cmake: Export compile_commands.json for all generated code

[sslupsky]

Presently, if you include the following setting in a CMakeLists.txt file in the project root, the targets listed in the compile_commands.json file generated by CMake are limited to the targets specified in the CMakeLists.txt file.

set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

I would prefer that the compile_commands.json file also include all the compiled code for Zephyr (the drivers, kernel, subsys, etc). There reason is that I can configure MS VSCode to read the compile_commands.json file and configure its intellisense feature to highlight coding errors.

I tried editing the CMakeLists.txt files in the following Zephyr tree subfolders:
arch/arm
boards
drivers
kernel
soc
subsys

This improved things quite a bit and many of the Zephyr targets now appear in the compile_commands.json file. However, there are a few that still do not appear. For instance, sam0_rtc_timer.c is not included as a target. Neither is wdt_sam0.c. I know these are being compiled because my application uses them and I have debugged them. There are likely a few other files that are not included as well, I have not yet performed an exhaustive analysis.

Is there another way to inform CMake so that a complete set of targets will be included in compile_commands.json?

[mbolivar-nordic]

Is there another way to inform CMake so that a complete set of targets will be included in compile_commands.json?

There are several examples in the west documentation that I believe do what you are asking about:

https://docs.zephyrproject.org/latest/guides/west/build-flash-debug.html#permanent-cmake-arguments

[sslupsky]

Thank you @mbolivar

I was able to get export setting to stick by adding

-DCMAKE_EXPORT_COMPILE_COMMANDS=1

to the west command line.

There is still a VSCode CMake-Tools issue where resolving the location of a header file can result in multiple paths. I have noticed this happens when there are headers with no target. That is, there is a <kernel.h> but there is no target "kernel.c". CMake-Tools attempts to look up "kernel.c" when I try to locate <kernel.h> Since "kernel.c" is not a target in compile_commands.json, the c/cpp extension defaults to another search process and comes up with multiple paths.