[clang] [Clang] Add explicit visibility symbol macros (PR #108276)

[Saleem Abdulrasool via cfe-commits]

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@@ -108,6 +108,10 @@ macro(add_clang_library name)
   endif()
   llvm_add_library(${name} ${LIBTYPE} ${ARG_UNPARSED_ARGUMENTS} ${srcs})
 
+  if(NOT ARG_SHARED AND NOT ARG_STATIC)
+    target_compile_definitions("obj.${name}" PRIVATE CLANG_EXPORTS)
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compnerd wrote:

Why is this being added?

https://github.com/llvm/llvm-project/pull/108276