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[C++] unknown argument: '-Kc++' #47790
Description
Describe the bug, including details regarding any error messages, version, and platform.
I'm trying to build arrow@19.0.1 which pulls in mimalloc (ARROW_MIMALLOC_BUILD_VERSION=v2.0.6). I am using the Intel OneAPI 2025.x compiler suite, which is Clang/LLVM based. This check doesn't seem to correctly detect this compiler:
https://github.com/microsoft/mimalloc/blob/09a27098aa6e9286518bd9c74e6ffa7199c3f04e/CMakeLists.txt#L361
resulting in
-- stderr output is:
icpx: error: unknown argument: '-Kc++'
icpx: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
make[5]: *** [CMakeFiles/mimalloc-static.dir/build.make:82: CMakeFiles/mimalloc-static.dir/src/stats.c.o] Error 1
make[4]: *** [CMakeFiles/Makefile2:90: CMakeFiles/mimalloc-static.dir/all] Error 2
make[3]: *** [Makefile:139: all] Error 2
I've also reported this upstream microsoft/mimalloc#1153
Component(s)
C++
Activity
[-]unknown argument: '-Kc++'[/-][+][C++] unknown argument: '-Kc++'[/+]thisisnic commentedon Oct 26, 2026
Thanks for the report. This error comes from the bundled mimalloc v2.0.6, which adds the classic ICC flag
-Kc++for any compiler ID matching "Intel", including icpx (IntelLLVM). mimalloc fixed that detection in v2.0.7, and Arrow picked up a newer mimalloc (v2.2.4) in GH-45978, first released in Arrow 21.0.0. Arrowmainis now on mimalloc v3.4.1. I am going to close this as resolved by GH-45978, but please open a new issue if you still hit the problem on 21.0.0 or later.