL);
+
+        saved_kind = diagnostic->kind;
+        saved_prefix = context->printer->prefix;
+        saved_location = diagnostic->location;
+
+        diagnostic->kind = DK_NOTE;
+        diagnostic->location = resolved_def_loc;
+        pp_base_set_prefix (context->printer,
+                            diagnostic_build_prefix (context,
+                                                     diagnostic));
+        pp_newline (context->printer);
+        pp_printf (context->printer, "in expansion of macro '%s'",
+                   linemap_map_get_macro_name (iter->map));
+        pp_destroy_prefix (context->printer);
+
+        diagnostic->location = resolved_exp_loc;
+        pp_base_set_prefix (context->printer,
+                            diagnostic_build_prefix (context,
+                                                     diagnostic));
+        pp_newline (context->printer);
+        pp_printf (context->printer, "expanded from here");
+        pp_destroy_prefix (context->printer);
+
+        diagnostic->kind = saved_kind;
+        diagnostic->location = saved_location;
+        context->printer->prefix = saved_prefix;
+      }
+
+  VEC_free (loc_t, heap, loc_vec);
+}
+
+/*  This is a diagnostic finalizer implementation that is aware of
+    virtual locations produced by libcpp.
+
+    It has to be called by the diagnostic finalizer of front ends that
+    uses libcpp and wish to get diagnostics involving tokens resulting
+    from macro expansion.
+
+    For a given location, if said location belongs to a token
+    resulting from a macro expansion, this starter prints the context
+    of the token.  E.g, for multiply nested macro expansion, it
+    unwinds the nested macro expansions and prints them in a manner
+    that is similar to what is done for function call stacks, or
+    template instantiation contexts.  */
+void
+virt_loc_aware_diagnostic_finalizer (diagnostic_context *context,
+				     diagnostic_info *diagnostic)
+{
+  maybe_unwind_expanded_macro_loc (context, diagnostic,
+				   diagnostic->location,
+				   NULL);
+}
diff --git a/gcc/tree-diagnostic.h b/gcc/tree-diagnostic.h
index 7d88089..6b8e8e6 100644
--- a/gcc/tree-diagnostic.h
+++ b/gcc/tree-diagnostic.h
@@ -52,5 +52,6 @@  along with GCC; see the file COPYING3.  If not see
 void default_tree_diagnostic_starter (diagnostic_context *, diagnostic_info *);
 extern void diagnostic_report_current_function (diagnostic_context *,
 						diagnostic_info *);
-
+void virt_loc_aware_diagnostic_finalizer (diagnostic_context *,
+					  diagnostic_info *);
 #endif /* ! GCC_TREE_DIAGNOSTIC_H */
-- 
1.7.6.2

From: Dodji Seketeli <dodji@redhat.com>
Date: Fri, 3 Dec 2010 13:20:26 +0100
Subject: [PATCH 1/7] Linemap infrastructure for virtual locations

This is the first instalment of a set which goal is to track locations
of tokens across macro expansions.  Tom Tromey did the original work
and attached the patch to PR preprocessor/7263.  This opus is a
derivative of that original work.

This patch modifies the linemap module of libcpp to add virtual
locations support.

A virtual location is a mapped location that can resolve to several
different physical locations.  It can always resolve to the spelling
location of a token.  For tokens resulting from macro expansion it can
resolve to:
  - either the location of the expansion point of the macro.
  - or the location of the token in the definition of the
  macro
  - or, if the token is an argument of a function-like macro,
  the location of the use of the matching macro parameter in
  the definition of the macro

The patch creates a new type of line map called a macro map.  For every
single macro expansion, there is a macro map that generates a virtual
location for every single resulting token of the expansion.

The good old type of line map we all know is now called an ordinary
map.  That one still encodes spelling locations as it has always had.

As a result linemap_lookup as been extended to return a macro map when
given a virtual location resulting from a macro expansion.  The layout
of structs line_map has changed to support this new type of map.  So
did the layout of struct line_maps.  Accessor macros have been
introduced to avoid messing with the implementation details of these
datastructures directly.  This helped already as we have been testing
different ways of arranging these datastructure.  Having to constantly
adjust client code that is too tied with the internals of line_map and
line_maps would have been even more painful.

Of course, many new public functions have been added to the linemap
module to handle the resolution of virtual locations.

This patch introduces the infrastructure but no part of the compiler
uses virtual locations yet.

However the client code of the linemap data structures has been
adjusted as per the changes.  E.g, it's not anymore reliable for a
client code to manipulate struct line_map directly if it just wants to
deal with spelling locations, because struct line_map can now
represent a macro map as well.  In that case, it's better to use the
convenient API to resolve the initial (possibly virtual) location to a
spelling location (or to an ordinary map) and use that.

This is the reason why the patch adjusts the Java, Ada and Fortran
front ends.

Also, note that virtual locations are not supposed to be ordered for
relations '<' and '>' anymore.  To test if a virtual location appears
"before" another one, one has to use a new operator exposed by the
line map interface.  The patch updates the only spot (in the
diagnostics module) I have found that was making the assumption that
locations were ordered for these relations.  This is the only change
that introduces a use of the new line map API in this patch, so I am
adding a regression test for it only.

Boostrapped with --enable-languages=all,ada and passed regression
tests on x86_unknown-linux-gnu against trunk.

libcpp/

	* include/line-map.h (enum lc_reason)<LC_ENTER_MACRO>: New enum
	member.
	(MAX_SOURCE_LOCATION): New constant.
	(struct line_map_ordinary, struct line_map_macro): New structs.
	(struct line_map): Turn this into a union of the two above.  Add
	comments.
	(struct maps_info): New struct.
	(struct line_maps)<info_ordinary, info_macro>: Two new fields.
	These now carry the map information that was previously scattered
	in struct line_maps.
	(struct map_info::allocated): Fix comment.
	(MAP_START_LOCATION, ORDINARY_MAP_FILE_NAME)
	(ORDINARY_MAP_STARTING_LINE_NUMBER)
	(ORDINARY_MAP_INCLUDER_FILE_INDEX)
	(ORDINARY_MAP_IN_SYSTEM_HEADER_P)
	(ORDINARY_MAP_NUMBER_OF_COLUMN_BITS, MACRO_MAP_MACRO)
	(MACRO_MAP_NUM_MACRO_TOKENS MACRO_MAP_LOCATIONS)
	(MACRO_MAP_EXPANSION_POINT_LOCATION)
	(LOCATION_POSSIBLY_IN_MACRO_MAP_P, LINEMAPS_MAP_INFO)
	(LINEMAPS_MAPS, LINEMAPS_ALLOCATE, LINEMAPS_USED, LINEMAPS_CACHE)
	(LINEMAPS_LAST_MAP, LINEMAPS_LAST_ALLOCATED_MAP)
	(LINEMAPS_ORDINARY_MAPS, LINEMAPS_ORDINARY_ALLOCATED)
	(LINEMAPS_ORDINARY_USED, LINEMAPS_ORDINARY_CACHE)
	(LINEMAPS_LAST_ORDINARY_MAP, LINEMAPS_LAST_ALLOCATED_ORDINARY_MAP)
	(LINEMAPS_MACRO_MAPS, LINEMAPS_MACRO_ALLOCATED)
	(LINEMAPS_MACRO_USED, LINEMAPS_MACRO_CACHE)
	(LINEMAPS_LAST_MACRO_MAP, LINEMAPS_LAST_ALLOCATED_MACRO_MAP)
	(LINEMAPS_MAP_AT, LINEMAPS_ORDINARY_MAP_AT)
	(LINEMAPS_MACRO_MAP_AT): New accessors for ordinary and macro map
	information.
	(linemap_check_ordinary, linemap_assert): New macros.
	(linemap_position_for_line_and_column)
	(linemap_tracks_macro_expansion_locs_p, linemap_enter_macro)
	(linemap_add_macro_token, linemap_macro_expansion_map_p)
	(linemap_macro_map_loc_to_def_point)
	(linemap_macro_map_loc_unwind_once)
	(linemap_macro_map_loc_to_exp_point, linemap_step_out_once)
	(linemap_get_source_line linemap_get_source_column)
	(linemap_map_get_macro_name, linemap_get_file_path)
	(linemap_location_in_system_header_p)
	(linemap_location_from_macro_expansion_p): Declare new functions.
	(SOURCE_LINE, SOURCE_COLUMN, LAST_SOURCE_LINE_LOCATION)
	(LINEMAP_FILE, LINEMAP_LINE, LINEMAP_SYSP): Assert that this
	accessors act on ordinary maps only.
	(INCLUDED_FROM): Return NULL for main files; use the new
	accessors.
	(LINEMAP_POSITION_FOR_COLUMN): Use the new accessors.
	(struct expanded_location): Move here from gcc/input.h
	(linemap_resolve_location, linemap_expand_location)
	(linemap_expand_location_full): Declare new functions.
	* line-map.c: Include cpplib.h
	(linemap_assert): New macro.
	(linemap_macro_loc_to_exp_point, linemap_macro_loc_to_exp_point)
	(linemap_macro_loc_unwind): New static functions.
	(new_linemap): Define new static functions.  Extracted and
	enhanced from ...
	(linemap_add): ... here.  Use linemap_assert in lieu of abort
	previously.
	(linemap_tracks_macro_expansion_locs_p, linemap_enter_macro)
	(linemap_add_macro_token, linemap_macro_expansion_map_p)
	(linemap_check_ordinary, linemap_macro_map_loc_to_exp_point)
	(linemap_macro_map_loc_to_def_point, linemap_macro_map_loc_unwind_once)
	(linemap_step_out_once, linemap_map_get_index)
	(linemap_get_source_line,linemap_get_source_column)
	(linemap_get_file_path, linemap_map_get_macro_name)
	(linemap_location_in_system_header_p)
	(linemap_location_originated_from_system_header_p)
	(linemap_location_from_macro_expansion_p)
	(linemap_tracks_macro_expansion_locs_p)
	(linemap_resolve_location, linemap_expand_location)
	(linemap_expand_location_full)
	(linemap_tracks_macro_expansion_locs_p)
	(linemap_position_for_line_and_column, linemap_location_before_p):
	Define new public functions.
	(linemap_init): Initialize ordinary and macro maps information in
	the map set.
	(linemap_check_files_exited): Use the new accessors.
	(linemap_free): Remove this dead code.
	(linemap_line_start): Assert this uses an ordinary map.  Adjust to
	use the new ordinary map accessors and data structures.  Don't
	overflow past the lowest possible macro token's location.
	(linemap_position_for_column): Assert the ordinary maps of the map
	set are really ordinary.  Use ordinary map accessors.
	(linemap_lookup): Keep the same logic but generalize to allow
	lookup of both ordinary and macro maps.  Do not crash when called
	with an empty line table.
	* directives-only.c (_cpp_preprocess_dir_only): Adjust to use the
	new API of line-map.h.
	* directives.c (start_directive, do_line, do_linemarker)
	(do_linemarker): Likewise.
	* files.c (_cpp_find_file, _cpp_stack_include, open_file_failed)
	(make_cpp_dir, cpp_make_system_header): Likewise.
	* init.c (cpp_read_main_file): Likewise.
	* internal.h (CPP_INCREMENT_LINE): Likewise.
	* lex.c (_cpp_process_line_notes, _cpp_skip_block_comment)
	(skip_line_comment, skip_whitespace, lex_raw_string)
	(_cpp_lex_direct): Likewise.
	* macro.c (_cpp_builtin_macro_text): Likewise.
	(_cpp_aligned_alloc): Initialize the new name member of the macro.
	* traditional.c (copy_comment, _cpp_scan_out_logical_line):
	Likewise.
	* errors.c (cpp_diagnostic): Adjust to new linemap API.

gcc/
	* input.h (struct expanded_location): Move to libcpp/line-map.h.
	(LOCATION_COLUMN): New accessor
	(in_system_header_at): Use linemap_location_in_system_header_p.
	* diagnostic.c (diagnostic_report_current_module): Adjust to avoid
	touching the internals of struct line_map.  Use the public API.
	instead.
	(diagnostic_report_diagnostic): Don't use relational operator '<'
	on virtual locations.  Use linemap_location_before_p instead.
	* input.c (expand_location): Adjust to expand to the tokens'
	spelling location when macro location tracking is on.

gcc/c-family

	* c-ppoutput.c (scan_translation_unit, maybe_print_line)
	(print_line, cb_define, do_line_change): Adjust to avoid touching
	the internals of struct line_map.  Use the public API instead.
	* c-pch.c (c_common_read_pch): Likewise.
	* c-lex.c (fe_file_change): Likewise.

gcc/java/

	* jcf-parse.c (set_source_filename): Adjust to the new map API.

gcc/ada/

	* gcc-interface/trans.c (gigi, Sloc_to_locus): Adjust to use the
	new public ordinary map interface.

gcc/fortran/

	* cpp.c (print_line, cb_define): Adjust to avoid using internals
	of struct line_map.  Use the public API instead.

gcc/testsuite/

	* gcc.dg/cpp/pragma-diagnostic-1.c: New test.
---
 gcc/ada/gcc-interface/trans.c                  |   10 +-
 gcc/c-family/c-lex.c                           |    6 +-
 gcc/c-family/c-ppoutput.c                      |   43 +-
 gcc/diagnostic.c                               |   11 +-
 gcc/fortran/cpp.c                              |   22 +-
 gcc/input.c                                    |    9 +-
 gcc/input.h                                    |   18 +-
 gcc/java/jcf-parse.c                           |    2 +-
 gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-1.c |   32 +
 libcpp/directives.c                            |   16 +-
 libcpp/files.c                                 |    5 +-
 libcpp/include/line-map.h                      |  698 +++++++++++++++++-
 libcpp/init.c                                  |    4 +-
 libcpp/internal.h                              |    3 +-
 libcpp/line-map.c                              |  893 +++++++++++++++++++++--
 libcpp/macro.c                                 |   12 +-
 16 files changed, 1583 insertions(+), 201 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-1.c

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index 27e2402..252a360 100644
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -278,7 +278,7 @@  gigi (Node_Id gnat_root, int max_gnat_node, int number_name ATTRIBUTE_UNUSED,
 	     (Get_Name_String (file_info_ptr[i].File_Name))));
 
       /* We rely on the order isomorphism between files and line maps.  */
-      gcc_assert ((int) line_table->used == i);
+      gcc_assert ((int) LINEMAPS_ORDINARY_USED (line_table) == i);
 
       /* We create the line map for a source file at once, with a fixed number
 	 of columns chosen to avoid jumping over the next power of 2.  */
@@ -7881,12 +7881,10 @@  Sloc_to_locus (Source_Ptr Sloc, location_t *locus)
       Source_File_Index file = Get_Source_File_Index (Sloc);
       Logical_Line_Number line = Get_Logical_Line_Number (Sloc);
       Column_Number column = Get_Column_Number (Sloc);
-      struct line_map *map = &line_table->maps[file - 1];
+      struct line_map *map = LINEMAPS_ORDINARY_MAP_AT (line_table, file - 1);
 
