[Valgrind-developers] [valgrind] Darwin regtest: small tweak for memcheck str_tester

[Paul F. <pa...@so...>]

https://sourceware.org/cgit/valgrind/commit/?id=58bb429efb320233aa433356ce7e1f9a343b2d62

commit 58bb429efb320233aa433356ce7e1f9a343b2d62
Author: Paul Floyd <pj...@wa...>
Date:   Fri Mar 13 13:40:37 2026 +0100

    Darwin regtest: small tweak for memcheck str_tester
    
    On Darwin 17 (macOs 10.13) this test fails standalone and under
    Valgrind.
    
    The failing test is
    
      check(memcmp("a\203", "a\003", 2) > 0, 6);
    
    I think that the compiler is using a builtin that does not behave
    identically to libc memcmp. It's all a quastion of signed and
    unsigned char. If char is unsigned then \203 is positive and
    greater than \003. This is the Darwin libc behaviour. If
    char is signed \203 is negative and the return value is negative
    and the test fails.  That seems to be the builtin behaviour.
    
    This change inhibits use of a builtin for that one test.

Diff:
---
 memcheck/tests/str_tester.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/memcheck/tests/str_tester.c b/memcheck/tests/str_tester.c
index 1201bbfc22..01c5834099 100644
--- a/memcheck/tests/str_tester.c
+++ b/memcheck/tests/str_tester.c
@@ -984,7 +984,8 @@ test_memcmp (void)
   check(memcmp("abcd", "abce", 4) < 0, 3);	/* Honestly unequal. */
   check(memcmp("abce", "abcd", 4) > 0, 4);
   check(memcmp("alph", "beta", 4) < 0, 5);
-  check(memcmp("a\203", "a\003", 2) > 0, 6);
+  // Darwin 17 uses a builtin which fails test 6. Use parens to inhibit the use of builtins.
+  check((memcmp)("a\203", "a\003", 2) > 0, 6);
   check(memcmp("abce", "abcd", 3) == 0, 7);	/* Count limited. */
   check(memcmp("abc", "def", 0) == 0, 8);	/* Zero count. */
 }