Make clangd CompletionModel not depend on directory layout.

[hvdijk]

Summary

The current code accounts for two possible layouts, but there is at least a third supported layout: clang-tools-extra may also be checked out as clang/tools/extra with the releases, which was not yet handled. Rather than treating that as a special case, use the location of CompletionModel.cmake to handle all three cases. This should address the problems that prompted D96787 and the problems that prompted the proposed revert D100625.

[usaxena95]

clang-tools-extra/clangd/quality/CompletionModel.cmake

7

nit: Directly refer to code generator instead of storing quality dir.
set(CLANGD_COMPLETION_MODEL_COMPILER ${CMAKE_CURRENT_LIST_DIR}/CompletionModelCodegen.py)

[hvdijk]

clang-tools-extra/clangd/quality/CompletionModel.cmake

7

Alright, done. Testing in progress just to be on the safe side. We could also get rid of model_compiler and use ${CLANGD_COMPLETION_MODEL_COMPILER} directly, but I felt that looked bad due to the conflicting variable naming styles and the long lines, so I left that.

[usaxena95]

clang-tools-extra/clangd/quality/CompletionModel.cmake

9

We can remove this variable as well and use the above var at all places.

clang-tools-extra/clangd/quality/CompletionModel.cmake

 # Run the Completion Model Codegenerator on the model present in the 
 # ${model} directory.
 # Produces a pair of files called ${filename}.h and  ${filename}.cpp in the 
 # ${CMAKE_CURRENT_BINARY_DIR}. The generated header
 # will define a C++ class called ${cpp_class} - which may be a
 # namespace-qualified class name.
+set(CLANGD_COMPLETION_MODEL_COMPILER ${CMAKE_CURRENT_LIST_DIR}/CompletionModelCodegen.py)
 function(gen_decision_forest model filename cpp_class)
-  set(model_compiler ${LLVM_EXTERNAL_CLANG_TOOLS_EXTRA_SOURCE_DIR}/clangd/quality/CompletionModelCodegen.py)
+  set(model_compiler ${CLANGD_COMPLETION_MODEL_COMPILER})
 
   set(output_dir ${CMAKE_CURRENT_BINARY_DIR})
   set(header_file ${output_dir}/${filename}.h)
   set(cpp_file ${output_dir}/${filename}.cpp)
 
   add_custom_command(OUTPUT ${header_file} ${cpp_file}
     COMMAND "${Python3_EXECUTABLE}" ${model_compiler}
       --model ${model}