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| author | Eric Blake <eblake@redhat.com> | 2011-06-14 07:45:29 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2011-06-14 07:45:29 -0600 |
| commit | 1a956c4b1e8f52b55a2225ace6422c4739f1e43e (patch) | |
| tree | dbbe6f0b834df97b036bcfe6edb2b5b88bfa05c9 | |
| parent | 2105ae97000c7c77442b3a788c90d8fee63bd2b3 (diff) | |
| download | autoconf-1a956c4b1e8f52b55a2225ace6422c4739f1e43e.tar.gz | |
doc: update quoting example
The existing example triggers an autoconf warning, due to the
change in AC_COMPILE_IFELSE probing for an AC_LANG_SOURCE use.
* doc/autoconf.texi (Autoconf Language): Add AC_LANG_SOURCE use.
* THANKS: Update.
Reported by Křištof Želechovski.
Signed-off-by: Eric Blake <eblake@redhat.com>
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | THANKS | 1 | ||||
| -rw-r--r-- | doc/autoconf.texi | 17 |
3 files changed, 20 insertions, 5 deletions
@@ -1,3 +1,10 @@ +2011-06-14 Eric Blake <eblake@redhat.com> + + doc: update quoting example + * doc/autoconf.texi (Autoconf Language): Add AC_LANG_SOURCE use. + * THANKS: Update. + Reported by Křištof Želechovski. + 2011-05-05 Eric Blake <eblake@redhat.com> doc: document dash bug with positional parameters @@ -235,6 +235,7 @@ Kevin Ryde user42@zip.com.au Klee Dienes kdienes@apple.com Koji Arai JCA02266@nifty.ne.jp Kristian Kvilekval kris@cs.ucsb.edu +Křištof Želechovski giecrilj@stegny.2a.pl Kurt D. Zeilenga kurt@openldap.org Larry Jones larry.jones@sdrc.com Larry Schmitt larry@mail.haleakalawebdesigns.com diff --git a/doc/autoconf.texi b/doc/autoconf.texi index 7ff693f5..99b1fd1f 100644 --- a/doc/autoconf.texi +++ b/doc/autoconf.texi @@ -1288,19 +1288,26 @@ has been continually misunderstood@enddots{} The rule of thumb is that i.e., expect one level of quotes to be lost. For instance: @example -AC_COMPILE_IFELSE([char b[10];], [], [AC_MSG_ERROR([you lose])]) +AC_COMPILE_IFELSE(AC_LANG_SOURCE([char b[10];]), [], + [AC_MSG_ERROR([you lose])]) @end example @noindent -is incorrect: here, the first argument of @code{AC_COMPILE_IFELSE} is +is incorrect: here, the first argument of @code{AC_LANG_SOURCE} is @samp{char b[10];} and is expanded once, which results in -@samp{char b10;}. (There was an idiom common in Autoconf's past to +@samp{char b10;}; and the @code{AC_LANG_SOURCE} is also expanded prior +to being passed to @code{AC_COMPILE_IFELSE}. (There was an idiom common +in Autoconf's past to address this issue via the M4 @code{changequote} primitive, but do not use it!) Let's take a closer look: the author meant the first argument -to be understood as a literal, and therefore it must be quoted twice: +to be understood as a literal, and therefore it must be quoted twice; +likewise, the intermediate @code{AC_LANG_SOURCE} macro should be quoted +once so that it is only expanded after the rest of the body of +@code{AC_COMPILE_IFELSE} is in place: @example -AC_COMPILE_IFELSE([[char b[10];]], [], [AC_MSG_ERROR([you lose])]) +AC_COMPILE_IFELSE([AC_LANG_SOURCE([[char b[10];]])], [], + [AC_MSG_ERROR([you lose])]) @end example @noindent |