'__config_site' file not found

[alexirion]

Using a self-build clang 14.0.6, setup for cross compiling for arm-linux-gnueabihf, leads to the compilation error:

/usr/local/bin/../include/c++/v1/__config:13:10: fatal error: '__config_site' file not found

I build clang 14.0.6 by:

cmake -G Ninja -S llvm -B build -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" -DLLVM_RUNTIME_TARGETS="arm-linux-gnueabihf" \
-DLLVM_TARGETS_TO_BUILD="ARM"

When I use -I/usr/local/include/arm-linux-gnueabihf/c++/v1 the compilation works, however I would expect that clang could find that target non-agnostic file without explicitly setting the include directory, by using the value of the -target option.

CXXFLAGS is set to --target=arm-linux-gnueabihf -march=armv8-a -mcpu=cortex-a72 -mfpu=neon-fp-armv8 -mfloat-abi=hard -stdlib=libc++.

Here the full verbose compilation output, which fails:

/usr/local/bin/clang++   --target=arm-linux-gnueabihf -march=armv8-a -mcpu=cortex-a72 -mfpu=neon-fp-armv8 -mfloat-abi=hard -stdlib=libc++ -v -fcolor-diagnostics -Wall -Wpedantic -Werror -Wconversion -std=gnu++20 -MD -MT homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -MF homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o.d -o homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -c /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp
clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
Target: arm-unknown-linux-gnueabihf
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc-cross/arm-linux-gnueabihf/8
Found candidate GCC installation: /usr/lib/gcc/arm-linux-gnueabihf/8
Selected GCC installation: /usr/lib/gcc-cross/arm-linux-gnueabihf/8
Candidate multilib: .;@m32
Selected multilib: .;@m32
 (in-process)
 "/usr/local/bin/clang-14" -cc1 -triple armv8-unknown-linux-gnueabihf -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model static -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu cortex-a72 -target-feature +crc -target-feature -dotprod -target-feature +dsp -target-feature -mve -target-feature -mve.fp -target-feature -ras -target-feature -bf16 -target-feature -sb -target-feature -i8mm -target-feature -lob -target-feature -cdecp0 -target-feature -cdecp1 -target-feature -cdecp2 -target-feature -cdecp3 -target-feature -cdecp4 -target-feature -cdecp5 -target-feature -cdecp6 -target-feature -cdecp7 -target-feature -pacbti -target-feature +hwdiv-arm -target-feature +hwdiv -target-feature +vfp2 -target-feature +vfp2sp -target-feature +vfp3 -target-feature +vfp3d16 -target-feature +vfp3d16sp -target-feature +vfp3sp -target-feature +fp16 -target-feature +vfp4 -target-feature +vfp4d16 -target-feature +vfp4d16sp -target-feature +vfp4sp -target-feature +fp-armv8 -target-feature +fp-armv8d16 -target-feature +fp-armv8d16sp -target-feature +fp-armv8sp -target-feature -fullfp16 -target-feature +fp64 -target-feature +d32 -target-feature +neon -target-feature -fp16fml -target-feature -crypto -target-feature -sha2 -target-feature -aes -target-abi aapcs-linux -mfloat-abi hard -fallow-half-arguments-and-returns -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/airion/projects/homenet/products/rpi4 -resource-dir /usr/local/lib/clang/14.0.6 -dependency-file homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o.d -MT homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -sys-header-deps -internal-isystem /usr/local/bin/../include/c++/v1 -internal-isystem /usr/local/lib/clang/14.0.6/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc-cross/arm-linux-gnueabihf/8/../../../../arm-linux-gnueabihf/include -internal-externc-isystem /usr/include/arm-linux-gnueabihf -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wall -Wpedantic -Werror -Wconversion -std=gnu++20 -fdeprecated-macro -fdebug-compilation-dir=/home/airion/projects/homenet/products/rpi4 -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -x c++ /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp
clang -cc1 version 14.0.6 based upon LLVM 14.0.6 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/bin/../include/c++/v1
 /usr/local/lib/clang/14.0.6/include
 /usr/local/include
 /usr/lib/gcc-cross/arm-linux-gnueabihf/8/../../../../arm-linux-gnueabihf/include
 /usr/include/arm-linux-gnueabihf
 /usr/include
End of search list.
In file included from /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp:1:
In file included from /usr/local/bin/../include/c++/v1/cstdio:98:
/usr/local/bin/../include/c++/v1/__config:13:10: fatal error: '__config_site' file not found
#include <__config_site>

[victorstewart]

this still isn't fixed in 15.0.2?

[mizvekov]

I see this problem when running lldb tests from the test suite on a linux system.

Copying __config_site into the main include dir helps getting everything to work (Horrible workaround, but indicates this is the only problem affecting the system).

[ldionne]

I think this is a Clang problem -- the Clang driver for that target isn't looking into the right directory.

@petrhosek Any clue about this? Shouldn't the driver for all targets now be looking into the per-target include dir?

[petrhosek]

Clang should add that include path automatically, see

llvm-project/clang/lib/Driver/ToolChains/Gnu.cpp

Lines 3073 to 3076 in 13b8362

	// First add the per-target include path if it exists.
	std::string TargetDir = Path + "/" + Target + "/c++/" + Version;
	if (D.getVFS().exists(TargetDir))
	addSystemInclude(DriverArgs, CC1Args, TargetDir);

I think the issue here is the triple. You pass --target=arm-linux-gnueabihf (that is 32-bit ARM Linux) but also -march=armv8-a -mcpu=cortex-a72 which overrides the triple, so the effective normalized triple is going to be aarch64-unknown-linux-gnu (that is 64-bit ARM Linux) and Clang will end up looking in /usr/local/include/aarch64-unknown-linux-gnu/c++/v1 which doesn't exist since you've built libc++ for arm-linux-gnueabihf.

