commit c81e9deba2f73ddc6f62a9d41684824c854366c6

Author: Joseph Myers <joseph@codesourcery.com>

Date:   Wed Dec 10 00:43:36 2014 +0000

    Disable -Wdiv-by-zero for some tests in stdio-common/tst-unlockedio.c.

    This patch uses diagnostic control pragmas to disable some

    division-by-zero warnings in stdio-common/tst-unlockedio.c.  This is

    another test where disabling warnings using diagnostic pragmas seems

    appropriate (the warnings are not wildly inappropriate for what the

    test deliberately does; the deliberate use of unusual arguments to the

    macros being tested means that changing the arguments in a way that

    avoids the warning would also unduly perturb what is being tested).

    Tested for x86_64.

            * stdio-common/tst-unlockedio.c: Include <libc-internal.h>.

            (do_test): Disable -Wdiv-by-zero around some calls to

            fwrite_unlocked and fread_unlocked.

diff --git a/stdio-common/tst-unlockedio.c b/stdio-common/tst-unlockedio.c

index 2e5848ec5f49b693..5ce02fe6f5c7ea5c 100644

--- a/stdio-common/tst-unlockedio.c

+++ b/stdio-common/tst-unlockedio.c

@@ -20,6 +20,7 @@

 #include <stdlib.h>

 #include <stdio.h>

 #include <string.h>

+#include <libc-internal.h>

 int fd;

 static void do_prepare (void);

@@ -44,6 +45,13 @@ do_test (void)

   f = fp;

   cp = blah;

+  /* These tests deliberately use fwrite_unlocked with the size

+     argument specified as 0, which results in "division by zero"

+     warnings from the expansion of that macro (in code that is not

+     evaluated for a size of 0).  This applies to the tests of

+     fread_unlocked below as well.  */

+  DIAG_PUSH_NEEDS_COMMENT;

+  DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdiv-by-zero");

   if (ftello (fp) != 0

       || fwrite_unlocked (blah, blah - blah, strlen (blah), f++) != 0

       || f != fp + 1

@@ -59,6 +67,7 @@ do_test (void)

       puts ("One of fwrite_unlocked tests failed");

       exit (1);

     }

+  DIAG_POP_NEEDS_COMMENT;

   if (fwrite_unlocked (blah, 1, strlen (blah) - 2, fp) != strlen (blah) - 2)

     {

@@ -93,6 +102,9 @@ do_test (void)

   f = fp;

   wp = buf;

   memset (buf, ' ', sizeof (buf));

+  /* See explanation above.  */

+  DIAG_PUSH_NEEDS_COMMENT;

+  DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdiv-by-zero");

   if (ftello (fp) != 0

       || fread_unlocked (buf, buf - buf, strlen (blah), f++) != 0

       || f != fp + 1

@@ -109,6 +121,7 @@ do_test (void)

       puts ("One of fread_unlocked tests failed");

       exit (1);

     }

+  DIAG_POP_NEEDS_COMMENT;

   if (fread_unlocked (buf, 1, strlen (blah) - 2, fp) != strlen (blah) - 2)

     {