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[libc] Include Linux kernel headers in the full build #97486

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Merged
merged 3 commits into from
Jul 2, 2024
Merged

[libc] Include Linux kernel headers in the full build #97486

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6edadbc
[libc] Include Linux kernel headers in the full build
petrhosek Jul 2, 2024
db7380a
Add a comment explaining the use of -idirafter
petrhosek Jul 2, 2024
e78388f
Add TODO for COMPILER_RESOURCE_DIR
petrhosek Jul 2, 2024
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2 changes: 2 additions & 0 deletions libc/CMakeLists.txt
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Expand Up @@ -39,6 +39,8 @@ set(LIBC_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR})

set(LIBC_ENABLE_USE_BY_CLANG OFF CACHE BOOL "Whether or not to place libc in a build directory findable by a just built clang")

set(LIBC_KERNEL_HEADERS "/usr/include" CACHE STRING "Path to Linux kernel headers")

# Defining a global namespace to enclose all libc functions.
set(default_namespace "__llvm_libc")
if(LLVM_VERSION_MAJOR)
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8 changes: 8 additions & 0 deletions libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
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Expand Up @@ -51,9 +51,17 @@ function(_get_common_compile_options output_var flags)
if(LIBC_CC_SUPPORTS_NOSTDLIBINC)
list(APPEND compile_options "-nostdlibinc")
elseif(COMPILER_RESOURCE_DIR)
# TODO: We should require COMPILER_RESOURCE_DIR to be set.
list(APPEND compile_options "-isystem${COMPILER_RESOURCE_DIR}/include")
list(APPEND compile_options "-nostdinc")
endif()
# TODO: We should set this unconditionally on Linux.
if(LIBC_TARGET_OS_IS_LINUX AND
(LIBC_CC_SUPPORTS_NOSTDLIBINC OR COMPILER_RESOURCE_DIR))
# We use -idirafter to avoid preempting libc's own headers in case the
# directory (e.g. /usr/include) contains other headers.
list(APPEND compile_options "-idirafter${LIBC_KERNEL_HEADERS}")
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It merits a comment about why we want to use -idirafter, which is in case it's a directory like /usr/include that might contain other headers that we don't want to risk preempting libc's own headers.

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Done.

endif()
endif()

if(LIBC_COMPILER_HAS_FIXED_POINT)
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