diff mbox

[PR,53001] Re: Patch to split out new warning flag for floating point conversion

Message ID 526D1E17.80001@yahoo.com
State New
Headers show

Commit Message

Joshua J Cogliati Oct. 27, 2013, 2:07 p.m. UTC 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

== Administrivia ==

This is my first patch.  I have emailed in the signed copyright transfer
documents already.  Several versions of this patch have been sent to
the mailing list already.  I believe that I have incorporated all
comments into the attached patches.


=== Description ===

As required by the C and C++ standards, gcc automatically converts
floating point numbers to lower precision or integer values.  Silently
converting these values is a problem for numerical programs.  GCC
already has a flag -Wconversion which does warn about these conversions,
but -Wconversion also warns about integer conversion which means for
many programs the number of warnings will be large.

This patch adds a -Wfloat-conversion that only warns on float
conversions.  Here are three examples that are warned by this new flag:

int main(int argc, char ** argv) {
  int i = 3.14;
  return i;
}

int foo(double x)
{
  return x;
}

float foo2(double x) {
  return x;
}

Additional examples can be seen in the new_testcase variants.

The -Wfloat-conversion is enabled by -Wconversion (since it is a
subset)

It was suggested on the discussion for bug 53001 that this be enabled by
- -Wextra, but this version of the patch does not because that requires
additional changes to other parts of gcc to still be able to bootstrap
with -Werror since they rely on C and C++'s implicit conversion from
floating point to integer types.

I am not certain that c.opt was modified correctly.

There are three different variants attached, they are identical but
for the testcases, so see that section for details on the differences.
 Only one of them should be applied.

== Testcases ==

There are three different methods of doing the testcase for these.

0.  warn_float_patch_simple_trunk.diff
This version changes the existing tests to check for float-coversion
instead of conversion in the warning text.  Since the testcases
already check for floating conversion in warnings, this is a possible
method of doing this.

1. warn_float_patch_and_new_testcase.diff
This adds a new testcase and checks for float-conversion in the
warning.  This will add somewhat more time for running the testcases
compared to version 1 while still testing more or less the same code
paths.  This does however check that the warning occurs when
- -Wconversion is not used.

2. warn_float_patch_and_new_testcase2.diff
This is the same as 1., but the warning check is more specific.  So
for example we have lines like:
fsi (3.1f); /* { dg-warning "conversion to 'int' alters 'float'
constant valu
e" } */
I am worried (possibly groundlessly) that this might not pass the
testcase on machines with different types that are available.


If you have a strong opinion or good reasons on which of these you
prefer, please tell me.

== Change logs ==
Changelog for warn_float_patch_simple_trunk.diff:


	Splitting out a -Wfloat-conversion from -Wconversion for
	conversions that lower floating point number precision
	or conversion from floating point numbers to integers
	* c-family/c-common.c Switching unsafe_conversion_p to
	return an enumeration with more detail, and conversion_warning
	to use this information.
	* c-family/c-common.h Adding conversion_safety enumeration
	and switching return type of unsafe_conversion_p
	* c-family/c.opt Adding new warning float-conversion and
	enabling it -Wconversion
	* doc/invoke.texi Adding documentation about
	-Wfloat-conversion
	* testsuite/c-c++-common/Wconversion-real.c Switching tests
	to use float-conversion
	* testsuite/gcc.dg/Wconversion-real-integer.c Switching
	tests to use float-conversion
	* testsuite/gcc.dg/pr35635.c Switching tests to use
	float-conversion

Changelog for warn_float_patch_and_new_testcase.diff and
warn_float_patch_and_new_testcase2.diff:

	Splitting out a -Wfloat-conversion from -Wconversion for
	conversions that lower floating point number precision
	or conversion from floating point numbers to integers
	* c-family/c-common.c Switching unsafe_conversion_p to
	return an enumeration with more detail, and conversion_warning
	to use this information.
	* c-family/c-common.h Adding conversion_safety enumeration
	and switching return type of unsafe_conversion_p
	* c-family/c.opt Adding new warning float-conversion and
	enabling it -Wconversion
	* doc/invoke.texi Adding documentation about
	-Wfloat-conversion
	* testsuite/c-c++-common/Wfloat-conversion.c Copies relevant
	tests from c-c++-common/Wconversion-real.c,
	gcc.dg/Wconversion-real-integer.c and gcc.dg/pr35635.c into
	new testcase for ones that are warned about by
	-Wfloat-conversion


== Bootstrapping and testing ==

Tested bootstrap on x86_64-unknown-linux-gnu for
- --enable-languages=c,c++,fortran,java,lto,objc with trunk on 203640
for variants 1. and 2.

