From c31c2913381bad74c5f1f5c67c4d9c6e037550ad Mon Sep 17 00:00:00 2001
From: Father Chrysostomos <sprout@cpan.org>
Date: Tue, 5 Apr 2011 21:39:01 -0700
Subject: [PATCH] [perl #87708] atan2 $tied, $tied

This fixes atan2 when the same tied scalar is used for both operands
and returns two different values. Before this commit, get-magic would
be called only once and the same value used. In 5.12.x, the operands
would be reversed.
---
 pp.c                   | 2 +-
 pp.h                   | 5 +++++
 t/op/tie_fetch_count.t | 6 +++---
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/pp.c b/pp.c
index 8b15b6e..9858f91 100644
--- a/pp.c
+++ b/pp.c
@@ -3082,7 +3082,7 @@ PP(pp_atan2)
     dVAR; dSP; dTARGET;
     tryAMAGICbin_MG(atan2_amg, 0);
     {
-      dPOPTOPnnrl_nomg;
+      dPOPTOPnnrl_halfmg;
       SETn(Perl_atan2(left, right));
       RETURN;
     }
diff --git a/pp.h b/pp.h
index 6903069..eef6a0b 100644
--- a/pp.h
+++ b/pp.h
@@ -370,6 +370,11 @@ Does not use C<TARG>.  See also C<XPUSHu>, C<mPUSHu> and C<PUSHu>.
 #define dPOPTOPnnrl_ul	dPOPXnnrl_ul(TOP)
 #define dPOPTOPnnrl_nomg \
     NV right = SvNV_nomg(TOPs); NV left = (sp--, SvNV_nomg(TOPs))
+#ifdef PERL_CORE
+# define dPOPTOPnnrl_halfmg \
+    NV left  = SvNV_nomg(TOPm1s); \
+    NV right = TOPs == TOPm1s ? SvNV(TOPs) : SvNV_nomg(TOPs); sp--
+#endif
 #define dPOPTOPiirl	dPOPXiirl(TOP)
 #define dPOPTOPiirl_ul	dPOPXiirl_ul(TOP)
 #define dPOPTOPiirl_ul_nomg dPOPXiirl_ul_nomg(TOP)
diff --git a/t/op/tie_fetch_count.t b/t/op/tie_fetch_count.t
index 9ab77d9..a0e7491 100644
--- a/t/op/tie_fetch_count.t
+++ b/t/op/tie_fetch_count.t
@@ -252,9 +252,9 @@ bin_test '.' ,  1, 2, 12;
     bin_int_test '==',  1, 2, "";
     bin_int_test '!=',  1, 2, 1;
     bin_int_test '<=>', 1, 2, -1;
-    tie $var, "main", 1, 4;
-    cmp_ok(atan2($var, $var), '<', .3, 'retval of atan2 $var, $var');
-    check_count 'atan2',  2;
 }
+tie $var, "main", 1, 4;
+cmp_ok(atan2($var, $var), '<', .3, 'retval of atan2 $var, $var');
+check_count 'atan2',  2;
 
 __DATA__
-- 
2.7.4