Nested formats

Are nested formats a good idea?  Probably not.  But the only rea-
son they don’t work is that the parser becomes confused and loses
track of where it is.

And it would be nice to have some consistency.  I can put sub defini-
tions inside a format:

format =
@
;sub foo {
    bar
}
.

and:

format =
@
{
    sub foo {
        bar
    }
}
.

so why not these?

format foo =
@
;format bar =
@
.
.

format foo =
@
{
    format bar =
@
.
}
.

In perl 5.17.2 and earlier, you can nest formats, but, due to the
parser being confused, the outer format must be terminated with }
instead of a dot.  That stopped working with commit 7c70caa5333.

format =
@<<<<<<<<<<<<<<<
"Just another"; format STDERR =
@<<<<<<<<<<<<<<<
"Perl hacker"
.
}
write; select STDERR;
write;

1 files changed, 19 insertions, 1 deletions

diff --git a/t/op/write.t b/t/op/write.t
index 17b8869eb5..2d5b0ac79a 100644
--- a/t/op/write.t
+++ b/t/op/write.t
@@ -61,7 +61,7 @@ for my $tref ( @NumTests ){
 my $bas_tests = 20;
 
 # number of tests in section 3
-my $bug_tests = 8 + 3 * 3 * 5 * 2 * 3 + 2 + 66 + 4 + 2 + 3 + 96 + 4;
+my $bug_tests = 8 + 3 * 3 * 5 * 2 * 3 + 2 + 66 + 4 + 2 + 3 + 96 + 5;
 
 # number of tests in section 4
 my $hmb_tests = 35;
@@ -1017,6 +1017,24 @@ format =
 ;1
 |, 'format = ... } is not allowed';
 
+open(NEST, '>Op_write.tmp') || die "Can't create Op_write.tmp";
+format NEST =
+@<<<
+{
+    my $birds = "birds";
+    local *NEST = *BIRDS{FORMAT};
+    write NEST;
+    format BIRDS =
+@<<<<<
+$birds;
+.
+    "nest"
+}
+.
+write NEST;
+close NEST or die "Could not close: $!";
+is cat('Op_write.tmp'), "birds\nnest\n", 'nested formats';
+
 
 #############################
 ## Section 4