localename: Fix test failure on OpenBSD >= 6.2

[Bruno Haible]

While testing a grep snapshot on OpenBSD 6.3, I see a test failure of
test-localename. The cause is that in OpenBSD >= 6.2, the locale_t
type and uselocale() etc. are now available, but with a terribly dumbed-
down implementation that makes it impossible to use these per-thread
locales for anything real (including gettext()).

This patch adjusts the gnulib code so that it treats OpenBSD >= 6.2 like
the platforms without locale_t and uselocale().


2018-12-16  Bruno Haible  <address@hidden>

        localename: Fix test failure on OpenBSD >= 6.2.
        * m4/intl-thread-locale.m4 (gt_INTL_THREAD_LOCALE_NAME): Test for fake
        locale system. Define HAVE_FAKE_LOCALES in this case.
        * lib/localename.c (HAVE_GOOD_USELOCALE): New macro. Use it instead of
        HAVE_USELOCALE.
        * tests/test-localename.c (HAVE_GOOD_USELOCALE): New macro. Use it
        instead of HAVE_NEWLOCALE && HAVE_USELOCALE.
        * doc/posix-functions/uselocale.texi: Mention OpenBSD problem. Update
        platforms list.
        * doc/posix-functions/newlocale.texi: Likewise.
        * doc/posix-functions/duplocale.texi: Update platforms list.
        * doc/posix-functions/freelocale.texi: Likewise.

diff --git a/doc/posix-functions/uselocale.texi 
b/doc/posix-functions/uselocale.texi
index 07711df..2d8b947 100644
--- a/doc/posix-functions/uselocale.texi
+++ b/doc/posix-functions/uselocale.texi
@@ -14,5 +14,9 @@ Portability problems not fixed by Gnulib:
 @itemize
 @item
 This function is missing on many platforms:
-Mac OS X 10.3, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
+Mac OS X 10.3, FreeBSD 9.0, NetBSD 5.0, OpenBSD 6.1, Minix 3.1.8, AIX 6.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
address@hidden
+This function is useless because the @code{locale_t} type contains basically
+no information on some platforms:
+OpenBSD 6.3.
 @end itemize
diff --git a/doc/posix-functions/newlocale.texi 
b/doc/posix-functions/newlocale.texi
index c15b1bd..376f7e8 100644
--- a/doc/posix-functions/newlocale.texi
+++ b/doc/posix-functions/newlocale.texi
@@ -14,5 +14,9 @@ Portability problems not fixed by Gnulib:
 @itemize
 @item
 This function is missing on many platforms:
-Mac OS X 10.3, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
+Mac OS X 10.3, FreeBSD 9.0, NetBSD 5.0, OpenBSD 6.1, Minix 3.1.8, AIX 6.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
address@hidden
+This function is useless because the @code{locale_t} type contains basically
+no information on some platforms:
+OpenBSD 6.3.
 @end itemize
diff --git a/doc/posix-functions/duplocale.texi 
b/doc/posix-functions/duplocale.texi
index a328a67..000300b 100644
--- a/doc/posix-functions/duplocale.texi
+++ b/doc/posix-functions/duplocale.texi
@@ -21,5 +21,5 @@ Portability problems not fixed by Gnulib:
 @itemize
 @item
 This function is missing on many platforms:
-Mac OS X 10.3, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
+Mac OS X 10.3, FreeBSD 9.0, NetBSD 5.0, OpenBSD 6.1, Minix 3.1.8, AIX 6.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
 @end itemize
diff --git a/doc/posix-functions/freelocale.texi 
b/doc/posix-functions/freelocale.texi
index 50e448e..e4ff00f 100644
--- a/doc/posix-functions/freelocale.texi
+++ b/doc/posix-functions/freelocale.texi
@@ -14,5 +14,5 @@ Portability problems not fixed by Gnulib:
 @itemize
 @item
 This function is missing on many platforms:
-Mac OS X 10.3, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
+Mac OS X 10.3, FreeBSD 9.0, NetBSD 5.0, OpenBSD 6.1, Minix 3.1.8, AIX 6.1, 
HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.3, Cygwin, mingw, MSVC 14, Interix 
3.5, BeOS, Android 4.4.
 @end itemize
diff --git a/m4/intl-thread-locale.m4 b/m4/intl-thread-locale.m4
index d7ad0ac..0666e39 100644
--- a/m4/intl-thread-locale.m4
+++ b/m4/intl-thread-locale.m4
@@ -1,4 +1,4 @@
-# intl-thread-locale.m4 serial 2
+# intl-thread-locale.m4 serial 3
 dnl Copyright (C) 2015-2018 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -24,6 +24,57 @@ AC_DEFUN([gt_INTL_THREAD_LOCALE_NAME],
 
