meta-clang and meta-tegra apparently not compatible in kirkstone?

[MaxMatti]

I'm currently trying to upgrade an existing project that is using yocto from dunfell to kirkstone. After some (to me) confusing error message I managed to track the problem to only occur when meta-clang and meta-tegra are used. I created a new testproject and whenever I add the line TOOLCHAIN = "clang" to the main conf file (testproj/conf/distro/testproj.conf) bitbake is no longer able to build the recipe libgcc-8 due to the step do_configure failing.

At first there was the error that -flto -fuse-ld=lld was given to the configure script as parameters, so I added the file testproj/recipes-devtools/gcc-for-nvcc/libgcc-8_8.5.bbappend with the line LTO:remove = "-flto -fuse-ld=lld" but now the following error occurs in the do_configure step for libgcc-8:

DEBUG: Executing python function extend_recipe_sysroot
NOTE: Direct dependencies are ['/home/yocto/testproject/meta-tegra/recipes-devtools/gcc-for-nvcc/gcc-8-cross_8.5.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-core/glibc/glibc_2.35.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-devtools/binutils/binutils-cross_2.38.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-devtools/libtool/libtool-native_2.4.7.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-devtools/quilt/quilt-native_0.67.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-extended/texinfo-dummy-native/texinfo-dummy-native.bb:do_populate_sysroot', '/home/yocto/testproject/poky/meta/recipes-kernel/linux-libc-headers/linux-libc-headers_5.16.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-core/zlib/zlib_1.2.11.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/autoconf/autoconf_2.71.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/automake/automake_1.16.5.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/flex/flex_2.6.4.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/gnu-config/gnu-config_git.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/patch/patch_2.7.6.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-devtools/pseudo/pseudo_git.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-extended/xz/xz_5.2.5.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-support/gmp/gmp_6.2.1.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-support/libmpc/libmpc_1.2.1.bb:do_populate_sysroot', 'virtual:native:/home/yocto/testproject/poky/meta/recipes-support/mpfr/mpfr_4.1.0.bb:do_populate_sysroot']
NOTE: Installed into sysroot: []
NOTE: Skipping as already exists in sysroot: ['gcc-8-cross-aarch64', 'glibc', 'binutils-cross-aarch64', 'libtool-native', 'quilt-native', 'texinfo-dummy-native', 'linux-libc-headers', 'zlib-native', 'autoconf-native', 'automake-native', 'flex-native', 'gnu-config-native', 'patch-native', 'pseudo-native', 'xz-native', 'gmp-native', 'libmpc-native', 'mpfr-native', 'gettext-minimal-native', 'm4-native', 'attr-native']
DEBUG: Python function extend_recipe_sysroot finished
DEBUG: Executing shell function autotools_preconfigure
DEBUG: Shell function autotools_preconfigure finished
DEBUG: Executing python function autotools_aclocals
DEBUG: SITE files ['endian-little', 'bit-64', 'arm-common', 'arm-64', 'common-linux', 'common-glibc', 'aarch64-linux', 'common']
DEBUG: Python function autotools_aclocals finished
DEBUG: Executing python function gcc_multilib_setup
DEBUG: Python function gcc_multilib_setup finished
DEBUG: Executing python function extract_stashed_builddir
