On Wed, Aug 12, 2026 at 6:00 AM Peter Marko via lists.openembedded.org <[email protected]> wrote:
> From: Peter Marko <[email protected]> > > This assignment was present in scarthgap meta-clang. > * commit adding it: [1] > * commit removing it from native case: [2] > * it was removed completely when migrating clang to oe-core > > After migration from scarthgap to wrynose (or current master), clang > extra tools like clang-tidy do not work anymore. > > Test recipe used for fix validation: > > test-recipe.bb: > SUMMARY = "clang-tidy demonstration program" > SECTION = "examples" > HOMEPAGE = "n/a" > LICENSE = "GPL-2.0-only" > LIC_FILES_CHKSUM = > "file://${COREBASE}/meta/files/common-licenses/GPL-2.0-only;md5=801f80980d171dd6425610833a22dbe6" > SRC_URI = "file://CMakeLists.txt file://hello-world.cpp" > S = "${UNPACKDIR}" > TOOLCHAIN = "clang" > inherit cmake > > CMakeLists.txt > project(hello-world) > cmake_minimum_required(VERSION 3.5) > find_program(CLANG_TIDY NAMES clang-tidy) > set(CMAKE_CXX_CLANG_TIDY "${CLANG_TIDY}" "--checks=*") > add_executable(${PROJECT_NAME} hello-world.cpp) > > hello-world.cpp > #include <iostream> > int main() { > std::cout << "Hello World!"; > return 0; > } > > I have asked AI agent to analyze clang sources for side-effects which > are mentioned in patch removing this with following result: > > When a cmake recipe uses CMAKE_CXX_CLANG_TIDY (or runs clang-tidy in any > mode that passes the compile command via -- on the command line), CMake > invokes clang-tidy through its __run_co_compile path. This path > constructs a FixedCompilationDatabase from the arguments following --. > Inside FixedCompilationDatabase::loadFromCommandLine() the original > cross-compiler binary name (e.g. x86_64-poky-linux-clang++) is stripped > by stripPositionalArgs() and replaced with a dummy argv[0]. As a result > the target triple encoded in the cross-compiler name is never seen by > clang-tidy. > > JSONCompilationDatabase (used when clang-tidy is run with -p <build_dir>) > wraps its commands with inferTargetAndDriverMode(), which calls > addTargetAndModeForProgramName() and would correctly inject > --target=x86_64-poky-linux. FixedCompilationDatabase has no equivalent > step, so the native clang-tidy falls back to the build-host default > triple and cannot locate C++ headers under the target sysroot: > > hello-world.cpp:1:10: error: 'iostream' file not found > > The fix is to make the -target flag explicit in the compile commands. > The cross-compiler already has LLVM_DEFAULT_TARGET_TRIPLE compiled in as > HOST_SYS, so adding -target ${HOST_SYS} to HOST_CC_ARCH is a no-op for > the compiler itself. For clang-tidy and other Clang-based tools that > parse compile commands but do not inherit the binary's baked-in default > triple the flag is the only reliable channel to communicate the intended > target. > > On a typical GNU/Linux host the GCC runtime is installed under a > vendor-qualified tuple (e.g. aarch64-linux-gnu/) that clang probes at > runtime. Providing an explicit -target aarch64-linux overrides that > probe and prevents clang-native from finding libgcc and crt objects, > which was the original motivation for removing the assignment. > > [1] > https://github.com/kraj/meta-clang/commit/503aa977b27be0506fb6ac21fbf9e8b049b82247 > [2] > https://github.com/kraj/meta-clang/commit/6da0abaa33b458a37b97f42e3755245e3220bf27 > > Signed-off-by: Peter Marko <[email protected]> > --- > meta/classes/toolchain/clang.bbclass | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/meta/classes/toolchain/clang.bbclass > b/meta/classes/toolchain/clang.bbclass > index 9a3cd0e584..862ecb5e10 100644 > --- a/meta/classes/toolchain/clang.bbclass > +++ b/meta/classes/toolchain/clang.bbclass > @@ -34,6 +34,9 @@ LDFLAGS:append:class-nativesdk:x86-64 = " > -Wl,-dynamic-linker,${base_libdir}/ld- > LDFLAGS:append:class-nativesdk:aarch64 = " > -Wl,-dynamic-linker,${base_libdir}/ld-linux-aarch64.so.1" > LDFLAGS:append:class-cross-canadian = " > -Wl,-dynamic-linker,${base_libdir}/placeholder/to/be/rewritten/by/sdk/installer" > > +# helps extra tools like clang-tidy to find arch-specific macros and > headers in a cross compile environment > +HOST_CC_ARCH:prepend = "-target ${HOST_SYS} " > This will impact all variants of clang compiler invocations e.g. native/nativesdk etc. I hope it does not impact sstate sharing. > + > # do_populate_sysroot needs STRIP, do_package_qa needs OBJDUMP > POPULATESYSROOTDEPS:append:class-target = " > llvm-native:do_populate_sysroot" > > > > >
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