-      /* Translate the location according to the line-map.h formula.  */
-      *locus = map->start_location
-		+ ((line - map->to_line) << map->column_bits)
-		+ (column & ((1 << map->column_bits) - 1));
+      /* Translate the location.  */
+      *locus = linemap_position_for_line_and_column (map, line, column);
     }
 
   ref_filename
diff --git a/gcc/c-family/c-lex.c b/gcc/c-family/c-lex.c
index e60dcc5..be83b61 100644
--- a/gcc/c-family/c-lex.c
+++ b/gcc/c-family/c-lex.c
@@ -207,7 +207,7 @@  fe_file_change (const struct line_map *new_map)
 	    line = SOURCE_LINE (new_map - 1, included_at);
 
 	  input_location = new_map->start_location;
-	  (*debug_hooks->start_source_file) (line, new_map->to_file);
+	  (*debug_hooks->start_source_file) (line, LINEMAP_FILE (new_map));
 #ifndef NO_IMPLICIT_EXTERN_C
 	  if (c_header_level)
 	    ++c_header_level;
@@ -231,10 +231,10 @@  fe_file_change (const struct line_map *new_map)
 #endif
       input_location = new_map->start_location;
 
-      (*debug_hooks->end_source_file) (new_map->to_line);
+      (*debug_hooks->end_source_file) (LINEMAP_LINE (new_map));
     }
 
-  update_header_times (new_map->to_file);
+  update_header_times (LINEMAP_FILE (new_map));
   input_location = new_map->start_location;
 }
 
diff --git a/gcc/c-family/c-ppoutput.c b/gcc/c-family/c-ppoutput.c
index 16d4f7d..892f1ea 100644
--- a/gcc/c-family/c-ppoutput.c
+++ b/gcc/c-family/c-ppoutput.c
@@ -190,9 +190,7 @@  scan_translation_unit (cpp_reader *pfile)
       /* Subtle logic to output a space if and only if necessary.  */
       if (avoid_paste)
 	{
-	  const struct line_map *map
-	    = linemap_lookup (line_table, loc);
-	  int src_line = SOURCE_LINE (map, loc);
+	  int src_line = LOCATION_LINE (loc);
 
 	  if (print.source == NULL)
 	    print.source = token;
@@ -212,9 +210,7 @@  scan_translation_unit (cpp_reader *pfile)
 	}
       else if (token->flags & PREV_WHITE)
 	{
-	  const struct line_map *map
-	    = linemap_lookup (line_table, loc);
-	  int src_line = SOURCE_LINE (map, loc);
+	  int src_line = LOCATION_LINE (loc);
 
 	  if (src_line != print.src_line
 	      && do_line_adjustments
@@ -304,8 +300,9 @@  scan_translation_unit_trad (cpp_reader *pfile)
 static void
 maybe_print_line (source_location src_loc)
 {
-  const struct line_map *map = linemap_lookup (line_table, src_loc);
-  int src_line = SOURCE_LINE (map, src_loc);
+  int src_line = LOCATION_LINE (src_loc);
+  const char *src_file = LOCATION_FILE (src_loc);
+
   /* End the previous line of text.  */
   if (print.printed)
     {
@@ -317,7 +314,7 @@  maybe_print_line (source_location src_loc)
   if (!flag_no_line_commands
       && src_line >= print.src_line
       && src_line < print.src_line + 8
-      && strcmp (map->to_file, print.src_file) == 0)
+      && strcmp (src_file, print.src_file) == 0)
     {
       while (src_line > print.src_line)
 	{
@@ -341,28 +338,30 @@  print_line (source_location src_loc, const char *special_flags)
 
   if (!flag_no_line_commands)
     {
-      const struct line_map *map = linemap_lookup (line_table, src_loc);
-
-      size_t to_file_len = strlen (map->to_file);
+      const char *file_path = LOCATION_FILE (src_loc);
+      int sysp;
+      size_t to_file_len = strlen (file_path);
       unsigned char *to_file_quoted =
          (unsigned char *) alloca (to_file_len * 4 + 1);
       unsigned char *p;
 
-      print.src_line = SOURCE_LINE (map, src_loc);
-      print.src_file = map->to_file;
+      print.src_line = LOCATION_LINE (src_loc);
+      print.src_file = file_path;
 
       /* cpp_quote_string does not nul-terminate, so we have to do it
 	 ourselves.  */
       p = cpp_quote_string (to_file_quoted,
-			    (const unsigned char *) map->to_file, to_file_len);
+			    (const unsigned char *) file_path,
+			    to_file_len);
       *p = '\0';
       fprintf (print.outf, "# %u \"%s\"%s",
 	       print.src_line == 0 ? 1 : print.src_line,
 	       to_file_quoted, special_flags);
 
-      if (map->sysp == 2)
+      sysp = in_system_header_at (src_loc);
+      if (sysp == 2)
 	fputs (" 3 4", print.outf);
-      else if (map->sysp == 1)
+      else if (sysp == 1)
 	fputs (" 3", print.outf);
 
       putc ('\n', print.outf);
@@ -391,8 +390,7 @@  do_line_change (cpp_reader *pfile, const cpp_token *token,
      ought to care.  Some things do care; the fault lies with them.  */
   if (!CPP_OPTION (pfile, traditional))
     {
-      const struct line_map *map = linemap_lookup (line_table, src_loc);
-      int spaces = SOURCE_COLUMN (map, src_loc) - 2;
+      int spaces = LOCATION_COLUMN (src_loc) - 2;
       print.printed = 1;
 
       while (-- spaces >= 0)
@@ -421,6 +419,8 @@  cb_ident (cpp_reader *pfile ATTRIBUTE_UNUSED, source_location line,
 static void
 cb_define (cpp_reader *pfile, source_location line, cpp_hashnode *node)
 {
+  const struct line_map *map;
+
   maybe_print_line (line);
   fputs ("#define ", print.outf);
 
@@ -432,7 +432,10 @@  cb_define (cpp_reader *pfile, source_location line, cpp_hashnode *node)
     fputs ((const char *) NODE_NAME (node), print.outf);
 
   putc ('\n', print.outf);
-  if (linemap_lookup (line_table, line)->to_line != 0)
+  linemap_resolve_location (line_table, line,
+			    LRK_MACRO_DEFINITION_LOCATION,
+			    &map);
+  if (LINEMAP_LINE (map) != 0)
     print.src_line++;
 }
 
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index d297cdd..b46eb35 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -278,18 +278,18 @@  diagnostic_report_current_module (diagnostic_context *context)
 	  if (context->show_column)
 	    pp_verbatim (context->printer,
 			 "In file included from %s:%d:%d",
-			 map->to_file,
+			 LINEMAP_FILE (map),
 			 LAST_SOURCE_LINE (map), LAST_SOURCE_COLUMN (map));
 	  else
 	    pp_verbatim (context->printer,
 			 "In file included from %s:%d",
-			 map->to_file, LAST_SOURCE_LINE (map));
+			 LINEMAP_FILE (map), LAST_SOURCE_LINE (map));
 	  while (! MAIN_FILE_P (map))
 	    {
 	      map = INCLUDED_FROM (line_table, map);
 	      pp_verbatim (context->printer,
 			   ",\n                 from %s:%d",
-			   map->to_file, LAST_SOURCE_LINE (map));
+			   LINEMAP_FILE (map), LAST_SOURCE_LINE (map));
 	    }
 	  pp_verbatim (context->printer, ":");
 	  pp_newline (context->printer);
@@ -459,7 +459,10 @@  diagnostic_report_diagnostic (diagnostic_context *context,
 	  /* FIXME: Stupid search.  Optimize later. */
 	  for (i = context->n_classification_history - 1; i >= 0; i --)
 	    {
-	      if (context->classification_history[i].location <= location)
+	      if (linemap_location_before_p
+		  (line_table,
+		   context->classification_history[i].location,
+		   location))
 		{
 		  if (context->classification_history[i].kind == (int) DK_POP)
 		    {
diff --git a/gcc/fortran/cpp.c b/gcc/fortran/cpp.c
index 9368d89..2f18893 100644
--- a/gcc/fortran/cpp.c
+++ b/gcc/fortran/cpp.c
@@ -818,27 +818,29 @@  print_line (source_location src_loc, const char *special_flags)
 
   if (!gfc_cpp_option.no_line_commands)
     {
-      const struct line_map *map = linemap_lookup (line_table, src_loc);
-
-      size_t to_file_len = strlen (map->to_file);
-      unsigned char *to_file_quoted =
-         (unsigned char *) alloca (to_file_len * 4 + 1);
+      expanded_location loc;
+      size_t to_file_len;
+      unsigned char *to_file_quoted;
       unsigned char *p;
 
-      print.src_line = SOURCE_LINE (map, src_loc);
+      loc = expand_location (src_loc);
+      to_file_len = strlen (loc.file);
+      to_file_quoted = (unsigned char *) alloca (to_file_len * 4 + 1);
+
+      print.src_line = loc.line;
 
       /* cpp_quote_string does not nul-terminate, so we have to do it
 	 ourselves.  */
       p = cpp_quote_string (to_file_quoted,
-			    (const unsigned char *) map->to_file, to_file_len);
+			    (const unsigned char *) loc.file, to_file_len);
       *p = '\0';
       fprintf (print.outf, "# %u \"%s\"%s",
 	       print.src_line == 0 ? 1 : print.src_line,
 	       to_file_quoted, special_flags);
 
-      if (map->sysp == 2)
+      if (loc.sysp == 2)
 	fputs (" 3 4", print.outf);
-      else if (map->sysp == 1)
+      else if (loc.sysp == 1)
 	fputs (" 3", print.outf);
 
       putc ('\n', print.outf);
@@ -935,7 +937,7 @@  cb_define (cpp_reader *pfile ATTRIBUTE_UNUSED, source_location line,
     fputs ((const char *) NODE_NAME (node), print.outf);
 
   putc ('\n', print.outf);
-  if (linemap_lookup (line_table, line)->to_line != 0)
+  if (LOCATION_LINE (line) != 0)
     print.src_line++;
 }
 
diff --git a/gcc/input.c b/gcc/input.c
index e5e051f..83344d7 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -42,12 +42,7 @@  expand_location (source_location loc)
       xloc.sysp = 0;
     }
   else
-    {
-      const struct line_map *map = linemap_lookup (line_table, loc);
-      xloc.file = map->to_file;
-      xloc.line = SOURCE_LINE (map, loc);
-      xloc.column = SOURCE_COLUMN (map, loc);
-      xloc.sysp = map->sysp != 0;
-    };
+    xloc = linemap_expand_location_full (line_table, loc,
+					 LRK_SPELLING_LOCATION);
   return xloc;
 }
diff --git a/gcc/input.h b/gcc/input.h
index 5929064..9fc55f3 100644
--- a/gcc/input.h
+++ b/gcc/input.h
@@ -37,20 +37,6 @@  extern GTY(()) struct line_maps *line_table;
 extern char builtins_location_check[(BUILTINS_LOCATION
 				     < RESERVED_LOCATION_COUNT) ? 1 : -1];
 
-typedef struct
-{
-  /* The name of the source file involved.  */
-  const char *file;
-
-  /* The line-location in the source file.  */
-  int line;
-
-  int column;
-
-  /* In a system header?. */
-  bool sysp;
-} expanded_location;
-
 extern expanded_location expand_location (source_location);
 
 /* Historically GCC used location_t, while cpp used source_location.
@@ -61,10 +47,12 @@  extern location_t input_location;
 
 #define LOCATION_FILE(LOC) ((expand_location (LOC)).file)
 #define LOCATION_LINE(LOC) ((expand_location (LOC)).line)
+#define LOCATION_COLUMN(LOC)((expand_location (LOC)).column)
 
 #define input_line LOCATION_LINE (input_location)
 #define input_filename LOCATION_FILE (input_location)
-#define in_system_header_at(LOC) ((expand_location (LOC)).sysp != 0)
+#define in_system_header_at(LOC) \
+  ((linemap_location_in_system_header_p (line_table, LOC)))
 #define in_system_header (in_system_header_at (input_location))
 
 #endif
diff --git a/gcc/java/jcf-parse.c b/gcc/java/jcf-parse.c
index 37cea28..04c04f5 100644
--- a/gcc/java/jcf-parse.c
+++ b/gcc/java/jcf-parse.c
@@ -355,7 +355,7 @@  set_source_filename (JCF *jcf, int index)
     }
       
   sfname = find_sourcefile (sfname);
-  line_table->maps[line_table->used-1].to_file = sfname;
+  ORDINARY_MAP_FILE_NAME (LINEMAPS_LAST_ORDINARY_MAP (line_table)) = sfname;
   if (current_class == main_class) main_input_filename = sfname;
 }
 
diff --git a/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-1.c b/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-1.c
new file mode 100644
index 0000000..3a2f9da
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pragma-diagnostic-1.c
@@ -0,0 +1,32 @@ 
+/*
+  { dg-options "-Wuninitialized" }
+  { dg-do compile }
+*/
+
+void f (unsigned);
+
+#define CODE_WITH_WARNING \
+  int a;		  \
+  f (a)
+
+#pragma GCC diagnostic ignored "-Wuninitialized"
+
+void
+g (void)
+{
+  CODE_WITH_WARNING;
+}
+
+#pragma GCC diagnostic push
+
+#pragma GCC diagnostic error "-Wuninitialized"
+
+void
+h (void)
+{
+  CODE_WITH_WARNING;		/* { dg-error "uninitialized" } */
+}
+
+/*
+  { dg-message "some warnings being treated as errors" "" {target *-*-*} 0 }
+*/
diff --git a/libcpp/directives.c b/libcpp/directives.c
index 83d4a0e..a62ddeb 100644
--- a/libcpp/directives.c
+++ b/libcpp/directives.c
@@ -884,14 +884,14 @@  static void
 do_line (cpp_reader *pfile)
 {
   const struct line_maps *line_table = pfile->line_table;
-  const struct line_map *map = &line_table->maps[line_table->used - 1];
+  const struct line_map *map = LINEMAPS_LAST_ORDINARY_MAP (line_table);
 
   /* skip_rest_of_line() may cause line table to be realloc()ed so note down
      sysp right now.  */
 
-  unsigned char map_sysp = map->sysp;
+  unsigned char map_sysp = ORDINARY_MAP_IN_SYSTEM_HEADER_P (map);
   const cpp_token *token;
-  const char *new_file = map->to_file;
+  const char *new_file = ORDINARY_MAP_FILE_NAME (map);
   linenum_type new_lineno;
 
