Compiler probe failure with clang and -Xclang arg #6356
Description
Brief Issue Summary
Either cmake-tools or cpptools (I'm not quite sure) apparently aren't correctly probing clang on my system, resulting in broken IntelliSense. This only applies if I use precompiled headers in my project. gcc works as expected with precompiled headers.
Expected:
cmake-tools use my compiler (Kit) configuration and build system information to provide IntelliSense.
Apparent Behavior:
The C++ log in VSCode shows:
Compiler probe command line: "/usr/bin/clang++-10" -fsanitize=undefined -fsanitize=address -g -fPIC -fvisibility=hidden -Wall -Wextra -Wunused -Wignored-qualifiers -Wmissing-braces -Wreturn-type -Wswitch -Wswitch-default -Wuninitialized -Wmissing-field-initializers -Wcast-align -Wmissing-declarations -Wpedantic -Wreorder -Wreturn-stack-address -std=c++17 -Xclang -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx.pch -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx -Wp,-v -E -dD -x c++ -m64 -fno-blocks /dev/null
Done discovering files.
Populate include completion cache.
Discovering files...
Processing folder (recursive): /usr/local/include/
Processing folder (recursive): /usr/lib64/clang/10.0.1/include/
Failed to query compiler. Falling back to 32-bit intelliSenseMode.
Compiler probe command line: "/usr/bin/clang++-10" -fsanitize=undefined -fsanitize=address -g -fPIC -fvisibility=hidden -Wall -Wextra -Wunused -Wignored-qualifiers -Wmissing-braces -Wreturn-type -Wswitch -Wswitch-default -Wuninitialized -Wmissing-field-initializers -Wcast-align -Wmissing-declarations -Wpedantic -Wreorder -Wreturn-stack-address -std=c++17 -Xclang -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx.pch -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx -Wp,-v -E -dD -x c++ -m32 -fno-blocks /dev/null
Processing folder (recursive): /usr/include/
Failed to query compiler. Falling back to no bitness.
Compiler probe command line: "/usr/bin/clang++-10" -fsanitize=undefined -fsanitize=address -g -fPIC -fvisibility=hidden -Wall -Wextra -Wunused -Wignored-qualifiers -Wmissing-braces -Wreturn-type -Wswitch -Wswitch-default -Wuninitialized -Wmissing-field-initializers -Wcast-align -Wmissing-declarations -Wpedantic -Wreorder -Wreturn-stack-address -std=c++17 -Xclang -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx.pch -Xclang /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx -Wp,-v -E -dD -x c++ -fno-blocks /dev/null
clang-10: warning: /path/to/build/Debug/source/main/CMakeFiles/main.dir/cmake_pch.hxx.pch: previously preprocessed input [-Wunused-command-line-argument]
error: unknown argument: '-Xclang'
The main issue here seems to be "-Xclang" twice in sequence, which is incorrect. I'm not sure where it comes from. The compile commands typically have -Xclang -include -Xclang /path/to/something.pch to include precompiled headers, so maybe VSCode is doing some strange postprocessing on the compiler flags.
Platform and Versions
- Operating System: Fedora 32
- CMake Version: 3.17.4
- VSCode Version: 1.50.1
- CMake Tools Extension Version: 1.4.2 (cpptools: 1.1.0-insiders2, but same behavior with stable version)
- Compiler/Toolchain: clang 10.0.1