[perl #29070] Add vstring set-magic

Some operators, like pp_complement, assign their argument to TARG
(which copies vstring magic), modify it in place, and then call set-
magic.  That’s supposed to work, but vstring magic was remaining as it
was, such that ~v7 would still be treated as "v7" by vstring-aware
code, even though the resulting string is not "\7".

This commit adds vstring set-magic that checks to see whether the pv
still matches the vstring.  It cannot simply free the vstring magic,
as that would prevent $x=v0 from working.

1 files changed, 6 insertions, 2 deletions

diff --git a/mg_vtable.h b/mg_vtable.h
index 2e3ca3522f..12f2fa35f3 100644
--- a/mg_vtable.h
+++ b/mg_vtable.h
@@ -90,6 +90,7 @@ enum {		/* pass one of these to get_vtbl */
     want_vtbl_utf8,
     want_vtbl_uvar,
     want_vtbl_vec,
+    want_vtbl_vstring,
     magic_vtable_max
 };
 
@@ -124,7 +125,8 @@ EXTCONST char *PL_magic_vtable_names[magic_vtable_max] = {
     "taint",
     "utf8",
     "uvar",
-    "vec"
+    "vec",
+    "vstring"
 };
 #else
 EXTCONST char *PL_magic_vtable_names[magic_vtable_max];
@@ -186,7 +188,8 @@ EXT_MGVTBL PL_magic_vtables[magic_vtable_max] = {
   { Perl_magic_gettaint, Perl_magic_settaint, 0, 0, 0, 0, 0, 0 },
   { 0, Perl_magic_setutf8, 0, 0, 0, 0, 0, 0 },
   { Perl_magic_getuvar, Perl_magic_setuvar, 0, 0, 0, 0, 0, 0 },
-  { Perl_magic_getvec, Perl_magic_setvec, 0, 0, 0, 0, 0, 0 }
+  { Perl_magic_getvec, Perl_magic_setvec, 0, 0, 0, 0, 0, 0 },
+  { 0, Perl_magic_setvstring, 0, 0, 0, 0, 0, 0 }
 };
 #else
 EXT_MGVTBL PL_magic_vtables[magic_vtable_max];
@@ -227,5 +230,6 @@ EXT_MGVTBL PL_magic_vtables[magic_vtable_max];
 #define PL_vtbl_utf8 PL_magic_vtables[want_vtbl_utf8]
 #define PL_vtbl_uvar PL_magic_vtables[want_vtbl_uvar]
 #define PL_vtbl_vec PL_magic_vtables[want_vtbl_vec]
+#define PL_vtbl_vstring PL_magic_vtables[want_vtbl_vstring]
 
 /* ex: set ro: */