   /* C99 raised the minimum limit on #line numbers.  */
@@ -946,11 +946,11 @@  static void
 do_linemarker (cpp_reader *pfile)
 {
   const struct line_maps *line_table = pfile->line_table;
-  const struct line_map *map = &line_table->maps[line_table->used - 1];
+  const struct line_map *map = LINEMAPS_LAST_ORDINARY_MAP (line_table);
   const cpp_token *token;
-  const char *new_file = map->to_file;
+  const char *new_file = ORDINARY_MAP_FILE_NAME (map);
   linenum_type new_lineno;
-  unsigned int new_sysp = map->sysp;
+  unsigned int new_sysp = ORDINARY_MAP_IN_SYSTEM_HEADER_P (map);
   enum lc_reason reason = LC_RENAME_VERBATIM;
   int flag;
   bool wrapped;
@@ -1038,7 +1038,9 @@  _cpp_do_file_change (cpp_reader *pfile, enum lc_reason reason,
   const struct line_map *map = linemap_add (pfile->line_table, reason, sysp,
 					    to_file, file_line);
   if (map != NULL)
-    linemap_line_start (pfile->line_table, map->to_line, 127);
+    linemap_line_start (pfile->line_table,
+			ORDINARY_MAP_STARTING_LINE_NUMBER (map),
+			127);
 
   if (pfile->cb.file_change)
     pfile->cb.file_change (pfile, map);
diff --git a/libcpp/files.c b/libcpp/files.c
index d2c6b8b..fad8b75 100644
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -1220,13 +1220,12 @@  cpp_make_system_header (cpp_reader *pfile, int syshdr, int externc)
 {
   int flags = 0;
   const struct line_maps *line_table = pfile->line_table;
-  const struct line_map *map = &line_table->maps[line_table->used-1];
-
+  const struct line_map *map = LINEMAPS_LAST_ORDINARY_MAP (line_table);
   /* 1 = system header, 2 = system header to be treated as C.  */
   if (syshdr)
     flags = 1 + (externc != 0);
   pfile->buffer->sysp = flags;
-  _cpp_do_file_change (pfile, LC_RENAME, map->to_file,
+  _cpp_do_file_change (pfile, LC_RENAME, ORDINARY_MAP_FILE_NAME (map),
 		       SOURCE_LINE (map, pfile->line_table->highest_line), flags);
 }
 
diff --git a/libcpp/include/line-map.h b/libcpp/include/line-map.h
index 3c84035..460ffa7 100644
--- a/libcpp/include/line-map.h
+++ b/libcpp/include/line-map.h
@@ -27,13 +27,22 @@  along with this program; see the file COPYING3.  If not see
 #define GTY(x) /* nothing */
 #endif
 
-/* Reason for adding a line change with add_line_map ().  LC_ENTER is
+/* Reason for creating a new line map with linemap_add.  LC_ENTER is
    when including a new file, e.g. a #include directive in C.
    LC_LEAVE is when reaching a file's end.  LC_RENAME is when a file
    name or line number changes for neither of the above reasons
    (e.g. a #line directive in C); LC_RENAME_VERBATIM is like LC_RENAME
-   but a filename of "" is not specially interpreted as standard input.  */
-enum lc_reason {LC_ENTER = 0, LC_LEAVE, LC_RENAME, LC_RENAME_VERBATIM};
+   but a filename of "" is not specially interpreted as standard
+   input. LC_ENTER_MACRO is when a macro expansion is about to start.  */
+enum lc_reason
+{
+  LC_ENTER = 0,
+  LC_LEAVE,
+  LC_RENAME,
+  LC_RENAME_VERBATIM,
+  LC_ENTER_MACRO
+  /* FIXME: add support for stringize and paste.  */
+};
 
 /* The type of line numbers.  */
 typedef unsigned int linenum_type;
@@ -44,37 +53,230 @@  typedef unsigned int source_location;
 /* Memory allocation function typedef.  Works like xrealloc.  */
 typedef void *(*line_map_realloc) (void *, size_t);
 
-/* Physical source file TO_FILE at line TO_LINE at column 0 is represented
+/* An ordinary line map encodes physical source locations. Those
+   physical source locations are called "spelling locations".
+   
+   Physical source file TO_FILE at line TO_LINE at column 0 is represented
    by the logical START_LOCATION.  TO_LINE+L at column C is represented by
    START_LOCATION+(L*(1<<column_bits))+C, as long as C<(1<<column_bits),
    and the result_location is less than the next line_map's start_location.
    (The top line is line 1 and the leftmost column is column 1; line/column 0
    means "entire file/line" or "unknown line/column" or "not applicable".)
-   INCLUDED_FROM is an index into the set that gives the line mapping
-   at whose end the current one was included.  File(s) at the bottom
-   of the include stack have this set to -1.  REASON is the reason for
-   creation of this line map, SYSP is one for a system header, two for
-   a C system header file that therefore needs to be extern "C"
-   protected in C++, and zero otherwise.  */
-struct GTY(()) line_map {
+
+   The highest possible source location is MAX_SOURCE_LOCATION.  */
+struct GTY(()) line_map_ordinary {
   const char *to_file;
   linenum_type to_line;
-  source_location start_location;
+
+  /* An index into the set that gives the line mapping at whose end
+     the current one was included.  File(s) at the bottom of the
+     include stack have this set to -1.  */
   int included_from;
-  ENUM_BITFIELD (lc_reason) reason : CHAR_BIT;
-  /* The sysp field isn't really needed now that it's in cpp_buffer.  */
+
+  /* SYSP is one for a system header, two for a C system header file
+     that therefore needs to be extern "C" protected in C++, and zero
+     otherwise.  This field isn't really needed now that it's in
+     cpp_buffer.  */
   unsigned char sysp;
+
   /* Number of the low-order source_location bits used for a column number.  */
   unsigned int column_bits : 8;
 };
 
-/* A set of chronological line_map structures.  */
-struct GTY(()) line_maps {
+/* This is the highest possible source location encoded within an
+   ordinary or macro map.  */
+#define MAX_SOURCE_LOCATION 0xFFFFFFFF
+
+struct cpp_hashnode;
+
+/* A macro line map encodes locations coming from a macro expansion.
+   
+   Please note that this struct line_map_macro is a field of struct
+   line_map below, go read the comments of struct line_map below and
+   then come back here.
+   
+   The offset from START_LOCATION is used to index into
+   MACRO_LOCATIONS; this holds the original location of the token.  */
+struct GTY(()) line_map_macro {
+  /* The cpp macro which expansion gave birth to this macro map.  */
+  struct cpp_hashnode * GTY ((nested_ptr (union tree_node,
+				   "%h ? CPP_HASHNODE (GCC_IDENT_TO_HT_IDENT (%h)) : NULL",
+				   "%h ? HT_IDENT_TO_GCC_IDENT (HT_NODE (%h)) : NULL")))
+    macro;
+
+  /* The number of tokens inside the replacement-list of MACRO.  */
+  unsigned int n_tokens;
+
+  /* This array of location is actually an array of pairs of
+     locations. The elements inside it thus look like:
+
+           x0,y0, x1,y1, x2,y2, ...., xn,yn.
+
+     where n == n_tokens;
+
+     Remember we are at the expansion point of MACRO.  Each xI is the
+     location of the Ith token of the replacement-list. Now it gets
+     confusing. the xI is the location of the Ith token of the
+     replacement-list at the macro *definition* point. Not at the
+     macro replacement point. Okay, let's try to explain this below.
+
+     Imagine this:
+
+        #define OPERATION(OP0, OPERATOR, OP1) \
+                OP0 OPERATOR OP1 <-- #0
+
+	#define PLUS(A, B) OPERATION (A, +, B)  <--- #1
+
+	int a = PLUS (1,2); <--- #2
+     
+     In #2, there is a macro map for the expansion of PLUS. PLUS is
+     expanded into the replacement-list made of the tokens:
+     
+        OPERATION, (, A, +, B, )
+
+     and then further expanded into the tokens:
+
+        1, +, 2.
+
+     Let's consider the case of token "+" here. That will help us
+     understand what the xI we were talking about earlier means.
+
+     The token '+' has two locations, so to speak. One in the context
+     of the macro *expansion* of PLUS in #2 and one in the context of
+     the macro *definition* of PLUS in #1. These two locations are
+     encoded in the the latter context, somehow in the xI we are
+     talking about.
+
+     xI is roughly the index of the token inside the replacement-list
+     at the expansion point. So for '+', its index would then be 1
+     [The index of token '1' would be 0 and the index of token 2 would
+     be 1]. So if '+' is our current xI, it is actualy an x1.
+
+     The value of x1 is the location of the token '+' inside the
+     replacement-list of PLUS at the definition point of PLUS. It is
+     its spelling location in #1.
+
+     So x0 would have described the token '1', x1 describes the token
+     '+' and x2 describes the token '2'.
+
+     Now what's the y1 then? Remember, we said macro_locations is an
+     array of pairs (xI,yI). We now know what the xI is, now let's
+     look at the yI.
+
+     Let's look at the token '+' again. We said it has two locations
+     somehow. Actually it has 3. Kind of. As '+' is an argument passed
+     to the macro OPERATION [at the definition point of the macro
+     PLUS], it would be nice to record the source location of the
+     *parameter* of OPERATION that is replaced by the argument '+'.
+     In other words, we want to record the location of the token
+     "OPERATOR" in the replacement-list of OPERATION, at the
+     /definition/ point of OPERATION in #0. And that is y1.
+
+     So when (xI,yI) describes a token that is passed as an argument
+     to a macro M, the yI is the location of the macro parameter that
+     the argument replaces, at the definition point of M. If (xI,yI)
+     does not describe a token that is passed as an argument to a
+     macro, xI == yI.  */
+  source_location * GTY((length ("2 * %h.n_tokens"))) macro_locations;
+
+  /* This is the location of the expansion point of the current macro
+     map.  That expansion point location is held by the map that was
+     current right before the current one. It could have been either
+     a macro or an ordinary map, depending on if we are in a
+     nested expansion context not.  */
+  source_location expansion;
+};
+
+/* A line_map encodes a sequence of locations.
+   There are two kinds of maps. Ordinary maps and macro expansion
+   maps, a.k.a macro maps.
+
+   A macro map encodes source locations of tokens that are part of a
+   macro replacement-list, at a macro expansion point. E.g, in:
+
+            #define PLUS(A,B) A + B
+
+   No macro map is going to be created there, because we are not at a
+   macro expansion point. We are at a macro /definition/ point. So the
+   locations of the tokens of the macro replacement-list (i.e, A + B)
+   will be locations in an ordinary map, not a macro map.
+
+   On the other hand, if we later do:
+
+        int a = PLUS (1,2);
+
+   The invocation of PLUS here is a macro expansion. So we are at a
+   macro expansion point. The preprocessor expands PLUS (1,2) and
+   replaces it with the tokens of its replacement-list: 1 + 2. A macro
+   map is going to be created to hold (or rather to map, haha ...) the
+   locations of the tokens 1, + and 2. The macro map also records the
+   location of the expansion point of PLUS. That location is mapped in
+   the map that is active right before the location of the invocation
+   of PLUS.  */
+struct GTY(()) line_map {
+  source_location start_location;
+
+  /* The reason for creation of this line map.  */
+  ENUM_BITFIELD (lc_reason) reason : CHAR_BIT;
+
+  union map_u {
+    struct line_map_ordinary GTY((tag ("0"))) ordinary;
+    struct line_map_macro GTY((tag ("1"))) macro;
+  } GTY((desc ("%1.reason == LC_ENTER_MACRO"))) d;
+};
+
+#define MAP_START_LOCATION(MAP) (MAP)->start_location
+
+#define ORDINARY_MAP_FILE_NAME(MAP) \
+  linemap_check_ordinary (MAP)->d.ordinary.to_file
+
+#define ORDINARY_MAP_STARTING_LINE_NUMBER(MAP) \
+  linemap_check_ordinary (MAP)->d.ordinary.to_line
+
+#define ORDINARY_MAP_INCLUDER_FILE_INDEX(MAP) \
+  linemap_check_ordinary (MAP)->d.ordinary.included_from
+
+#define ORDINARY_MAP_IN_SYSTEM_HEADER_P(MAP) \
+  linemap_check_ordinary (MAP)->d.ordinary.sysp
+
+#define ORDINARY_MAP_NUMBER_OF_COLUMN_BITS(MAP) \
+  linemap_check_ordinary (MAP)->d.ordinary.column_bits
+
+#define MACRO_MAP_MACRO(MAP) (MAP)->d.macro.macro
+
+#define MACRO_MAP_NUM_MACRO_TOKENS(MAP) (MAP)->d.macro.n_tokens
+
+#define MACRO_MAP_LOCATIONS(MAP) (MAP)->d.macro.macro_locations
+
+#define MACRO_MAP_EXPANSION_POINT_LOCATION(MAP) (MAP)->d.macro.expansion
+
+/* The abstraction of a set of location maps. There can be several
+   types of location maps. This abstraction contains the attributes
+   that are independent from the type of the map.  */
+struct GTY(()) maps_info {
+  /* This array contains the different line maps.
+     A line map is created for the following events:
+       - when a new preprocessing unit start. 
+       - when a preprocessing unit ends.
+       - when a macro expansion occurs.  */
   struct line_map * GTY ((length ("%h.used"))) maps;
+
+  /* The total number of allocated maps.  */
   unsigned int allocated;
+
+  /* The number of elements used in maps. This number is smaller
+     or equal to ALLOCATED.  */
   unsigned int used;
 
   unsigned int cache;
+};
+
+/* A set of chronological line_map structures.  */
+struct GTY(()) line_maps {
+  
+  struct maps_info info_ordinary;
+
+  struct maps_info info_macro;
 
   /* Depth of the include stack, including the current file.  */
   unsigned int depth;
@@ -97,12 +299,126 @@  struct GTY(()) line_maps {
   line_map_realloc reallocator;
 };
 
