PR preprocessor/7263 - Avoid pedantic warnings on system headers macro tokens

Hello,

Now that we track token locations accross macro expansions, it would
be cool to be able to fix PR preprocessor/7263 for real.  That is,
consider this example where we have a system header named header.h
like this:

	#define _Complex __complex__ #define _Complex_I 1.0iF

and then a normal C file like this:

    #include "header.h"

    static _Complex float c = _Complex_I;

If we compile the file with -pedantic, the usages of _Complex or
_Complex_I should not trigger any warning, even though __complex__ and
the complex literal are extensions to the standard C.

They shouldn't trigger any warning because _Complex and _Complex_I are
defined in a system header (and expanded in normal user code).

To be able to handle this, we must address two separate concerns.

First, warnings about non-standard usage of numerical literals are emitted
directly from within libcpp.  So we must teach libcpp's parser for numerical
literals to use virtual locations, instead of the spelling
location it uses today.  Once we have that, as the diagnostics machinery
already knows how to avoid emitting errors happening on tokens that come from
system headers, we win.

Second, there is the issue of tracking locations for declaration
specifiers, like the "_Complex" in the declaration:

	static _Complex float c;

For that, we need to arrange for each possible declaration specifier
to have its own location, because otherwise, we'd warn on e.g, on:

_Complex float c;

but not on:

    static _Complex float c;

So this patch addresses the two concerns above.  It's actually a
follow-up on an earlier patch[1] I wrote as part of my initial work on
virtual locations.  We then agreed[2] that the second concern was
important to address before the patch could get a chance to go in.

[1]: http://gcc.gnu.org/ml/gcc-patches/2011-09/msg00957.html
[2]: http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00264.html

Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk.

libcpp/

	PR preprocessor/7263
	* include/cpplib.h (cpp_classify_number): Take a location
	parameter.
	* expr.c (SYNTAX_ERROR_AT, SYNTAX_ERROR2_AT): New diagnostic
	macros that take a location parameter.
	(cpp_classify_number): Take a (virtual) location parameter.  Use
	it for diagnostics.  Adjust comments.
	(eval_token): Take a location parameter.  Pass it to
	cpp_classify_number and to diagnostic routines.
	(_cpp_parse_expr): Use virtual locations of tokens when parsing
	expressions.  Pass a virtual location to eval_token and to
	diagnostic routines.

gcc/c-family/

	PR preprocessor/7263
	* c-lex.c (c_lex_with_flags):  Pass a virtual location to the call
	to cpp_classify_number.  For diagnostics, use the precise location
	instead of the global input_location.

gcc/
	PR preprocessor/7263
	* c-tree.h (enum c_declspec_word): Declare new enum.
	(struct c_declspecs::locations): New member.
	(declspecs_add_qual, declspecs_add_scspec)
	(declspecs_add_addrspace, declspecs_add_alignas): Take a new
	location parameter.
	* c-decl.c (build_null_declspecs): Initialize the new struct
	c_declspecs::locations member.
	(declspecs_add_addrspace): Take a location parameter for the
	address space.  Store it onto declaration specifiers.
	(declspecs_add_qual): Likewise, take a location parameter for the
	qualifier.
	(declspecs_add_type): Likewise, take a location parameter for the
	type specifier.
	(declspecs_add_scspec): Likewise, take a location parameter for
	the storage class specifier.
	(declspecs_add_attrs): Likewise, take a location parameter for the
	first attribute.
	(declspecs_add_alignas): Likewise, take a location parameter for
	the alignas token.
	(finish_declspecs): For diagnostics, use the location of the
	relevant declspec, instead of the global input_location.
	* c-parser.c (c_parser_parameter_declaration): Pass the precise
	virtual location of the declspec to the declspecs-setters.
	(c_parser_declspecs): Likewise.  Avoid calling c_parser_peek_token
	repeatedly.

