[perl #120657] Fix require PADTMP when @INC=(sub{},sub{})

It was passing a freed scalar to subsequent subs, breaking
Test::Without::Module:

sub fake_module {
    my (undef,$module_file) = @_;
    !1
}
unshift @INC, (\&fake_module)x2;
require "${\'whatever'}";
__END__
panic: attempt to copy freed scalar 7fe8d0829820 to 7fe8d082a0f0 at - line 3.

Obviously, doing:

    SAVETMPS;
    ...
    nsv = sv_newmortal();
    ...
    FREETMPS; # free all tmps created since SAVETMPS

inside a loop that only assigns to nsv the first time through will
cause nsv to point to a freed scalar on subsequent iterations.

It was stupid of me to make that mistake in commit 9ffd39a to
begin with.

The extra file name SV here will simply have to last until the
require call finishes, something I was trying to avoid by putting it
after SAVETMPS.

2 files changed, 18 insertions, 3 deletions

diff --git a/pp_ctl.c b/pp_ctl.c
index c8c67736b0..7236921455 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -3833,12 +3833,13 @@ PP(pp_require)
 		    tryname = SvPVX_const(namesv);
 		    tryrsfp = NULL;
 
-		    ENTER_with_name("call_INC");
-		    SAVETMPS;
 		    if (SvPADTMP(nsv)) {
 			nsv = sv_newmortal();
 			SvSetSV_nosteal(nsv,sv);
 		    }
+
+		    ENTER_with_name("call_INC");
+		    SAVETMPS;
 		    EXTEND(SP, 2);
 
 		    PUSHMARK(SP);
diff --git a/t/op/inccode.t b/t/op/inccode.t
index b00959c67c..0712956f3e 100644
--- a/t/op/inccode.t
+++ b/t/op/inccode.t
@@ -21,7 +21,7 @@ unless (is_miniperl()) {
 
 use strict;
 
-plan(tests => 61 + !is_miniperl() * (3 + 14 * $can_fork));
+plan(tests => 62 + !is_miniperl() * (3 + 14 * $can_fork));
 
 sub get_temp_fh {
     my $f = tempfile();
@@ -267,6 +267,20 @@ is $_||$@, "are temps freed prematurely?",
            "are temps freed prematurely when returned from inc filters?";
 shift @INC;
 
+# [perl #120657]
+sub fake_module {
+    my (undef,$module_file) = @_;
+    !1
+}
+{
+    local @INC = @INC;
+    unshift @INC, (\&fake_module)x2;
+    eval { require "${\'bralbalhablah'}" };
+    like $@, qr/^Can't locate/,
+        'require PADTMP passing freed var when @INC has multiple subs';

+}    
+
+
 exit if is_miniperl();
 
 SKIP: {