+/* Returns the pointer to the memory region where information about
+   maps are stored in the line table SET. MACRO_MAP_P is a flag
+   telling if we want macro or ordinary maps.  */
+#define LINEMAPS_MAP_INFO(SET, MACRO_MAP_P)				\
+  ((MACRO_MAP_P)							\
+   ? &((SET)->info_macro)						\
+   : &((SET)->info_ordinary))
+
+/* Returns the pointer to the memory region where maps are stored in
+   the line table SET. MAP_KIND shall be TRUE if we are interested in
+   macro maps false otherwise.  */
+#define LINEMAPS_MAPS(SET, MAP_KIND) \
+  (LINEMAPS_MAP_INFO (SET, MAP_KIND))->maps
+
+/* Returns the number of allocated maps so far. MAP_KIND shall be TRUE
+   if we are interested in macro maps, FALSE otherwise.  */
+#define LINEMAPS_ALLOCATED(SET, MAP_KIND) \
+  (LINEMAPS_MAP_INFO (SET, MAP_KIND))->allocated
+
+/* Returns the number of used maps so far. MAP_KIND shall be TRUE if
+   we are interested in macro maps, FALSE otherwise.*/
+#define LINEMAPS_USED(SET, MAP_KIND) \
+  (LINEMAPS_MAP_INFO (SET, MAP_KIND))->used
+
+/* Returns the index of the last map that was looked up with
+   linemap_lookup. MAP_KIND shall be TRUE if we are interested in
+   macro maps, FALSE otherwise.  */
+#define LINEMAPS_CACHE(SET, MAP_KIND) \
+  (LINEMAPS_MAP_INFO (SET, MAP_KIND))->cache
+
+/* Return the map at a given index.  */
+#define LINEMAPS_MAP_AT(SET, MAP_KIND, INDEX)	\
+  (&((LINEMAPS_MAPS (SET, MAP_KIND))[(INDEX)]))
+
+/* Returns the last map used in the line table SET. MAP_KIND
+   shall be TRUE if we are interested in macro maps, FALSE
+   otherwise.*/
+#define LINEMAPS_LAST_MAP(SET, MAP_KIND) \
+  LINEMAPS_MAP_AT (SET, MAP_KIND, (LINEMAPS_USED (SET, MAP_KIND) - 1))
+
+/* Returns the last map that was allocated in the line table SET.
+   MAP_KIND shall be TRUE if we are interested in macro maps, FALSE
+   otherwise.*/
+#define LINEMAPS_LAST_ALLOCATED_MAP(SET, MAP_KIND) \
+  LINEMAPS_MAP_AT (SET, MAP_KIND, LINEMAPS_ALLOCATED (SET, MAP_KIND) - 1)
+
+/* Returns a pointer to the memory region where ordinary maps are
+   allocated in the line table SET.  */
+#define LINEMAPS_ORDINARY_MAPS(SET) \
+  LINEMAPS_MAPS (SET, false)
+
+/* Returns the INDEXth ordinary map.  */
+#define LINEMAPS_ORDINARY_MAP_AT(SET, INDEX)	\
+  LINEMAPS_MAP_AT (SET, false, INDEX)
+
+/* Return the number of ordinary maps allocated in the line table
+   SET.  */
+#define LINEMAPS_ORDINARY_ALLOCATED(SET) \
+  LINEMAPS_ALLOCATED(SET, false)
+
+/* Return the number of ordinary maps used in the line table SET.  */
+#define LINEMAPS_ORDINARY_USED(SET) \
+  LINEMAPS_USED(SET, false)
+
+/* Return the index of the last ordinary map that was looked up with
+   linemap_lookup.  */
+#define LINEMAPS_ORDINARY_CACHE(SET) \
+  LINEMAPS_CACHE(SET, false)
+
+/* Returns a pointer to the last ordinary map used in the line table
+   SET.  */
+#define LINEMAPS_LAST_ORDINARY_MAP(SET) \
+  LINEMAPS_LAST_MAP(SET, false)
+
+/* Returns a pointer to the last ordinary map allocated the line table
+   SET.  */
+#define LINEMAPS_LAST_ALLOCATED_ORDINARY_MAP(SET) \
+  LINEMAPS_LAST_ALLOCATED_MAP(SET, false)
+
+/* Returns a pointer to the begining of the region where macro maps
+   are allcoated.  */
+#define LINEMAPS_MACRO_MAPS(SET) \
+  LINEMAPS_MAPS(SET, true)
+
+/* Returns the INDEXth macro map.  */
+#define LINEMAPS_MACRO_MAP_AT(SET, INDEX)	\
+  LINEMAPS_MAP_AT (SET, true, INDEX)
+
+/* Returns the number of macro maps that were allocated in the line
+   table SET.  */
+#define LINEMAPS_MACRO_ALLOCATED(SET) \
+  LINEMAPS_ALLOCATED(SET, true)
+
+/* Returns the number of macro maps used in the line table SET.  */
+#define LINEMAPS_MACRO_USED(SET) \
+  LINEMAPS_USED(SET, true)
+
+/* Returns the index of the last macro map looked up with
+   linemap_lookup.  */
+#define LINEMAPS_MACRO_CACHE(SET) \
+  LINEMAPS_CACHE(SET, true)
+
+/* Returns the lowest location [of a token resulting from macro
+   expansion] encoded in this line table.  */
+#define LINEMAPS_MACRO_LOWEST_LOCATION(SET)			\
+  (LINEMAPS_MACRO_USED (set)					\
+   ? MAP_START_LOCATION (LINEMAPS_LAST_MACRO_MAP (set))		\
+   : MAX_SOURCE_LOCATION)
+
+/* Returns the last macro map used in the line table SET.  */
+#define LINEMAPS_LAST_MACRO_MAP(SET) \
+  LINEMAPS_LAST_MAP (SET, true)
+
+/* Returns the last macro map allocated in the line table SET.  */
+#define LINEMAPS_LAST_ALLOCATED_MACRO_MAP(SET) \
+  LINEMAPS_LAST_ALLOCATED_MAP (SET, true)
+
 /* Initialize a line map set.  */
 extern void linemap_init (struct line_maps *);
 
-/* Free a line map set.  */
-extern void linemap_free (struct line_maps *);
-
 /* Check for and warn about line_maps entered but not exited.  */
 
 extern void linemap_check_files_exited (struct line_maps *);
@@ -117,10 +433,12 @@  extern source_location linemap_line_start
 (struct line_maps *set, linenum_type to_line,  unsigned int max_column_hint);
 
 /* Add a mapping of logical source line to physical source file and
-   line number.
+   line number. This function creates an "ordinary map", which is a
+   map that records locations of tokens that are not part of macro
+   replacement-lists present at a macro expansion point.
 
    The text pointed to by TO_FILE must have a lifetime
-   at least as long as the final call to lookup_line ().  An empty
+   at least as long as the lifetime of SET.  An empty
    TO_FILE means standard input.  If reason is LC_LEAVE, and
    TO_FILE is NULL, then TO_FILE, TO_LINE and SYSP are given their
    natural values considering the file we are returning to.
@@ -131,41 +449,343 @@  extern const struct line_map *linemap_add
   (struct line_maps *, enum lc_reason, unsigned int sysp,
    const char *to_file, linenum_type to_line);
 
-/* Given a logical line, returns the map from which the corresponding
-   (source file, line) pair can be deduced.  */
+/* Given a logical source location, returns the map which the
+   corresponding (source file, line, column) triplet can be deduced
+   from. Since the set is built chronologically, the logical lines are
+   monotonic increasing, and so the list is sorted and we can use a
+   binary search. If no line map have been allocated yet, this
+   function returns NULL.  */
 extern const struct line_map *linemap_lookup
   (struct line_maps *, source_location);
 
+/* Returns TRUE if the line table set tracks token locations accross
+   macro expansion, FALSE otherwise.  */
+bool linemap_tracks_macro_expansion_locs_p (struct line_maps *);
+
+/* Create a macro map.  A macro map encodes source locations of tokens
+   that are part of a macro replacement-list, at a macro expansion
+   point. See the extensive comments of struct line_map and struct
+   line_map_macro, in line-map.h.
+
+   This map shall be created when the macro is expanded. The map
+   encodes the source location of the expansion point of the macro as
+   well as the "original" source location of each token that is part
+   of the macro replacement-list. If a macro is defined but never
+   expanded, it has no macro map.  SET is the set of maps the macro
+   map should be part of.  MACRO_NODE is the macro which the new macro
+   map should encode source locations for.  EXPANSION is the location
+   of the expansion point of MACRO. For function-like macros
+   invocations, it's best to make it point to the closing parenthesis
+   of the macro, rather than the the location of the first character
+   of the macro.  NUM_TOKENS is the number of tokens that are part of
+   the replacement-list of MACRO.  */
+const struct line_map *linemap_enter_macro (struct line_maps *,
+					    struct cpp_hashnode*,
+					    source_location,
+					    unsigned int);
+
+/* Create and return a source location for a token that is part of a
+   macro replacement-list at a macro expansion point.
+
+   A call to this function must come after a call to
+   linemap_enter_macro.
+
+   MAP is the map into which the source location is created.  TOKEN_NO
+   is the index of the token in the macro replacement-list, starting
+   at number 0.
+
+   ORIG_LOC is the orginal location of the token at the definition
+   point of the macro. If you read the extensive comments of struct
+   line_map_macro in line-map.h, this is the xI.
+
+   If the token is part of a macro argument, ORIG_PARM_REPLACEMENT_LOC
+   is the location of the point at wich the token (the argument)
+   replaces the macro parameter in the context of the relevant macro
+   definition. If you read the comments of struct line_map_macro in
+   line-map.h, this is the yI.  */
+source_location linemap_add_macro_token (const struct line_map *,
+					 unsigned int,
+					 source_location,
+					 source_location);
+
+/* Return TRUE if MAP encodes locations coming from a macro
+   replacement-list at macro expansion point.  */
+bool linemap_macro_expansion_map_p (const struct line_map *);
+
+/* If LOCATION is the locus of a token in a replacement-list of a
+   macro expansion, return the location of said token in the
+   definition of the macro.  If LOCATION is the locus of a token that
+   is an argument of a function-like macro (and that appears in the
+   expansion of a macro), return the location of the parameter (inside
+   the replacement-list of the macro) that the argument replaces.
+
+   In other words, this function returns the yI explained in the
+   comments of line_map_macro above.
+
+   Note that if the token is a builtin the function returns the
+   location of the expansion point of the macro.  */
+source_location linemap_macro_map_loc_to_def_point (const struct line_map*,
+						    source_location);
+
+/* If LOCATION is the locus of a token that is an argument of a
+   function-like macro M and appears in the expansion of M, return the
+   locus of that argument in the context of the caller of M.
+
+   In other words, this returns the xI location presented in the
+   comments of line_map_macro above.  */
+source_location linemap_macro_map_loc_unwind_once (const struct line_map*,
+						   source_location);
+
+/* If LOCATION is the locus of a token in a replacement-list of a
+   macro expansion return the location of the macro expansion point.
+
+   Read the comments of struct line_map and struct line_map_macro in
+   line-map.h to understand what a macro expansion point is.  */
+source_location linemap_macro_map_loc_to_exp_point (const struct line_map*,
+						    source_location);
+
+/* Return the source line number corresponding to source location
+   LOCATION.  SET is the line map set LOCATION comes from.  If
+   LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the line number of the
+   macro expansion point.  */
+int linemap_get_source_line (struct line_maps *,
+			     source_location);
+
+/* Return the column number corresponding to location LOCATION.
+
+   If LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the column number of
+   the macro expansion point.
+
+   SET is the line map set LOCATION comes from.  */
+int linemap_get_source_column (struct line_maps *,
+			       source_location);
+
+/* Return the name of the macro associated to MACRO_MAP.  */
+const char* linemap_map_get_macro_name (const struct line_map*);
+
+/* Return the path of the file corresponding to source code location
+   LOCATION.
+
+   If LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the file path of the
+   macro expansion point.
+
+   SET is the line map set LOCATION comes from.  */
+const char* linemap_get_file_path (struct line_maps *,
+				   source_location);
+
+/* Return a positive value if LOCATION is the locus of a token that is
+   located in a system header, O otherwise. It returns 1 if LOCATION
+   is the locus of a token that is located in a system header, and 2
+   if LOCATION is the locus of a token located in a C system header
+   that therefore needs to be extern "C" protected in C++.
+
+   Note that this function returns 0 if LOCATION belongs to a token
+   that is part of a macro replacement-list defined in a system
+   header, but expanded in a non-system file.  */
+int linemap_location_in_system_header_p (struct line_maps *,
+					 source_location);
+
+/* Return TRUE if LOCATION is a source code location of a token coming
+   from a macro replacement-list at a macro expansion point, FALSE
+   otherwise.  */
+bool linemap_location_from_macro_expansion_p (struct line_maps *,
+					      source_location);
+
 /* source_location values from 0 to RESERVED_LOCATION_COUNT-1 will
    be reserved for libcpp user as special values, no token from libcpp
    will contain any of those locations.  */
 #define RESERVED_LOCATION_COUNT	2
 
 /* Converts a map and a source_location to source line.  */
-#define SOURCE_LINE(MAP, LOC) \
-  ((((LOC) - (MAP)->start_location) >> (MAP)->column_bits) + (MAP)->to_line)
-
-#define SOURCE_COLUMN(MAP, LOC) \
-  (((LOC) - (MAP)->start_location) & ((1 << (MAP)->column_bits) - 1))
-
-/* Returns the last source line within a map.  This is the (last) line
-   of the #include, or other directive, that caused a map change.  */
+#define SOURCE_LINE(MAP, LOC)						\
+  (((((LOC) - linemap_check_ordinary (MAP)->start_location)		\
+     >> (MAP)->d.ordinary.column_bits) + (MAP)->d.ordinary.to_line))
+
+/* Convert a map and source_location to source column number.  */
+#define SOURCE_COLUMN(MAP, LOC)						\
+  ((((LOC) - linemap_check_ordinary (MAP)->start_location)		\
+    & ((1 << (MAP)->d.ordinary.column_bits) - 1)))
+
+/* Returns the last source line number within an ordinary map.  This
+   is the (last) line of the #include, or other directive, that caused
+   a map change.  */
 #define LAST_SOURCE_LINE(MAP) \
   SOURCE_LINE (MAP, LAST_SOURCE_LINE_LOCATION (MAP))
+
+/* Return the last column number within an ordinary map.  */
 #define LAST_SOURCE_COLUMN(MAP) \
   SOURCE_COLUMN (MAP, LAST_SOURCE_LINE_LOCATION (MAP))
-#define LAST_SOURCE_LINE_LOCATION(MAP) \
-  ((((MAP)[1].start_location - 1 - (MAP)->start_location) \
-    & ~((1 << (MAP)->column_bits) - 1))			  \
-   + (MAP)->start_location)
 
-/* Returns the map a given map was included from.  */
-#define INCLUDED_FROM(SET, MAP) (&(SET)->maps[(MAP)->included_from])
+/* Return the location of the last source line within an ordinary
+   map.  */
+#define LAST_SOURCE_LINE_LOCATION(MAP)					\
+  ((((linemap_check_ordinary (MAP)[1].start_location - 1		\
+      - (MAP)->start_location)						\
+     & ~((1 << (MAP)->d.ordinary.column_bits) - 1))			\
+    + (MAP)->start_location))
+
+/* Returns the map a given map was included from, or NULL if the map
+   belongs to the main file, i.e, a file that wasn't included by
+   another one.  */
+#define INCLUDED_FROM(SET, MAP)						\
+  ((linemap_check_ordinary (MAP)->d.ordinary.included_from == -1)	\
+   ? NULL								\
+   : (&LINEMAPS_ORDINARY_MAPS (SET)[(MAP)->d.ordinary.included_from]))
 
