Clangd build failure on WSL with GCC 9.3.0

[ArcsinX]

After this commit llvm/llvm-project@0c96a92#diff-c32c7f73f1328b7df01bcf4544f15843fdabc3838436374c35ab930e44463a74
clangd can't be built on WSL with GCC 9.3.0 (unsure if the version is important) with a lot of errors and the reason is here:

[1/108] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Config.cpp.o
FAILED: tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Config.cpp.o
/usr/bin/c++  -DGTEST_HAS_RTTI=0 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Itools/clang/tools/extra/clangd -I/mnt/d/work/llvm-project/clang-tools-extra/clangd -Itools/clang/tools/extra/clangd/../clang-tidy -I/mnt/d/work/llvm-project/clang/include -Itools/clang/include -Iinclude -I/mnt/d/work/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wmisleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -fno-common -Woverloaded-virtual -fno-strict-aliasing -O3 -DNDEBUG    -fno-exceptions -fno-rtti -std=c++14 -MD -MT tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Config.cpp.o -MF tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Config.cpp.o.d -o tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Config.cpp.o -c /mnt/d/work/llvm-project/clang-tools-extra/clangd/Config.cpp
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:524,
                 from /usr/include/c++/9/string:38,
                 from /mnt/d/work/llvm-project/clang-tools-extra/clangd/features.h:11,
                 from /usr/include/inttypes.h:25,
                 from /mnt/d/work/llvm-project/llvm/include/llvm-c/DataTypes.h:27,
                 from /mnt/d/work/llvm-project/llvm/include/llvm/Support/DataTypes.h:19,
                 from /mnt/d/work/llvm-project/llvm/include/llvm/ADT/Hashing.h:47,
                 from /mnt/d/work/llvm-project/llvm/include/llvm/ADT/Optional.h:18,
                 from /mnt/d/work/llvm-project/llvm/include/llvm/ADT/STLExtras.h:19,
                 from /mnt/d/work/llvm-project/clang-tools-extra/clangd/support/Context.h:17,
                 from /mnt/d/work/llvm-project/clang-tools-extra/clangd/Config.h:27,
                 from /mnt/d/work/llvm-project/clang-tools-extra/clangd/Config.cpp:9:
/usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:44:19: error: missing binary operator before token "("
   44 | #if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
.....

As we can see, wrong features.h (from clangd sources instead of system header) is used. This looks like the problem of case-insensitivity (because the real name for the file inside clangd sources is Features.h). I tried to rename Features.h to another name and it helped.

I want to fix my WSL build, but unsure what is the legal way to do this =)

[sam-mccall]

Haha, wow, sorry about that.
I guess I'll just rename the header.