[SCM] GNU Autoconf source repository branch, master, updated. v2.68-69-g1a956c4

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- Log -----------------------------------------------------------------
commit 1a956c4b1e8f52b55a2225ace6422c4739f1e43e
Author: Eric Blake <[email protected]>
Date:   Tue Jun 14 07:45:29 2011 -0600

    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 <[email protected]>

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

Summary of changes:
 ChangeLog         |    7 +++++++
 THANKS            |    1 +
 doc/autoconf.texi |   17 ++++++++++++-----
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1fca7bb..03541e0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2011-06-14  Eric Blake  <[email protected]>
+
+	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  <[email protected]>
 
 	doc: document dash bug with positional parameters
diff --git a/THANKS b/THANKS
index 7679b05..e125ebe 100644
--- a/THANKS
+++ b/THANKS
@@ -235,6 +235,7 @@ Kevin Ryde                  [email protected]
 Klee Dienes                 [email protected]
 Koji Arai                   [email protected]
 Kristian Kvilekval          [email protected]
+Křištof Želechovski         [email protected]
 Kurt D. Zeilenga            [email protected]
 Larry Jones                 [email protected]
 Larry Schmitt               [email protected]
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 7ff693f..99b1fd1 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


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