On 1/20/20 2:49 AM, Martin Liška wrote:
In this case an infinite loop is highly undesirable.
Sure, but the regex code is littered with highly undesirable code like this, as
it's easy to use a weird regexp to make the code explode exponentially and
there's little practical difference between that an infinite loop.
Come to think of it, the grep test infrastructure already has a way to deal with
this sort of thing, so all we need to do to fix this particular glitch is adjust
triple-backref to use timeout, which I did by installing the attached patch.
Thanks Andreas for diagnosing the problem. I hope there's a gcc bug report about
it somewhere. I could not use Martin's recipe on Fedora 31 x86-64 because gcc
-m32 -flto didn't look inside the .a files that the grep build procedure creates
and uses. I've never had much luck with -flto anyway as it has a habit of
running into compiler bugs. I now also see that Red Hat has qualms about the
GOLD linker <https://fedoraproject.org/wiki/Changes/BINUTILS_GOLD> which the
recipe relies on, as Google has decided not to continue GOLD development (which
was news to me).
I'll mark Bug#21513 as done again, since the original report is fixed. The
triple-backref bug is Bug#22793 and also glibc bug 11053, both of which are
still open.
>From 759745166c0503680bb8fa1f4f60209292740492 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Mon, 20 Jan 2020 09:32:49 -0800
Subject: [PATCH] tests: work around GCC -fprofile-generate bug
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* tests/triple-backref: Add a 10 s timeout to work around
what appears to be a GCC bug with -fprofile-generate.
Problem reported by Martin Liška, with diagnosis by
Andreas Schwab (Bug#21513).
---
tests/triple-backref | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
mode change 100755 => 100644 tests/triple-backref
diff --git a/tests/triple-backref b/tests/triple-backref
old mode 100755
new mode 100644
index 27ab9a3..167b8ac
--- a/tests/triple-backref
+++ b/tests/triple-backref
@@ -8,11 +8,12 @@
# notice and this notice are preserved.
. "${srcdir=.}/init.sh"; path_prepend_ ../src
+require_timeout_
echo a > in || framework_failure_
fail=0
-grep -E '(.?)(.?)(.?)\3\2\1' in > out || fail=1
+timeout 10 grep -E '(.?)(.?)(.?)\3\2\1' in > out || fail=1
compare out in || fail=1
Exit $fail
--
2.17.1
