Cope if platform declares mbstowcs_l(), but not locale_t, in <xlocale.h>.

Previously, we included <xlocale.h> only if necessary to get the definition
of type locale_t.  According to notes in PGAC_TYPE_LOCALE_T, this is
important because on some versions of glibc that file supplies an
incompatible declaration of locale_t.  (This info may be obsolete, because
on my RHEL6 box that seems to be the *only* definition of locale_t; but
there may still be glibc's in the wild for which it's a live concern.)

It turns out though that on FreeBSD and maybe other BSDen, you can get
locale_t from stdlib.h or locale.h but mbstowcs_l() and friends only from
<xlocale.h>.  This was leaving us compiling calls to mbstowcs_l() and
friends with no visible prototype, which causes a warning and could
possibly cause actual trouble, since it's not declared to return int.

Hence, adjust the configure checks so that we'll include <xlocale.h>
either if it's necessary to get type locale_t or if it's necessary to
get a declaration of mbstowcs_l().

Report and patch by Aleksander Alekseev, somewhat whacked around by me.
Back-patch to all supported branches, since we have been using
mbstowcs_l() since 9.1.

config/c-library.m4

@@ -316,4 +316,34 @@ fi
 if test "$pgac_cv_type_locale_t" = 'yes (in xlocale.h)'; then
   AC_DEFINE(LOCALE_T_IN_XLOCALE, 1,
             [Define to 1 if `locale_t' requires <xlocale.h>.])
-fi])])# PGAC_HEADER_XLOCALE
+fi])# PGAC_TYPE_LOCALE_T
+
+
+# PGAC_FUNC_WCSTOMBS_L
+# --------------------
+# Try to find a declaration for wcstombs_l().  It might be in stdlib.h
+# (following the POSIX requirement for wcstombs()), or in locale.h, or in
+# xlocale.h.  If it's in the latter, define WCSTOMBS_L_IN_XLOCALE.
+#
+AC_DEFUN([PGAC_FUNC_WCSTOMBS_L],
+[AC_CACHE_CHECK([for wcstombs_l declaration], pgac_cv_func_wcstombs_l,
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+[#include <stdlib.h>
+#include <locale.h>],
+[#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif])],
+[pgac_cv_func_wcstombs_l='yes'],
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+[#include <stdlib.h>
+#include <locale.h>
+#include <xlocale.h>],
+[#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif])],
+[pgac_cv_func_wcstombs_l='yes (in xlocale.h)'],
+[pgac_cv_func_wcstombs_l='no'])])])
+if test "$pgac_cv_func_wcstombs_l" = 'yes (in xlocale.h)'; then
+  AC_DEFINE(WCSTOMBS_L_IN_XLOCALE, 1,
+            [Define to 1 if `wcstombs_l' requires <xlocale.h>.])
+fi])# PGAC_FUNC_WCSTOMBS_L

configure

@@ -12364,6 +12364,59 @@ $as_echo "#define GETTIMEOFDAY_1ARG 1" >>confdefs.h
 
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for wcstombs_l declaration" >&5
+$as_echo_n "checking for wcstombs_l declaration... " >&6; }
+if ${pgac_cv_func_wcstombs_l+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdlib.h>
+#include <locale.h>
+int
+main ()
+{
+#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_func_wcstombs_l='yes'
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdlib.h>
+#include <locale.h>
+#include <xlocale.h>
+int
+main ()
+{
+#ifndef wcstombs_l
+(void) wcstombs_l;
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_func_wcstombs_l='yes (in xlocale.h)'
+else
+  pgac_cv_func_wcstombs_l='no'
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_func_wcstombs_l" >&5
+$as_echo "$pgac_cv_func_wcstombs_l" >&6; }
+if test "$pgac_cv_func_wcstombs_l" = 'yes (in xlocale.h)'; then
+
+$as_echo "#define WCSTOMBS_L_IN_XLOCALE 1" >>confdefs.h
+
+fi
 
 # Some versions of libedit contain strlcpy(), setproctitle(), and other
 # symbols that that library has no business exposing to the world.  Pending

configure.in

@@ -1423,6 +1423,7 @@ fi
 PGAC_VAR_INT_TIMEZONE
 AC_FUNC_ACCEPT_ARGTYPES
 PGAC_FUNC_GETTIMEOFDAY_1ARG
+PGAC_FUNC_WCSTOMBS_L
 
 # Some versions of libedit contain strlcpy(), setproctitle(), and other
 # symbols that that library has no business exposing to the world.  Pending

src/include/pg_config.h.in

@@ -851,6 +851,9 @@
 /* Define to select Win32-style shared memory. */
 #undef USE_WIN32_SHARED_MEMORY
 
+/* Define to 1 if `wcstombs_l' requires <xlocale.h>. */
+#undef WCSTOMBS_L_IN_XLOCALE
+
 /* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
    significant byte first (like Motorola and SPARC, unlike Intel). */
 #if defined AC_APPLE_UNIVERSAL_BUILD

src/include/pg_config.h.win32

@@ -657,6 +657,9 @@
 /* Define to select Win32-style semaphores. */
 #define USE_WIN32_SEMAPHORES 1
 
+/* Define to 1 if `wcstombs_l' requires <xlocale.h>. */
+/* #undef WCSTOMBS_L_IN_XLOCALE */
+
 /* Number of bits in a file offset, on hosts where this is settable. */
 /* #undef _FILE_OFFSET_BITS */
 

src/include/utils/pg_locale.h

@@ -13,7 +13,7 @@
 #define _PG_LOCALE_
 
 #include <locale.h>
-#ifdef LOCALE_T_IN_XLOCALE
+#if defined(LOCALE_T_IN_XLOCALE) || defined(WCSTOMBS_L_IN_XLOCALE)
 #include <xlocale.h>
 #endif