[clang] [libc] [llvm] [libc][Github] Perform baremetal libc builds (PR #167583)

[Petr Hosek via llvm-commits]

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@@ -0,0 +1,17 @@
+# Expects target triple to be passed as `ARCH_TRIPLE`
+
+set(CMAKE_SYSTEM_NAME Generic CACHE STRING "")
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY CACHE STRING "")
+set(LLVM_ENABLE_RUNTIMES "libc" CACHE STRING "")
+set(LLVM_INCLUDE_TESTS OFF CACHE BOOL "")
+set(CMAKE_C_COMPILER_WORKS ON CACHE BOOL "")
+set(CMAKE_CXX_COMPILER_WORKS ON CACHE BOOL "")
+set(CMAKE_SYSROOT "" CACHE STRING "")
+
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petrhosek wrote:

You should also include the following:
```suggestion
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
```

https://github.com/llvm/llvm-project/pull/167583