   AC_CHECK_FUNCS_ONCE([uselocale])
 
+  dnl On OpenBSD >= 6.2, the locale_t type and the uselocale(), newlocale(),
+  dnl duplocale(), freelocale() functions exist but are effectively useless,
+  dnl because the locale_t value depends only on the LC_CTYPE category of the
+  dnl locale and furthermore contains only one bit of information (it
+  dnl distinguishes the "C" locale from the *.UTF-8 locales). See
+  dnl 
<https://cvsweb.openbsd.org/src/lib/libc/locale/newlocale.c?rev=1.1&content-type=text/x-cvsweb-markup>.
+  dnl In the setlocale() implementation they have thought about the programs
+  dnl that use the API ("Even though only LC_CTYPE has any effect in the
+  dnl OpenBSD base system, store complete information about the global locale,
+  dnl such that third-party software can access it"), but for uselocale()
+  dnl they did not think about the programs.
+  dnl In this situation, even the HAVE_NAMELESS_LOCALES support does not work.
+  dnl So, define HAVE_FAKE_LOCALES and disable all locale_t support.
+  if test $ac_cv_func_uselocale = yes; then
+    AC_CHECK_HEADERS_ONCE([xlocale.h])
+    AC_CACHE_CHECK([for fake locale system (OpenBSD)],
+      [gt_cv_locale_fake],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <locale.h>
+#if HAVE_XLOCALE_H
+# include <xlocale.h>
+#endif
+int main ()
+{
+  locale_t loc1, loc2;
+  if (setlocale (LC_ALL, "de_DE.UTF-8") == NULL) return 1;
+  if (setlocale (LC_ALL, "fr_FR.UTF-8") == NULL) return 1;
+  loc1 = newlocale (LC_ALL_MASK, "de_DE.UTF-8", (locale_t)0);
+  loc2 = newlocale (LC_ALL_MASK, "fr_FR.UTF-8", (locale_t)0);
+  return !(loc1 == loc2);
+}]])],
+         [gt_cv_locale_fake=yes],
+         [gt_cv_locale_fake=no],
+         [dnl Guess the locale system is fake only on OpenBSD.
+          case "$host_os" in
+            openbsd*) gt_cv_locale_fake="guessing yes" ;;
+            *)        gt_cv_locale_fake="guessing no" ;;
+          esac
+         ])
+      ])
+  else
+    gt_cv_locale_fake=no
+  fi
+  case "$gt_cv_locale_fake" in
+    *yes)
+      AC_DEFINE([HAVE_FAKE_LOCALES], [1],
+        [Define if the locale_t type contains insufficient information, as on 
OpenBSD.])
+      ;;
+  esac
+
   if test $ac_cv_func_uselocale = yes; then
     AC_CACHE_CHECK([for Solaris 11.4 locale system],
       [gt_cv_locale_solaris114],
diff --git a/lib/localename.c b/lib/localename.c
index aa3cc13..28b3d61 100644
--- a/lib/localename.c
+++ b/lib/localename.c
@@ -35,7 +35,13 @@
 
 #include "flexmember.h"
 
-#if HAVE_USELOCALE
+/* We cannot support uselocale() on platforms where the locale_t type is fake.
+   See intl-thread-locale.m4 for details.  */
+#if HAVE_USELOCALE && !HAVE_FAKE_LOCALES
+# define HAVE_GOOD_USELOCALE 1
+#endif
+
+#if HAVE_GOOD_USELOCALE
 /* Mac OS X 10.5 defines the locale_t type in <xlocale.h>.  */
 # if defined __APPLE__ && defined __MACH__
 #  include <xlocale.h>
@@ -2623,8 +2629,8 @@ get_lcid (const char *locale_name)
 #endif
 
 
-#if HAVE_USELOCALE /* glibc, Mac OS X, FreeBSD >= 9.1, AIX >= 7,
-                      Solaris 11 OpenIndiana, or Solaris >= 11.4  */
+#if HAVE_GOOD_USELOCALE /* glibc, Mac OS X, FreeBSD >= 9.1, AIX >= 7,
+                           Solaris 11 OpenIndiana, or Solaris >= 11.4  */
 
 /* Simple hash set of strings.  We don't want to drag in lots of hash table
    code here.  */
@@ -2709,7 +2715,7 @@ struniq (const char *string)
 #endif
 