DEBUG: sed -e 's:^[^/]*/:/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/gcc-8.5.0/build.aarch64-poky-linux.aarch64-poky-linux/:g' /home/yocto/testproject/build/tmp/sysroots-components/x86_64/gcc-8-stashed-builddir-aarch64-poky-linux/fixmepath | xargs sed -i -e 's:FIXMESTAGINGDIRTARGET:/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/recipe-sysroot:g; s:FIXMESTAGINGDIRHOST:/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/recipe-sysroot-native:g' -e 's:FIXME_PSEUDO_SYSROOT:/home/yocto/testproject/build/tmp/sysroots-components/x86_64/pseudo-native:g' -e 's:FIXME_HOSTTOOLS_DIR:/home/yocto/testproject/build/tmp/hosttools:g' -e 's:FIXME_PKGDATA_DIR:/home/yocto/testproject/build/tmp/pkgdata/jetson-nano-devkit:g' -e 's:FIXME_PSEUDO_LOCALSTATEDIR:/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/pseudo/:g' -e 's:FIXME_LOGFIFO:/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/temp/fifo.4031149:g'
DEBUG: Python function extract_stashed_builddir finished
DEBUG: Executing shell function do_configure
configure: WARNING: unrecognized options: --disable-silent-rules, --disable-dependency-tracking, --with-libtool-sysroot, --with-gxx-include-dir, --with-gnu-ld, --enable-languages, --enable-threads, --disable-multilib, --enable-default-pie, --enable-c99, --enable-long-long, --enable-symvers, --disable-install-libiberty, --enable-libstdcxx-pch, --without-local-prefix, --disable-libssp, --enable-libitm, --disable-bootstrap, --disable-libmudflap, --with-system-zlib, --with-linker-hash-style, --enable-linker-build-id, --with-ppl, --with-cloog, --enable-checking, --enable-cheaders, --without-isl, --with-gxx-include-dir, --with-sysroot, --with-build-sysroot, --disable-static, --disable-nls, --enable-initfini-array, --enable-__cxa_atexit
checking build system type... x86_64-pc-linux-gnu
checking host system type... aarch64-poky-linux-gnu
checking for --enable-version-specific-runtime-libs... yes
checking for a BSD-compatible install... /home/yocto/testproject/build/tmp/hosttools/install -c
checking for gawk... gawk
checking for aarch64-poky-linux-ar... aarch64-poky-linux-llvm-ar
checking for aarch64-poky-linux-lipo... no
checking for lipo... no
checking for aarch64-poky-linux-nm... aarch64-poky-linux-llvm-nm
checking for aarch64-poky-linux-ranlib... aarch64-poky-linux-llvm-ranlib
checking for aarch64-poky-linux-strip... aarch64-poky-linux-llvm-strip
checking whether ln -s works... yes
checking for aarch64-poky-linux-gcc... aarch64-poky-linux-clang -target aarch64-poky-linux  -march=armv8-a+crc -mlittle-endian -Qunused-arguments -fstack-protector-strong  -O2 -D_FORTIFY_SOURCE=2 -Wformat -Wformat-security -Werror=format-security --sysroot=/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/recipe-sysroot
checking for suffix of object files... configure: error: in `/home/yocto/testproject/build/tmp/work/armv8a-poky-linux/libgcc-8/8.5.0-r0/gcc-8.5.0/build.aarch64-poky-linux.aarch64-poky-linux/libgcc':
configure: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details.
WARNING: exit code 1 from a shell command.

Unfortunately I was not able to find out why this error occurs. Is there some setting I am missing or is this a bug?

[madisongh]

You could try adding some overrides in your local.conf, similar to what in meta-clang's nonclangable.conf file for gcc and libgcc. When I get a chance, I'll try and research this further.

That said, I'm not sure how well clang will work for targeting the Jetson platforms. I've certainly never tested it. You're charting new territory here. :)

[MaxMatti]

Thanks for the hint, but I can't quite figure out what exactly should go in that line, so far I've tried:

TOOLCHAIN_pn-libgcc-8 = "gcc"
TOOLCHAIN_pn-libgcc = "gcc"
TOOLCHAIN_pn-gcc-8 = "gcc"
TOOLCHAIN_pn-gcc = "gcc"
TOOLCHAIN_pn-gcc-for-nvcc = "gcc"

But none of those did the trick.

[MaxMatti]

Nevermind I should not have copied the config from our project which still uses the old syntax. With the new one (colons instead of underscores) it works. Thanks a lot for that trick!

Edit: It's TOOLCHAIN:pn-libgcc-8 = "gcc"