Try another way to detect the result type of strerror_r().

The method we've traditionally used, of redeclaring strerror_r() to
see if the compiler complains of inconsistent declarations, turns out
not to work reliably because some compilers only report a warning,
not an error.  Amazingly, this has gone undetected for years, even
though it certainly breaks our detection of whether strerror_r
succeeded.

Let's instead test whether the compiler will take the result of
strerror_r() as a switch() argument.  It's possible this won't
work universally either, but it's the best idea I could come up with
on the spur of the moment.

We should probably back-patch this once the dust settles, but
first let's see what the buildfarm thinks of it.

Discussion: https://postgr.es/m/10877.1537993279@sss.pgh.pa.us

diff --git a/config/c-library.m4 b/config/c-library.m4
index d371f1ba6ee2b915d1d72a33da9b608e313491a7..6f2b0fbb4e6ec9484302916984a276e53d821313 100644 (file)
--- a/config/c-library.m4
+++ b/config/c-library.m4
@@ -82,23 +82,23 @@ AH_VERBATIM(GETTIMEOFDAY_1ARG_,
 
 # PGAC_FUNC_STRERROR_R_INT
 # ---------------------------
-# Check if strerror_r() returns an int (SUSv3) rather than a char * (GNU libc)
-# If so, define STRERROR_R_INT
+# Check if strerror_r() returns int (POSIX) rather than char * (GNU libc).
+# If so, define STRERROR_R_INT.
+# The result is uncertain if strerror_r() isn't provided,
+# but we don't much care.
 AC_DEFUN([PGAC_FUNC_STRERROR_R_INT],
 [AC_CACHE_CHECK(whether strerror_r returns int,
 pgac_cv_func_strerror_r_int,
 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <string.h>],
-[#ifndef _AIX
-int strerror_r(int, char *, size_t);
-#else
-/* Older AIX has 'int' for the third argument so we don't test the args. */
-int strerror_r();
-#endif])],
+[[char buf[100];
+  switch (strerror_r(1, buf, sizeof(buf)))
+  { case 0: break; default: break; }
+]])],
 [pgac_cv_func_strerror_r_int=yes],
 [pgac_cv_func_strerror_r_int=no])])
 if test x"$pgac_cv_func_strerror_r_int" = xyes ; then
   AC_DEFINE(STRERROR_R_INT, 1,
-            [Define to 1 if strerror_r() returns a int.])
+            [Define to 1 if strerror_r() returns int.])
 fi
 ])# PGAC_FUNC_STRERROR_R_INT
 

diff --git a/configure b/configure
index c4ce1506b06f9340d3c7ae1788a8570c19435b63..6414ec1ea6dfe3f322660da88df9724f76a8be87 100755 (executable)
--- a/configure
+++ b/configure
@@ -10792,12 +10792,10 @@ else
 int
 main ()
 {
-#ifndef _AIX
-int strerror_r(int, char *, size_t);
-#else
-/* Older AIX has 'int' for the third argument so we don't test the args. */
-int strerror_r();
-#endif
+char buf[100];
+  switch (strerror_r(1, buf, sizeof(buf)))
+  { case 0: break; default: break; }
+
   ;
   return 0;
 }

diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 7cabcd1e7537c5be127d8222448405a2c2287214..90dda8ea050c58de7d1018bb73f66f8e8c8045ee 100644 (file)
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -852,7 +852,7 @@
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS
 
-/* Define to 1 if strerror_r() returns a int. */
+/* Define to 1 if strerror_r() returns int. */
 #undef STRERROR_R_INT
 
 /* Define to 1 if your <sys/time.h> declares `struct tm'. */

diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 45d47e996a0339ac381e818d866a0bfd64b4afe4..93bb77349e049240398256e55d0028f12065dbd8 100644 (file)
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -665,7 +665,7 @@
 /* Define to 1 if you have the ANSI C header files. */
 #define STDC_HEADERS 1
 
-/* Define to 1 if strerror_r() returns a int. */
+/* Define to 1 if strerror_r() returns int. */
 /* #undef STRERROR_R_INT */
 
 /* Define to 1 if your <sys/time.h> declares `struct tm'. */