Thank you for consideration of this patch.

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Comments

Dodji Seketeli Oct. 28, 2013, 8:50 a.m. UTC | #1 
Hello Joshua,

Joshua J Cogliati <jrincayc@yahoo.com> writes:

> I am not certain that c.opt was modified correctly.

I don't see any problem with the c.opt part.  So unless another
maintainer says otherwise, I'd say this is OK.

> 1. warn_float_patch_and_new_testcase.diff
> This adds a new testcase and checks for float-conversion in the
> warning.  This will add somewhat more time for running the testcases
> compared to version 1 while still testing more or less the same code
> paths.  This does however check that the warning occurs when
> -Wconversion is not used.

As said earlier, I'd really prefer this approach because it leaves the
existing tests alone and just adds new one.  I guess we cannot do much
at this point for the speed concern (okay, we could try and make the
test harness run more tests in parallel but that is a separate
discussion) and I think Joseph agrees too.  So please let's stick to
this approach.


> Changelog for warn_float_patch_and_new_testcase.diff and
> warn_float_patch_and_new_testcase2.diff:
> 
> 	Splitting out a -Wfloat-conversion from -Wconversion for
> 	conversions that lower floating point number precision
> 	or conversion from floating point numbers to integers
> 	* c-family/c-common.c Switching unsafe_conversion_p to
> 	return an enumeration with more detail, and conversion_warning
> 	to use this information.

Please, strictly follow the same format as the others entries in the
ChangeLog file.  That is, explicitly write the names of the functions
you changed, in parenthesis, followed by a colon.  That would make the
entry look like:

	* c-family/c-common.c (unsafe_conversion_p): Make this function
	return an enumeration with more detail.
	(conversion_warning): Use the new return type of
	unsafe_conversion_p to separately warn either about conversions
	that lower floating point number precision or about the other
	kinds of conversions.


> 	* c-family/c-common.h Adding conversion_safety enumeration
> 	and switching return type of unsafe_conversion_p

Likewise.

> 	* c-family/c.opt Adding new warning float-conversion and
> 	enabling it -Wconversion
> 	* doc/invoke.texi Adding documentation about
> 	-Wfloat-conversion

Likewise (colon missing at the end of the file name).


> 	* testsuite/c-c++-common/Wfloat-conversion.c Copies relevant
> 	tests from c-c++-common/Wconversion-real.c,
> 	gcc.dg/Wconversion-real-integer.c and gcc.dg/pr35635.c into
> 	new testcase for ones that are warned about by
> 	-Wfloat-conversion


You need to add the above ChangeLog entry to the ChangeLog file in
gcc/testsuite/ChangeLog.  Thus, the entry would look like (note how the
prefix testsuite/ is removed from the path name):

	* c-c++-common/Wfloat-conversion.c: New test file.  Its content
	started as a copy of c-c++-common/Wconversion-real.c,
	gcc.dg/Wconversion-real-integer.c and gcc.dg/pr35635.c.  It has
	been augmented by new tests to exercise the -Wfloat-conversion
	option.


> Index: gcc/testsuite/c-c++-common/Wfloat-conversion.c
> ===================================================================
> --- gcc/testsuite/c-c++-common/Wfloat-conversion.c	(working copy)
> +++ gcc/testsuite/c-c++-common/Wfloat-conversion.c	(working copy)
> @@ -1,85 +1,58 @@
>  /* Test for diagnostics for Wconversion for floating-point.  */

Hmmh.  I think this diff hunk should say that this is a new file.  Here
what it says is that it's a modification of an existing file.

Thank you for your time on this.
Joseph Myers Oct. 28, 2013, 1:11 p.m. UTC | #2 
On Mon, 28 Oct 2013, Dodji Seketeli wrote:

> 	* c-family/c-common.c (unsafe_conversion_p): Make this function

As previously noted, c-family/ has its own ChangeLog, so the c-family/ 
part does not go in the ChangeLog entry.
Dodji Seketeli Oct. 28, 2013, 2:19 p.m. UTC | #3 
"Joseph S. Myers" <joseph@codesourcery.com> writes:

> On Mon, 28 Oct 2013, Dodji Seketeli wrote:
>
>> 	* c-family/c-common.c (unsafe_conversion_p): Make this function
>
> As previously noted, c-family/ has its own ChangeLog, so the c-family/ 
> part does not go in the ChangeLog entry.

