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re PR c/2098 (compare with unsigned variable - no error reporting)

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PR c/2098
        * c-common.c (shorten_compare): Simplfy conditions leading to
        the generation of a warning.

	* gcc.dg/compare6.c: New.

From-SVN: r52778
This commit is contained in:
Richard Henderson 2002-04-25 19:15:52 -07:00 • committed by Richard Henderson
parent 28ce94d46b
commit 5c5b228389
3 changed files with 20 additions and 12 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2002-04-25 Richard Henderson <rth@redhat.com>
PR c/2098
* c-common.c (shorten_compare): Simplfy conditions leading to
the generation of a warning.
2002-04-25 Richard Henderson <rth@redhat.com>
PR c/2035

13
gcc/c-common.c
View file

@ -1999,19 +1999,8 @@ shorten_compare (op0_ptr, op1_ptr, restype_ptr, rescode_ptr)
type = c_common_unsigned_type (type);
}
if (!max_gt && !unsignedp0 && TREE_CODE (primop0) != INTEGER_CST)
if (TREE_CODE (primop0) != INTEGER_CST)
{
/* This is the case of (char)x >?< 0x80, which people used to use
expecting old C compilers to change the 0x80 into -0x80. */
if (val == boolean_false_node)
warning ("comparison is always false due to limited range of data type");
if (val == boolean_true_node)
warning ("comparison is always true due to limited range of data type");
}
if (!min_lt && unsignedp0 && TREE_CODE (primop0) != INTEGER_CST)
{
/* This is the case of (unsigned char)x >?< -1 or < 0. */
if (val == boolean_false_node)
warning ("comparison is always false due to limited range of data type");
if (val == boolean_true_node)

13
gcc/testsuite/gcc.dg/compare6.c Normal file
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@ -0,0 +1,13 @@
/* PR c/2098 */
/* Test for a warning on comparison on out-of-range data. */
/* { dg-do compile { xfail c4x-*-* } } */
/* { dg-options "-Wall" } */
signed char sc;
unsigned char uc;
void foo()
{
if (sc == 10000) return; /* { dg-warning "always false" "signed" } */
if (uc == 10000) return; /* { dg-warning "always false" "unsigned" } */
}