map and grep weren't working correctly with lexical $_ in

scalar context, because pp_mapwhile and pp_grepwhile were using
their target as a temporary slot to store the return value.

p4raw-id: //depot/perl@22289

3 files changed, 31 insertions, 5 deletions

diff --git a/pp_ctl.c b/pp_ctl.c
index 42d63c6d55..c5f802ab74 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -954,8 +954,15 @@ PP(pp_mapwhile)
 	(void)POPMARK;				/* pop dst */
 	SP = PL_stack_base + POPMARK;		/* pop original mark */
 	if (gimme == G_SCALAR) {
-	    dTARGET;
-	    XPUSHi(items);
+	    if (PL_op->op_private & OPpGREP_LEX) {
+		SV* sv = sv_newmortal();
+		sv_setiv(sv, items);
+		PUSHs(sv);
+	    }
+	    else {
+		dTARGET;
+		XPUSHi(items);
+	    }
 	}
 	else if (gimme == G_ARRAY)
 	    SP += items;
diff --git a/pp_hot.c b/pp_hot.c
index e884e2dbe1..ccfbf4181c 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2294,8 +2294,15 @@ PP(pp_grepwhile)
 	(void)POPMARK;				/* pop dst */
 	SP = PL_stack_base + POPMARK;		/* pop original mark */
 	if (gimme == G_SCALAR) {
-	    dTARGET;
-	    XPUSHi(items);
+	    if (PL_op->op_private & OPpGREP_LEX) {
+		SV* sv = sv_newmortal();
+		sv_setiv(sv, items);
+		PUSHs(sv);
+	    }
+	    else {
+		dTARGET;
+		XPUSHi(items);
+	    }
 	}
 	else if (gimme == G_ARRAY)
 	    SP += items;
diff --git a/t/op/mydef.t b/t/op/mydef.t
index 0770e78f0b..485f8431a5 100644
--- a/t/op/mydef.t
+++ b/t/op/mydef.t
@@ -5,7 +5,7 @@ BEGIN {
     @INC = '../lib';
 }
 
-print "1..64\n";
+print "1..66\n";
 
 my $test = 0;
 sub ok ($$) {
@@ -118,6 +118,12 @@ $_ = "global";
     ok( $x eq '1globallocal-2globallocal', 'map without {}' );
 }
 {
+    for my $_ (1) {
+	my $x = map $_, qw(a b);
+	ok( $x == 2, 'map in scalar context' );
+    }
+}
+{
     my $buf = '';
     sub tgrep1 { /(.)/; $buf .= $1 }
     my $_ = 'y';
@@ -142,6 +148,12 @@ $_ = "global";
     ok( $_ eq 'local', '...but without extraneous side-effects' );
 }
 {
+    for my $_ (1) {
+	my $x = grep $_, qw(a b);
+	ok( $x == 2, 'grep in scalar context' );
+    }
+}
+{
     my $s = "toto";
     my $_ = "titi";
     $s =~ /to(?{ ok( $_ eq 'toto', 'my $_ in code-match # TODO' ) })to/