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Ignore -Wmaybe-uninitialized in stdlib/bug-getcontext.c
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Fri, 4 Nov 2016 17:26:59 +0000
- Subject: Ignore -Wmaybe-uninitialized in stdlib/bug-getcontext.c
- Authentication-results: sourceware.org; auth=none
Doing all-ABIs compile testing produces a compiler warning in
stdlib/bug-getcontext.c on nios2 and tilepro (with GCC 5 branch):
bug-getcontext.c: In function 'do_test':
bug-getcontext.c:53:6: error: 'except_mask' may be used uninitialized in this function [-Werror=maybe-uninitialized]
if (mask != except_mask)
^
This warning appears nonsensical; except_mask is initialized where
it's declared. I think what must be happening here is that the
compiler is confused by the returns-twice nature of getcontext: if
there were a call to setcontext, local variables could indeed have
lost their values on the second return from getcontext. This patch
duly uses the DIAG_* macros to disable the warning here.
Tested for nios2 and tilepro (compilation only; after this patch all
the tests compile, though there are other failures) and x86_64 (full
testsuite run).
2016-11-04 Joseph Myers <joseph@codesourcery.com>
* stdlib/bug-getcontext.c: Include <libc-internal.h>.
(do_test): Disable -Wmaybe-uninitialized around uses of
except_mask.
diff --git a/stdlib/bug-getcontext.c b/stdlib/bug-getcontext.c
index 133ee91..c407212 100644
--- a/stdlib/bug-getcontext.c
+++ b/stdlib/bug-getcontext.c
@@ -5,6 +5,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <ucontext.h>
+#include <libc-internal.h>
static int
do_test (void)
@@ -49,6 +50,13 @@ do_test (void)
printf ("\nDone with getcontext()!\n");
fflush (NULL);
+ /* On nios2 and tilepro, GCC 5 warns that except_mask may be used
+ uninitialized. Because it is always initialized and nothing in
+ this test ever calls setcontext (a setcontext call could result
+ in local variables being clobbered on the second return from
+ getcontext), in fact an uninitialized use is not possible. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
int mask = fegetexcept ();
if (mask != except_mask)
{
@@ -59,6 +67,7 @@ do_test (void)
printf("\nAt end fegetexcept() returned %d, expected: %d.\n",
mask, except_mask);
+ DIAG_POP_NEEDS_COMMENT;
return 0;
}
--
Joseph S. Myers
joseph@codesourcery.com