Make list assignment respect foreach aliasing

See ff2a62e0c8 for the explanation.  The bug fix in that commit did
not apply to foreach’s aliasing.

In short, ($a,$b)=($c,$d) needs to account for whether two of those
variable names could be referring to the same variable.

This commit causes the test suite to exercise a code path in scope.c
added by ff2a62e0c8, which turned out to be buggy.  (I forgot to test
it at the time.)

1 files changed, 12 insertions, 0 deletions

diff --git a/scope.c b/scope.c
index ada0a19029..1084484e92 100644
--- a/scope.c
+++ b/scope.c
@@ -701,6 +701,16 @@ Perl_save_alloc(pTHX_ I32 size, I32 pad)
     return start;
 }
 
+void
+Perl_save_aliased_sv(pTHX_ GV *gv)
+{
+    dSS_ADD;
+    PERL_ARGS_ASSERT_SAVE_ALIASED_SV;
+    SS_ADD_PTR(gp_ref(GvGP(gv)));
+    SS_ADD_UV(SAVEt_GP_ALIASED_SV | cBOOL(GvALIASED_SV(gv)) << 8);
+    SS_ADD_END(2);
+}
+
 
 
 #define ARG0_SV  MUTABLE_SV(arg0.any_ptr)
@@ -1231,8 +1241,10 @@ Perl_leave_scope(pTHX_ I32 base)
 	    GP * const gp = (GP *)ARG0_PTR;
 	    if (gp->gp_refcnt == 1) {
 		GV * const gv = (GV *)sv_2mortal(newSV_type(SVt_PVGV));
+		isGV_with_GP_on(gv);
 		GvGP_set(gv,gp);
 		gp_free(gv);
+		isGV_with_GP_off(gv);
 	    }
 	    else {
 		gp->gp_refcnt--;