[SCM] GNU Autoconf source repository branch, master, updated. v2.69-171-g527f183

[Eric Blake]

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- Log -----------------------------------------------------------------
commit 527f183f232e14ebf0ef2b8a086d675e78700af2
Author: Paolo Bonzini <***@gnu.org>
Date: Mon Oct 31 18:08:08 2016 +0100

autoconf: refine quadrigraph test in _AC_DEFINE_UNQUOTED

It is a very common case that a quadrigraph appears in the argument of
_AC_DEFINE_UNQUOTED, because "#define" is expanded through a quadrigraph.
Therefore, restrict the quadrigraph tests to "$" (for "$(" and "${")
and "(" (for "$(").

At the same time, "#" should not be used inside AC_ECHO because it confuses
m4's comment parsing. This pre-existing latent bug is caught by test 251:

AC_DEFINE_UNQUOTED([bar], [[%!_!# X]])

Previously the quadrigraph in "@%:@define bar %!_!# X" made Autoconf fall back
to cat anyway. Now that Autoconf is not fooled by the quadrigraph, the test
catches that "#" is not special-cased. Kudos to Eric for coming up with it!

* lib/autoconf/general (_AC_DEFINE_UNQUOTED): Do not blindly
use cat on all quadrigraphs.

Signed-off-by: Paolo Bonzini <***@gnu.org>
Message-Id: <1477933688-4884-4-git-send-email-***@gnu.org>

-----------------------------------------------------------------------

Summary of changes:
lib/autoconf/general.m4 | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index c15fb13..ef6285d 100644
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -2167,9 +2167,11 @@ m4_define([AC_DEFINE_UNQUOTED], [_AC_DEFINE_Q([_$0], $@)])
# Append the pre-expanded STRING and a newline to confdefs.h, as if
# with an unquoted here-doc, but avoiding a fork in the common case of
# no backslash, no command substitution, no complex variable
-# substitution, and no quadrigraphs.
+# substitution (taking into account quadrigraphs as well). Also
+# avoid AS_ECHO if "#" is present to avoid confusing m4 with comments,
+# but quadrigraphs are fine in that case.
m4_define([_AC_DEFINE_UNQUOTED],
-[m4_if(m4_bregexp([$1], [\\\|`\|\$(\|\${\|@]), [-1],
+[m4_if(m4_bregexp([$1], [#\|\\\|`\|\(\$\|@S|@\)\((|{|@{:@\)]), [-1],
[AS_ECHO(["AS_ESCAPE([$1], [""])"]) >>confdefs.h],
[cat >>confdefs.h <<_ACEOF
[$1]


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