Add USE_LOCALE_THREADS #define

This is in preparation for supporting configurations where there threads
are available, but the locale handling code should ignore that fact.

This stems from the unusual locale handling of z/OS, where any attempt
is ignored to change locales after the first thread is created.

3 files changed, 15 insertions, 10 deletions

diff --git a/locale.c b/locale.c
index 35b55d7fb7..81c42e0d0d 100644
--- a/locale.c
+++ b/locale.c
@@ -3540,7 +3540,7 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
 
     for (i = 0; i < NOMINAL_LC_ALL_INDEX; i++) {
 
-#  if defined(USE_ITHREADS) && ! defined(USE_THREAD_SAFE_LOCALE)
+#  if defined(USE_LOCALE_THREADS) && ! defined(USE_THREAD_SAFE_LOCALE)
 
         /* This caches whether each category's locale is UTF-8 or not.  This
          * may involve changing the locale.  It is ok to do this at
@@ -4440,7 +4440,7 @@ Perl__is_cur_LC_category_utf8(pTHX_ int category)
             int len;
             dSAVEDERRNO;
 
-#      if defined(HAS_MBRTOWC) && defined(USE_ITHREADS)
+#      if defined(HAS_MBRTOWC) && defined(USE_LOCALE_THREADS)
 
             mbstate_t ps;
 
@@ -4450,7 +4450,7 @@ Perl__is_cur_LC_category_utf8(pTHX_ int category)
              * character.  Feed a byte string to one of them and check that the
              * result is the expected Unicode code point */
 
-#      if defined(HAS_MBRTOWC) && defined(USE_ITHREADS)
+#      if defined(HAS_MBRTOWC) && defined(USE_LOCALE_THREADS)
             /* Prefer this function if available, as it's reentrant */
 
             memzero(&ps, sizeof(ps));;
@@ -4901,7 +4901,7 @@ Perl_my_strerror(pTHX_ const int errnum)
 
     const bool within_locale_scope = IN_LC(LC_MESSAGES);
 
-#  ifndef USE_ITHREADS
+#  ifndef USE_LOCALE_THREADS
 
     /* This function is trivial without threads. */
     if (within_locale_scope) {
diff --git a/makedef.pl b/makedef.pl
index b1663b31e3..f5d98d1be1 100644
--- a/makedef.pl
+++ b/makedef.pl
@@ -140,11 +140,14 @@ if (! $define{NO_LOCALE}) {
 
 # https://en.wikipedia.org/wiki/Microsoft_Visual_C%2B%2B#Internal_version_numbering
 my $cctype = $ARGS{CCTYPE} =~ s/MSVC//r;
+if ($define{USE_ITHREADS} && ! $define{NO_LOCALE_THREADS}) {
+    $define{USE_LOCALE_THREADS} = 1;
+}
 if (! $define{HAS_SETLOCALE} && $define{HAS_POSIX_2008_LOCALE}) {
     $define{USE_POSIX_2008_LOCALE} = 1;
     $define{USE_THREAD_SAFE_LOCALE} = 1;
 }
-elsif (   ($define{USE_ITHREADS} || $define{USE_THREAD_SAFE_LOCALE})
+elsif (   ($define{USE_LOCALE_THREADS} || $define{USE_THREAD_SAFE_LOCALE})
        && (    $define{HAS_POSIX_2008_LOCALE}
            || ($ARGS{PLATFORM} eq 'win32' && (   $cctype !~ /\D/
                                               && $cctype >= 80)))
@@ -405,8 +408,7 @@ unless ($define{'USE_ITHREADS'}) {
 			 );
 }
 
-if (      $define{NO_LOCALE}
-    || (! $define{USE_ITHREADS} && ! $define{USE_THREAD_SAFE_LOCALE}))
+unless ($define{USE_POSIX_2008_LOCALE})
 {
     ++$skip{$_} foreach qw(
         PL_C_locale_obj
diff --git a/perl.h b/perl.h
index b26b0e4a80..55f91185db 100644
--- a/perl.h
+++ b/perl.h
@@ -1270,6 +1270,9 @@ violations are fatal.
 /* XXX The next few defines are unfortunately duplicated in makedef.pl, and
  * changes here MUST also be made there */
 
+#  if defined(USE_ITHREADS) && ! defined(NO_LOCALE_THREADS)
+#    define USE_LOCALE_THREADS
+#  endif
 #  if ! defined(HAS_SETLOCALE) && defined(HAS_POSIX_2008_LOCALE)
 #      define USE_POSIX_2008_LOCALE
 #      ifndef USE_THREAD_SAFE_LOCALE
@@ -1278,7 +1281,7 @@ violations are fatal.
                                    /* If compiled with
                                     * -DUSE_THREAD_SAFE_LOCALE, will do so even
                                     * on unthreaded builds */
-#  elif   (defined(USE_ITHREADS) || defined(USE_THREAD_SAFE_LOCALE))         \
+#  elif   (defined(USE_LOCALE_THREADS) || defined(USE_THREAD_SAFE_LOCALE))   \
        && (    defined(HAS_POSIX_2008_LOCALE)                                \
            || (defined(WIN32) && defined(_MSC_VER)))                         \
        && ! defined(NO_THREAD_SAFE_LOCALE)
@@ -6842,7 +6845,7 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
 
 /* Locale/thread synchronization macros. */
 #if ! (   defined(USE_LOCALE)                                               \
-       &&    defined(USE_ITHREADS)                                          \
+       &&    defined(USE_LOCALE_THREADS)                                    \
        && (  ! defined(USE_THREAD_SAFE_LOCALE)                              \
            || (   defined(HAS_LOCALECONV)                                   \
                && (  ! defined(HAS_LOCALECONV_L)                            \
@@ -7364,7 +7367,7 @@ cannot have changed since the precalculation.
 
 #endif /* !USE_LOCALE_NUMERIC */
 
-#ifdef USE_ITHREADS
+#ifdef USE_LOCALE_THREADS
 #  define ENV_LOCK            PERL_WRITE_LOCK(&PL_env_mutex)
 #  define ENV_UNLOCK          PERL_WRITE_UNLOCK(&PL_env_mutex)
 #  define ENV_READ_LOCK       PERL_READ_LOCK(&PL_env_mutex)