From 4c3ac4ba94c3963cbfea8fd6a28648d68ac6063a Mon Sep 17 00:00:00 2001
From: Father Chrysostomos <sprout@cpan.org>
Date: Wed, 6 Apr 2011 17:43:29 -0700
Subject: [PATCH] [perl #87708] $tied + $tied
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This is just part of #87708.

This fixes the + operator outside of any ‘use integer’ when the same
tied scalar is used for both operands and returns two different val-
ues. Before this commit, get-magic would be called only once and the
same value used. In 5.12.x it worked.
---
 pp_hot.c               | 10 ++++++++++
 t/lib/warnings/9uninit | 10 ++++++++++
 t/op/tie_fetch_count.t |  2 +-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/pp_hot.c b/pp_hot.c
index f8a61cb..3d46287 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -501,6 +501,16 @@ PP(pp_add)
     svl = TOPm1s;
 
     useleft = USE_LEFT(svl);
+    if(useleft && svr == svl) {
+	/* Print the uninitialized warning now, so it includes the vari-
+	   able name. */
+	if (!SvOK(svl)) report_uninit(svl), useleft = 0;
+	/* Non-magical sv_mortalcopy */
+	svl = sv_newmortal();
+	sv_setsv_flags(svl, svr, 0);
+	SvGETMAGIC(svr);
+    }
+
 #ifdef PERL_PRESERVE_IVUV
     /* We must see if we can perform the addition with integers if possible,
        as the integer code detects overflow while the NV code doesn't.
diff --git a/t/lib/warnings/9uninit b/t/lib/warnings/9uninit
index a16fd35..33cc2b9 100644
--- a/t/lib/warnings/9uninit
+++ b/t/lib/warnings/9uninit
@@ -689,6 +689,16 @@ Use of uninitialized value $g1 in subtraction (-) at - line 20.
 Use of uninitialized value $m1 in subtraction (-) at - line 20.
 ########
 use warnings 'uninitialized';
+sub TIESCALAR{bless[]}
+sub FETCH { undef }
+
+tie my $m1, "";
+my $v = $m1 + $m1;
+EXPECT
+Use of uninitialized value $m1 in addition (+) at - line 6.
+Use of uninitialized value $m1 in addition (+) at - line 6.
+########
+use warnings 'uninitialized';
 my ($m1, $v);
 our ($g1);
 
diff --git a/t/op/tie_fetch_count.t b/t/op/tie_fetch_count.t
index d6cf9c6..be339cd 100644
--- a/t/op/tie_fetch_count.t
+++ b/t/op/tie_fetch_count.t
@@ -228,8 +228,8 @@ bin_test '.' ,  1, 2, 12;
 {
     local $TODO = $todo ;
     bin_test '==',  1, 2, "";
-    bin_test '+' ,  1, 2, 3;
 }
+bin_test '+' ,  1, 2, 3;
 bin_int_test '*' ,  2, 3, 6;
 bin_int_test '/' , 10, 2, 5;
 bin_int_test '%' , 11, 2, 1;
-- 
2.7.4