How to add "local" includes when use bzlmod

[fausturs]

How to add "local" includes when use bzlmod

Consider we are writing the cc_library for a library

In the document of cc_library, we can find an explanation of the includes parameter

Subject to "Make variable" substitution. Each string is prepended with -isystem and added to COPTS. Unlike COPTS, these flags are added for this rule and every rule that depends on it. (Note: not the rules it depends upon!) Be very careful, since this may have far-reaching effects. When in doubt, add "-I" flags to COPTS instead.

It seems that "-I" flags should be used when we want to add a search path that only takes effect when compiling this cc_library.

So if we use the relative path to the root of this library in the -I flag, e.g.

"-Isrc"

This option will not work when using bzlmod and this library deps by other code, because the library may layout in the sandbox like

external/libname~version/src/...

Since most make variables only return path of files, it's hard to get the correct path of the lib.

I have try

"-I$(dirname $(location src/include/a.h))/.."
"-I$$(dirname $(location src/include/a.h))/.."
"-I`dirname $(location src/include/a.h)`/.."

But it seems like bazel does not allow bash commands to be executed at this location

So my question is, what is the best way to handle this problem？

If there is no good solution for the time being, is it recommended to use the includes field directly? How will this be handled in the future, adding a local_includes parameter? Or add new make variables?

[meteorcloudy]

See #15553 (comment), you can use this workaround to get the canonical repo name.

[fmeum]

With the long-term solution probably being #16472, not a Bzlmod-specific feature.

[fausturs]

I also think "local_includes" is a good idea