106 lines
3.1 KiB
Diff
106 lines
3.1 KiB
Diff
From 695d6585affc8f13711f013329fb4810ab89d833 Mon Sep 17 00:00:00 2001
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From: Father Chrysostomos <sprout@cpan.org>
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Date: Tue, 14 Nov 2017 18:55:55 -0800
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Subject: [PATCH] [perl #132442] Fix stack with do {my sub l; 1}
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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A block in perl usually compiles to a leave op with an enter inside
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it, followed by the statements:
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leave
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enter
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nextstate
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... expr ...
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nextstate
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... expr ...
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If a block contains only one statement, and that statement is suffic-
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iently innocuous, then the enter/leave pair to create the scope at run
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time get skipped, and instead we have a simple scope op which is not
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even executed:
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scope
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ex-nextstate
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... expr ...
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The nextstate in this case also gets nulled.
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In the case of do { my sub l; 1 } we were getting a variation of the
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latter, that looked like this:
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scope
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introcv
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clonecv
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nextstate
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... expr ...
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The problem here is that nextstate resets the stack, even though a new
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scope has not been pushed, so we end up with all existing stack items
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from the *outer* scope getting clobbered.
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One can have fun with this and erase everything pushed on to the stack
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so far in a given statement:
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$ ./perl -le 'print join "-", 1..10, do {my sub l; ","}, 11..20'
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11,12,13,14,15,16,17,18,19,20
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Here I replaced the first argument to join() from within the do{}
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block, after having cleared the stack.
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Why was the op tree was getting muddled up like this? The ‘my sub’
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declaration does not immediately add any ops to the op tree; those ops
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get added when the current scope finishing compiling, since those ops
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must be inserted at the beginning of the block.
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I have not fully looked into the order that things happen, and why the
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nextstate op does not get nulled; but it did not matter, because of
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the simple fix: Treat lexical sub declarations as ‘not innocuous’ by
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setting the HINT_BLOCK_SCOPE flag when a lexical sub is declared.
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Thus, we end up with an enter/leave pair, which creates a
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proper scope.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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op.c | 2 ++
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t/op/lexsub.t | 5 ++++-
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2 files changed, 6 insertions(+), 1 deletion(-)
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diff --git a/op.c b/op.c
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index 8fa5aad876..c617ad2a00 100644
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--- a/op.c
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+++ b/op.c
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@@ -9243,6 +9243,8 @@ Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
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PERL_ARGS_ASSERT_NEWMYSUB;
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+ PL_hints |= HINT_BLOCK_SCOPE;
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+
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/* Find the pad slot for storing the new sub.
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We cannot use PL_comppad, as it is the pad owned by the new sub. We
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need to look in CvOUTSIDE and find the pad belonging to the enclos-
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diff --git a/t/op/lexsub.t b/t/op/lexsub.t
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index 3fa17acdda..f085cd97e8 100644
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--- a/t/op/lexsub.t
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+++ b/t/op/lexsub.t
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@@ -7,7 +7,7 @@ BEGIN {
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*bar::is = *is;
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*bar::like = *like;
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}
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-plan 149;
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+plan 150;
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# -------------------- our -------------------- #
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@@ -957,3 +957,6 @@ like runperl(
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{
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my sub h; sub{my $x; sub{h}}
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}
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+
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+is join("-", qw(aa bb), do { my sub lleexx; 123 }, qw(cc dd)),
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+ "aa-bb-123-cc-dd", 'do { my sub...} in a list [perl #132442]';
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--
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2.13.6
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