Hi Paul,
The module 'qsort_r' does not work at all on systems that don't have this
function.
For example, on AIX 7.1, with a gnulib testdir:
test-qsort_r.c: In function 'main':
test-qsort_r.c:40:3: warning: implicit declaration of function 'qsort_r'
[-Wimplicit-function-declaration]
qsort_r (buf, sizeof buf - 1, 1, cmp, );
^
gcc -mlong-double-64 -D_ALL_SOURCE -std=gnu11 -g -O2 -o test-qsort_r
test-qsort_r.o ../gllib/libgnu.a -lm -lm -lm -lm -lm -lm -lm -lm -lm -lm
ld: 0711-317 ERROR: Undefined symbol: .qsort_r
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
collect2: error: ld returned 8 exit status
make: 1254-004 The error code from the last command is 1.
The problems are:
1) The gl_FUNC_QSORT_R macro finds that
checking for qsort_r signature... GNU
2) The function does not get declared in gnulib's stdlib.h replacement.
3) It also is not included in libgnu.a (neither qsort.o nor qsort_r.o gets
included in gl_LIBOBJS).
Ad 1) Yes really it needs an AC_CHECK_FUNC call, because a program such as
#define __EXTENSIONS__ 1
#define _ALL_SOURCE 1
#define _DARWIN_C_SOURCE 1
#define _GNU_SOURCE 1
#include
#define qsort_t any_nonexistent_name
void qsort_r (void *, size_t, size_t,
int (*) (void const *, void const *,
void *),
void *);
void (*p) (void *, size_t, size_t,
int (*) (void const *, void const *,
void *),
void *) = qsort_r;
int main () { return 0; }
compiles and links perfectly fine.
Ad 2) The idiom in stdlib.h is incomplete. You need to pick the complete one
(e.g. copy from the 'ptsname_r' declaration).
Additionally:
4) The qsort_r function would not be warned about in GNULIB_POSIXCHECK mode.
Here's a proposed fix.
2016-10-16 Bruno Haible
qsort_r: Fix macrology for platforms that lack the function.
* m4/stdlib_h.m4 (gl_STDLIB_H): Check for qsort_r.
(gl_STDLIB_H_DEFAULTS): Initialize HAVE_QSORT_R.
* modules/stdlib (Makefile.am): Substitute HAVE_QSORT_R.
* lib/stdlib.in.h (qsort_r): Provide declaration if the function does
not exist.
* m4/qsort_r.m4 (gl_FUNC_QSORT_R): Use AC_CHECK_FUNCS to test whether
the function exists.
* modules/qsort_r: Add comments.
diff --git a/lib/stdlib.in.h b/lib/stdlib.in.h
index 70dc88d..db3253b 100644
--- a/lib/stdlib.in.h
+++ b/lib/stdlib.in.h
@@ -521,6 +521,9 @@ _GL_CXXALIASWARN (putenv);
#endif
#if @GNULIB_QSORT_R@
+/* Sort an array of NMEMB elements, starting at address BASE, each element
+ occupying SIZE bytes, in ascending order according to the comparison
+ function COMPARE. */
# if @REPLACE_QSORT_R@
# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
# undef qsort_r
@@ -535,12 +538,24 @@ _GL_CXXALIAS_RPL (qsort_r, void, (void *base, size_t
nmemb, size_t size,
void *),
void *arg));
# else
+# if !@HAVE_QSORT_R@
+_GL_FUNCDECL_SYS (qsort_r, void, (void *base, size_t nmemb, size_t size,
+ int (*compare) (void const *, void const *,
+ void *),
+ void *arg) _GL_ARG_NONNULL ((1, 4)));
+# endif
_GL_CXXALIAS_SYS (qsort_r, void, (void *base, size_t nmemb, size_t size,
int (*compare) (void const *, void const *,
void *),
void *arg));
# endif
_GL_CXXALIASWARN (qsort_r);
+#elif defined GNULIB_POSIXCHECK
+# undef qsort_r
+# if HAVE_RAW_DECL_QSORT_R
+_GL_WARN_ON_USE (qsort_r, "qsort_r is not portable - "
+ "use gnulib module qsort_r for portability");
+# endif
#endif
diff --git a/m4/qsort_r.m4 b/m4/qsort_r.m4
index f3d2927..f1de7d4 100644
--- a/m4/qsort_r.m4
+++ b/m4/qsort_r.m4
@@ -14,35 +14,39 @@ AC_DEFUN([gl_FUNC_QSORT_R],
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
- AC_CACHE_CHECK([for qsort_r signature], [gl_cv_qsort_r_signature],
-[AC_LINK_IFELSE(
- [AC_LANG_PROGRAM([[#include
- void qsort_r (void *, size_t, size_t,
-int (*) (void const *, void const *,
- void *),
-void *);
- void (*p) (void *, size_t, size_t,
- int (*) (void const *, void const *,
-
