Allow to generate compile_commands.json using bear

[kamilrakoczy]

Pre-PR to: #4228

This PR adds support for compile_commands.json to clang_check_attributes as well as automatically generates compile_commands.json using bear (if found).

[kamilrakoczy]

But if the submakes do nothing, does this break? #4228 (comment)

I'm not sure what you meant by this. Could you please elaborate?

If you meant that there will be wrong compile_commands.json file when bear will ran on already built target, I've fixed this case. We didn't need to remove compile_commands.json file before generating it again, as we pass --append flag to bear.

[wsnyder]

Thanks, seems reasonable. Please make sure "lint-py" is clean (if you didn't already), and update docs/install.rst to mention installing bear for developers.

[wsnyder]

Also please merge in master to cleanup the test failure - sorry about that instability.

[gezalore]

I'm curious why we use the opt build for the compile_commands.json? Generally the dbg build has "more stuff" in it, like assertions and debug checks, which are compiled out of the opt build. I have been using the commands from the dbg build for IDE use for a long time as it has the right defines for working on debug code as well.

[kamilrakoczy]

Thanks, seems reasonable. Please make sure "lint-py" is clean (if you didn't already), and update docs/install.rst to mention installing bear for developers.

I've checked "lint-py" and it is clean. I've also added bear to install.rst.

I'm curious why we use the opt build for the compile_commands.json? Generally the dbg build has "more stuff" in it, like assertions and debug checks, which are compiled out of the opt build. I have been using the commands from the dbg build for IDE use for a long time as it has the right defines for working on debug code as well.

For our usage opt build had all necessary defines, but dbg have them too.
You are right that compile_commands.json from dbg build can be more useful for IDE/development, so I've moved generation of compile_commands.json to dbg.