SEGV in "Subroutine redefined" warning

RT #128257

The following SEGVed:

    sub P::f{}
    undef *P::;
    *P::f =sub{};

due to the code which generates the "Subroutine STASH::NAME redefined"
warning assuming that the GV always has a stash. Make it so that if it
hasn't, the message changes to  "Subroutine NAME redefined" rather than
just crashing.

diff --git a/sv.c b/sv.c
index 1b7a283..0cbe371 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -4074,14 +4074,18 @@ Perl_gv_setref(pTHX_ SV *const dstr, SV *const sstr)
                            CvCONST((const CV *)sref)
                                 ? cv_const_sv((const CV *)sref)
                                 : NULL;
+                        HV * const stash = GvSTASH((const GV *)dstr);
                        report_redefined_cv(
-                          sv_2mortal(Perl_newSVpvf(aTHX_
-                               "%"HEKf"::%"HEKf,
-                               HEKfARG(
-                                HvNAME_HEK(GvSTASH((const GV *)dstr))
-                               ),
-                               HEKfARG(GvENAME_HEK(MUTABLE_GV(dstr)))
-                          )),
+                          sv_2mortal(
+                             stash
+                               ? Perl_newSVpvf(aTHX_
+                                   "%"HEKf"::%"HEKf,
+                                   HEKfARG(HvNAME_HEK(stash)),
+                                   HEKfARG(GvENAME_HEK(MUTABLE_GV(dstr))))
+                               : Perl_newSVpvf(aTHX_
+                                   "%"HEKf,
+                                   HEKfARG(GvENAME_HEK(MUTABLE_GV(dstr))))
+                          ),
                           cv,
                           CvCONST((const CV *)sref) ? &new_const_sv : NULL
                        );

diff --git a/t/lib/warnings/sv b/t/lib/warnings/sv
index 5ddd4fe..c8e0e62 100644 (file)
--- a/t/lib/warnings/sv
+++ b/t/lib/warnings/sv
@@ -413,3 +413,11 @@ Argument "a_c" isn't numeric in preincrement (++) at - line 5.
 Argument "(?^:abc)" isn't numeric in preincrement (++) at - line 6.
 Argument "123x" isn't numeric in preincrement (++) at - line 7.
 Argument "123e" isn't numeric in preincrement (++) at - line 8.
+########
+# RT #128257 This used to SEGV
+use warnings;
+sub Foo::f {}
+undef *Foo::;
+*Foo::f =sub {};
+EXPECT
+Subroutine f redefined at - line 5.