STL headers not found when using clang with `--gcc-toolchain`

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1

We cross compile our project by using llvm with the gcc backend (--gcc-toolchain). cfamily scanner seems to not recognize that parameter and does not realise the STL headers live in there.

So with compile command similar to:

<clang_path>/bin/clang++
 --sysroot=<sysroot_path>
 --gcc-toolchain=<gcc_path>
 --target=arm-linux-gnueabihf
 -march=armv7-a -mfloat-abi=hard -mfpu=neon -mtune=cortex-a9
 file.cpp

clang find the STL headers in <gcc_path>/arm-linux-gnueabihf/include/c++/13.3.0

But cfamily reports this:

Probing compiler: [<clang_path>/bin/clang++, -x, c++, --std, c++17, -target, arm-linux-gnueabihf, --sysroot=<sysroot_path>, -mfloat-abi=hard, -mfpu=neon, -v, -dM, -E, -]
...
clang version 17.0.6
Target: arm-unknown-linux-gnueabihf
Thread model: posix
InstalledDir: /usr/local/adyen/clang+llvm/bin
 (in-process)
"<clang_path>/clang-17" -cc1 -triple armv6kz-unknown-linux-gnueabihf -E -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name - -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 -debugger-tuning=gdb -target-linker-version 1015.7 -v -fcoverage-compilation-dir=/Users/michale/workspace/vos/builds/vos2/test-ccache -resource-dir <clang_path>lib/clang/17 -isysroot <sysroot_path> -internal-isystem <clang_path>lib/clang/17/include -internal-isystem <sysroot_path>/usr/local/include -internal-externc-isystem <sysroot_path>/include -internal-externc-isystem <sysroot_path>/usr/include -std=c++17 -fdeprecated-macro -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -dM -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o - -x c++ -

clang -cc1 version 17.0.6 based upon LLVM 17.0.6 default target arm64-apple-darwin23.6.0
#include "..." search starts here:
#include <...> search starts here:
 <clang_path>/lib/clang/17/include
 <sysroot_path>/usr/local/include
 <sysroot_path>/include
 <sysroot_path>/usr/include
End of search list.

With this search list missing <gcc_path>/arm-linux-gnueabihf/include/c++/13.3.0, analysis of the file brings this error:

The analyzer was not able to find file
  string
  included from file file.cpp

SonarQube: v10.6
SonarScanner CLI 6.1.0.4477

3

Hello @mejdys.adyen ,

Unfortunately, --gcc-toolchain is not forwarded to the compiler when probing. I have created a ticket to add support for it,

https://sonarsource.atlassian.net/browse/CPP-5738

In the meantime, can you try doing the wrapped compilation with the environment variable CPLUS_INCLUDE_PATH pointing to <gcc_path>/arm-linux-gnueabihf/include/c++/13.3.0 ? It should not change the compiler behavior (it is going to look there anyway), but it will influence the probe.

Let me know if it helps.

4

Thanks for the quick suggestion and raising an issue. Luckily, we have another workaround possible, we still have a gcc-only setup, which we will lean on for now. I will keep an eye on the ticket you raised. Thanks!

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