Looks like libTooling might also depend on ClangDiagnosticCommon.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160313 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Tooling/CMakeLists.txt b/lib/Tooling/CMakeLists.txt
index 9216538..0ee05e7 100644
--- a/lib/Tooling/CMakeLists.txt
+++ b/lib/Tooling/CMakeLists.txt
@@ -8,6 +8,10 @@
   ArgumentsAdjusters.cpp
   )
 
+add_dependencies(clangEdit
+  ClangDiagnosticCommon
+)
+
 target_link_libraries(clangTooling
   clangBasic
   clangFrontend