libstdc++-v3/

	* configure.ac: Move guarded checks for CC and CXX ...
	* acinclude.m4 (GLIBCXX_CONFIGURE): ... from here.
	* configure: Regenerate.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@150788 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 30 insertions, 1 deletions

diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 977e12cf91d..0b1edfd7c75 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -78,7 +78,36 @@ AM_INIT_AUTOMAKE([1.9.3 no-define foreign no-dependencies -Wall -Wno-portability
 AH_TEMPLATE(PACKAGE, [Name of package])
 AH_TEMPLATE(VERSION, [Version number of package])
 
-# Runs configure.host, finds CC, CXX, and assorted other critical bits.  Sets
+# We're almost certainly being configured before anything else which uses
+# C++, so all of our AC_PROG_* discoveries will be cached.  It's vital that
+# we not cache the value of CXX that we "discover" here, because it's set
+# to something unique for us and libjava.  Other target libraries need to
+# find CXX for themselves.  We yank the rug out from under the normal AC_*
+# process by sneakily renaming the cache variable.  This also lets us debug
+# the value of "our" CXX in postmortems.
+#
+# We must also force CXX to /not/ be a precious variable, otherwise the
+# wrong (non-multilib-adjusted) value will be used in multilibs.  This
+# little trick also affects CPPFLAGS, CXXFLAGS, and LDFLAGS.  And as a side
+# effect, CXXFLAGS is no longer automagically subst'd, so we have to do
+# that ourselves.  Un-preciousing AC_PROG_CC also affects CC and CFLAGS.
+#
+# -fno-builtin must be present here so that a non-conflicting form of
+# std::exit can be guessed by AC_PROG_CXX, and used in later tests.
+
+m4_define([ac_cv_prog_CXX],[glibcxx_cv_prog_CXX])
+m4_rename([_AC_ARG_VAR_PRECIOUS],[glibcxx_PRECIOUS])
+m4_define([_AC_ARG_VAR_PRECIOUS],[])
+save_CXXFLAGS="$CXXFLAGS"
+CXXFLAGS="$CXXFLAGS -fno-builtin"
+AC_PROG_CC
+AC_PROG_CXX
+CXXFLAGS="$save_CXXFLAGS"
+m4_rename_force([glibcxx_PRECIOUS],[_AC_ARG_VAR_PRECIOUS])
+AC_SUBST(CFLAGS)
+AC_SUBST(CXXFLAGS)
+
+# Runs configure.host, and assorted other critical bits.  Sets
 # up critical shell variables.
 GLIBCXX_CONFIGURE