I'd also point out that you're only building the 32-bit ARM backend because you pass -DLLVM_TARGETS_TO_BUILD="ARM", so I'd expect -march=armv8-a -mcpu=cortex-a72 to cause an error during later stages since there's no 64-bit backend.

I'm not sure what's the right behavior in this case, maybe Clang should complain that the --target, -march and -mcpu are incompatible?

[alexirion]

Same issue, when I only pass --target=arm-linux-gnueabihf without -march and -cpu. The /usr/local/include/arm-linux-gnueabihf/c++/v1 is not in the search path.
It makes now arm-unknown-linux-gnueabihf from --target=arm-linux-gnueabihf.

/usr/local/bin/clang++ --target=arm-linux-gnueabihf -D_FILE_OFFSET_BITS=64 -v -stdlib=libc++ -fcolor-diagnostics -Wall -Wpedantic -Werror -Wconversion -std=gnu++20 -MD -MT homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -MF homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o.d -o homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -c /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp
clang version 15.0.0 (https://github.com/llvm/llvm-project.git 4ba6a9c)
Target: arm-unknown-linux-gnueabihf
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/arm-linux-gnueabihf/8
Selected GCC installation: /usr/lib/gcc/arm-linux-gnueabihf/8
Candidate multilib: .;@m32
Selected multilib: .;@m32
(in-process)
"/usr/local/bin/clang-15" -cc1 -triple armv6kz-unknown-linux-gnueabihf -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu arm1176jzf-s -target-feature +vfp2 -target-feature +vfp2sp -target-feature -vfp3 -target-feature -vfp3d16 -target-feature -vfp3d16sp -target-feature -vfp3sp -target-feature -fp16 -target-feature -vfp4 -target-feature -vfp4d16 -target-feature -vfp4d16sp -target-feature -vfp4sp -target-feature -fp-armv8 -target-feature -fp-armv8d16 -target-feature -fp-armv8d16sp -target-feature -fp-armv8sp -target-feature -fullfp16 -target-feature +fp64 -target-feature -d32 -target-feature -neon -target-feature -sha2 -target-feature -aes -target-feature -fp16fml -target-feature +strict-align -target-abi aapcs-linux -mfloat-abi hard -Wunaligned-access -fallow-half-arguments-and-returns -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/airion/projects/homenet/products/rpi4 -resource-dir /usr/local/lib/clang/15.0.0 -dependency-file homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o.d -MT homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -sys-header-deps -D _FILE_OFFSET_BITS=64 -internal-isystem /usr/local/bin/../include/c++/v1 -internal-isystem /usr/local/lib/clang/15.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/arm-linux-gnueabihf/8/../../../../arm-linux-gnueabihf/include -internal-externc-isystem /usr/include/arm-linux-gnueabihf -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wall -Wpedantic -Werror -Wconversion -std=gnu++20 -fdeprecated-macro -fdebug-compilation-dir=/home/airion/projects/homenet/products/rpi4 -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o homenet/test/helloworld/CMakeFiles/helloworld.dir/main.cpp.o -x c++ /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp
clang -cc1 version 15.0.0 based upon LLVM 15.0.0 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/lib/gcc/arm-linux-gnueabihf/8/../../../../arm-linux-gnueabihf/include"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/bin/../include/c++/v1
/usr/local/lib/clang/15.0.0/include
/usr/local/include
/usr/include/arm-linux-gnueabihf
/usr/include
End of search list.
In file included from /home/airion/projects/homenet/myhomenet/homenet/test/helloworld/main.cpp:1:
In file included from /usr/local/bin/../include/c++/v1/cstdio:98:
In file included from /usr/local/bin/../include/c++/v1/__assert:13:
/usr/local/bin/../include/c++/v1/__config:13:10: fatal error: '__config_site' file not found
#include <__config_site>
^~~~~~~~~~~~~~~
1 error generated.

[GavinRay97]

Also having with problem, with LLVM 16 dev and Fedora Rawhide on x86_x64-linux-gnu

I built from source using:

$ cmake -S llvm -B build -G Ninja \
	-DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" \
 	-DLLVM_ENABLE_RUNTIMES="compiler-rt;libcxx;libcxxabi" \
	-DLLVM_USE_LINKER=mold \
	-DCMAKE_BUILD_TYPE=Release \
	-DCMAKE_C_COMPILER=clang \
	-DCMAKE_CXX_COMPILER=clang++
$ cd build
$ cmake --build . --target install

[alexirion]

With setting -DLLVM_RUNTIME_TARGETS="arm-unknown-linux-gnueabihf" it has finally worked! :-) Here the unknown is important! The __config_site file is then created in /usr/local/include/arm-unknown-linux-gnueabihf/c++/v1 and is later on found when compiling a program with --target=arm-unknown-linux-gnueabihf.
Might be better when the value of LLVM_RUNTIME_TARGETS would also be normalized, then leaving out the "unknown" would work in the same way?

[petrhosek]

Yes, normalizing triples in LLVM_RUNTIME_TARGETS is planned, but there's some groundwork we need to do first.