Mistaken type checking error

[carlocab]

I'm getting the following error which I believe to be mistaken:

object, array, and null values should not be evaluated in template with ${{ }} but evaluating the value of type array<any> [expression]

Here's a minimal reproducer.

The value of matrix.PR is, of course, an array. actionlint doesn't seem to recognise here that I will have a different job dispatched for each entry in the matrix.PR array, and each job will only see one value for matrix.PR.

[rhysd]

The error looks correct. The PR matrix value is an array because it is generated by filter syntax (github.event.workflow_run.pull_requests.*.number). An array value can not be embedded with ${{ }} syntax directly. I think probably what you want to do is:

- run: echo '${{ toJSON(matrix.PR) }}'

[carlocab]

But matrix.PR is a scalar when evaluated inside the run: statement because of the way GitHub Actions handles matrix, so doing

- run: echo '${{ matrix.PR }}'

is not an error.

[rhysd]

But matrix.PR is a scalar when evaluated inside the run: statement

That's because the result of the filter syntax happened to be an array with a single element, am I correct? If the result contained two elements, the result would've been different.

[carlocab]

That's because the result of the filter syntax happened to be an array with a single element, am I correct?

No, that is not correct.

If the result contained two elements, the result would've been different.

github.event.workflow_run.pull_requests.*.number can contain any number of elements. Regardless of the number of elements this array contains, in the context of run:, matrix.PR is always a scalar (conditional on the run: statement being reached).

Please see: https://docs.github.com/en/actions/using-jobs/using-a-matrix-for-your-jobs

[rhysd]

Oh, OK, I misread your workflow. Yes, since it is a row of matrix, the value should be scalar. Thanks for your explanation.

[carlocab]

Thanks, @rhysd!

[rhysd]

@carlocab This was a bug of actionlint. Thank you for your report with the nice reproduction.