No dependencies when using ninja -t deps

[amirbarak]

Heya. Using ninja 1.11.1 on Linux + cmake to manage a C project.

I'm trying to use ninja to map which headers are used by source files for a given target. I generate my build.ninja rules using cmake with the ninja multi-config generator, and while ninja -t inputs works given my targets, ninja -t deps outputs nothing - and if given a specific target, outputs test: deps not found.

My .ninja_deps file seems to be pretty big and populated, so I must be missing something basic. Is there any documentation specifically for the deps tool that could explain why I'm getting no output?

Thank you!

[digit-google]

ninja -t deps <target> only prints the implicit dependencies recorded in the depfile generated the last time <target> was generated by Ninja. If the corresponding command in the Ninja build plan doesn't use a depfile, this will be empty. Which is what the deps not found seems to indicate.

Note: if your <target> is a phony target, it won't have a depfile ever, you must look at the real output target paths to get anything sensible.

Otherwise, you could try rebuilding ninja -d keepdepfile <target> to keep the depfile in the output directory, and look at its content to see whether it is empty or not.

[amirbarak]

Thanks @digit-google . Is there a way to pass the keepdepfile through CMake or do I need to invoke ninja directly to "force" create the depfile?

[digit-google]

As far as I know, you will need to invoke Ninja directly. I suggest asking in the CMake forums / mailing list otherwise.

[digit-google]

Note that you can use ninja -t commands -s <target> to look at the command that generates <target>. It should be easy to see if it generates a depfile or not. This would be empty for phony target too.