[NFC][Docs] Fix RAVFrontendAction doc's CMakelists.txt for Shared build

[xgupta]

Summary

Example tutorial giving undefine reference error while building with BUILD_SHARED_LIBS=ON.

[xgupta]

I build the project on my system x64 with shared libraries enable. It is working correctly. It is also NFC.

[awarzynski]

Hi @xgupta , thank you for working on this!

It's quite easy to miss dependencies when building with BUILD_SHARED_LIBS=Off (i.e. with the default setting - static libs). IIUC, that's what happened here. This example clearly requires the following:

• ASTConsumer implemented in clangAST
• FullSourceLoc implemented in clangBasic
• ASTFrontendAction implemented in clangFrontend
• PCHContainerOperations (required for the invocation of runToolOnCode) implemented in clangSerialization

All the above were missing and your patch fixes that, thank you a ton! I think that this is also missing (implements llvm::outs()):

set(LLVM_LINK_COMPONENTS
  Support
  )

I tested on Darwin with BUILD_SHARED_LIBS=On and I'm getting build errors without it:

Undefined symbols for architecture x86_64:
  "llvm::outs()", referenced from:
      FindNamedClassVisitor::VisitCXXRecordDecl(clang::CXXRecordDecl*) in FindClassDecls.cpp.o

PS Apologies for taking so much time to review this!

[xgupta]

Thank @awarzynski for reviewing and explaining the details. I somehow missed it. Should be fixed by https://github.com/llvm/llvm-project/commit/d1ef9a63a68850bbe8cd8877f69c41833804c8dc

clang/docs/RAVFrontendAction.rst

 
 We store this into a file called FindClassDecls.cpp and create the
 following CMakeLists.txt to link it:
 
 ::
 
     add_clang_executable(find-class-decls FindClassDecls.cpp)
 
-    target_link_libraries(find-class-decls clangTooling)
+    target_link_libraries(find-class-decls 
+      PRIVATE
+      clangAST
+      clangBasic
+      clangFrontend
+      clangSerialization
+      clangTooling
+      )
 
 When running this tool over a small code snippet it will output all
 declarations of a class n::m::C it found:
 
 ::
 
       $ ./bin/find-class-decls "namespace n { namespace m { class C {}; } }"
       Found declaration at 1:29