clangd no longer works out of the box with compile-commands.json #141640
Description
I'm seeing Unknown argument: '-i' at the top of every C++ file in the engine as reported by clangd:
{
"file": "../../flutter/common/settings.cc",
"directory": "/Users/matanl/Developer/engine/src/out/android_debug_unopt_arm64",
"command": "/Users/matanl/Developer/engine/src/buildtools/mac-x64/goma/gomacc ../../buildtools/mac-x64/clang/bin/clang++ -MD -MF obj/flutter/common/common.settings.o.d -DUSE_OPENSSL=1 -DUSE_OPENSSL_CERTS=1 -DANDROID -DHAVE_SYS_UIO_H -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -D__compiler_offsetof=__builtin_offsetof -Dnan=__builtin_nan -D_LIBCPP_DISABLE_AVAILABILITY=1 -D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS -D_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS -D_DEBUG -DFLUTTER_RUNTIME_MODE_DEBUG=1 -DFLUTTER_RUNTIME_MODE_PROFILE=2 -DFLUTTER_RUNTIME_MODE_RELEASE=3 -DFLUTTER_RUNTIME_MODE_JIT_RELEASE=4 \"-DDART_LEGACY_API=[[deprecated]]\" -DFLUTTER_RUNTIME_MODE=1 -DFLUTTER_JIT_RUNTIME=1 -I../.. -Igen -I../../third_party/libcxx/include -I../../third_party/libcxxabi/include -I../../flutter/build/secondary/third_party/libcxx/config -I../../flutter -fno-strict-aliasing -fPIC -pipe -fcolor-diagnostics -ffunction-sections -funwind-tables -fno-short-enums -nostdinc++ -mno-outline-atomics --target=aarch64-linux-android -Wall -Wextra -Wendif-labels -Werror -Wno-missing-field-initializers -Wno-unused-parameter -Wno-unused-but-set-parameter -Wno-unused-but-set-variable -Wno-implicit-int-float-conversion -Wno-deprecated-copy -Wno-psabi -Wno-deprecated-literal-operator -Wno-unqualified-std-cast-call -Wno-non-c-typedef-for-linkage -Wno-range-loop-construct -D__ANDROID_API__=22 -fvisibility=hidden --sysroot=../../third_party/android_tools/ndk/toolchains/llvm/prebuilt/darwin-x86_64/sysroot -Wstring-conversion -Wnewline-eof -O0 -g2 -Wunreachable-code -fvisibility-inlines-hidden -std=c++17 -fno-rtti -nostdinc++ -nostdinc++ -fvisibility=hidden -fno-exceptions -c ../../flutter/common/settings.cc -o obj/flutter/common/common.settings.o && sed -i '' 's@/b/f/w@../..@g' obj/flutter/common/common.settings.o.d"
}On Discord I asked:
Is there any reason
sedis being used? Is this part of Clang, or something specific to our infrastructure?
To which @jason-simmons responded:
This is a workaround for a behavior in the RBE/Goma workers used for distributed compilation.
The depfiles generated on those workers contain absolute paths to directories on the worker's filesystem. Those paths will not behave correctly when copied to the local filesystem and used in other contexts.
The
sedcommand runs after the compile command and converts the absolute path to a usable relative path.The clang-tidy driver script reads
compile_commands.jsonand then filters out the sed command to obtain the compile command.
I noted:
It used to just work out of the box, I'd prefer RBE did the post-processing and not every single user that wants an IDE
After talking to @zanderso:
Ok. @zanderso informed me in person that "we're holding it wrong" and it should be possible after some interdeterminate change to have both RBE and clangd working out of the box
This issue should track no longer needing this sed hack. I'll also file a bug that we should keep clangd working on CI.