From: Nicholas Clark <nick@ccl4.org>
Date: Sat, 22 Sep 2007 15:46:44 +0000 (+0000)
Subject: Fix bug 45607 - for the corner case *{"BONK"} = \&{"BONK"} the order
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=53a42478dbff55e7fc2f0fe0876cb4ceeaba894c;p=p5sagit%2Fp5-mst-13.2.git

Fix bug 45607 - for the corner case *{"BONK"} = \&{"BONK"} the order
of op evaluation means that what had been a reference to a constant
can turn into a typeglob before the sassign gets to run.

p4raw-id: //depot/perl@31940
---

diff --git a/pp_hot.c b/pp_hot.c
index 62eddad..6fb53d4 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -168,18 +168,44 @@ PP(pp_sassign)
 	if (!got_coderef) {
 	    /* We've been returned a constant rather than a full subroutine,
 	       but they expect a subroutine reference to apply.  */
-	    ENTER;
-	    SvREFCNT_inc_void(SvRV(cv));
-	    /* newCONSTSUB takes a reference count on the passed in SV
-	       from us.  We set the name to NULL, otherwise we get into
-	       all sorts of fun as the reference to our new sub is
-	       donated to the GV that we're about to assign to.
-	    */
-	    SvRV_set(left, (SV *)newCONSTSUB(GvSTASH(right), NULL,
+	    if (SvROK(cv)) {
+		ENTER;
+		SvREFCNT_inc_void(SvRV(cv));
+		/* newCONSTSUB takes a reference count on the passed in SV
+		   from us.  We set the name to NULL, otherwise we get into
+		   all sorts of fun as the reference to our new sub is
+		   donated to the GV that we're about to assign to.
+		*/
+		SvRV_set(left, (SV *)newCONSTSUB(GvSTASH(right), NULL,
 						 SvRV(cv)));
-	    SvREFCNT_dec(cv);
-	    LEAVE;
+		SvREFCNT_dec(cv);
+		LEAVE;
+	    } else {
+		/* What can happen for the corner case *{"BONK"} = \&{"BONK"};
+		   is that
+		   First:   ops for \&{"BONK"}; return us the constant in the
+			    symbol table
+		   Second:  ops for *{"BONK"} cause that symbol table entry
+			    (and our reference to it) to be upgraded from RV
+			    to typeblob)
+		   Thirdly: We get here. cv is actually PVGV now, and its
+			    GvCV() is actually the subroutine we're looking for
+
+		   So change the reference so that it points to the subroutine
+		   of that typeglob, as that's what they were after all along.
+		*/
+		GV *const upgraded = (GV *) cv;
+		CV *const source = GvCV(upgraded);
+
+		assert(source);
+		assert(CvFLAGS(source) & CVf_CONST);
+
+		SvREFCNT_inc_void(source);
+		SvREFCNT_dec(upgraded);
+		SvRV_set(left, (SV *)source);
+	    }
 	}
+
     }
     SvSetMagicSV(right, left);
     SETs(right);
diff --git a/t/op/gv.t b/t/op/gv.t
index bca84e7..5b04f87 100755
--- a/t/op/gv.t
+++ b/t/op/gv.t
@@ -12,7 +12,7 @@ BEGIN {
 use warnings;
 
 require './test.pl';
-plan( tests => 160 );
+plan( tests => 161 );
 
 # type coersion on assignment
 $foo = 'foo';
@@ -485,6 +485,15 @@ foreach my $value ([1,2,3], {1=>2}, *STDOUT{IO}, \&ok, *STDOUT{FORMAT}) {
     eval "`` if 0";
     is($@, '', "Can't trip up readpipe overloading");
 }
+
+{
+    die if exists $::{BONK};
+    $::{BONK} = \"powie";
+    *{"BONK"} = \&{"BONK"};
+    eval 'is(BONK(), "powie",
+             "Assigment works when glob created midway (bug 45607)"); 1'
+	or die $@;
+}
 __END__
 Perl
 Rules