Make stacked -l work

Perl 5.10.0 introduced stacked filetest operators,

   -x -r $foo

being equivalent to

    -r $foo && -x _

That does not work with -l.  It was these suspicious lines in
Perl_my_lstat_flags that drew my attention to it:

>     else if (PL_laststype != OP_LSTAT
> 	    && (PL_op->op_private & OPpFT_STACKED) && ckWARN(WARN_IO))
> 	Perl_croak(aTHX_ no_prev_lstat);

That croak only happens when warnings are on.  Warnings are just
supposed to be warnings, unless the ‘user’ explicitly requests
fatal warnings.

$ perl -le 'print "foo", -l -e "miniperl"'
foo
$ perl -lwe 'print "foo", -l -e "miniperl"'
The stat preceding -l _ wasn't an lstat at -e line 1.

That it doesn’t die in the first example is a bug.

In fact, it’s using the return value of -e as a file name:

$ ln -s miniperl 1
$ ./miniperl -le 'print -l -e "miniperl"'
1

And, with warnings on, if the preceding stat *was* an lstat, it
falls back to the pre-stacked behaviour, just as it does when warn-
ings are off.

It’s meant to be equivalent to -e "miniperl" && -l _ (which is why the
error message above says ‘The stat preceding -l _’).

1 files changed, 24 insertions, 1 deletions

diff --git a/t/op/filetest.t b/t/op/filetest.t
index 08380d1c97..3b09c2b10c 100644
--- a/t/op/filetest.t
+++ b/t/op/filetest.t
@@ -10,7 +10,7 @@ BEGIN {
 }
 
 use Config;
-plan(tests => 30 + 27*14);
+plan(tests => 33 + 27*14);
 
 ok( -d 'op' );
 ok( -f 'TEST' );
@@ -89,6 +89,29 @@ is( -f -s $tempfile, 0 );
 is( -s -f $tempfile, 0 );
 unlink_all $tempfile;
 
+# stacked -l
+eval { -l -e "TEST" };
+like $@, qr/^The stat preceding -l _ wasn't an lstat at /,
+  'stacked -l non-lstat error with warnings off';
+{
+ local $^W = 1;
+ eval { -l -e "TEST" };
+ like $@, qr/^The stat preceding -l _ wasn't an lstat at /,
+  'stacked -l non-lstat error with warnings on';
+}
+# Make sure -l is using the previous stat buffer, and not using the previ-
+# ous op’s return value as a file name.
+SKIP: {
+ use Perl::OSType 'os_type';
+ if (os_type ne 'Unix') { skip "Not Unix", 1 }
+ chomp(my $ln = `which ln`);
+ if ( ! -e $ln ) { skip "No ln"   , 1 }
+ lstat "TEST";
+ `ln -s TEST 1`;
+ ok ! -l -e _, 'stacked -l uses previous stat, not previous retval';
+ unlink 1;
+}
+
 # test that _ is a bareword after filetest operators
 
 -f 'TEST';