Split out study magic from pos magic.

study uses magic to call SvSCREAM_off() if the scalar is modified. Allocate it
its own magic type ('G' for now - pos magic is 'g'). Share the same "set"
routine and vtable as regexp/bm/fm (setregxp and vtbl_regexp).

1 files changed, 4 insertions, 2 deletions

diff --git a/mg.c b/mg.c
index 1bdf5c4cda..9e1891833b 100644
--- a/mg.c
+++ b/mg.c
@@ -2358,9 +2358,8 @@ Perl_magic_setmglob(pTHX_ SV *sv, MAGIC *mg)
 {
     PERL_ARGS_ASSERT_MAGIC_SETMGLOB;
     PERL_UNUSED_CONTEXT;
+    PERL_UNUSED_ARG(sv);
     mg->mg_len = -1;
-    if (!isGV_with_GP(sv))
-	SvSCREAM_off(sv);
     return 0;
 }
 
@@ -2387,6 +2386,9 @@ Perl_magic_setregexp(pTHX_ SV *sv, MAGIC *mg)
     } else if (type == PERL_MAGIC_bm) {
 	SvTAIL_off(sv);
 	SvVALID_off(sv);
+    } else if (type == PERL_MAGIC_study) {
+	if (!isGV_with_GP(sv))
+	    SvSCREAM_off(sv);
     } else {
 	assert(type == PERL_MAGIC_fm);
     }