Add MAYBE_DEREF_GV macro

There are so many parts of the core (mostly pp functions or functions
they call) that need a glob or a globref, including many that call
get-magic at the wrong time (or not at all in some cases, that it
makes sense to add a macro to do it.

It can be used like this:

   if (gv = MAYBE_DEREF_GV(sv)) /* calls get-magic */
   {

   }
   else { /* avoid magic here */

   }

1 files changed, 1 insertions, 1 deletions

diff --git a/sv.h b/sv.h
index c838367d93..534535204c 100644
--- a/sv.h
+++ b/sv.h
@@ -1919,7 +1919,7 @@ Returns a pointer to the character buffer.
 #define SvUNLOCK(sv) PL_unlockhook(aTHX_ sv)
 #define SvDESTROYABLE(sv) PL_destroyhook(aTHX_ sv)
 
-#define SvGETMAGIC(x) STMT_START { if (SvGMAGICAL(x)) mg_get(x); } STMT_END
+#define SvGETMAGIC(x) ((void)(SvGMAGICAL(x) && mg_get(x)))
 #define SvSETMAGIC(x) STMT_START { if (SvSMAGICAL(x)) mg_set(x); } STMT_END
 
 #define SvSetSV_and(dst,src,finally) \