Agreed.  I missed this.
diff mbox

Patch

Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c	(revision 203640)
+++ gcc/c-family/c-common.c	(working copy)
@@ -2518,7 +2518,7 @@  shorten_binary_op (tree result_type, tre
 }
 
 /* Checks if expression EXPR of real/integer type cannot be converted 
-   to the real/integer type TYPE. Function returns true when:
+   to the real/integer type TYPE. Function returns non-zero when:
 	* EXPR is a constant which cannot be exactly converted to TYPE 
 	* EXPR is not a constant and size of EXPR's type > than size of TYPE, 
 	  for EXPR type and TYPE being both integers or both real.
@@ -2526,12 +2526,12 @@  shorten_binary_op (tree result_type, tre
 	* EXPR is not a constant of integer type which cannot be 
 	  exactly converted to real type.  
    Function allows conversions between types of different signedness and
-   does not return true in that case.  Function can produce signedness
-   warnings if PRODUCE_WARNS is true.  */
-bool
+   can return SAFE_CONVERSION (zero) in that case.  Function can produce
+   signedness warnings if PRODUCE_WARNS is true.  */
+enum conversion_safety
 unsafe_conversion_p (tree type, tree expr, bool produce_warns)
 {
-  bool give_warning = false;
+  enum conversion_safety give_warning = SAFE_CONVERSION; /* is 0 or false */
   tree expr_type = TREE_TYPE (expr);
   location_t loc = EXPR_LOC_OR_HERE (expr);
 
@@ -2543,7 +2543,7 @@  unsafe_conversion_p (tree type, tree exp
 	  && TREE_CODE (type) == INTEGER_TYPE)
 	{
 	  if (!real_isinteger (TREE_REAL_CST_PTR (expr), TYPE_MODE (expr_type)))
-	    give_warning = true;
+	    give_warning = UNSAFE_REAL;
 	}
       /* Warn for an integer constant that does not fit into integer type.  */
       else if (TREE_CODE (expr_type) == INTEGER_TYPE
@@ -2564,7 +2564,7 @@  unsafe_conversion_p (tree type, tree exp
 			    " constant value to negative integer");
 	    }
 	  else
-	    give_warning = true;
+	    give_warning = UNSAFE_OTHER;
 	}
       else if (TREE_CODE (type) == REAL_TYPE)
 	{
@@ -2573,7 +2573,7 @@  unsafe_conversion_p (tree type, tree exp
 	    {
 	      REAL_VALUE_TYPE a = real_value_from_int_cst (0, expr);
 	      if (!exact_real_truncate (TYPE_MODE (type), &a))
-		give_warning = true;
+		give_warning = UNSAFE_REAL;
 	    }
 	  /* Warn for a real constant that does not fit into a smaller
 	     real type.  */
@@ -2582,7 +2582,7 @@  unsafe_conversion_p (tree type, tree exp
 	    {
 	      REAL_VALUE_TYPE a = TREE_REAL_CST (expr);
 	      if (!exact_real_truncate (TYPE_MODE (type), &a))
-		give_warning = true;
+		give_warning = UNSAFE_REAL;
 	    }
 	}
     }
@@ -2591,7 +2591,7 @@  unsafe_conversion_p (tree type, tree exp
       /* Warn for real types converted to integer types.  */
       if (TREE_CODE (expr_type) == REAL_TYPE
 	  && TREE_CODE (type) == INTEGER_TYPE)
-	give_warning = true;
+	give_warning = UNSAFE_REAL;
 
       else if (TREE_CODE (expr_type) == INTEGER_TYPE
 	       && TREE_CODE (type) == INTEGER_TYPE)
@@ -2629,7 +2629,7 @@  unsafe_conversion_p (tree type, tree exp
 			  && int_fits_type_p (op1, c_common_signed_type (type))
 			  && int_fits_type_p (op1,
 					      c_common_unsigned_type (type))))
-		    return false;
+		    return SAFE_CONVERSION;
 		  /* If constant is unsigned and fits in the target
 		     type, then the result will also fit.  */
 		  else if ((TREE_CODE (op0) == INTEGER_CST
@@ -2638,12 +2638,12 @@  unsafe_conversion_p (tree type, tree exp
 			   || (TREE_CODE (op1) == INTEGER_CST
 			       && unsigned1
 			       && int_fits_type_p (op1, type)))
-		    return false;
+		    return SAFE_CONVERSION;
 		}
 	    }
 	  /* Warn for integer types converted to smaller integer types.  */
 	  if (TYPE_PRECISION (type) < TYPE_PRECISION (expr_type))
-	    give_warning = true;
+	    give_warning = UNSAFE_OTHER;
 
