Hi! On Thu, 17 Jan 2013 17:18:41 +0000, "Joseph S. Myers" <jos...@codesourcery.com> wrote: > Really, for glibc bootstrapping I don't think you want to include any > headers there. If $CPP is defined and nonempty, use that, otherwise use > $CC -E; no testing for a "working" preprocessor is needed; we require GCC > 4.3 or later for building glibc.
OK. I'd still be interested in hearing from the Autoconf folks whether
something should be done on Autoconf side, too. Also, regarding the
/lib/cpp fallback in the cross-compilation case.
> > Issue 3: Assuming fixing Autoconf is the way to go, what do we do in
> > glibc until we upgrade to the respective future version of Autoconf?
> > Supply our own copy of _AC_PROG_PREPROC_WORKS_IFELSE (or AC_PROG_CPP)?
>
> Yes. There's already code in configure.in to do something special with
> _AC_INCLUDES_DEFAULT_REQUIREMENTS.
Yep -- I had submitted an equivalent patch months before H.J.'s was then
applied. ;-)
Here's now one for AC_PROG_CPP, borrowing from Autoconf's definition of
AC_PROG_CPP, leaving out the "details" we're not interested in (in
particular also the final »C preprocessor "$CPP" [...] sanity check«).
Tested on x86_64 GNU/Linux for a ARM GNU/Linux host. OK to apply?
* configure.in (AC_PROG_CPP): New definition.
diff --git configure.in configure.in
index 05cbad5..ee72c17 100644
--- configure.in
+++ configure.in
@@ -17,6 +17,32 @@ AC_DEFUN([_AC_INCLUDES_DEFAULT_REQUIREMENTS],
[m4_divert_text([DEFAULTS],
[ac_includes_default='/* none */'])])
+# We require GCC, and by default use its preprocessor. Override AC_PROG_CPP
+# here to work around the Autoconf issue discussed in
+#
<http://news.gmane.org/find-root.php?message_id=%3c87y5frpwhe....@schwinge.name%3E>.
+AC_DEFUN([AC_PROG_CPP],
+[AC_REQUIRE([AC_PROG_CC])dnl
+AC_ARG_VAR([CPP], [C preprocessor])dnl
+_AC_ARG_VAR_CPPFLAGS()dnl
+AC_MSG_CHECKING([how to run the C preprocessor])
+# On Suns, sometimes $CPP names a directory.
+if test -n "$CPP" && test -d "$CPP"; then
+ CPP=
+fi
+if test -z "$CPP"; then
+ AC_CACHE_VAL([ac_cv_prog_CPP],
+ [dnl
+ ac_cv_prog_CPP="$CC -E"
+ ])dnl
+ CPP=$ac_cv_prog_CPP
+else
+ ac_cv_prog_CPP=$CPP
+fi
+AC_MSG_RESULT([$CPP])
+AC_SUBST(CPP)dnl
+])# AC_PROG_CPP
+
+
dnl This is here so we can set $subdirs directly based on configure fragments.
AC_CONFIG_SUBDIRS()
Grüße,
Thomas
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