copysignl tests: Avoid failure on Solaris 11.4

[Bruno Haible]

Building a testdir for module 'copysignl' on Solaris 11.4, with gcc
in 64-bit mode without optimizations, I see a test failure:


FAIL: test-copysignl
====================

../../gltests/test-copysignl.c:90: assertion 'memcmp (&z, &zero, sizeof z) == 
0' failed
Stack trace:
0x408050 print_stack_trace
        ../../gllib/abort-debug.c:40
0x408050 rpl_abort
        ../../gllib/abort-debug.c:94
0x407cb9 main
        ../../gltests/test-copysignl.c:90
../../build-aux/test-driver: line 114: 29294: Abort(coredump)
FAIL test-copysignl (exit status: 262)


The cause is that 'long double' has onlu 80 bits, but sizeof (long double)
is 16, not 10.

This patch fixes the test failure.

This test code exists since 2011, and x86_64 platforms are not rare.
It's astonishing that this test failure has not been seen earlier.


2024-06-18  Bruno Haible  <br...@clisp.org>

        copysignl tests: Avoid failure on Solaris 11.4.
        * tests/test-copysignl.c: Include <float.h>.
        (LDBL_BYTES): New macro.
        (main): Use it instead of sizeof (long double).
        * modules/copysignl-tests (Depends-on): Add float.

diff --git a/modules/copysignl-tests b/modules/copysignl-tests
index 1cb5f829aa..e3a5b79c96 100644
--- a/modules/copysignl-tests
+++ b/modules/copysignl-tests
@@ -5,6 +5,7 @@ tests/minus-zero.h
 tests/macros.h
 
 Depends-on:
+float
 
 configure.ac:
 
diff --git a/tests/test-copysignl.c b/tests/test-copysignl.c
index 8f5f188872..f17d045b40 100644
--- a/tests/test-copysignl.c
+++ b/tests/test-copysignl.c
@@ -26,6 +26,7 @@ SIGNATURE_CHECK (copysignl, long double, (long double, long 
double));
 #include "macros.h"
 #include "minus-zero.h"
 
+#include <float.h>
 #include <string.h>
 
 volatile long double x;
@@ -33,6 +34,14 @@ volatile long double y;
 long double z;
 long double zero = 0.0L;
 
+/* Number of bytes occupied by a 'long double' in memory.  */
+#if (defined __ia64 || (defined __x86_64__ || defined __amd64__) || (defined 
__i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined 
_X86_)) && LDBL_MANT_DIG == 64
+/* 'long double' is little-endian 80-bits "extended precision".  */
+# define LDBL_BYTES 10
+#else
+# define LDBL_BYTES sizeof (long double)
+#endif
+
 int
 main ()
 {
@@ -87,25 +96,25 @@ main ()
   y = 1.0L;
   z = copysignl (x, y);
   ASSERT (z == 0.0L);
-  ASSERT (memcmp (&z, &zero, sizeof z) == 0);
+  ASSERT (memcmp (&z, &zero, LDBL_BYTES) == 0);
 
   x = 0.0L;
   y = -1.0L;
   z = copysignl (x, y);
   ASSERT (z == 0.0L);
-  ASSERT (memcmp (&z, &zero, sizeof z) != 0);
+  ASSERT (memcmp (&z, &zero, LDBL_BYTES) != 0);
 
   x = minus_zerol;
   y = 1.0L;
   z = copysignl (x, y);
   ASSERT (z == 0.0L);
-  ASSERT (memcmp (&z, &zero, sizeof z) == 0);
+  ASSERT (memcmp (&z, &zero, LDBL_BYTES) == 0);
 
   x = minus_zerol;
   y = -1.0L;
   z = copysignl (x, y);
   ASSERT (z == 0.0L);
-  ASSERT (memcmp (&z, &zero, sizeof z) != 0);
+  ASSERT (memcmp (&z, &zero, LDBL_BYTES) != 0);
 
   return test_exit_status;
 }