sort(!) out CXt_NULL and CXp_MULTICALL

A sort BLOCK is done using a CXt_NULL context type. Currently it has
the CXp_MULTICALL flag set. Remove this flag so that CXp_MULTICALL is
only set on CXt_SUB contexts.

Also add code comments in various places explainging that CXt_NULL is
likely to a sort BLOCK, and fix the comments in pp_return which said
a particular code path was only taken by sort BLOCK; it's also taken
be (?{...}) too.

1 files changed, 1 insertions, 4 deletions

diff --git a/sv.c b/sv.c
index 87c48ac8a8..558ecd5a57 100644
--- a/sv.c
+++ b/sv.c
@@ -16292,13 +16292,10 @@ Perl_report_uninit(pTHX_ const SV *uninit_sv)
 		sv_insert(varname, 0, 0, " ", 1);
 	}
     }
-    else if (PL_curstackinfo->si_type == PERLSI_SORT
-             &&  CxMULTICALL(&cxstack[cxstack_ix]))
-    {
+    else if (PL_curstackinfo->si_type == PERLSI_SORT && cxstack_ix == 0)
         /* we've reached the end of a sort block or sub,
          * and the uninit value is probably what that code returned */
         desc = "sort";
-    }
 
     /* PL_warn_uninit_sv is constant */
     GCC_DIAG_IGNORE(-Wformat-nonliteral);