[C++] Export compile commands database by default

[bkietz]

Describe the enhancement requested

CMakePresets.json does not export compile commands by default. The relevant option is "CMAKE_EXPORT_COMPILE_COMMANDS": "ON", and produces a file compile_commands.json which is used by clang tooling. The file is not huge; about 1MB. IMHO it'd be worthwhile to enable this by default so that developers always have access to it without needing to regenerate their cmake build dir; language servers and other tooling can be silently disabled without the compile commands database. See also discussion here

Component(s)

C++

[lidavidm]

CMake also reads this from an environment variable (in 3.17+), so developers can just individually set that in their shell configuration and get it for all CMake projects.

[zeroshade]

I'm gonna +1 this issue as when I was setting up my tooling it took a bit of research before I found the CMAKE_EXPORT_COMPILE_COMMANDS option and it would have been much easier if it just exported the compile commands by default.

[js8544]

+1, whenever I set up a new dev environment I'll need to google this variable because it's hard to remember the name verbatim. Would be nice to have it in the preset.

[pitrou]

This sounds reasonable, do you want to do it @bkietz ?