Generate and merge compile_commands.json fo ULP subprojects in the build system (IDFGH-10664)

[andylinpersonal]

Is your feature request related to a problem?

I would like to generate compile_commands.json for all ULP-RISC-V binaries to use auto-completion and code navigation (with clang or vscode intellisense LSPs).

Describe the solution you'd like.

esp-idf version: release/v5.1

1. Add -DCMAKE_EXPORT_COMPILE_COMMANDS to the subproject created in the ${IDF_PATH}/components/ulp/project_include.cmake.
2. Merge all generated compile_commands.json into a single file to the topmost level of cmake's workspace.

Currently, I've only done step.1 and merge all compile_commands.jsons to build/compile_commands.json in a launch.json task.

Describe alternatives you've considered.

No response

Additional context.

No response

[SoucheSouche]

0494dc4

[KaeLL]

It didn't address the merging part.
I run a jq oneliner to merge the bootloader and app compile_commands when I'm fiddling with the bootloader, but I'm sure it can be done in python and added to idf.py somewhere, optionally or otherwise, so that it can merge all compile_commands.json files.
@sudeep-mohanty thoughts?

[sudeep-mohanty]

@KaeLL Thanks for the suggestion. Indeed, there can several ways of merging the various compile_commands.json but if it's done as part of the build then it would be most seamless. In that regard, I will consult the tools team and check how best this can be done.

[andylinpersonal]

By migrating to the newer version of clangd, which supports multiple compile_commands.json, can solve this problem and have better hinting and completion experience.