 /* Nonzero if the map is at the bottom of the include stack.  */
-#define MAIN_FILE_P(MAP) ((MAP)->included_from < 0)
+#define MAIN_FILE_P(MAP)						\
+  ((linemap_check_ordinary (MAP)->d.ordinary.included_from < 0))
+
+#if defined ENABLE_CHECKING && (GCC_VERSION >= 2007)
+
+/* Assertion macro to be used in line-map code.  */
+#define linemap_assert(EXPR)			\
+  do {						\
+    if (! (EXPR))				\
+      abort ();					\
+  } while (0)
+
+/* Assert that MAP encodes locations of tokens that are not part of
+   the replacement-list of a macro expansion.  */
+#define linemap_check_ordinary(LINE_MAP) __extension__		\
+  ({linemap_assert (!linemap_macro_expansion_map_p (LINE_MAP)); \
+    (LINE_MAP);})
+#else
+#define linemap_assert(EXPR)
+#define linemap_check_ordinary(LINE_MAP) (LINE_MAP)
+#endif
 
+/* Encode and return a source_location from a column number. The
+   source line considered is the last source line used to call
+   linemap_line_start, i.e, the last source line which a location was
+   encoded from.  */
 extern source_location
-linemap_position_for_column (struct line_maps *set, unsigned int to_column);
+linemap_position_for_column (struct line_maps *, unsigned int);
+
+/* Encode and return a source location from a given line and
+   column.  */
+source_location linemap_position_for_line_and_column (struct line_map *,
+						      linenum_type,
+						      unsigned int);
+/* Return the file this map is for.  */
+#define LINEMAP_FILE(MAP)					\
+  (linemap_check_ordinary (MAP)->d.ordinary.to_file)
+
+/* Return the line number this map started encoding location from.  */
+#define LINEMAP_LINE(MAP)					\
+  (linemap_check_ordinary (MAP)->d.ordinary.to_line)
+
+/* Return a positive value if map encodes locations from a system
+   header, 0 otherwise. Returns 1 if MAP encodes locations in a
+   system header and 2 if it encodes locations in a C system header
+   that therefore needs to be extern "C" protected in C++.  */
+#define LINEMAP_SYSP(MAP)					\
+  (linemap_check_ordinary (MAP)->d.ordinary.sysp)
+
+/* Return TRUE if PRE denotes a location that is before POST, FALSE
+   otherwise. LINE_MAPS is the set of line maps PRE and POST were
+   allocated from.  */
+bool linemap_location_before_p (struct line_maps *set,
+				source_location   pre,
+				source_location   post);
+
+typedef struct
+{
+  /* The name of the source file involved.  */
+  const char *file;
+
+  /* The line-location in the source file.  */
+  int line;
+
+  int column;
+
+  /* In a system header?. */
+  bool sysp;
+} expanded_location;
+
+/* This is enum is used by the function linemap_resolve_location
+   below.  The meaning of the values is explained in the comment of
+   that function.  */
+enum location_resolution_kind
+{
+  LRK_MACRO_EXPANSION_POINT,
+  LRK_SPELLING_LOCATION,
+  LRK_MACRO_DEFINITION_LOCATION
+};
+
+/* Resolve a virtual location into either a spelling location, an
+   expansion point location or a token argument replacement point
+   location.  Return the map that encodes the virtual location as well
+   as the resolved location.
+
+   If LOC is *NOT* the location of a token resulting from the
+   expansion of a macro, then the parameter LRK (which stands for
+   Location Resolution Kind) is ignored and the resulting location
+   just equals the one given in argument.
+
+   Now if LOC *IS* the location of a token resulting from the
+   expansion of a macro, this is what happens.
+
+   * If LRK is set to LRK_MACRO_EXPANSION_POINT
+   -------------------------------
+
+   The virtual location is resolved to the locus of the expansion
+   point of the macro.
+
+   * If LRK is set to LRK_SPELLING_LOCATION
+   -------------------------------------
+
+   The virtual location is resolved to the locus where the token has
+   been spelled in the source.   This can follow through all the macro
+   expansions that led to the token.
+
+   * If LRK is set to LRK_MACRO_DEFINITION_LOCATION
+   --------------------------------------
+
+   If LOC is the locus of a token that is an argument of a
+   function-like macro [replacing a parameter in the replacement list
+   of the macro] the virtual location is resolved to the locus of the
+   parameter that is replaced, in the context of the definition of the
+   macro.
+
+   If LOC is the locus of a token that is not an argument of a
+   function-like macro, then the function behaves as if LRK was set to
+   LRK_SPELLING_LOCATION.
+
+   Finally, if SPELLING_LOC is not NULL, *RESULTING_LOC is set to the
+   location to which LOC was resolved, and similarly, *LOC_MAP is set
+   to its map.  */
+
+source_location linemap_resolve_location (struct line_maps *,
+					  source_location loc,
+					  enum location_resolution_kind lrk,
+					  const struct line_map **loc_map);
+
+/* Suppose that LOC is the virtual location of a token coming from the
+   expansion of a macro M.  This function then steps up to get the
+   location L of the point where M got expanded.  If L is a spelling
+   location inside a macro expansion M', then this function returns
+   the point where M' was expanded.  LOC_MAP is an output parameter.
+   When non-NULL, *LOC_MAP is set the the map of the returned
+   location.  */
+source_location linemap_step_out_once (struct line_maps *,
+				       source_location loc,
+				       const struct line_map **loc_map);
+
+/* Expand source code location LOC and return a user readable source
+   code location.  */
+expanded_location linemap_expand_location (const struct line_map *,
+					   source_location loc);
+
+/* Expand source code location LOC and return a user readable source
+   code location.  The LRK parameter is the same as for
+   linemap_resolve_location.  */
+
+expanded_location linemap_expand_location_full (struct line_maps *,
+						source_location loc,
+						enum location_resolution_kind lrk);
 
 #endif /* !LIBCPP_LINE_MAP_H  */
diff --git a/libcpp/init.c b/libcpp/init.c
index c5c5325..6303868 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -586,7 +586,9 @@  cpp_read_main_file (cpp_reader *pfile, const char *fname)
   if (CPP_OPTION (pfile, preprocessed))
     {
       read_original_filename (pfile);
-      fname = pfile->line_table->maps[pfile->line_table->used-1].to_file;
+      fname =
+	ORDINARY_MAP_FILE_NAME
+	((LINEMAPS_LAST_ORDINARY_MAP (pfile->line_table)));
     }
   return fname;
 }
diff --git a/libcpp/internal.h b/libcpp/internal.h
index 6c423f0..588e8ed 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -67,7 +67,8 @@  struct cset_converter
 
 #define CPP_INCREMENT_LINE(PFILE, COLS_HINT) do { \
     const struct line_maps *line_table = PFILE->line_table; \
-    const struct line_map *map = &line_table->maps[line_table->used-1]; \
+    const struct line_map *map = \
+      LINEMAPS_LAST_ORDINARY_MAP (line_table); \
     linenum_type line = SOURCE_LINE (map, line_table->highest_line); \
     linemap_line_start (PFILE->line_table, line + 1, COLS_HINT); \
   } while (0)
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index 2a0749a..b56467c 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -23,24 +23,31 @@  along with this program; see the file COPYING3.  If not see
 #include "config.h"
 #include "system.h"
 #include "line-map.h"
+#include "cpplib.h"
 
 static void trace_include (const struct line_maps *, const struct line_map *);
+static const struct line_map * linemap_ordinary_map_lookup (struct line_maps *,
+							    source_location);
+static const struct line_map* linemap_macro_map_lookup (struct line_maps *,
+							source_location);
+static source_location linemap_macro_loc_unwind (struct line_maps *,
+						 source_location,
+						 const struct line_map **);
+static source_location linemap_macro_loc_to_def_point (struct line_maps *,
+						       source_location,
+						       const struct line_map **);
+static source_location linemap_macro_loc_to_exp_point (struct line_maps *,
+						       source_location,
+						       const struct line_map **);
 
 /* Initialize a line map set.  */
 
 void
 linemap_init (struct line_maps *set)
 {
-  set->maps = NULL;
-  set->allocated = 0;
-  set->used = 0;
-  set->trace_includes = false;
-  set->depth = 0;
-  set->cache = 0;
+  memset (set, 0, sizeof (struct line_maps));
   set->highest_location = RESERVED_LOCATION_COUNT - 1;
   set->highest_line = RESERVED_LOCATION_COUNT - 1;
-  set->max_column_hint = 0;
-  set->reallocator = 0;
 }
 
 /* Check for and warn about line_maps entered but not exited.  */
@@ -51,23 +58,55 @@  linemap_check_files_exited (struct line_maps *set)
   struct line_map *map;
   /* Depending upon whether we are handling preprocessed input or
      not, this can be a user error or an ICE.  */
-  for (map = &set->maps[set->used - 1]; ! MAIN_FILE_P (map);
+  for (map = LINEMAPS_LAST_ORDINARY_MAP (set);
+       ! MAIN_FILE_P (map);
        map = INCLUDED_FROM (set, map))
     fprintf (stderr, "line-map.c: file \"%s\" entered but not left\n",
-	     map->to_file);
+	     ORDINARY_MAP_FILE_NAME (map));
 }
- 
-/* Free a line map set.  */
 
-void
-linemap_free (struct line_maps *set)
+/* Create a new line map in the line map set SET, and return it.
+   REASON is the reason of creating the map. It determines the type
+   of map created (ordinary or macro map). Note that ordinary maps and
+   macro maps are allocated in different memory location.  */
+
+static struct line_map *
+new_linemap (struct line_maps *set,
+	     enum lc_reason reason)
 {
-  if (set->maps)
+  /* Depending on this variable, a macro map would be allocated in a
+     different memory location than an ordinary map.  */
+  bool macro_map_p = (reason == LC_ENTER_MACRO);
+  struct line_map *result;
+
+  if (LINEMAPS_USED (set, macro_map_p) == LINEMAPS_ALLOCATED (set, macro_map_p))
     {
-      linemap_check_files_exited (set);
+      /* We ran out of allocated line maps. Let's allocate more.  */
 
-      free (set->maps);
+      line_map_realloc reallocator
+	= set->reallocator ? set->reallocator : xrealloc;
+      LINEMAPS_ALLOCATED (set, macro_map_p) =
+	2 * LINEMAPS_ALLOCATED (set, macro_map_p) + 256;
+      LINEMAPS_MAPS (set, macro_map_p)
+	= (struct line_map *) (*reallocator) (LINEMAPS_MAPS (set, macro_map_p),
+					      LINEMAPS_ALLOCATED (set,
+								  macro_map_p)
+					      * sizeof (struct line_map));
+      result =
+	&LINEMAPS_MAPS (set, macro_map_p)[LINEMAPS_USED (set, macro_map_p)];
+      memset (result, 0,
+	      ((LINEMAPS_ALLOCATED (set, macro_map_p)
+		- LINEMAPS_USED (set, macro_map_p))
+	       * sizeof (struct line_map)));
     }
+  else
+    result =
+      &LINEMAPS_MAPS (set, macro_map_p)[LINEMAPS_USED (set, macro_map_p)];
+
+  LINEMAPS_USED (set, macro_map_p)++;
+
+  result->reason = reason;
+  return result;
 }
 
 /* Add a mapping of logical source line to physical source file and
@@ -90,23 +129,24 @@  linemap_add (struct line_maps *set, enum lc_reason reason,
   struct line_map *map;
   source_location start_location = set->highest_location + 1;
 
-  if (set->used && start_location < set->maps[set->used - 1].start_location)
-    abort ();
+  linemap_assert (!(LINEMAPS_ORDINARY_USED (set)
+		    && (start_location
+			< MAP_START_LOCATION (LINEMAPS_LAST_ORDINARY_MAP (set)))));
 
-  if (set->used == set->allocated)
+  /* When we enter the file for the first time reason cannot be
+     LC_RENAME.  */
+  linemap_assert (!(set->depth == 0 && reason == LC_RENAME));
+
+  /* If we are leaving the main file, return a NULL map.  */
+  if (reason == LC_LEAVE
+      && MAIN_FILE_P (LINEMAPS_LAST_ORDINARY_MAP (set))
+      && to_file == NULL)
     {
-      line_map_realloc reallocator
-	= set->reallocator ? set->reallocator : xrealloc;
-      set->allocated = 2 * set->allocated + 256;
-      set->maps
-	= (struct line_map *) (*reallocator) (set->maps,
-					      set->allocated
-					      * sizeof (struct line_map));
-      memset (&set->maps[set->used], 0, ((set->allocated - set->used)
-					 * sizeof (struct line_map)));
+      set->depth--;
+      return NULL;
     }
 
-  map = &set->maps[set->used];
+  map = new_linemap (set, reason);
 
   if (to_file && *to_file == '\0' && reason != LC_RENAME_VERBATIM)
     to_file = "<stdin>";
@@ -114,29 +154,35 @@  linemap_add (struct line_maps *set, enum lc_reason reason,
   if (reason == LC_RENAME_VERBATIM)
     reason = LC_RENAME;
 
-  if (set->depth == 0 && reason == LC_RENAME)
-    abort ();
-
   if (reason == LC_LEAVE)
     {
+      /* When we are just leaving an "included" file, and jump to the next
+	 location inside the "includer" right after the #include
+	 "included", this variable points the map in use right before the
+	 #include "included", inside the same "includer" file.  */
       struct line_map *from;
       bool error;
 
       if (MAIN_FILE_P (map - 1))
 	{
-	  if (to_file == NULL)
-	    {
-	      set->depth--;
-	      return NULL;
-	    }
+	  /* So this _should_ means we are leaving the main file --
+	     effectively ending the compilation unit. But to_file not
+	     being NULL means the caller thinks we are leaving to
+	     another file. This is an erroneous behaviour but we'll
+	     try to recover from it. Let's pretend we are not leaving
+	     the main file.  */
 	  error = true;
           reason = LC_RENAME;
           from = map - 1;
 	}
       else
 	{
+	  /* (MAP - 1) points to the map we are leaving. The
+	     map from which (MAP - 1) got included should be the map
+	     that comes right before MAP in the same file.  */
 	  from = INCLUDED_FROM (set, map - 1);
-	  error = to_file && filename_cmp (from->to_file, to_file);
+	  error = to_file && filename_cmp (ORDINARY_MAP_FILE_NAME (from),
+					   to_file);
 	}
 
