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Support unbalanced () in AT_SETUP by adding two new quadrigraphs.
* bin/autom4te.in (handle_output): Substitute @{:@ and @:}@.
(handle_traces): Likewise.
* lib/m4sugar/m4sugar.m4 (m4_qlen): Account for new quadrigraphs.
* tests/autotest.at (AT_CHECK_AT_TITLE_CHAR): Add new tests.
* doc/autoconf.texi (Quadrigraphs): Document them.
(Evaluation Macros) <m4_expand>: Enhance documentation.
(Text processing Macros) <m4_text_box>: Document cases where
quadrigraphs can help for problemetic unbalanced parentheses.
(Pretty Help Strings) <AS_HELP_STRING>: Likewise.
(Writing Testsuites) <AT_SETUP>: Likewise.
(Limitations of Builtins) <case>: Consolidate text on unbalanced
parentheses, and add an example of creative comments.
* NEWS: Document the addition.
Reported by Joel E. Denny.
Signed-off-by: Eric Blake <ebb9@byu.net>
This commit is contained in:
Eric Blake
parent
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18
ChangeLog
18
ChangeLog
@ -1,3 +1,21 @@
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2008-04-22 Eric Blake <ebb9@byu.net>
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Support unbalanced () in AT_SETUP by adding two new quadrigraphs.
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* bin/autom4te.in (handle_output): Substitute @{:@ and @:}@.
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(handle_traces): Likewise.
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* lib/m4sugar/m4sugar.m4 (m4_qlen): Account for new quadrigraphs.
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* tests/autotest.at (AT_CHECK_AT_TITLE_CHAR): Add new tests.
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* doc/autoconf.texi (Quadrigraphs): Document them.
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(Evaluation Macros) <m4_expand>: Enhance documentation.
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(Text processing Macros) <m4_text_box>: Document cases where
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quadrigraphs can help for problemetic unbalanced parentheses.
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(Pretty Help Strings) <AS_HELP_STRING>: Likewise.
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(Writing Testsuites) <AT_SETUP>: Likewise.
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(Limitations of Builtins) <case>: Consolidate text on unbalanced
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parentheses, and add an example of creative comments.
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* NEWS: Document the addition.
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Reported by Joel E. Denny.
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2008-04-16 Eric Blake <ebb9@byu.net>
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Document pdksh exec behavior.
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5
NEWS
5
NEWS
@ -2,6 +2,11 @@ GNU Autoconf NEWS - User visible changes.
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* Major changes in Autoconf 2.62a (2008-??-??)
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** Two new quadrigraphs have been introduced: @{:@ for (, and @:}@ for ),
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allowing the output of unbalanced parantheses in contexts such as
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AS_HELP_STRING or AT_SETUP that must determine the length of
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expanded text.
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* Major changes in Autoconf 2.62 (2008-04-05) [stable]
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Released by Eric Blake, based on git versions 2.61a.*.
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@ -575,6 +575,8 @@ sub handle_output ($$)
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s/__oline__/$./g;
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s/\@<:\@/[/g;
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s/\@:>\@/]/g;
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s/\@\{:\@/(/g;
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s/\@:\}\@/)/g;
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s/\@S\|\@/\$/g;
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s/\@%:\@/#/g;
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@ -856,6 +858,8 @@ EOF
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# It makes no sense to try to transform __oline__.
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s/\@<:\@/[/g;
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s/\@:>\@/]/g;
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s/\@\{:\@/(/g;
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s/\@:\}\@/)/g;
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s/\@S\|\@/\$/g;
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s/\@%:\@/#/g;
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s/\@&t\@//g;
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@ -9619,13 +9619,18 @@ the one they were implemented with.
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@c @cindex @samp{@@<:@@}
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@c @cindex @samp{@@:>@@}
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@c @cindex @samp{@@%:@@}
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@c @cindex @samp{@@@{:@@}
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@c @cindex @samp{@@:@}@@}
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When writing an Autoconf macro you may occasionally need to generate
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special characters that are difficult to express with the standard
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Autoconf quoting rules. For example, you may need to output the regular
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expression @samp{[^[]}, which matches any character other than @samp{[}.
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This expression contains unbalanced brackets so it cannot be put easily
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into an M4 macro.
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into an M4 macro. There are also a few macros, such as
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@code{m4_text_box}, @code{AS_HELP_STRING}, or @code{AT_SETUP}, which
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require balanced parentheses, regardless of the quoting, because the
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macro needs to compute the length of the expansion of its arguments.
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You can work around this problem by using one of the following
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@dfn{quadrigraphs}:
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@ -9639,6 +9644,10 @@ You can work around this problem by using one of the following
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@samp{$}
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@item @@%:@@
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@samp{#}
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@item @@@{:@@
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@samp{(}
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@item @@:@}@@
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@samp{)}
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@item @@&t@@
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Expands to nothing.
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@end table
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@ -10887,12 +10896,6 @@ collection rules discard the whitespace. However, with @code{m4_expand},
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whitespace is preserved, even after the expansion of macros contained in
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@var{arg}.
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Note that @code{m4_expand} cannot parse everything. The expansion of
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@var{arg} must not contain unbalanced quotes (although quadrigraphs can
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get around this), nor unbalanced parentheses (portable shell @code{case}
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statements are a major culprit here, but creative shell comments can get
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around this).