 	  /* When they are the same width but different signedness,
 	     then the value may change.  */
@@ -2679,14 +2679,14 @@  unsafe_conversion_p (tree type, tree exp
 
 	  if (!exact_real_truncate (TYPE_MODE (type), &real_low_bound)
 	      || !exact_real_truncate (TYPE_MODE (type), &real_high_bound))
-	    give_warning = true;
+	    give_warning = UNSAFE_OTHER;
 	}
 
       /* Warn for real types converted to smaller real types.  */
       else if (TREE_CODE (expr_type) == REAL_TYPE
 	       && TREE_CODE (type) == REAL_TYPE
 	       && TYPE_PRECISION (type) < TYPE_PRECISION (expr_type))
-	give_warning = true;
+	give_warning = UNSAFE_REAL;
     }
 
   return give_warning;
@@ -2700,8 +2700,9 @@  conversion_warning (tree type, tree expr
 {
   tree expr_type = TREE_TYPE (expr);
   location_t loc = EXPR_LOC_OR_HERE (expr);
+  enum conversion_safety conversion_kind;
 
-  if (!warn_conversion && !warn_sign_conversion)
+  if (!warn_conversion && !warn_sign_conversion && !warn_float_conversion)
     return;
 
   switch (TREE_CODE (expr))
@@ -2728,7 +2729,12 @@  conversion_warning (tree type, tree expr
 
     case REAL_CST:
     case INTEGER_CST:
-      if (unsafe_conversion_p (type, expr, true))
+      conversion_kind = unsafe_conversion_p (type, expr, true);
+      if (conversion_kind == UNSAFE_REAL)
+	warning_at (loc, OPT_Wfloat_conversion,
+		    "conversion to %qT alters %qT constant value",
+		    type, expr_type);
+      else if (conversion_kind)
 	warning_at (loc, OPT_Wconversion,
 		    "conversion to %qT alters %qT constant value",
 		    type, expr_type);
@@ -2747,7 +2753,12 @@  conversion_warning (tree type, tree expr
       }
 
     default: /* 'expr' is not a constant.  */
-      if (unsafe_conversion_p (type, expr, true))
+      conversion_kind = unsafe_conversion_p (type, expr, true);
+      if (conversion_kind == UNSAFE_REAL)
+	warning_at (loc, OPT_Wfloat_conversion,
+		    "conversion to %qT from %qT may alter its value",
+		    type, expr_type);
+      else if (conversion_kind)
 	warning_at (loc, OPT_Wconversion,
 		    "conversion to %qT from %qT may alter its value",
 		    type, expr_type);
Index: gcc/c-family/c-common.h
===================================================================
--- gcc/c-family/c-common.h	(revision 203640)
+++ gcc/c-family/c-common.h	(working copy)
@@ -685,6 +685,16 @@  struct visibility_flags
   unsigned inlines_hidden : 1;	/* True when -finlineshidden in effect.  */
 };
 
+/* These enumerators are possible types of unsafe conversions.
+   SAFE_CONVERSION The conversion is safe
+   UNSAFE_OTHER Another type of conversion with problems
+   UNSAFE_SIGN Conversion between signed and unsigned integers
+    which are all warned about immediately, so this is unused
+   UNSAFE_REAL Conversions that reduce the precision of reals
+    including conversions from reals to integers
+ */
+enum conversion_safety { SAFE_CONVERSION = 0, UNSAFE_OTHER, UNSAFE_SIGN, UNSAFE_REAL };
+
 /* Global visibility options.  */
 extern struct visibility_flags visibility_options;
 
