Simplify checking for xlocale.h

Instead of XXX_IN_XLOCALE_H for several features XXX, let's just
include <xlocale.h> if HAVE_XLOCALE_H.  The reason for the extra
complication was apparently that some old glibc systems also had an
<xlocale.h>, and you weren't supposed to include it directly, but it's
gone now (as far as I can tell it was harmless to do so anyway).

Author: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/CWZBBRR6YA8D.8EHMDRGLCKCD%40neon.tech

config/c-library.m4

@@ -81,58 +81,3 @@ AC_DEFUN([PGAC_STRUCT_SOCKADDR_SA_LEN],
 [#include <sys/types.h>
 #include <sys/socket.h>
 ])])# PGAC_STRUCT_SOCKADDR_MEMBERS
-
-
-# PGAC_TYPE_LOCALE_T
-# ------------------
-# Check for the locale_t type and find the right header file.  macOS
-# needs xlocale.h; standard is locale.h, but glibc <= 2.25 also had an
-# xlocale.h file that we should not use, so we check the standard
-# header first.
-AC_DEFUN([PGAC_TYPE_LOCALE_T],
-[AC_CACHE_CHECK([for locale_t], pgac_cv_type_locale_t,
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
-[#include <locale.h>
-locale_t x;],
-[])],
-[pgac_cv_type_locale_t=yes],
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
-[#include <xlocale.h>
-locale_t x;],
-[])],
-[pgac_cv_type_locale_t='yes (in xlocale.h)'],
-[pgac_cv_type_locale_t=no])])])
-if test "$pgac_cv_type_locale_t" = 'yes (in xlocale.h)'; then
-  AC_DEFINE(LOCALE_T_IN_XLOCALE, 1,
-            [Define to 1 if `locale_t' requires <xlocale.h>.])
-fi])# PGAC_TYPE_LOCALE_T
-
-
-# PGAC_FUNC_WCSTOMBS_L
-# --------------------
-# Try to find a declaration for wcstombs_l().  It might be in stdlib.h
-# (following the POSIX requirement for wcstombs()), or in locale.h, or in
-# xlocale.h.  If it's in the latter, define WCSTOMBS_L_IN_XLOCALE.
-#
-AC_DEFUN([PGAC_FUNC_WCSTOMBS_L],
-[AC_CACHE_CHECK([for wcstombs_l declaration], pgac_cv_func_wcstombs_l,
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
-[#include <stdlib.h>
-#include <locale.h>],
-[#ifndef wcstombs_l
-(void) wcstombs_l;
-#endif])],
-[pgac_cv_func_wcstombs_l='yes'],
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
-[#include <stdlib.h>
-#include <locale.h>
-#include <xlocale.h>],
-[#ifndef wcstombs_l
-(void) wcstombs_l;
-#endif])],
-[pgac_cv_func_wcstombs_l='yes (in xlocale.h)'],
-[pgac_cv_func_wcstombs_l='no'])])])
-if test "$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

@@ -13219,7 +13219,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
 fi
 
 
-for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h mbarrier.h sys/epoll.h sys/event.h sys/personality.h sys/prctl.h sys/procctl.h sys/signalfd.h sys/ucred.h termios.h ucred.h
+for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h mbarrier.h sys/epoll.h sys/event.h sys/personality.h sys/prctl.h sys/procctl.h sys/signalfd.h sys/ucred.h termios.h ucred.h xlocale.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
@@ -14547,55 +14547,6 @@ _ACEOF
 fi
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for locale_t" >&5
-$as_echo_n "checking for locale_t... " >&6; }
-if ${pgac_cv_type_locale_t+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <locale.h>
-locale_t x;
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv_type_locale_t=yes
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <xlocale.h>
-locale_t x;
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv_type_locale_t='yes (in xlocale.h)'
-else
-  pgac_cv_type_locale_t=no
-fi
-rm -f core conftest.err conftest.$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: $pgac_cv_type_locale_t" >&5
-$as_echo "$pgac_cv_type_locale_t" >&6; }
-if test "$pgac_cv_type_locale_t" = 'yes (in xlocale.h)'; then
-
-$as_echo "#define LOCALE_T_IN_XLOCALE 1" >>confdefs.h
-
-fi
-
 # MSVC doesn't cope well with defining restrict to __restrict, the
 # spelling it understands, because it conflicts with
 # __declspec(restrict). Therefore we define pg_restrict to the
@@ -15082,59 +15033,6 @@ if test x"$pgac_cv_var_int_timezone" = xyes ; then
 
 $as_echo "#define HAVE_INT_TIMEZONE 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

configure.ac

@@ -1446,6 +1446,7 @@ AC_CHECK_HEADERS(m4_normalize([
 	sys/ucred.h
 	termios.h
 	ucred.h
+	xlocale.h
 ]))
 
 if expr x"$pgac_cv_check_readline" : 'x-lreadline' >/dev/null ; then
@@ -1608,8 +1609,6 @@ PGAC_UNION_SEMUN
 AC_CHECK_TYPES(socklen_t, [], [], [#include <sys/socket.h>])
 PGAC_STRUCT_SOCKADDR_SA_LEN
 
