locale.c: Add fcn to hide edge case undefined behavior

The POSIX 2008 API has an edge case in that the result of most of the
functions when called with a global (as opposed to a per-thread) locale
is undefined.

The duplocale() function is the exception which will create a per-thread
locale containing the values copied from the global one.

This commit just calls duplocale, if needed, and the caller need not
concern itself with this possibility

1 files changed, 3 insertions, 0 deletions

diff --git a/sv.c b/sv.c
index 6f8fe602ed..bb30c91937 100644
--- a/sv.c
+++ b/sv.c
@@ -15845,6 +15845,9 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_underlying_numeric_obj = NULL;
 #  endif
 #endif /* !USE_LOCALE_NUMERIC */
+#if defined(USE_POSIX_2008_LOCALE)
+    PL_scratch_locale_obj = NULL;
+#endif
 
 #ifdef HAS_MBRLEN
     PL_mbrlen_ps = proto_perl->Imbrlen_ps;