gcc/cp/

	PR preprocessor/7263
	* cp-tree.h (enum cp_decl_spec_word): Declare new enum.
	(struct cp_decl_specifier_seq::locations): Declare new member.
	(struct cp_decl_specifier_seq::type_location): Remove.
	* parser.c (cp_parser_check_decl_spec): Remove the location
	parameter.  For diagnostics, use the location from the relevant
	declspec.
	(cp_parser_decl_specifier_seq, cp_parser_function_specifier_opt)
	(cp_parser_type_specifier, cp_parser_simple_type_specifier)
	(cp_parser_set_storage_class, cp_parser_set_decl_spec_type): Set
	the locations for each declspec.
	(cp_parser_explicit_instantiation, cp_parser_init_declarator)
	(cp_parser_member_declaration): Use the new declspec location for
	type specifiers.
	(cp_parser_type_specifier_seq): Adjust call to
	cp_parser_check_decl_spec.

gcc/testsuite/

	PR preprocessor/7263
	* gcc.dg/binary-constants-2.c: Run without tracking locations
	accross macro expansion.
	* gcc.dg/binary-constants-3.c: Likewise.
	* gcc.dg/cpp/sysmac2.c: Likewise.
	* testsuite/gcc.dg/nofixed-point-2.c: Adjust for more precise
	location.
	* gcc.dg/cpp/syshdr3.c: New test.
	* gcc.dg/cpp/syshdr3.h: New header for the new test above.
	* gcc.dg/system-binary-constants-1.c: New test.
	* gcc.dg/system-binary-constants-1.h: New header for the new test
	above.
	* g++.dg/cpp/syshdr3.C: New test.
	* g++.dg/cpp/syshdr3.h: New header the new test above.
	* g++.dg/system-binary-constants-1.C: New test.
	* g++.dg/system-binary-constants-1.h: New header the new test
	above.
---
 gcc/c-decl.c                                     |  127 ++++++++++++----
 gcc/c-family/c-lex.c                             |    4 +-
 gcc/c-parser.c                                   |   22 ++--
 gcc/c-tree.h                                     |   54 ++++++-
 gcc/cp/cp-tree.h                                 |   43 +++++-
 gcc/cp/parser.c                                  |   76 +++++++---
 gcc/testsuite/g++.dg/cpp/syshdr3.C               |   16 ++
 gcc/testsuite/g++.dg/cpp/syshdr3.h               |    7 +
 gcc/testsuite/g++.dg/system-binary-constants-1.C |   18 ++
 gcc/testsuite/g++.dg/system-binary-constants-1.h |    3 +
 gcc/testsuite/gcc.dg/binary-constants-2.c        |    2 +-
 gcc/testsuite/gcc.dg/binary-constants-3.c        |    2 +-
 gcc/testsuite/gcc.dg/cpp/pr7263-3.c              |    2 +-
 gcc/testsuite/gcc.dg/cpp/syshdr3.c               |   16 ++
 gcc/testsuite/gcc.dg/cpp/syshdr3.h               |    7 +
 gcc/testsuite/gcc.dg/cpp/sysmac1.c               |    2 +-
 gcc/testsuite/gcc.dg/cpp/sysmac2.c               |    2 +-
 gcc/testsuite/gcc.dg/nofixed-point-2.c           |    6 +-
 gcc/testsuite/gcc.dg/system-binary-constants-1.c |   18 ++
 gcc/testsuite/gcc.dg/system-binary-constants-1.h |    3 +
 libcpp/expr.c                                    |  182 +++++++++++++---------
 libcpp/include/cpplib.h                          |    2 +-
 22 files changed, 459 insertions(+), 155 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp/syshdr3.C
 create mode 100644 gcc/testsuite/g++.dg/cpp/syshdr3.h
 create mode 100644 gcc/testsuite/g++.dg/system-binary-constants-1.C
 create mode 100644 gcc/testsuite/g++.dg/system-binary-constants-1.h
 create mode 100644 gcc/testsuite/gcc.dg/cpp/syshdr3.c
 create mode 100644 gcc/testsuite/gcc.dg/cpp/syshdr3.h
 create mode 100644 gcc/testsuite/gcc.dg/system-binary-constants-1.c
 create mode 100644 gcc/testsuite/gcc.dg/system-binary-constants-1.h

PR preprocessor/7263 - Avoid pedantic warnings on system headers macro tokens

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