       /* Depending upon whether we are handling preprocessed input or
@@ -148,55 +194,173 @@  linemap_add (struct line_maps *set, enum lc_reason reason,
       /* A TO_FILE of NULL is special - we use the natural values.  */
       if (error || to_file == NULL)
 	{
-	  to_file = from->to_file;
+	  to_file = ORDINARY_MAP_FILE_NAME (from);
 	  to_line = SOURCE_LINE (from, from[1].start_location);
-	  sysp = from->sysp;
+	  sysp = ORDINARY_MAP_IN_SYSTEM_HEADER_P (from);
 	}
     }
 
-  map->reason = reason;
-  map->sysp = sysp;
-  map->start_location = start_location;
-  map->to_file = to_file;
-  map->to_line = to_line;
-  set->cache = set->used++;
-  map->column_bits = 0;
+  linemap_assert (reason != LC_ENTER_MACRO);
+  ORDINARY_MAP_IN_SYSTEM_HEADER_P (map) = sysp;
+  MAP_START_LOCATION (map) = start_location;
+  ORDINARY_MAP_FILE_NAME (map) = to_file;
+  ORDINARY_MAP_STARTING_LINE_NUMBER (map) = to_line;
+  LINEMAPS_ORDINARY_CACHE (set) = LINEMAPS_ORDINARY_USED (set) - 1;
+  ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map) = 0;
   set->highest_location = start_location;
   set->highest_line = start_location;
   set->max_column_hint = 0;
 
   if (reason == LC_ENTER)
     {
-      map->included_from = set->depth == 0 ? -1 : (int) (set->used - 2);
+      ORDINARY_MAP_INCLUDER_FILE_INDEX (map) = 
+	set->depth == 0 ? -1 : (int) (LINEMAPS_ORDINARY_USED (set) - 2);
       set->depth++;
       if (set->trace_includes)
 	trace_include (set, map);
     }
   else if (reason == LC_RENAME)
-    map->included_from = map[-1].included_from;
+    ORDINARY_MAP_INCLUDER_FILE_INDEX (map) =
+      ORDINARY_MAP_INCLUDER_FILE_INDEX (&map[-1]);
   else if (reason == LC_LEAVE)
     {
       set->depth--;
-      map->included_from = INCLUDED_FROM (set, map - 1)->included_from;
+      ORDINARY_MAP_INCLUDER_FILE_INDEX (map) =
+	ORDINARY_MAP_INCLUDER_FILE_INDEX (INCLUDED_FROM (set, map - 1));
     }
 
   return map;
 }
 
+/* Returns TRUE if the line table set tracks token locations accross
+   macro expansion, FALSE otherwise.  */
+
+bool
+linemap_tracks_macro_expansion_locs_p (struct line_maps *set)
+{
+  return LINEMAPS_MACRO_MAPS (set) != NULL;
+}
+
+/* Create a macro map.  A macro map encodes source locations of tokens
+   that are part of a macro replacement-list, at a macro expansion
+   point.  See the extensive comments of struct line_map and struct
+   line_map_macro, in line-map.h.
+
+   This map shall be created when the macro is expanded.  The map
+   encodes the source location of the expansion point of the macro as
+   well as the "original" source location of each token that is part
+   of the macro replacement-list.  If a macro is defined but never
+   expanded, it has no macro map.  SET is the set of maps the macro
+   map should be part of.  MACRO_NODE is the macro which the new macro
+   map should encode source locations for.  EXPANSION is the location
+   of the expansion point of MACRO. For function-like macros
+   invocations, it's best to make it point to the closing parenthesis
+   of the macro, rather than the the location of the first character
+   of the macro.  NUM_TOKENS is the number of tokens that are part of
+   the replacement-list of MACRO.
+
+   Note that when we run out of the integer space available for source
+   locations, this function returns NULL.  In that case, callers of
+   this function cannot encode {line,column} pairs into locations of
+   macro tokens anymore.  */
+
+const struct line_map *
+linemap_enter_macro (struct line_maps *set, struct cpp_hashnode *macro_node,
+		     source_location expansion, unsigned int num_tokens)
+{
+  struct line_map *map;
+  source_location start_location;
+  line_map_realloc reallocator
+    = set->reallocator ? set->reallocator : xrealloc;
+
+  start_location = LINEMAPS_MACRO_LOWEST_LOCATION (set) - num_tokens;
+
+  if (start_location <= set->highest_line
+      || start_location > LINEMAPS_MACRO_LOWEST_LOCATION (set))
+    /* We ran out of macro map space.   */
+    return NULL;
+
+  map = new_linemap (set, LC_ENTER_MACRO);
+
+  MAP_START_LOCATION (map) = start_location;
+  MACRO_MAP_MACRO (map) = macro_node;
+  MACRO_MAP_NUM_MACRO_TOKENS (map) = num_tokens;
+  MACRO_MAP_LOCATIONS (map)
+    = (source_location*) reallocator (NULL,
+				      2 * num_tokens
+				      * sizeof (source_location));
+  MACRO_MAP_EXPANSION_POINT_LOCATION (map) = expansion;
+  memset (MACRO_MAP_LOCATIONS (map), 0,
+	  num_tokens * sizeof (source_location));
+
+  LINEMAPS_MACRO_CACHE (set) = LINEMAPS_MACRO_USED (set) - 1;
+  set->max_column_hint = 0;
+
+  return map;
+}
+
+/* Create and return a source location for a token that is part of a
+   macro replacement-list at a macro expansion point.
+
+   A call to this function must come after a call to
+   linemap_enter_macro.
+
+   MAP is the map into which the source location is created.  TOKEN_NO
+   is the index of the token in the macro replacement-list, starting
+   at number 0.
+
+   ORIG_LOC is the orginal location of the token at the definition
+   point of the macro. If you read the extensive comments of struct
+   line_map_macro in line-map.h, this is the xI.
+
+   If the token is part of a macro argument, ORIG_PARM_REPLACEMENT_LOC
+   is the location of the point at wich the token (the argument)
+   replaces the macro parameter in the context of the relevant macro
+   definition. If you read the comments of struct line_map_macro in
+   line-map.h, this is the yI.  */
+
+source_location
+linemap_add_macro_token (const struct line_map *map,
+			 unsigned int token_no,
+			 source_location orig_loc,
+			 source_location orig_parm_replacement_loc)
+{
+  source_location result;
+
+  linemap_assert (linemap_macro_expansion_map_p (map));
+  linemap_assert (token_no < MACRO_MAP_NUM_MACRO_TOKENS (map));
+
+  MACRO_MAP_LOCATIONS (map)[2 * token_no] = orig_loc;
+  MACRO_MAP_LOCATIONS (map)[2 * token_no + 1] = orig_parm_replacement_loc;
+
+  result = MAP_START_LOCATION (map) + token_no;
+  return result;
+}
+
+/* Return a source_location for the start (i.e. column==0) of
+   (physical) line TO_LINE in the current source file (as in the
+   most recent linemap_add).   MAX_COLUMN_HINT is the highest column
+   number we expect to use in this line (but it does not change
+   the highest_location).  */
+
 source_location
 linemap_line_start (struct line_maps *set, linenum_type to_line,
 		    unsigned int max_column_hint)
 {
-  struct line_map *map = &set->maps[set->used - 1];
+  struct line_map *map = LINEMAPS_LAST_ORDINARY_MAP (set);
   source_location highest = set->highest_location;
   source_location r;
-  linenum_type last_line = SOURCE_LINE (map, set->highest_line);
+  linenum_type last_line =
+    SOURCE_LINE (map, set->highest_line);
   int line_delta = to_line - last_line;
   bool add_map = false;
+
   if (line_delta < 0
-      || (line_delta > 10 && line_delta * map->column_bits > 1000)
-      || (max_column_hint >= (1U << map->column_bits))
-      || (max_column_hint <= 80 && map->column_bits >= 10))
+      || (line_delta > 10
+	  && line_delta * ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map) > 1000)
+      || (max_column_hint >= (1U << ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map)))
+      || (max_column_hint <= 80
+	  && ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map) >= 10))
     {
       add_map = true;
     }
@@ -224,16 +388,27 @@  linemap_line_start (struct line_maps *set, linenum_type to_line,
       /* Allocate the new line_map.  However, if the current map only has a
 	 single line we can sometimes just increase its column_bits instead. */
       if (line_delta < 0
-	  || last_line != map->to_line
+	  || last_line != ORDINARY_MAP_STARTING_LINE_NUMBER (map)
 	  || SOURCE_COLUMN (map, highest) >= (1U << column_bits))
-	map = (struct line_map *) linemap_add (set, LC_RENAME, map->sysp,
-					       map->to_file, to_line);
-      map->column_bits = column_bits;
-      r = map->start_location + ((to_line - map->to_line) << column_bits);
+	map = (struct line_map *) linemap_add (set, LC_RENAME,
+					       ORDINARY_MAP_IN_SYSTEM_HEADER_P
+					       (map),
+					       ORDINARY_MAP_FILE_NAME (map),
+					       to_line);
+      ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map) = column_bits;
+      r = (MAP_START_LOCATION (map)
+	   + ((to_line - ORDINARY_MAP_STARTING_LINE_NUMBER (map))
+	      << column_bits));
     }
   else
     r = highest - SOURCE_COLUMN (map, highest)
-      + (line_delta << map->column_bits);
+      + (line_delta << ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map));
+
+  /* Locations of ordinary tokens are always lower than locations of
+     macro tokens.  */
+  if (r >= LINEMAPS_MACRO_LOWEST_LOCATION (set))
+    return 0;
+
   set->highest_line = r;
   if (r > set->highest_location)
     set->highest_location = r;
@@ -241,10 +416,19 @@  linemap_line_start (struct line_maps *set, linenum_type to_line,
   return r;
 }
 
+/* Encode and return a source_location from a column number. The
+   source line considered is the last source line used to call
+   linemap_line_start, i.e, the last source line which a location was
+   encoded from.  */
+
 source_location
 linemap_position_for_column (struct line_maps *set, unsigned int to_column)
 {
   source_location r = set->highest_line;
+
+  linemap_assert
+    (!linemap_macro_expansion_map_p (LINEMAPS_LAST_ORDINARY_MAP (set)));
+
   if (to_column >= set->max_column_hint)
     {
       if (r >= 0xC000000 || to_column > 100000)
@@ -254,7 +438,7 @@  linemap_position_for_column (struct line_maps *set, unsigned int to_column)
 	}
       else
 	{
-	  struct line_map *map = &set->maps[set->used - 1];
+	  struct line_map *map = LINEMAPS_LAST_ORDINARY_MAP (set);
 	  r = linemap_line_start (set, SOURCE_LINE (map, r), to_column + 50);
 	}
     }
@@ -264,25 +448,55 @@  linemap_position_for_column (struct line_maps *set, unsigned int to_column)
   return r;
 }
 
-/* Given a logical line, returns the map from which the corresponding
-   (source file, line) pair can be deduced.  Since the set is built
-   chronologically, the logical lines are monotonic increasing, and so
-   the list is sorted and we can use a binary search.  */
+/* Encode and return a source location from a given line and
+   column.  */
 
-const struct line_map *
+source_location
+linemap_position_for_line_and_column (struct line_map *map,
+				      linenum_type line,
+				      unsigned column)
+{
+  linemap_assert (ORDINARY_MAP_STARTING_LINE_NUMBER (map) <= line);
+
+  return (MAP_START_LOCATION (map)
+	  + ((line - ORDINARY_MAP_STARTING_LINE_NUMBER (map))
+	     << ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map))
+	  + (column & ((1 << ORDINARY_MAP_NUMBER_OF_COLUMN_BITS (map)) - 1)));
+}
+
+/* Given a virtual source location yielded by a map (either an
+   ordinary or a macro map), returns that map.  */
+
+const struct line_map*
 linemap_lookup (struct line_maps *set, source_location line)
 {
+  if (linemap_location_from_macro_expansion_p (set, line))
+    return linemap_macro_map_lookup (set, line);
+  return linemap_ordinary_map_lookup (set, line);
+}
+
+/* Given a source location yielded by an ordinary map, returns that
+   map.  Since the set is built chronologically, the logical lines are
+   monotonic increasing, and so the list is sorted and we can use a
+   binary search.  */
+
+static const struct line_map *
+linemap_ordinary_map_lookup (struct line_maps *set, source_location line)
+{
   unsigned int md, mn, mx;
-  const struct line_map *cached;
+  const struct line_map *cached, *result;
+
+  if (set ==  NULL || line < RESERVED_LOCATION_COUNT)
+    return NULL;
 
-  mn = set->cache;
-  mx = set->used;
+  mn = LINEMAPS_ORDINARY_CACHE (set);
+  mx = LINEMAPS_ORDINARY_USED (set);
   
-  cached = &set->maps[mn];
+  cached = LINEMAPS_ORDINARY_MAP_AT (set, mn);
   /* We should get a segfault if no line_maps have been added yet.  */
-  if (line >= cached->start_location)
+  if (line >= MAP_START_LOCATION (cached))
     {
-      if (mn + 1 == mx || line < cached[1].start_location)
+      if (mn + 1 == mx || line < MAP_START_LOCATION (&cached[1]))
 	return cached;
     }
   else
@@ -294,14 +508,293 @@  linemap_lookup (struct line_maps *set, source_location line)
   while (mx - mn > 1)
     {
       md = (mn + mx) / 2;
-      if (set->maps[md].start_location > line)
+      if (MAP_START_LOCATION (LINEMAPS_ORDINARY_MAP_AT (set, md)) > line)
 	mx = md;
       else
 	mn = md;
     }
 
