[perl #123103] Just set SVf_READONLY on magic vars

a623f8939 was arguably a little too eager.  It’s purpose is to protect
vars whose modification can causes hangs and crashes.  I don’t believe
that is the case for any magic vars.

1 files changed, 10 insertions, 0 deletions

diff --git a/gv.c b/gv.c
index c8d434544c..eaf9d21501 100644
--- a/gv.c
+++ b/gv.c
@@ -1767,6 +1767,12 @@ S_find_default_stash(pTHX_ HV **stash, const char *name, STRLEN len,
     return TRUE;
 }
 
+/* gv_magicalize only turns on the SVf_READONLY flag, not SVf_PROTECT.  So
+   redefine SvREADONLY_on for that purpose.  We don’t use it later on in
+   this file.  */
+#undef SvREADONLY_on
+#define SvREADONLY_on(sv) (SvFLAGS(sv) |= SVf_READONLY)
+
 /* gv_magicalize() is called by gv_fetchpvn_flags when creating
  * a new GV.
  * Note that it does not insert the GV into the stash prior to
@@ -2148,6 +2154,10 @@ S_gv_magicalize(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len,
     return addmg;
 }
 
+/* If we do ever start using this later on in the file, we need to make
+   sure we don’t accidentally use the wrong definition.  */
+#undef SvREADONLY_on
+
 /* This function is called when the stash already holds the GV of the magic
  * variable we're looking for, but we need to check that it has the correct
  * kind of magic.  For example, if someone first uses $! and then %!, the