 
-#if HAVE_USELOCALE && HAVE_NAMELESS_LOCALES
+#if HAVE_GOOD_USELOCALE && HAVE_NAMELESS_LOCALES
 
 /* The 'locale_t' object does not contain the names of the locale categories.
    We have to associate them with the object through a hash table.
@@ -3089,7 +3095,7 @@ freelocale (locale_t locale)
 #endif
 
 
-#if defined IN_LIBINTL || HAVE_USELOCALE
+#if defined IN_LIBINTL || HAVE_GOOD_USELOCALE
 
 /* Like gl_locale_name_thread, except that the result is not in storage of
    indefinite extent.  */
@@ -3099,7 +3105,7 @@ static
 const char *
 gl_locale_name_thread_unsafe (int category, const char *categoryname)
 {
-# if HAVE_USELOCALE
+# if HAVE_GOOD_USELOCALE
   {
     locale_t thread_locale = uselocale (NULL);
     if (thread_locale != LC_GLOBAL_LOCALE)
@@ -3212,7 +3218,7 @@ gl_locale_name_thread_unsafe (int category, const char 
*categoryname)
 const char *
 gl_locale_name_thread (int category, const char *categoryname)
 {
-#if HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   const char *name = gl_locale_name_thread_unsafe (category, categoryname);
   if (name != NULL)
     return struniq (name);
diff --git a/tests/test-localename.c b/tests/test-localename.c
index 4e8d146..8c3c425 100644
--- a/tests/test-localename.c
+++ b/tests/test-localename.c
@@ -26,8 +26,12 @@
 
 #include "macros.h"
 
+#if HAVE_NEWLOCALE && HAVE_USELOCALE && !HAVE_FAKE_LOCALES
+# define HAVE_GOOD_USELOCALE 1
+#endif
+
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
 
 static struct { int cat; int mask; const char *string; } const categories[] =
   {
@@ -70,7 +74,7 @@ test_locale_name (void)
 
   /* Get into a defined state,  */
   setlocale (LC_ALL, "en_US.UTF-8");
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   uselocale (LC_GLOBAL_LOCALE);
 #endif
 
@@ -181,7 +185,7 @@ test_locale_name (void)
       ASSERT (strcmp (name, "fr_FR.UTF-8") == 0);
     }
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   /* Check that gl_locale_name considers the thread locale.  */
   {
     locale_t locale = newlocale (LC_ALL_MASK, "fr_FR.UTF-8", NULL);
@@ -241,7 +245,7 @@ test_locale_name_thread (void)
   /* Get into a defined state,  */
   setlocale (LC_ALL, "en_US.UTF-8");
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   /* Check that gl_locale_name_thread returns NULL when no thread locale is
      set.  */
   uselocale (LC_GLOBAL_LOCALE);
@@ -496,7 +500,7 @@ test_locale_name_posix (void)
 
   /* Get into a defined state,  */
   setlocale (LC_ALL, "en_US.UTF-8");
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   uselocale (LC_GLOBAL_LOCALE);
 #endif
 
@@ -605,7 +609,7 @@ test_locale_name_posix (void)
       ASSERT (strcmp (name, "fr_FR.UTF-8") == 0);
     }
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   /* Check that gl_locale_name_posix ignores the thread locale.  */
   {
     locale_t locale = newlocale (LC_ALL_MASK, "fr_FR.UTF-8", NULL);
@@ -634,7 +638,7 @@ test_locale_name_environ (void)
 
   /* Get into a defined state,  */
   setlocale (LC_ALL, "en_US.UTF-8");
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   uselocale (LC_GLOBAL_LOCALE);
 #endif
 
@@ -719,7 +723,7 @@ test_locale_name_environ (void)
   name = gl_locale_name_environ (LC_MESSAGES, "LC_MESSAGES");
   ASSERT (strcmp (name, "fr_FR.UTF-8") == 0);
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   /* Check that gl_locale_name_environ ignores the thread locale.  */
   {
     locale_t locale = newlocale (LC_ALL_MASK, "fr_FR.UTF-8", NULL);
@@ -754,7 +758,7 @@ test_locale_name_default (void)
   ASSERT (strcmp (name, "C") == 0);
 #endif
 
-#if HAVE_NEWLOCALE && HAVE_USELOCALE
+#if HAVE_GOOD_USELOCALE
   /* Check that gl_locale_name_default ignores the thread locale.  */
   {
     locale_t locale = newlocale (LC_ALL_MASK, "fr_FR.UTF-8", NULL);