When build != host, the build compiler obviously isn't the same as the
host compiler, but BUILD_CXXFLAGS is currently ALL_CXXFLAGS.
ALL_CXXFLAGS contains flags for which we run configure tests on the
host compiler, which may not work on the build compiler. I ran into
this with -Wno-narrowing. It looks like this problem has been hit
before when we used to build gcc with a C compiler and solved, but the
solution needs extending now that we build with a C++ compiler.
The second problem is that GMPINC (specifying a host include path) may
not be correct for the build compiler. I found this caused a lot of
build configure failures when attempting a build=powerpc64-linux,
host=powerpc64le-linux, target=powerpc64le-linux toolchain due to
mismatches in various function declarations between build and host.
The configure problems caused later build failure. (Hint for anyone
trying to debug canadian crosses: comment out "rm -rf $tempdir" just a
few lines below the first hunk in the patch below to see the build
config.log.)
The other little tweak here is to omit saving CFLAGS. CFLAGS is set
here only in the environment of the called command, not the caller
shell. So there is no need to save and restore.
Bootstrapped etc. powerpc64-linux. OK mainline and 4.8 branch?
* configure.ac (BUILD_CXXFLAGS) Don't use ALL_CXXFLAGS for
build != host.
<recursive call for build != host>: Clear GMPINC. Don't bother
saving CFLAGS.
* configure: Regenerate.
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac (revision 205341)
+++ gcc/configure.ac (working copy)
@@ -1529,13 +1529,11 @@
/* | [A-Za-z]:[\\/]* ) realsrcdir=${srcdir};;
*) realsrcdir=../${srcdir};;
esac
- saved_CFLAGS="${CFLAGS}"
CC="${CC_FOR_BUILD}" CFLAGS="${CFLAGS_FOR_BUILD}" \
- LDFLAGS="${LDFLAGS_FOR_BUILD}" \
+ LDFLAGS="${LDFLAGS_FOR_BUILD}" GMPINC="" \
${realsrcdir}/configure \
--enable-languages=${enable_languages-all} \
--target=$target_alias --host=$build_alias --build=$build_alias
- CFLAGS="${saved_CFLAGS}"
# We just finished tests for the build machine, so rename
# the file auto-build.h in the gcc directory.
@@ -1900,6 +1898,7 @@
if test x$build != x$host || test "x$coverage_flags" != x
then
BUILD_CFLAGS='$(INTERNAL_CFLAGS) $(T_CFLAGS) $(CFLAGS_FOR_BUILD)'
+ BUILD_CXXFLAGS='$(INTERNAL_CFLAGS) $(T_CFLAGS) $(CXXFLAGS_FOR_BUILD)'
BUILD_LDFLAGS='$(LDFLAGS_FOR_BUILD)'
fi
--
Alan Modra
Australia Development Lab, IBM