@@ -738,7 +748,7 @@  extern tree c_common_signed_type (tree);
 extern tree c_common_signed_or_unsigned_type (int, tree);
 extern void c_common_init_ts (void);
 extern tree c_build_bitfield_integer_type (unsigned HOST_WIDE_INT, int);
-extern bool unsafe_conversion_p (tree, tree, bool);
+extern enum conversion_safety unsafe_conversion_p (tree, tree, bool);
 extern bool decl_with_nonnull_addr_p (const_tree);
 extern tree c_fully_fold (tree, bool, bool *);
 extern tree decl_constant_value_for_optimization (tree);
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt	(revision 203640)
+++ gcc/c-family/c.opt	(working copy)
@@ -387,6 +387,10 @@  Werror-implicit-function-declaration
 C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration)
 This switch is deprecated; use -Werror=implicit-function-declaration instead
 
+Wfloat-conversion
+C ObjC C++ ObjC++ Var(warn_float_conversion) LangEnabledBy(C ObjC C++ ObjC++,Wconversion)
+Warn for implicit type conversions that cause loss of floating point precision
+
 Wfloat-equal
 C ObjC C++ ObjC++ Var(warn_float_equal) Warning
 Warn if testing floating point numbers for equality
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 203640)
+++ gcc/doc/invoke.texi	(working copy)
@@ -263,7 +263,8 @@  Objective-C and Objective-C++ Dialects}.
 -Wpointer-arith  -Wno-pointer-to-int-cast @gol
 -Wredundant-decls  -Wno-return-local-addr @gol
 -Wreturn-type  -Wsequence-point  -Wshadow @gol
--Wsign-compare  -Wsign-conversion  -Wsizeof-pointer-memaccess @gol
+-Wsign-compare  -Wsign-conversion -Wfloat-conversion @gol
+-Wsizeof-pointer-memaccess @gol
 -Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol
 -Wstrict-aliasing=n @gol -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol
@@ -4570,6 +4571,14 @@  value, like assigning a signed integer e
 integer variable. An explicit cast silences the warning. In C, this
 option is enabled also by @option{-Wconversion}.
 
+@item -Wfloat-conversion
+@opindex Wfloat-conversion
+@opindex Wno-float-conversion
+Warn for implicit conversions that reduce the precision of a real value.
+This includes conversions from real to integer, and from higher precision
+real to lower precision real values.  This option is also enabled by
+@option{-Wconversion}.
+
 @item -Wsizeof-pointer-memaccess
 @opindex Wsizeof-pointer-memaccess
 @opindex Wno-sizeof-pointer-memaccess
Index: gcc/testsuite/c-c++-common/Wconversion-real.c
===================================================================
--- gcc/testsuite/c-c++-common/Wconversion-real.c	(revision 203640)
+++ gcc/testsuite/c-c++-common/Wconversion-real.c	(working copy)
@@ -2,8 +2,8 @@ 
 
 /* { dg-do compile } */
 /* { dg-skip-if "doubles are floats" { "avr-*-*" } { "*" } { "" } } */
-/* { dg-options "-std=c99 -Wconversion" { target c } } */
-/* { dg-options "-Wconversion" { target c++ } } */
+/* { dg-options "-std=c99 -Wfloat-conversion" { target c } } */
+/* { dg-options "-Wfloat-conversion" { target c++ } } */
 /* { dg-require-effective-target large_double } */
 
 float  vfloat;
@@ -20,18 +20,18 @@  void h (void)
   double d = 0;
   long double ld = 0;
 
-  ffloat (3.1); /* { dg-warning "conversion" } */
-  vfloat = 3.1; /* { dg-warning "conversion" } */
-  ffloat (3.1L); /* { dg-warning "conversion" } */
-  vfloat = 3.1L;  /* { dg-warning "conversion" } */
-  fdouble (3.1L); /* { dg-warning "conversion" "" { target large_long_double } } */
-  vdouble = 3.1L; /* { dg-warning "conversion" "" { target large_long_double } } */
-  ffloat (vdouble); /* { dg-warning "conversion" } */
-  vfloat = vdouble; /* { dg-warning "conversion" } */
-  ffloat (vlongdouble); /* { dg-warning "conversion" } */
-  vfloat = vlongdouble; /* { dg-warning "conversion" } */
-  fdouble (vlongdouble); /* { dg-warning "conversion" "" { target large_long_double } } */
-  vdouble = vlongdouble; /* { dg-warning "conversion" "" { target large_long_double } } */
+  ffloat (3.1); /* { dg-warning "float-conversion" } */
+  vfloat = 3.1; /* { dg-warning "float-conversion" } */
+  ffloat (3.1L); /* { dg-warning "float-conversion" } */
+  vfloat = 3.1L;  /* { dg-warning "float-conversion" } */
+  fdouble (3.1L); /* { dg-warning "float-conversion" "" { target large_long_double } } */
+  vdouble = 3.1L; /* { dg-warning "float-conversion" "" { target large_long_double } } */
+  ffloat (vdouble); /* { dg-warning "float-conversion" } */
+  vfloat = vdouble; /* { dg-warning "float-conversion" } */
+  ffloat (vlongdouble); /* { dg-warning "float-conversion" } */
+  vfloat = vlongdouble; /* { dg-warning "float-conversion" } */
+  fdouble (vlongdouble); /* { dg-warning "float-conversion" "" { target large_long_double } } */
+  vdouble = vlongdouble; /* { dg-warning "float-conversion" "" { target large_long_double } } */
 
