[clang] [llvm] [CMake] Version Darwin dylib identities (PR #189004)

[Steven Wu via llvm-commits]

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@@ -170,11 +170,12 @@ if(ENABLE_SHARED)
       # implicitly be exported from libclang.
       target_compile_definitions(libclang PRIVATE CLANG_BUILD_STATIC)
   elseif(APPLE)
-    set(LIBCLANG_LINK_FLAGS " -Wl,-compatibility_version -Wl,1")
-    set(LIBCLANG_LINK_FLAGS "${LIBCLANG_LINK_FLAGS} -Wl,-current_version -Wl,${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
-
-    set_property(TARGET libclang APPEND_STRING PROPERTY
-                 LINK_FLAGS ${LIBCLANG_LINK_FLAGS})
+    if(LLVM_VERSIONED_DYLIB_NAME_ON_DARWIN)
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cachemeifyoucan wrote:

libclang and libLTO has stable ABI.

It is a requirement on macOS and in our toolchain that we have to link across major version boundaries. 

I don't really mind the version number on llvm dylibs from `BUILD_SHARED_LIBS=YES` but libLTO and libeling cannot be versioned.

https://github.com/llvm/llvm-project/pull/189004