Targets to match one tag out of multiple

[mlabbe]

Is your feature request related to a problem? Please describe

I have a project with tag 'a' and a second project with tag 'b'. Is it possible to create a target with tags where if either 'a' OR 'b' is matched, then the task runs?

projects:
  proj_a:
    tags: [a]

  proj_b:
    tags: [b]

targets:
  a_or_b:
    tags: [a, b]

tasks:
  some_task:
    target:
      tags: [a, b]  

In this situation, mani run some_task says "no targets". This is because the projects only have one of the two tags.

Describe the solution you'd like

Possible solution would be to list multiple targets on a task, and if one is a match, then the task is ran.

Additional context

Thanks for your time and consideration!

[alajmo]

This should now be possible with 0.30.0 release:

Tag expressions allow filtering projects using boolean operations on their tags. The expression is evaluated for each project's tags to determine if the project should be included.

Operators (in precedence order):

(): Parentheses for grouping
!: NOT operator (logical negation)
&&: AND operator (logical conjunction)
||: OR operator (logical disjunction)
For example, the expression:

(main && (dev || prod)) && !test
requires the projects to pass these conditions:

Must have "main" tag
Must have either "dev" OR "prod" tag
Must NOT have "test" tag

So either specify it using --tags-expr 'a || b' or specify it via a target.