Stack overflow when indexing Firefox on Mac with clangd-indexer

[aslushnikov]

Hi folks,

I'm running clangd-indexer from llvm 12.0.0-rc2 against Firefox source code that we use at Playwright. Unfortunately, it is crashing for me, so I built a debug version with ASAN enabled

$ cmake -G Ninja -DCMAKE_EXPORT_COMPILE_COMMANDS=yes -DLLVM_ENABLE_PROJECTS='clang;clang-tools-extra;' -DCMAKE_BUILD_TYPE=Debug -DLLVM_USE_SANITIZER='Address' ../llvm

Running the ASAN build yields a "stackoverflow" signal from ASAN (full-asan-report.txt)

AddressSanitizer:DEADLYSIGNAL
=================================================================
==65787==ERROR: AddressSanitizer: stack-overflow on address 0x70000c408ff8 (pc 0x00010227ac48 bp 0x70000c409010 sp 0x70000c409000 T1)
    #0 0x10227ac48 in clang::QualType::isNull() const Type.h:726
    #1 0x10229381d in clang::QualType::getCommonPtr() const Type.h:677
    #2 0x102292c7b in clang::QualType::getCanonicalType() const Type.h:6452
    #3 0x10227ae30 in clang::ASTContext::getCanonicalType(clang::QualType) const ASTContext.h:2350
    #4 0x1013b8024 in clang::ASTContext::hasSameType(clang::QualType, clang::QualType) const ASTContext.h:2366
    #5 0x1066feb2f in clang::Sema::PerformImplicitConversion(clang::Expr*, clang::QualType, clang::StandardConversionSequence const&, clang::Sema::AssignmentAction, clang::Sema::CheckedConversionKind) SemaExprCXX.cpp:4120
    #6 0x1066fdd37 in clang::Sema::PerformImplicitConversion(clang::Expr*, clang::QualType, clang::ImplicitConversionSequence const&, clang::Sema::AssignmentAction, clang::Sema::CheckedConversionKind) SemaExprCXX.cpp:3991
    #7 0x106bf7a9f in CheckConvertedConstantExpression(clang::Sema&, clang::Expr*, clang::QualType, clang::APValue&, clang::Sema::CCEKind, bool, clang::NamedDecl*) SemaOverload.cpp:5694
    #8 0x106bf6ef3 in clang::Sema::CheckConvertedConstantExpression(clang::Expr*, clang::QualType, clang::APValue&, clang::Sema::CCEKind, clang::NamedDecl*) SemaOverload.cpp:5800
    #9 0x106d5fdbb in clang::Sema::CheckTemplateArgument(clang::NonTypeTemplateParmDecl*, clang::QualType, clang::Expr*, clang::TemplateArgument&, clang::Sema::CheckTemplateArgumentKind) SemaTemplate.cpp:6925
    #10 0x106d82e8b in clang::Sema::CheckTemplateArgument(clang::NamedDecl*, clang::TemplateArgumentLoc&, clang::NamedDecl*, clang::SourceLocation, clang::SourceLocation, unsigned int, llvm::SmallVectorImpl<clang::TemplateArgument>&, clang::Sema::CheckTemplateArgumentKind) SemaTemplate.cpp:5401
    #11 0x106fe10d6 in ConvertDeducedTemplateArgument(clang::Sema&, clang::NamedDecl*, clang::DeducedTemplateArgument, clang::NamedDecl*, clang::sema::TemplateDeductionInfo&, bool, llvm::SmallVectorImpl<clang::TemplateArgument>&)::$_15::operator()(clang::DeducedTemplateArgument, unsigned int) const SemaTemplateDeduction.cpp:2719
    #12 0x106fe030e in ConvertDeducedTemplateArgument(clang::Sema&, clang::NamedDecl*, clang::DeducedTemplateArgument, clang::NamedDecl*, clang::sema::TemplateDeductionInfo&, bool, llvm::SmallVectorImpl<clang::TemplateArgument>&) SemaTemplateDeduction.cpp:2788

Local reproduction is somewhat involved since it requires building firefox on mac, so I'd be happy to follow-up if you have any questions. If you still want to reproduce this locally, here are the instructions to do that:

1. Check out playwright and playwright's firefox

   $ git clone https://github.com/microsoft/playwright
   $ cd playwright
   $ ./browser_patches/prepare_checkout.sh firefox # this might take some time and eat many GBs

2. Install rust
3. Compile firefox:

   $ # This will yield an error on the first run and explain where to get a custom MacOS SDK.
   $ ./browser_patches/firefox/build.sh --full

   Note: custom SDK could be taken from https://github.com/phracker/MacOSX-SDKs for the sake of the repro.