-PGAC_TYPE_LOCALE_T
-
 # MSVC doesn't cope well with defining restrict to __restrict, the
 # spelling it understands, because it conflicts with
 # __declspec(restrict). Therefore we define pg_restrict to the
@@ -1708,7 +1707,6 @@ fi
 ##
 
 PGAC_VAR_INT_TIMEZONE
-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

meson.build

@@ -2403,6 +2403,7 @@ header_checks = [
   'sys/ucred.h',
   'termios.h',
   'ucred.h',
+  'xlocale.h',
 ]
 
 foreach header : header_checks
@@ -2546,15 +2547,6 @@ else
   cdata.set('STRERROR_R_INT', false)
 endif
 
-# Find the right header file for the locale_t type.  macOS needs xlocale.h;
-# standard is locale.h, but glibc <= 2.25 also had an xlocale.h file that
-# we should not use so we check the standard header first.  MSVC has a
-# replacement defined in src/include/port/win32_port.h.
-if not cc.has_type('locale_t', prefix: '#include <locale.h>') and \
-   cc.has_type('locale_t', prefix: '#include <xlocale.h>')
-  cdata.set('LOCALE_T_IN_XLOCALE', 1)
-endif
-
 # Check if the C compiler understands typeof or a variant.  Define
 # HAVE_TYPEOF if so, and define 'typeof' to the actual key word.
 foreach kw : ['typeof', '__typeof__', 'decltype']
@@ -2580,29 +2572,6 @@ int main(void)
 endforeach
 
 
-# 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.
-wcstombs_l_test = '''
-#include <stdlib.h>
-#include <locale.h>
-@0@
-
-void main(void)
-{
-#ifndef wcstombs_l
-    (void) wcstombs_l;
-#endif
-}
-'''
-if (not cc.compiles(wcstombs_l_test.format(''),
-      name: 'wcstombs_l') and
-    cc.compiles(wcstombs_l_test.format('#include <xlocale.h>'),
-      name: 'wcstombs_l in xlocale.h'))
-    cdata.set('WCSTOMBS_L_IN_XLOCALE', 1)
-endif
-
-
 # MSVC doesn't cope well with defining restrict to __restrict, the spelling it
 # understands, because it conflicts with __declspec(restrict). Therefore we
 # define pg_restrict to the appropriate definition, which presumably won't

src/include/c.h

@@ -71,6 +71,9 @@
 #include <fcntl.h>				/* ensure O_BINARY is available */
 #endif
 #include <locale.h>
+#ifdef HAVE_XLOCALE_H
+#include <xlocale.h>
+#endif
 #ifdef ENABLE_NLS
 #include <libintl.h>
 #endif

src/include/pg_config.h.in

@@ -499,6 +499,9 @@
 /* Define to 1 if the assembler supports X86_64's POPCNTQ instruction. */
 #undef HAVE_X86_64_POPCNTQ
 
+/* Define to 1 if you have the <xlocale.h> header file. */
+#undef HAVE_XLOCALE_H
+
 /* Define to 1 if you have XSAVE intrinsics. */
 #undef HAVE_XSAVE_INTRINSICS
 
@@ -559,9 +562,6 @@
 /* Define to the appropriate printf length modifier for 64-bit ints. */
 #undef INT64_MODIFIER
 
-/* Define to 1 if `locale_t' requires <xlocale.h>. */
-#undef LOCALE_T_IN_XLOCALE
-
 /* Define as the maximum alignment requirement of any C data type. */
 #undef MAXIMUM_ALIGNOF
 
@@ -748,9 +748,6 @@
 /* Define to 1 to build with ZSTD support. (--with-zstd) */
 #undef USE_ZSTD
 
-/* 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/utils/pg_locale.h

@@ -12,9 +12,6 @@
 #ifndef _PG_LOCALE_
 #define _PG_LOCALE_
 
-#if defined(LOCALE_T_IN_XLOCALE) || defined(WCSTOMBS_L_IN_XLOCALE)
-#include <xlocale.h>
-#endif
 #ifdef USE_ICU
 #include <unicode/ucol.h>
 #endif

src/interfaces/ecpg/ecpglib/ecpglib_extern.h

@@ -13,9 +13,6 @@
 #ifndef CHAR_BIT
 #include <limits.h>
 #endif
-#ifdef LOCALE_T_IN_XLOCALE
-#include <xlocale.h>
-#endif
 
 enum COMPAT_MODE
 {

src/port/chklocale.c

@@ -23,10 +23,6 @@
 #include <langinfo.h>
 #endif
 
-#ifdef LOCALE_T_IN_XLOCALE
-#include <xlocale.h>
-#endif
-
 #include "mb/pg_wchar.h"