 
   ffloat ((float) 3.1); 
Index: gcc/testsuite/gcc.dg/Wconversion-real-integer.c
===================================================================
--- gcc/testsuite/gcc.dg/Wconversion-real-integer.c	(revision 203640)
+++ gcc/testsuite/gcc.dg/Wconversion-real-integer.c	(working copy)
@@ -25,18 +25,18 @@  void h (void)
   float  f = 3;
   double d = 3;
 
-  fsi (3.1f); /* { dg-warning "conversion" } */
-  si = 3.1f; /* { dg-warning "conversion" } */
-  fsi (3.1);  /* { dg-warning "conversion" } */
-  si = 3.1;  /* { dg-warning "conversion" } */
-  fsi (d);    /* { dg-warning "conversion" } */
-  si = d;    /* { dg-warning "conversion" } */
+  fsi (3.1f); /* { dg-warning "float-conversion" } */
+  si = 3.1f; /* { dg-warning "float-conversion" } */
+  fsi (3.1);  /* { dg-warning "float-conversion" } */
+  si = 3.1;  /* { dg-warning "float-conversion" } */
+  fsi (d);    /* { dg-warning "float-conversion" } */
+  si = d;    /* { dg-warning "float-conversion" } */
   fui (-1.0); /* { dg-warning "overflow" } */
   ui = -1.0;   /* { dg-warning "overflow" } */
-  ffloat (INT_MAX);  /* { dg-warning "conversion" } */
-  vfloat = INT_MAX;  /* { dg-warning "conversion" } */
-  ffloat (16777217); /* { dg-warning "conversion" } */
-  vfloat = 16777217; /* { dg-warning "conversion" } */
+  ffloat (INT_MAX);  /* { dg-warning "float-conversion" } */
+  vfloat = INT_MAX;  /* { dg-warning "float-conversion" } */
+  ffloat (16777217); /* { dg-warning "float-conversion" } */
+  vfloat = 16777217; /* { dg-warning "float-conversion" } */
   ffloat (si); /* { dg-warning "conversion" } */
   vfloat = si; /* { dg-warning "conversion" } */
   ffloat (ui); /* { dg-warning "conversion" } */
Index: gcc/testsuite/gcc.dg/pr35635.c
===================================================================
--- gcc/testsuite/gcc.dg/pr35635.c	(revision 203640)
+++ gcc/testsuite/gcc.dg/pr35635.c	(working copy)
@@ -45,7 +45,7 @@  void func2()
 
   /* At least one branch of ? does not fit in the destination, thus
      warn.  */
-  schar_x = bar != 0 ? 2.1 : 10; /* { dg-warning "conversion" } */
+  schar_x = bar != 0 ? 2.1 : 10; /* { dg-warning "float-conversion" } */
   schar_x = bar != 0 ? (signed char) 1024: -1024; /* { dg-warning "conversion" } */
 }
 
@@ -61,7 +61,7 @@  void func3()
 
   /* At least one branch of ? does not fit in the destination, thus
      warn.  */
-  uchar_x = bar != 0 ? 2.1 : 10; /* { dg-warning "conversion" } */
+  uchar_x = bar != 0 ? 2.1 : 10; /* { dg-warning "float-conversion" } */
   uchar_x = bar != 0 
     ? (unsigned char) 1024 
     : -1; /* { dg-warning "negative integer implicitly converted to unsigned type" } */