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@example
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m4_define([active], [ACT, IVE])dnl
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m4_define([active2], [[ACT, IVE]])dnl
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@ -10905,6 +10908,21 @@ m4_quote(active2, active2)
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m4_expand([active2, active2])
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@result{}ACT, IVE, ACT, IVE
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@end example
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Note that @code{m4_expand} cannot parse everything. The expansion of
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@var{arg} must not contain literal unbalanced quotes or parentheses;
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however, quadrigraphs can be used to generate unbalanced output.
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@example
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m4_define([pattern], [[!@@<:@@]])dnl
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m4_define([bar], [BAR])dnl
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m4_expand([case $foo in
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m4_defn([pattern])@@:@}@@ bar ;;
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esac])
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@result{}case $foo in
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@result{} [![]) BAR ;;
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@result{}esac
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@end example
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@end defmac
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@defmac m4_ignore (@dots{})
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@ -11183,6 +11201,9 @@ m4_text_box([macro])
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@result{}## abc ##
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@result{}## --- ##
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@end example
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The @var{message} must contain balanced quotes and parentheses, although
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quadrigraphs can be used to work around this.
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@end defmac
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@defmac m4_text_wrap (@var{string}, @ovar{prefix}, @
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@ -13754,13 +13775,32 @@ parentheses like this:
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@example
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case $file_name in
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(*.c) echo "C source code";;
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(*.c) echo "C source code";;
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esac
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@end example
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@noindent
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but the @code{(} in this example is not portable to many Bourne
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shell implementations. It can be omitted safely.
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shell implementations, which is a pity for those of us using tools that
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rely on balanced parentheses. For instance, with Solaris
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@command{/bin/sh}:
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@example
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$ @kbd{case foo in (foo) echo foo;; esac}
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@error{}syntax error: `(' unexpected
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@end example
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@noindent
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The leading @samp{(} can be omitted safely. In contexts where
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unbalanced parentheses cause other problems, such as when using a case
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statement as an argument to an Autoconf macro, you can also resort to
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creative shell comments to supply the balance:
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@example
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case $file_name in #(
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*.c) echo "C source code";;
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esac
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@end example
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Zsh handles pattern fragments derived from parameter expansions or
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command substitutions as though quoted:
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@ -13830,15 +13870,6 @@ ash-0.3.8 $ @kbd{case foo in esac;}
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@error{}Syntax error: ";" unexpected (expecting ")")
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@end example
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Many shells still do not support parenthesized cases, which is a pity
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for those of us using tools that rely on balanced parentheses. For
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instance, Solaris @command{/bin/sh}:
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@example
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$ @kbd{case foo in (foo) echo foo;; esac}
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@error{}syntax error: `(' unexpected
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@end example
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@item @command{cd}
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@c ---------------
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@ -17690,7 +17721,8 @@ Since it is not expanded, it should not be double quoted.
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The @code{AS_HELP_STRING} macro is particularly helpful when the
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@var{left-hand-side} and/or @var{right-hand-side} are composed of macro
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arguments, as shown in the following example. Be aware that
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@var{left-hand-side} may not contain unbalanced quotes or parentheses.
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@var{left-hand-side} may not contain unbalanced quotes or parentheses,
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although quadrigraphs can be used.
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@example
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AC_DEFUN([MY_ARG_WITH],
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@ -20280,7 +20312,7 @@ This macro starts a group of related tests, all to be executed in the
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same subshell. It accepts a single argument, which holds a few words
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(no more than about 30 or 40 characters) quickly describing the purpose
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of the test group being started. @var{test-group-name} must not contain
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unbalanced quotes or parentheses.
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unbalanced quotes or parentheses, although quadrigraphs can be used.
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@end defmac
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@defmac AT_KEYWORDS (@var{keywords})
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@ -2058,7 +2058,8 @@ m4_builtin([popdef], [m4_Border])dnl
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# Avoid bpatsubsts for the common case of no quadrigraphs.
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m4_define([m4_qlen],
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[m4_if(m4_index([$1], [@]), [-1], [m4_len([$1])],
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[m4_len(m4_bpatsubst([[$1]], [@\(\(<:\|:>\|S|\|%:\)\(@\)\|&t@\)],
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[m4_len(m4_bpatsubst([[$1]],
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[@\(\(<:\|:>\|S|\|%:\|\{:\|:\}\)\(@\)\|&t@\)],
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[\3]))])])
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@ -453,9 +453,14 @@ AT_CHECK_AT_TITLE_CHAR([Double-quote], ["])
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dnl restore font-lock: "
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AT_CHECK_AT_TITLE_CHAR([Backslash], [\])
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AT_CHECK_AT_TITLE_CHAR([Brackets], [[[]]], [[]])
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AT_CHECK_AT_TITLE_CHAR([Left bracket], [@<@&t@:@], [@<:@])
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AT_CHECK_AT_TITLE_CHAR([Right bracket], [@:@&t@>@], [@:>@])
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AT_CHECK_AT_TITLE_CHAR([Pound], [[#]], [#])
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AT_CHECK_AT_TITLE_CHAR([Quoted comma],[[,]], [,])
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AT_CHECK_AT_TITLE_CHAR([Comma], [,], [,])
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AT_CHECK_AT_TITLE_CHAR([Parentheses], [()])
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AT_CHECK_AT_TITLE_CHAR([Left paren], [@{@&t@:@], [(])
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AT_CHECK_AT_TITLE_CHAR([Right paren], [@:@&t@}@], [)])
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AT_CHECK_AT_TITLE_CHAR([Quoted Macro], [[macro_name]], [macro_name])
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AT_CHECK_AT_TITLE_CHAR([Macro], [macro_name], [macro_expanded])
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