[SCM] GNU Autoconf source repository branch, master, updated. v2.64-4-g9b849a9

[Paolo Bonzini]

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- Log -----------------------------------------------------------------
commit 9b849a97c69a4ab6063a8a3c794f4d5076a23c4c
Author: Paolo Bonzini <address@hidden>
Date:   Thu Jul 30 20:27:45 2009 +0200

    Clarify comparison of echo, printf, and AS_ECHO*.
    
    Discussed starting at
    <http://lists.gnu.org/archive/html/bug-autoconf/2009-07/msg00025.html>.
    
    * doc/autoconf.texi (Limitations of Builtins): In echo's entry,
    give a reason why printf is better than echo.  In printf's
    entry, cross-reference echo's entry.

commit a19e829e674a52dc9cad535be9dd56e651527e56
Author: Paolo Bonzini <address@hidden>
Date:   Wed Jul 29 16:28:56 2009 +0200

    Add back AH_CHECK_HEADERS.
    
    * lib/autoconf/general.m4 (AH_CHECK_HEADERS): New.
    * NEWS: Add new section.

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

Summary of changes:
 ChangeLog               |   14 ++++++++++++++
 NEWS                    |    9 +++++++++
 doc/autoconf.texi       |   27 +++++++++++++++++----------
 lib/autoconf/headers.m4 |    6 ++++++
 4 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 61bda1a..c307701 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2009-07-30  Paolo Bonzini  <address@hidden>
+           Joel E. Denny  <address@hidden>
+
+       Clarify comparison of echo, printf, and AS_ECHO*.
+       * doc/autoconf.texi (Limitations of Builtins): In echo's entry,
+       give a reason why printf is better than echo.  In printf's
+       entry, cross-reference echo's entry.
+
+2009-07-30  Paolo Bonzini  <address@hidden>
+
+       Add back AH_CHECK_HEADERS.
+       * lib/autoconf/general.m4 (AH_CHECK_HEADERS): New.
+       * NEWS: Create new section.
+
 2009-07-29  Ralf Wildenhues  <address@hidden>
 
        testsuite: avoid bogus hostname match from inner test logs.
diff --git a/NEWS b/NEWS
index fc5730f..7e8a522 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,14 @@
 GNU Autoconf NEWS - User visible changes.
 
+* Major changes in Autoconf 2.64a (????-??-??) [experimental]
+  Released by ???? ????
+
+** The following undocumented autoconf macros, removed in Autoconf 2.64,
+   have been reinstated:
+   AH_CHECK_HEADERS
+
+   These macros are present only for backwards compatibility purposes.
+
 * Major changes in Autoconf 2.64 (2009-07-26) [stable]
   Released by Eric Blake, based on git versions 2.63b.*.
 
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 4f046c0..c920d73 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -15826,9 +15826,15 @@ entirely drop the output of the next echo in a command 
substitution.
 
 Because of these problems, do not pass a string containing arbitrary
 characters to @command{echo}.  For example, @samp{echo "$foo"} is safe
-if you know that @var{foo}'s value cannot contain backslashes and cannot
-start with @samp{-}, but otherwise you should use a here-document like
-this:
+only if you know that @var{foo}'s value cannot contain backslashes and
+cannot start with @samp{-}.
+
+If this may not be true, @command{printf} is in general safer and
+easier to use than @command{echo} and @command{echo -n}.  Thus, scripts
+where portability is not a major concern should use @command{printf
+'%s\n'} whenever @command{echo} could fail, and similarly use
address@hidden %s} instead of @command{echo -n}. For portable shell
+scripts, instead, it is suggested to use a here-document like this:
 
 @example
 cat <<EOF
@@ -15836,12 +15842,10 @@ $foo
 EOF
 @end example
 
-New applications which are not aiming at portability should use
address@hidden instead of @command{echo}.  M4sh provides the
address@hidden and @code{AS_ECHO_N} macros, which choose between
address@hidden -n} on implementations where that works, @command{printf} if
-it is available, or other creative tricks in order to work around the
-above problems.
+Alternatively, M4sh provides @code{AS_ECHO} and @code{AS_ECHO_N} macros
+which choose between various portable implementations: @samp{echo}
+or @samp{print} where they work, @command{printf} if it is available,
+or else other creative tricks in order to work around the above problems.
 
 
 @item @command{eval}
@@ -16143,11 +16147,14 @@ example, @file{/usr/bin/printf} is buggy, so when 
using
 core.
 
 Since @command{printf} is not always a shell builtin, there is a
-potential speed penalty for using @code{printf %s\\n} as a replacement
+potential speed penalty for using @code{printf '%s\n'} as a replacement
 for an @command{echo} that does not interpret @samp{\} or leading
 @samp{-}. With Solaris @command{ksh}, it is possible to use @code{print
 -r --} for this role instead.
 
+For a discussion of portable alternatives to both @command{printf}
+and @command{echo}, @xref{echo, , Limitations of Shell Builtins}.
+
 
 @item @command{pwd}
 @c ----------------
diff --git a/lib/autoconf/headers.m4 b/lib/autoconf/headers.m4
index 21b512c..36c1899 100644
--- a/lib/autoconf/headers.m4
+++ b/lib/autoconf/headers.m4
@@ -253,6 +253,12 @@ m4_define([_AH_CHECK_HEADER],
   [Define to 1 if you have the <$1> header file.])])
 
 
+# AH_CHECK_HEADERS(HEADER-FILE...)
+# --------------------------------
+m4_define([AH_CHECK_HEADERS],
+[m4_foreach_w([AC_Header], [$1], [_AH_CHECK_HEADER(m4_defn([AC_Header]))])])
+
+
 # AC_CHECK_HEADERS(HEADER-FILE...,
 #                 [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
 #                 [INCLUDES])


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