[cmake] Reset variable before using it

A bunch of macros use the same variable name, and since CMake macros
don't get their own scope, the value persists across macro invocations,
and we can end up exporting targets which shouldn't be exported. Clear
the variable before each use to avoid this.

Converting these macros to functions would also help, since it would
avoid the variable leaking into its parent scope, and that's something I
plan to follow up with. It won't fully address the problem, however,
since functions still inherit variables from their parent scopes, so if
someone in the parent scope just happened to use the same variable name
we'd still have the same issue.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@357036 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/cmake/modules/AddClang.cmake b/cmake/modules/AddClang.cmake
index 76ff6b1f152d890bdb708580434cea47c19a299d..18bac7172b229caa5ca37a73fcabe91620dbbf28 100644 (file)
--- a/cmake/modules/AddClang.cmake
+++ b/cmake/modules/AddClang.cmake
@@ -89,7 +89,7 @@ macro(add_clang_library name)
     target_link_libraries(${name} INTERFACE ${LLVM_COMMON_LIBS})
 
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "libclang")
-
+      set(export_to_clangtargets)
       if(${name} IN_LIST LLVM_DISTRIBUTION_COMPONENTS OR
           "clang-libraries" IN_LIST LLVM_DISTRIBUTION_COMPONENTS OR
           NOT LLVM_DISTRIBUTION_COMPONENTS)
@@ -137,6 +137,7 @@ macro(add_clang_tool name)
   add_dependencies(${name} clang-resource-headers)
 
   if (CLANG_BUILD_TOOLS)
+    set(export_to_clangtargets)
     if(${name} IN_LIST LLVM_DISTRIBUTION_COMPONENTS OR
         NOT LLVM_DISTRIBUTION_COMPONENTS)
       set(export_to_clangtargets EXPORT ClangTargets)