Patchwork [C] Add -Wint-conversion option

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Submitter Marek Polacek
Date June 30, 2014, 6:31 p.m.
Message ID <20140630183149.GE20427@redhat.com>
Download mbox | patch
Permalink /patch/365714/
State New
Headers show

Comments

Marek Polacek - June 30, 2014, 6:31 p.m.
Basically everything I wrote in the patch for -Wincompatible-pointer-types
applies here as well.  A new option, -Wint-conversion (to be compatible
with clang), is added to allow more fine-grained control over the warnings.
I think we should print the types here as well, and moreover, we could hint the
user that & or * may be used to fix the code.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2014-06-30  Marek Polacek  <polacek@redhat.com>

	* doc/invoke.texi: Document -Wint-conversion.
c-family/
	* c.opt (Wint-conversion): New option.
c/
	* c-typeck.c (convert_for_assignment): Pass OPT_Wint_conversion
	instead of 0 to WARN_FOR_ASSIGNMENT.
testsuite/
	* gcc.dg/Wint-conversion.c: New test.


	Marek
Joseph S. Myers - June 30, 2014, 8:16 p.m.
On Mon, 30 Jun 2014, Marek Polacek wrote:

> Basically everything I wrote in the patch for -Wincompatible-pointer-types
> applies here as well.  A new option, -Wint-conversion (to be compatible
> with clang), is added to allow more fine-grained control over the warnings.
> I think we should print the types here as well, and moreover, we could hint the
> user that & or * may be used to fix the code.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

OK with the documentation amended to make clear this is about *implicit* 
conversions, not the cases covered by -Wno-int-to-pointer-cast and 
-Wno-pointer-to-int-cast.
Gerald Pfeifer - June 30, 2014, 8:51 p.m.
Can you please add this and the other one to gcc-4.10/changes.html?

I can provide help if you need any.

Gerald
Jakub Jelinek - June 30, 2014, 8:54 p.m.
On Mon, Jun 30, 2014 at 10:51:59PM +0200, Gerald Pfeifer wrote:
> Can you please add this and the other one to gcc-4.10/changes.html?
> 
> I can provide help if you need any.

We don't have gcc-4.10/ directory, because the version of the next release
is still to be decided (hopefully at Cauldron next month).

	Jakub
Gerald Pfeifer - June 30, 2014, 9:07 p.m.
On Mon, 30 Jun 2014, Jakub Jelinek wrote:
> We don't have gcc-4.10/ directory, because the version of the next 
> release is still to be decided (hopefully at Cauldron next month).

I'm a bit worried we'll miss entries in the meantime.

Can we use gcc-4.10/ for now and rename later if we go for
GCC V or whatever? :-)

Gerald
Marek Polacek - July 1, 2014, 9:33 a.m.
On Mon, Jun 30, 2014 at 11:07:57PM +0200, Gerald Pfeifer wrote:
> On Mon, 30 Jun 2014, Jakub Jelinek wrote:
> > We don't have gcc-4.10/ directory, because the version of the next 
> > release is still to be decided (hopefully at Cauldron next month).
> 
> I'm a bit worried we'll miss entries in the meantime.
> 
> Can we use gcc-4.10/ for now and rename later if we go for
> GCC V or whatever? :-)

Well, looks like I can't do much right now, so I'll go through my C FE
changes and new ubsan features after we have some actual changes.html,
and post a patch then...

	Marek

Patch

diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 6448b1b..c89040a 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -474,6 +474,10 @@  Winherited-variadic-ctor
 C++ ObjC++ Var(warn_inh_var_ctor) Init(1) Warning
 Warn about C++11 inheriting constructors when the base has a variadic constructor
 
+Wint-conversion
+C ObjC Var(warn_int_conversion) Init(1) Warning
+Warn about incompatible integer to pointer and pointer to integer conversions
+
 Wint-to-pointer-cast
 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
 Warn when there is a cast to a pointer from an integer of a different size
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index fff26a3..35bfd14 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -6213,7 +6213,8 @@  convert_for_assignment (location_t location, location_t expr_loc, tree type,
 	 or one that results from arithmetic, even including
 	 a cast to integer type.  */
       if (!null_pointer_constant)
-	WARN_FOR_ASSIGNMENT (location, expr_loc, 0,
+	WARN_FOR_ASSIGNMENT (location, expr_loc,
+			     OPT_Wint_conversion,
 			     G_("passing argument %d of %qE makes "
 				"pointer from integer without a cast"),
 			     G_("assignment makes pointer from integer "
@@ -6227,7 +6228,8 @@  convert_for_assignment (location_t location, location_t expr_loc, tree type,
     }
   else if (codel == INTEGER_TYPE && coder == POINTER_TYPE)
     {
-      WARN_FOR_ASSIGNMENT (location, expr_loc, 0,
+      WARN_FOR_ASSIGNMENT (location, expr_loc,
+			   OPT_Wint_conversion,
 			   G_("passing argument %d of %qE makes integer "
 			      "from pointer without a cast"),
 			   G_("assignment makes integer from pointer "
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index dfae4f0..e6e71c0 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -253,7 +253,7 @@  Objective-C and Objective-C++ Dialects}.
 -Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
 -Wignored-qualifiers  -Wincompatible-pointer-types @gol
 -Wimplicit  -Wimplicit-function-declaration  -Wimplicit-int @gol
--Winit-self  -Winline @gol
+-Winit-self  -Winline  -Wno-int-conversion @gol
 -Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
 -Winvalid-pch -Wlarger-than=@var{len}  -Wunsafe-loop-optimizations @gol
 -Wlogical-op -Wlogical-not-parentheses -Wlong-long @gol
@@ -4213,6 +4213,12 @@  can be used to suppress such a warning.
 Do not warn when there is a conversion between pointers that have incompatible
 types.
 
+@item -Wno-int-conversion @r{(C and Objective-C only)}
+@opindex Wno-int-conversion
+@opindex Wint-conversion
+Do not warn about incompatible integer to pointer and pointer to integer
+conversions.
+
 @item -Wno-div-by-zero
 @opindex Wno-div-by-zero
 @opindex Wdiv-by-zero
diff --git gcc/testsuite/gcc.dg/Wint-conversion.c gcc/testsuite/gcc.dg/Wint-conversion.c
index e69de29..1b7a03e 100644
--- gcc/testsuite/gcc.dg/Wint-conversion.c
+++ gcc/testsuite/gcc.dg/Wint-conversion.c
@@ -0,0 +1,22 @@ 
+/* { dg-do compile } */
+/* { dg-options "-Wno-int-conversion" } */
+
+int fn1 (int *), *fn2 (int);
+
+int
+fn1 (int *p)
+{
+  int i = p;
+  i = p;
+  fn2 (p);
+  return p;
+}
+
+int *
+fn2 (int i)
+{
+  int *p = i;
+  p = i;
+  fn1 (i);
+  return i;
+}