Bootstrapping glibc vs. dependency on system headers

[Thomas Schwinge]

Hi!

On Wed, 23 Jan 2013 14:34:09 -0800, Roland McGrath <roland@hack.frob.com> wrote:
> For libc, I think always using $CC -E is fine.  You don't need to bother
> with the MSG_CHECKING and CACHE_VAL boilerplate.

Ah, I thought the caching was required to have config.status' --recheck
do the right thing.  Which actually isn't.

> It's best if comments refer to a URL in a bug database (libc's bugzilla or
> another one, whatever) with details filed there rather than pointing to a
> mailing list thread.  If you do use URLs to mailing list archives, they
> must be to the canonical archive (http://sourceware.org/ml/libc-alpha/...)
> rather than to some third-party site.

Opening a bug for that issue seemed overkill to me.  What I don't like
about the sourceware archives is that they fail on non-ASCII characters
as well as indexing over month boundaries.

Pushed as commit bb931195fe780bb63e3d57d0742abad1d2128424:

	* configure.in (AC_PROG_CPP): New definition.
	* configure: Regenerate.

diff --git configure.in configure.in
index 4cfa36d..2c50d09 100644
--- configure.in
+++ configure.in
@@ -17,6 +17,23 @@ 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://sourceware.org/ml/libc-alpha/2013-01/msg00721.html>.
+AC_DEFUN([AC_PROG_CPP],
+[AC_REQUIRE([AC_PROG_CC])dnl
+AC_ARG_VAR([CPP],      [C preprocessor])dnl
+_AC_ARG_VAR_CPPFLAGS()dnl
+# On Suns, sometimes $CPP names a directory.
+if test -n "$CPP" && test -d "$CPP"; then
+  CPP=
+fi
+if test -z "$CPP"; then
+  CPP="$CC -E"
+fi
+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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