feat: create a symlink of complie_commands.json on the source dir

[FeignClaims]

#190 (comment)

It helps clang based tools to find compile_commands.json when using out-of-source builds, and to find the correct compile_commands.json when handling multiple builds.
Already tested in my FeignClaims/cmake_starter_template (for the orign extension version, see cmake/SymlinkCompileCommands.cmake) when I switch between clang and gcc on MacOS and Windows.

Users should be notified to add compile_commands.json to .gitignore though.

[aminya]

Users should be notified to add compile_commands.json to .gitignore though.

It would be great if we could automate the addition to .gitignore!

[FeignClaims]

Users should be notified to add compile_commands.json to .gitignore though.

It would be great if we could automate the addition to .gitignore!

This should be optional then. I prefer to automately add it only if .gitignore exists.

[aminya]

I tried this locally, but I got this error:

CMake Error at D:/GitHub/Cpp/project_options/src/Common.cmake:80 (cmake_host_system_information):
  cmake_host_system_information does not recognize <key> WINDOWS_REGISTRY
Call Stack (most recent call first):
  D:/GitHub/Cpp/project_options/src/Index.cmake:128 (common_project_options)
  CMakeLists.txt:53 (project_options)


CMake Error at D:/GitHub/Cpp/project_options/src/Common.cmake:96 (file):
  file failed to create symbolic link
  'D:/GitHub/Cpp/project_options/tests/myproj/compile_commands.json': A
  required privilege is not held by the client.

Call Stack (most recent call first):
  D:/GitHub/Cpp/project_options/src/Index.cmake:128 (common_project_options)
  CMakeLists.txt:53 (project_options)

[FeignClaims]

I tried this locally, but I got this error:

CMake Error at D:/GitHub/Cpp/project_options/src/Common.cmake:80 (cmake_host_system_information):
  cmake_host_system_information does not recognize <key> WINDOWS_REGISTRY
Call Stack (most recent call first):
  D:/GitHub/Cpp/project_options/src/Index.cmake:128 (common_project_options)
  CMakeLists.txt:53 (project_options)


CMake Error at D:/GitHub/Cpp/project_options/src/Common.cmake:96 (file):
  file failed to create symbolic link
  'D:/GitHub/Cpp/project_options/tests/myproj/compile_commands.json': A
  required privilege is not held by the client.

Call Stack (most recent call first):
  D:/GitHub/Cpp/project_options/src/Index.cmake:128 (common_project_options)
  CMakeLists.txt:53 (project_options)

The command requires CMake 3.24+. Maybe that's the reason? The debug here requires a lot of tedious edit-and-test work, so I suggest just ignore this pull request after I fix this.

[FeignClaims]

Should work now. Already tested on my windows virtual machine.

[FeignClaims]

Here's a summay feature of my pr:

• If .gitignore exists in ${CMAKE_SOURCE_DIR} and dosen't contain compile_commands.json, automatically add compile_commands.json into it. (this helps git based project.)
• If cmake generates compile_commands.json:
  • If users don't run cmake as non-administrator on Windows, symlink ${CMAKE_BINARY_DIR}/compile_commands.json to ${CMAKE_SOURCE_DIR}/compile_commands.json. (this helps clang based tools.)
  • If users run cmake as non-administrator on Windows, add a custom command _copy_compile_commands which copies ${CMAKE_BINARY_DIR}/compile_commands.json to ${CMAKE_SOURCE_DIR}/compile_commands.json.

[FeignClaims]

rebased on main and ready to merge now.

[aminya]

Let's use TRACE for the messages that are not necessary for the user.