-  set->cache = mn;
-  return &set->maps[mn];
+  LINEMAPS_ORDINARY_CACHE (set) = mn;
+  result = LINEMAPS_ORDINARY_MAP_AT (set, mn);
+  linemap_assert (line >= MAP_START_LOCATION (result));
+  return result;
+}
+
+/* Given a source location yielded by a macro map, returns that map.
+   Since the set is built chronologically, the logical lines are
+   monotonic decreasing, and so the list is sorted and we can use a
+   binary search.  */
+
+static const struct line_map*
+linemap_macro_map_lookup (struct line_maps *set, source_location line)
+{
+  unsigned int md, mn, mx;
+  const struct line_map *cached, *result;
+
+  linemap_assert (line >= LINEMAPS_MACRO_LOWEST_LOCATION (set));
+
+  if (set ==  NULL)
+    return NULL;
+
+  mn = LINEMAPS_MACRO_CACHE (set);
+  mx = LINEMAPS_MACRO_USED (set);
+  cached = LINEMAPS_MACRO_MAP_AT (set, mn);
+  
+  if (line >= MAP_START_LOCATION (cached))
+    {
+      if (mn == 0 || line < MAP_START_LOCATION (&cached[-1]))
+	return cached;
+      mx = mn - 1;
+      mn = 0;
+    }
+
+  while (mx - mn > 1)
+    {
+      md = (mx + mn) / 2;
+      if (MAP_START_LOCATION (LINEMAPS_MACRO_MAP_AT (set, md)) > line)
+	mn = md;
+      else
+	mx = md;
+    }
+
+  LINEMAPS_MACRO_CACHE (set) = mx;
+  result = LINEMAPS_MACRO_MAP_AT (set, LINEMAPS_MACRO_CACHE (set));
+  linemap_assert (MAP_START_LOCATION (result) <= line);
+
+  return result;
+}
+
+/* Return TRUE if MAP encodes locations coming from a macro
+   replacement-list at macro expansion point.  */
+
+bool
+linemap_macro_expansion_map_p (const struct line_map *map)
+{
+  if (!map)
+    return false;
+  return (map->reason == LC_ENTER_MACRO);
+}
+
+/* If LOCATION is the locus of a token in a replacement-list of a
+   macro expansion return the location of the macro expansion point.
+
+   Read the comments of struct line_map and struct line_map_macro in
+   line-map.h to understand what a macro expansion point is.  */
+
+source_location
+linemap_macro_map_loc_to_exp_point (const struct line_map *map,
+				    source_location location)
+{
+  unsigned token_no;
+
+  linemap_assert (linemap_macro_expansion_map_p (map)
+		  && location >= MAP_START_LOCATION (map));
+
+  /* Make sure LOCATION is correct.  */
+  token_no = location - MAP_START_LOCATION (map);
+  linemap_assert (token_no <  MACRO_MAP_NUM_MACRO_TOKENS (map));
+
+  return MACRO_MAP_EXPANSION_POINT_LOCATION (map);
+}
+
+/* If LOCATION is the source location of a token that belongs to a
+   macro replacement-list -- as part of a macro expansion -- then
+   return the location of the token at the definition point of the
+   macro.  Otherwise, return LOCATION.  SET is the set of maps
+   location come from.  ORIGINAL_MAP is an output parm. If non NULL,
+   the function sets *ORIGINAL_MAP to the ordinary (non-macro) map the
+   returned location comes from.  */
+
+source_location
+linemap_macro_map_loc_to_def_point (const struct line_map *map,
+				    source_location location)
+{
+  unsigned token_no;
+
+  linemap_assert (linemap_macro_expansion_map_p (map)
+		  && location >= MAP_START_LOCATION (map));
+  linemap_assert (location >= RESERVED_LOCATION_COUNT);
+
+  token_no = location - MAP_START_LOCATION (map);
+  linemap_assert (token_no < MACRO_MAP_NUM_MACRO_TOKENS (map));
+
+  location = MACRO_MAP_LOCATIONS (map)[2 * token_no + 1];
+
+  return location;
+}
+
+/* If LOCATION is the locus of a token that is an argument of a
+   function-like macro M and appears in the expansion of M, return the
+   locus of that argument in the context of the caller of M.  Note
+   that the caller of M is necessarily another macro.  The context of
+   M is a macro definition.
+
+   In other words, this returns the xI location presented in the
+   comments of line_map_macro above.  */
+source_location
+linemap_macro_map_loc_unwind_once (const struct line_map* map,
+				   source_location location)
+{
+  unsigned token_no;
+
+  linemap_assert (linemap_macro_expansion_map_p (map)
+		  && location >= MAP_START_LOCATION (map));
+  linemap_assert (location >= RESERVED_LOCATION_COUNT);
+
+  token_no = location - MAP_START_LOCATION (map);
+  linemap_assert (token_no < MACRO_MAP_NUM_MACRO_TOKENS (map));
+
+  location = MACRO_MAP_LOCATIONS (map)[2 * token_no];
+  
+  return location;
+}
+
+/* Return the source line number corresponding to source location
+   LOCATION.  SET is the line map set LOCATION comes from.  If
+   LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the line number of the
+   macro expansion point.  */
+
+int
+linemap_get_source_line (struct line_maps *set,
+			 source_location location)
+{
+  const struct line_map *map = NULL;
+
+  if (location < RESERVED_LOCATION_COUNT)
+    return 0;
+
+  location =
+    linemap_macro_loc_to_exp_point (set, location, &map);
+
+  return SOURCE_LINE (map, location);
+}
+
+/* Return the column number corresponding to location LOCATION.
+
+   If LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the column number of
+   the macro expansion point.
+
+   SET is the line map set LOCATION comes from.  */
+
+int
+linemap_get_source_column (struct line_maps *set,
+			   source_location location)
+{
+  const struct line_map *map = NULL;
+
+  if (location < RESERVED_LOCATION_COUNT)
+    return 0;
+
+  location =
+    linemap_macro_loc_to_exp_point (set, location, &map);
+
+  return SOURCE_COLUMN (map, location);
+}
+
+/* Return the path of the file corresponding to source code location
+   LOCATION.
+
+   If LOCATION is the source location of token that is part of the
+   replacement-list of a macro expansion return the file path of the
+   macro expansion point.
+
+   SET is the line map set LOCATION comes from.  */
+
+const char*
+linemap_get_file_path (struct line_maps *set,
+		       source_location location)
+{
+  const struct line_map *map = NULL;
+
+  if (location < RESERVED_LOCATION_COUNT)
+    return NULL;
+
+  location =
+    linemap_macro_loc_to_exp_point (set, location, &map);
+
+  return LINEMAP_FILE (map);
+}
+
+/* Return the name of the macro associated to MACRO_MAP.  */
+
+const char*
+linemap_map_get_macro_name (const struct line_map* macro_map)
+{
+  linemap_assert (macro_map && linemap_macro_expansion_map_p (macro_map));
+  return (const char*) NODE_NAME (MACRO_MAP_MACRO (macro_map));
+}
+
+/* Return a positive value if LOCATION is the locus of a token that is
+   located in a system header, O otherwise. It returns 1 if LOCATION
+   is the locus of a token that is located in a system header, and 2
+   if LOCATION is the locus of a token located in a C system header
+   that therefore needs to be extern "C" protected in C++.
+
+   Note that this function returns 0 if LOCATION belongs to a token
+   that is part of a macro replacement-list defined in a system
+   header, but expanded in a non-system file.  */
+
+int
+linemap_location_in_system_header_p (struct line_maps *set,
+				     source_location location)
+{
+  const struct line_map *map = NULL;
+
+  if (location < RESERVED_LOCATION_COUNT)
+    return false;
+
+  location =
+    linemap_resolve_location (set, location, LRK_SPELLING_LOCATION, &map);
+
+  return LINEMAP_SYSP (map);
+}
+
+/* Return TRUE if LOCATION is a source code location of a token coming
+   from a macro replacement-list at a macro expansion point, FALSE
+   otherwise.  */
+
+bool
+linemap_location_from_macro_expansion_p (struct line_maps *set,
+					 source_location location)
+{
+  linemap_assert (location <= MAX_SOURCE_LOCATION
+		  && (set->highest_location
+		      < LINEMAPS_MACRO_LOWEST_LOCATION (set)));
+  if (set == NULL)
+    return false;
+  return (location > set->highest_location);
+}
+
+/* Return TRUE if PRE denotes a location that is before POST, FALSE
+   otherwise. LINE_MAPS is the set of line maps PRE and POST were
+   allocated from.  */
+
+bool
+linemap_location_before_p (struct line_maps *set,
+			   source_location  pre,
+			   source_location post)
+{
+  bool pre_from_macro_p, post_from_macro_p;
+
+  if (pre == post)
+    return false;
+
+  pre_from_macro_p =
+    linemap_location_from_macro_expansion_p (set, pre);
+  post_from_macro_p =
+    linemap_location_from_macro_expansion_p (set, post);
+
+  if (pre_from_macro_p != post_from_macro_p)
+    {
+      if (pre_from_macro_p)
+	pre = linemap_macro_loc_to_exp_point (set, pre, NULL);
+      else
+	post = linemap_macro_loc_to_exp_point (set, post, NULL);
+    }
+
+  return pre < post;
 }
 
 /* Print an include trace, for e.g. the -H option of the preprocessor.  */
@@ -313,5 +806,249 @@  trace_include (const struct line_maps *set, const struct line_map *map)
 
   while (--i)
     putc ('.', stderr);
-  fprintf (stderr, " %s\n", map->to_file);
+
+  fprintf (stderr, " %s\n", ORDINARY_MAP_FILE_NAME (map));
+}
+
+/* If LOCATION is the locus of a token that is an argument of a
+   function-like macro M, return the location of that token in the
+   context of the definition of the first macro P which expansion
+   triggered the expansion of M.  Note that the token must be actually
+   present in the source of the definition of P.  If LOCATION is the
+   locus of a token that belongs to a macro replacement-list but is
+   not an argument to a function-like macro, return the same thing as
+   what linemap_macor_loc_to_def_point would have returned.
+   ORIGINAL_MAP is an output parm.  If non NULL, *ORIGINAL_MAP is set
+   to the ordinary (non-macro) map of the returned location comes
+   from.
+
+   This is a subroutine for linemap_resolve_location.  */
+
+static source_location
+linemap_macro_loc_unwind (struct line_maps *set,
+			  source_location location,
+			  const struct line_map **original_map)
+{
+  struct line_map *map;
+
+  linemap_assert (set && location >= RESERVED_LOCATION_COUNT);
+
+  while (true)
+    {
+      map = (struct line_map*) linemap_lookup (set, location);
+      if (!linemap_macro_expansion_map_p (map))
+	break;
+
+      location =
+	linemap_macro_map_loc_unwind_once (map, location);
+    }
+
+  if (original_map)
+    *original_map = map;
+  return location;
+}
+
+/* If LOCATION is the source location of a token that belongs to a
+   macro replacement-list -- as part of a macro expansion -- then
+   return the location of the token at the definition point of the
+   macro.  Otherwise, return LOCATION.  SET is the set of maps
+   location come from.  ORIGINAL_MAP is an output parm. If non NULL,
+   the function sets *ORIGINAL_MAP to the ordinary (non-macro) map the
+   returned location comes from. 
+
+   This is a subroutine of linemap_resolve_location.  */
+
+static source_location
+linemap_macro_loc_to_def_point (struct line_maps *set,
+				source_location location,
+				const struct line_map **original_map)
+{
+  struct line_map *map;
+
+  linemap_assert (set && location >= RESERVED_LOCATION_COUNT);
+
+  while (true)
+    {
+      map = (struct line_map*) linemap_lookup (set, location);
+      if (!linemap_macro_expansion_map_p (map))
+	break;
+
+      location =
+	linemap_macro_map_loc_to_def_point (map, location);
+    }
+
+  if (original_map)
+    *original_map = map;
+  return location;
+}
+
+/* If LOCATION is the source location of a token that belongs to a
+   macro replacement-list -- at a macro expansion point -- then return
+   the location of the topmost expansion point of the macro.  We say
+   topmost because if we are in the context of a nested macro
+   expansion, the function returns the source location of the first
+   macro expansion that triggered the nested expansions.
+
+   Otherwise, return LOCATION.  SET is the set of maps location come
+   from.  ORIGINAL_MAP is an output parm. If non NULL, the function
+   sets *ORIGINAL_MAP to the ordinary (non-macro) map the returned
+   location comes from.
+
+   This is a subroutine of linemap_resolve_location.  */
+
+static source_location
+linemap_macro_loc_to_exp_point (struct line_maps *set,
+				source_location location,
+				const struct line_map **original_map)
+{
+  struct line_map *map;
+
+  linemap_assert (set && location >= RESERVED_LOCATION_COUNT);
+
+  while (true)
+    {
+      map = (struct line_map*) linemap_lookup (set, location);
+      if (!linemap_macro_expansion_map_p (map))
+	break;
+      location = linemap_macro_map_loc_to_exp_point (map, location);
+    }
+
+  if (original_map)
+    *original_map = map;
+  return location;
+}
+
+/* Resolve a virtual location into either a spelling location, an
+   expansion point location or a token argument replacement point
+   location.  Return the map that encodes the virtual location as well
+   as the resolved location.
+
+   If LOC is *NOT* the location of a token resulting from the
+   expansion of a macro, then the parameter LRK (which stands for
+   Location Resolution Kind) is ignored and the resulting location
+   just equals the one given in argument.
+
+   Now if LOC *IS* the location of a token resulting from the
+   expansion of a macro, this is what happens.
+
+   * If LRK is set to LRK_MACRO_EXPANSION_POINT
+   -------------------------------
+
+   The virtual location is resolved to the location to the locus of
+   the expansion point of the macro.
+
+   * If LRK is set to LRK_SPELLING_LOCATION
+   -------------------------------------
+
+   The virtual location is resolved to the location to the locus where
+   the token has been spelled in the source. This can follow through
+   all the macro expansions that led to the token.
+
+   * If LRK is set to LRK_MACRO_PARM_REPLACEMENT_POINT
+   --------------------------------------
+
+   If LOC is the locus of a token that is an argument of a
+   function-like macro [replacing a parameter in the replacement list
+   of the macro] the virtual location is resolved to the locus of the
+   parameter that is replaced, in the context of the definition of the
+   macro.
+
+   If LOC is the locus of a token that is not an argument of a
+   function-like macro, then the function behaves as if LRK was set to
+   LRK_SPELLING_LOCATION.
+
+   If MAP is non-NULL, *MAP is set to the map of the resolved
+   location.  */
+
+source_location
+linemap_resolve_location (struct line_maps *set,
+			  source_location loc,
+			  enum location_resolution_kind lrk,
+			  const struct line_map **map)
+{
+  linemap_assert (set && loc >= RESERVED_LOCATION_COUNT);
+
+  switch (lrk)
+    {
+    case LRK_MACRO_EXPANSION_POINT:
+      loc = linemap_macro_loc_to_exp_point (set, loc, map);
+      break;
+    case LRK_SPELLING_LOCATION:
+      loc = linemap_macro_loc_unwind (set, loc, map);
+      break;
+    case LRK_MACRO_DEFINITION_LOCATION:
+      loc = linemap_macro_loc_to_def_point (set, loc, map);
+      break;
+    default:
+      abort ();
+    }
+  return loc;
+}
+
+/* 
+   Suppose that LOC is the virtual location of a token T coming from
+   the expansion of a macro M.  This function then steps up to get the
+   location L of the point where M got expanded.  If L is a spelling
+   location inside a macro expansion M', then this function returns
+   the locus of the point where M' was expanded.  Said otherwise, this
+   function returns the location of T in the context that triggered
+   the expansion of M. 
+
+   *LOC_MAP must be set to the map of LOC.  This function then sets it
+   to the map of the returned location.  */
+
+source_location
+linemap_step_out_once (struct line_maps *set,
+		       source_location loc,
+		       const struct line_map **map)
+{
+  source_location resolved_location;
+  const struct line_map *resolved_map;
+
+  resolved_location = linemap_macro_map_loc_unwind_once (*map, loc);
+  resolved_map = linemap_lookup (set, resolved_location);
+
+  if (!linemap_macro_expansion_map_p (resolved_map))
+    {
+      resolved_location = linemap_macro_map_loc_to_exp_point (*map, loc);
+      resolved_map = linemap_lookup (set, resolved_location);
+    }
+
+  *map = resolved_map;
+  return resolved_location;
+}
+
+/* Expand source code location LOC and return a user readable source
+   code location.  */
+
+expanded_location
+linemap_expand_location (const struct line_map *map,
+			 source_location loc)
+
+{
+  expanded_location xloc;
+
+  xloc.file = LINEMAP_FILE (map);
+  xloc.line = SOURCE_LINE (map, loc);
+  xloc.column = SOURCE_COLUMN (map, loc);
+  xloc.sysp = LINEMAP_SYSP (map) != 0;
+
+  return xloc;
+}
+
+/* Expand source code location LOC and return a user readable source
+   code location.  The LRK parameter is the same as for
+   linemap_resolve_location.  */
+
+expanded_location
+linemap_expand_location_full (struct line_maps *set,
+			      source_location loc,
+			      enum location_resolution_kind lrk)
+{
+  const struct line_map *map;
+  expanded_location xloc;
+
+  loc = linemap_resolve_location (set, loc, lrk, &map);
+  xloc = linemap_expand_location (map, loc);
+  return xloc;
 }
diff --git a/libcpp/macro.c b/libcpp/macro.c
index eba2349..03fe79e 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -177,7 +177,7 @@  _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node)
 	  while (! MAIN_FILE_P (map))
 	    map = INCLUDED_FROM (pfile->line_table, map);
 