4. Build compilation database for firefox:

   $ cd ./browser_patches/firefox/checkout
   $ ./mach build-backend -b CompileDB
   $ ls ./obj-build-playwright/compile_commands.json # here's the compilation database

5. Since MacOS has custom include paths, make sure to get those from clang++ -E -x c++ - -v < /dev/null and pass them all as --extra-arg="-I..." args to the clangd-indexer
6. Run indexer against the compilation database.

System information Output of clangd --version:

LLVM (http://llvm.org/):
  LLVM version 12.0.0
  Optimized build with assertions.
  Default target: x86_64-apple-darwin19.6.0
  Host CPU: skylake

Editor/LSP plugin: N/A Operating system: Mac 10.15.4

[HighCommander4]

It would be helpful if you could narrow down which source file triggers the stack overflow.

You can do this by running clangd-indexer with the additional argument --execute-concurrency=1. It will then perform the indexing on a single thread, and you can look for the last line of output of the form [X/Y] Processing file <filename> before the stack overflow.

[aslushnikov]

@HighCommander4 Thank you for the instructions! I reduced compilation database to the following:

[{
  "directory":"/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/parser/html",
  "command":"/usr/bin/clang++ -isysroot /Users/aslushnikov/SDK-archive/MacOSX10.12.sdk/ -std=gnu++17 -o /dev/null -c -fvisibility=hidden -fvisibility-inlines-hidden -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -DNDEBUG=1 -DTRIMMED=1 -DMOZ_HAS_MOZGLUE -DMOZILLA_INTERNAL_API -DIMPL_LIBXUL -DSTATIC_EXPORTABLE_JS_API -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/parser/html -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/dom/base -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/dist/include -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/dist/include/nspr -I/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/dist/include/nss -fPIC -DMOZILLA_CLIENT -include /Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/obj-build-playwright/mozilla-config.h -Qunused-arguments -Qunused-arguments -Wall -Wbitfield-enum-conversion -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wshadow-field-in-constructor-modified -Wsign-compare -Wtype-limits -Wunreachable-code -Wunreachable-code-return -Wwrite-strings -Wno-invalid-offsetof -Wclass-varargs -Wempty-init-stmt -Wfloat-overflow-conversion -Wfloat-zero-conversion -Wloop-analysis -Wno-range-loop-analysis -Wc++2a-compat -Wcomma -Wimplicit-fallthrough -Wunused-function -Wunused-variable -Wstring-conversion -Wtautological-overlap-compare -Wtautological-unsigned-enum-zero-compare -Wtautological-unsigned-zero-compare -Wno-error=tautological-type-limit-compare -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=backend-plugin -Wno-error=return-std-move -Wno-error=atomic-alignment -Wformat -Wformat-security -Wno-gnu-zero-variadic-macro-arguments -Wno-unknown-warning-option -fno-sized-deallocation -fno-aligned-new -fno-exceptions -fno-strict-aliasing -stdlib=libc++ -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -g -O3 -fomit-frame-pointer -funwind-tables -Wno-error=shadow -ferror-limit=0 Unified_cpp_parser_html0.cpp",
  "file":"/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5HtmlAttributes.cpp"
}]

Note that mozilla build system groups C++ sources. The Unified_cpp_parser_html0.cpp is a concatenation of 16 other sources:

Unified_cpp_parser_html0.cpp

```cpp #define MOZ_UNIFIED_BUILD #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AtomTable.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AtomTable.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AtomTable.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AttributeName.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AttributeName.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5AttributeName.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DependentUTF16Buffer.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DependentUTF16Buffer.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DependentUTF16Buffer.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DocumentBuilder.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DocumentBuilder.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5DocumentBuilder.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5ElementName.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5ElementName.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5ElementName.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Highlighter.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Highlighter.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Highlighter.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5HtmlAttributes.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5HtmlAttributes.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5HtmlAttributes.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5MetaScanner.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5MetaScanner.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5MetaScanner.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Module.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Module.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Module.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharacters.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharacters.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharacters.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharactersAccel.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharactersAccel.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5NamedCharactersAccel.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OplessBuilder.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OplessBuilder.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OplessBuilder.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OwningUTF16Buffer.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OwningUTF16Buffer.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5OwningUTF16Buffer.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Parser.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Parser.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Parser.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5PlainTextUtils.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5PlainTextUtils.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5PlainTextUtils.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif #include "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Portability.cpp" #ifdef PL_ARENA_CONST_ALIGN_MASK #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Portability.cpp uses PL_ARENA_CONST_ALIGN_MASK, so it cannot be built in unified mode." #undef PL_ARENA_CONST_ALIGN_MASK #endif #ifdef INITGUID #error "/Users/aslushnikov/prog/playwright/browser_patches/firefox/checkout/parser/html/nsHtml5Portability.cpp defines INITGUID, so it cannot be built in unified mode." #undef INITGUID #endif ```

[HighCommander4]

Do you get the stack overflow if you cd into that directory and manually run that command (using the clang from the same LLVM distrbution that your clangd is from)?

[aslushnikov]

Do you get the stack overflow if you cd into that directory and manually run that command (using the clang from the same LLVM distrbution that your clangd is from)?

@HighCommander4 No, there's no stack overflow.

Just in case, I forgot to mention that I have to add additional -I flags so that include paths work the same way as in my standard clang++ at /usr/bin/clang++. I pass these as multiple --extra-arg= CLI option to clangd-indexer.

I do get some error: use of undeclared identifier '__builtin_ia32_storehps' errors though, but I don't think that's of much importance for indexing.

[HighCommander4]

Thanks. One more thing that would be helpful: could you run the compile command, with the extra arguments added, and also with -c replaced with -E ("only preprocess, do not compile"), and -o /dev/null replaced with -o preprocessed.cpp, and then upload preprocessed.cpp as an attachment?

[aslushnikov]

@HighCommander4 sure thing, here it is: preprocessed.cpp.zip

[HighCommander4]

Thanks. I am not able to reproduce the stack overflow on the preprocessed source file.

However, I don't have a Mac and was testing on Linux, so I may not be exercising some relevant codepaths.

Perhaps someone with a Mac can test and see if they can reproduce the stack overflow on the preprocessed source file.

[aslushnikov]

@HighCommander4 I just tried running ./build/bin/clangd-indexer preprocessed.cpp > out.dex and it didn't crash for me as well. So maybe I did something wrong when generating the preprocessed.cpp - let me carefully check everything.

Meanwhile, if you have any more suggestions - I'd be happy to try things.

[HighCommander4]

I noticed the compile command contains a -include /<...>/mozilla-config.h argument as well. Could you upload that file as well?

[aslushnikov]

@HighCommander4 The following results in a stackoverflow error for me on Mac 10.15:

1. preprocessed.cpp.zip

2. compile_commands.json

   [{
     "directory":"/Users/aslushnikov/prog/llvm",
     "command":"/usr/bin/clang++ -std=gnu++17 -o /dev/null -c preprocessed.cpp",
     "file":"/Users/aslushnikov/prog/llvm/preprocessed.cpp"
   }]

3. running clangd-indexer:

   $ ./build/bin/clangd-indexer ./compile_commands.json --executor=all-TUs --execute-concurrency=1

Interestingly, simply running ./build/bin/clangd-indexer --extra-arg="-std=gnu++17" preprocessed.cpp > out.dex works fine.

[aslushnikov]

I noticed the compile command contains a -include /<...>/mozilla-config.h argument as well. Could you upload that file as well?

@HighCommander4 Here it is: mozilla-config.h.zip. Though I'm able to reproduce the same StackOverflow without this include.

[aslushnikov]

@HighCommander4 Unfortunately, I wasn't able to reproduce this crash on my Ubuntu 20.04. However, I was trying to reproduce the crash by cross-compiling from Linux to MacOS, so I'm not sure how relevant this is.

Cross-compilation steps I did on Ubuntu 20.04.

1. Compiled [`llvmorg-12.0.0-rc2`](https://github.com/llvm/llvm-project/releases/tag/llvmorg-12.0.0-rc2) on Ubuntu 20.04 in Release mode. (Debug + ASAN failed to compile for me for some reason) ```sh $ cmake -G Ninja -DCMAKE_EXPORT_COMPILE_COMMANDS=yes -DLLVM_ENABLE_PROJECTS='clang;clang-tools-extra;' -DCMAKE_BUILD_TYPE=Release ../llvm ``` 2. Got [unofficial macos10.12 sdk](https://github.com/phracker/MacOSX-SDKs) ```sh $ cd /tmp $ wget -O mac-sdk.tar.xz https://github.com/phracker/MacOSX-SDKs/releases/download/10.15/MacOSX10.12.sdk.tar.xz $ tar xf mac-sdk.tar.xz ``` 2. [preprocessed.cpp.zip](https://github.com/clangd/clangd/files/6098787/preprocessed.cpp.zip) 3. `compile_commands.json` has a few extra flags for cross-compilation ```json [{ "directory":"/home/aslushnikov/prog/llvm", "command":"/usr/bin/clang++ --sysroot /tmp/MacOSX10.12.sdk -mmacosx-version-min=10.12 -target x86_64-apple-darwin-macho -std=gnu++17 -o /dev/null -c preprocessed.cpp", "file":"/home/aslushnikov/prog/llvm/preprocessed.cpp" }] ``` 3. running clangd-indexer: ```sh $ ./build/bin/clangd-indexer ./compile_commands.json --executor=all-TUs --execute-concurrency=1 ```