-	name = map->to_file;
+	name = ORDINARY_MAP_FILE_NAME (map);
 	len = strlen (name);
 	buf = _cpp_unaligned_alloc (pfile, len * 2 + 3);
 	result = buf;
@@ -196,14 +196,14 @@  _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node)
       break;
 
     case BT_SPECLINE:
-      map = &pfile->line_table->maps[pfile->line_table->used-1];
+      map = LINEMAPS_LAST_ORDINARY_MAP (pfile->line_table);
       /* If __LINE__ is embedded in a macro, it must expand to the
 	 line of the macro's invocation, not its definition.
 	 Otherwise things like assert() will not work properly.  */
-      number = SOURCE_LINE (map, 
-			    CPP_OPTION (pfile, traditional) 
-			    ? pfile->line_table->highest_line
-			    : pfile->cur_token[-1].src_loc);
+      number = linemap_get_source_line (pfile->line_table,
+					CPP_OPTION (pfile, traditional)
+					? pfile->line_table->highest_line
+					: pfile->cur_token[-1].src_loc);
       break;
 
       /* __STDC__ has the value 1 under normal circumstances.
-- 
1.7.6.2


From: Dodji Seketeli <dodji@redhat.com>
Date: Sat, 4 Dec 2010 17:08:56 +0100
Subject: [PATCH 4/7] Support -fdebug-cpp option

This patch adds -fdebug-cpp option. When used with -E this dumps the
relevant macro map before every single token. This clutters the output
a lot but has proved to be invaluable in tracking some bugs during the
development of the virtual location support.

Tested on x86_64-unknown-linux-gnu against trunk.

libcpp/

	* include/cpplib.h (struct cpp_options)<debug>: New struct member.
	* include/line-map.h (linemap_dump_location): Declare ...
	* line-map.c (linemap_dump_location): ... new function.

gcc/

	* doc/cppopts.texi: Document -fdebug-cpp.
	* doc/invoke.texi: Add -fdebug-cpp to the list of preprocessor
	options.

gcc/c-family/

	* c.opt (fdebug-cpp): New option.
	* c-opts.c (c_common_handle_option): Handle the option.
	* c-ppoutput.c (maybe_print_line_1): New static function. Takes an
	output stream in parameter. Factorized from ...
	(maybe_print_line): ... this. Dump location debug information when
	-fdebug-cpp is in effect.
	(print_line_1): New static function. Takes an output stream in
	parameter. Factorized from ...
	(print_line): ... here. Dump location information when -fdebug-cpp
	is in effect.
	(scan_translation_unit): Dump location information when
	-fdebug-cpp is in effect.
---
 gcc/c-family/c-opts.c     |    4 +++
 gcc/c-family/c-ppoutput.c |   57 ++++++++++++++++++++++++++++++++++++--------
 gcc/c-family/c.opt        |    4 +++
 gcc/doc/cppopts.texi      |   13 ++++++++++
 gcc/doc/invoke.texi       |    2 +-
 libcpp/include/cpplib.h   |    4 +++
 libcpp/include/line-map.h |    4 +++
 libcpp/line-map.c         |   38 ++++++++++++++++++++++++++++++
 8 files changed, 114 insertions(+), 12 deletions(-)

diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 3184539..6869d5c 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -628,6 +628,10 @@  c_common_handle_option (size_t scode, const char *arg, int value,
       cpp_opts->preprocessed = value;
       break;
 
+    case OPT_fdebug_cpp:
+      cpp_opts->debug = 1;
+      break;
+
     case OPT_ftrack_macro_expansion:
       if (value)
 	value = 2;
diff --git a/gcc/c-family/c-ppoutput.c b/gcc/c-family/c-ppoutput.c
index 892f1ea..df46ce4 100644
--- a/gcc/c-family/c-ppoutput.c
+++ b/gcc/c-family/c-ppoutput.c
@@ -59,7 +59,9 @@  static void account_for_newlines (const unsigned char *, size_t);
 static int dump_macro (cpp_reader *, cpp_hashnode *, void *);
 static void dump_queued_macros (cpp_reader *);
 
+static void print_line_1 (source_location, const char*, FILE *);
 static void print_line (source_location, const char *);
+static void maybe_print_line_1 (source_location, FILE *);
 static void maybe_print_line (source_location);
 static void do_line_change (cpp_reader *, const cpp_token *,
 			    source_location, int);
@@ -243,7 +245,12 @@  scan_translation_unit (cpp_reader *pfile)
 	  in_pragma = false;
 	}
       else
-	cpp_output_token (token, print.outf);
+	{
+	  if (cpp_get_options (parse_in)->debug)
+	      linemap_dump_location (line_table, token->src_loc,
+				     print.outf);
+	  cpp_output_token (token, print.outf);
+	}
 
       if (token->type == CPP_COMMENT)
 	account_for_newlines (token->val.str.text, token->val.str.len);
@@ -297,8 +304,9 @@  scan_translation_unit_trad (cpp_reader *pfile)
 /* If the token read on logical line LINE needs to be output on a
    different line to the current one, output the required newlines or
    a line marker, and return 1.  Otherwise return 0.  */
+
 static void
-maybe_print_line (source_location src_loc)
+maybe_print_line_1 (source_location src_loc, FILE *stream)
 {
   int src_line = LOCATION_LINE (src_loc);
   const char *src_file = LOCATION_FILE (src_loc);
@@ -306,7 +314,7 @@  maybe_print_line (source_location src_loc)
   /* End the previous line of text.  */
   if (print.printed)
     {
-      putc ('\n', print.outf);
+      putc ('\n', stream);
       print.src_line++;
       print.printed = 0;
     }
@@ -318,22 +326,37 @@  maybe_print_line (source_location src_loc)
     {
       while (src_line > print.src_line)
 	{
-	  putc ('\n', print.outf);
+	  putc ('\n', stream);
 	  print.src_line++;
 	}
     }
   else
-    print_line (src_loc, "");
+    print_line_1 (src_loc, "", stream);
+
+}
+
+/* If the token read on logical line LINE needs to be output on a
+   different line to the current one, output the required newlines or
+   a line marker, and return 1.  Otherwise return 0.  */
+
+static void
+maybe_print_line (source_location src_loc)
+{
+  if (cpp_get_options (parse_in)->debug)
+    linemap_dump_location (line_table, src_loc,
+			   print.outf);
+  maybe_print_line_1 (src_loc, print.outf);
 }
 
 /* Output a line marker for logical line LINE.  Special flags are "1"
    or "2" indicating entering or leaving a file.  */
+
 static void
-print_line (source_location src_loc, const char *special_flags)
+print_line_1 (source_location src_loc, const char *special_flags, FILE *stream)
 {
   /* End any previous line of text.  */
   if (print.printed)
-    putc ('\n', print.outf);
+    putc ('\n', stream);
   print.printed = 0;
 
   if (!flag_no_line_commands)
@@ -354,20 +377,32 @@  print_line (source_location src_loc, const char *special_flags)
 			    (const unsigned char *) file_path,
 			    to_file_len);
       *p = '\0';
-      fprintf (print.outf, "# %u \"%s\"%s",
+      fprintf (stream, "# %u \"%s\"%s",
 	       print.src_line == 0 ? 1 : print.src_line,
 	       to_file_quoted, special_flags);
 
       sysp = in_system_header_at (src_loc);
       if (sysp == 2)
-	fputs (" 3 4", print.outf);
+	fputs (" 3 4", stream);
       else if (sysp == 1)
-	fputs (" 3", print.outf);
+	fputs (" 3", stream);
 
-      putc ('\n', print.outf);
+      putc ('\n', stream);
     }
 }
 
+/* Output a line marker for logical line LINE.  Special flags are "1"
+   or "2" indicating entering or leaving a file.  */
+
+static void
+print_line (source_location src_loc, const char *special_flags)
+{
+    if (cpp_get_options (parse_in)->debug)
+      linemap_dump_location (line_table, src_loc,
+			     print.outf);
+    print_line_1 (src_loc, special_flags, print.outf);
+}
+
 /* Helper function for cb_line_change and scan_translation_unit.  */
 static void
 do_line_change (cpp_reader *pfile, const cpp_token *token,
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 07a6b87..f9db8f1 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -739,6 +739,10 @@  fconstexpr-depth=
 C++ ObjC++ Joined RejectNegative UInteger Var(max_constexpr_depth) Init(512)
 -fconstexpr-depth=<number>	Specify maximum constexpr recursion depth
 
+fdebug-cpp
+C ObjC C++ ObjC++
+Emit debug annotations during preprocessing
+
 fdeduce-init-list
 C++ ObjC++ Var(flag_deduce_init_list) Init(1)
 -fno-deduce-init-list	disable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
diff --git a/gcc/doc/cppopts.texi b/gcc/doc/cppopts.texi
index b225236..ef3a0b2 100644
--- a/gcc/doc/cppopts.texi
+++ b/gcc/doc/cppopts.texi
@@ -583,6 +583,19 @@  correct column numbers in warnings or errors, even if tabs appear on the
 line.  If the value is less than 1 or greater than 100, the option is
 ignored.  The default is 8.
 
+@item -fdebug-cpp
+@opindex fdebug-cpp
+This option is only useful for debugging GCC.  When used with
+@option{-E}, dumps debugging information about location maps.  Every
+token in the output is preceded by the dump of the map its location
+belongs to.  The dump of the map holding the location of a token would
+be:
+@quotation
+@{@samp{P}:@file{/file/path};@samp{F}:@file{/includer/path};@samp{L}:@var{line_num};@samp{C}:@var{col_num};@samp{S}:@var{system_header_p};@samp{M}:@var{map_address};@samp{E}:@var{macro_expansion_p},@samp{loc}:@var{location}@}
+@end quotation
+
+When used without @option{-E}, this option has no effect.
+
 @item -ftrack-macro-expansion@r{[}=@var{level}@r{]}
 @opindex ftrack-macro-expansion
 Track locations of tokens across macro expansions. This allows the
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7e1b7c2..fedcf84 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -428,7 +428,7 @@  Objective-C and Objective-C++ Dialects}.
 -iwithprefixbefore @var{dir}  -isystem @var{dir} @gol
 -imultilib @var{dir} -isysroot @var{dir} @gol
 -M  -MM  -MF  -MG  -MP  -MQ  -MT  -nostdinc  @gol
--P -ftrack-macro-expansion -fworking-directory @gol
+-P  -fdebug-cpp -ftrack-macro-expansion -fworking-directory @gol
 -remap -trigraphs  -undef  -U@var{macro}  @gol
 -Wp,@var{option} -Xpreprocessor @var{option}}
 
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 3e01c11..825bf2f 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -392,6 +392,10 @@  struct cpp_options
   /* Nonzero means we're looking at already preprocessed code, so don't
      bother trying to do macro expansion and whatnot.  */
   unsigned char preprocessed;
+  
+  /* Nonzero means we are going to emit debugging logs during
+     preprocessing.  */
+  unsigned char debug;
 
   /* Nonzero means we are tracking locations of tokens involved in
      macro expansion. 1 Means we track the location in degraded mode
diff --git a/libcpp/include/line-map.h b/libcpp/include/line-map.h
index 3a6c08a..5dab4d0 100644
--- a/libcpp/include/line-map.h
+++ b/libcpp/include/line-map.h
@@ -788,4 +788,8 @@  expanded_location linemap_expand_location_full (struct line_maps *,
 						source_location loc,
 						enum location_resolution_kind lrk);
 
+/* Dump debugging information about source location LOC into the file
+   stream STREAM. SET is the line map set LOC comes from.  */
+void linemap_dump_location (struct line_maps *, source_location, FILE *);
+
 #endif /* !LIBCPP_LINE_MAP_H  */
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index ae73ed6..11703fc 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -1052,3 +1052,41 @@  linemap_expand_location_full (struct line_maps *set,
   xloc = linemap_expand_location (map, loc);
   return xloc;
 }
+
+/* Dump debugging information about source location LOC into the file
+   stream STREAM. SET is the line map set LOC comes from.  */
+
+void
+linemap_dump_location (struct line_maps *set,
+		       source_location loc,
+		       FILE *stream)
+{
+  const struct line_map *map;
+  source_location location;
+  const char *path, *from;
+  int l,c,s,e;
+
+  if (loc == 0)
+    return;
+
+  location =
+    linemap_resolve_location (set, loc, LRK_MACRO_DEFINITION_LOCATION, &map);
+  path = LINEMAP_FILE (map);
+
+  l = SOURCE_LINE (map, location);
+  c = SOURCE_COLUMN (map, location);
+  s = LINEMAP_SYSP (map) != 0;
+  e = location != loc;
+
+  if (e)
+    from = "N/A";
+  else
+    from = (INCLUDED_FROM (set, map))
+      ? LINEMAP_FILE (INCLUDED_FROM (set, map))
+      : "<NULL>";
+
+  /* P: path, L: line, C: column, S: in-system-header, M: map address,
+     E: macro expansion?.   */
+  fprintf (stream, "{P:%s;F:%s;L:%d;C:%d;S:%d;M:%p;E:%d,LOC:%d}",
+	   path, from, l, c, s, (void*)map, e, loc);
+}