mod: ignore files with "ignore" tags

[rogpeppe]

Currently there is no way of excluding a file from consideration from
the dependency analysis run by cue mod tidy other than by placing
inside an excluded directory such as .foo.

It might be good for cue mod tidy to check file-level build tags and
exclude files with an "ignore" tag, mirroring Go's behavior in this
respect.

[myitcv]

I think you're referring to the @if attribute in cue help injection here. That is not a tag. Please can you sketch what a solution would look like?

[rogpeppe]

I think you're referring to the @if attribute in cue help injection here. That is not a tag. Please can you sketch what a solution would look like?

The @if attribute selects files based on the values of tags. To quote the @if help from cue help injection:

The expression is a subset of CUE consisting only of identifiers
and the operators &&, ||, !, where identifiers refer to tags
defined by the user on the command line.

The logic in cue mod tidy that evaluates all dependencies does not currently look at @if attributes
or tags at all. It should probably do so (and exclude files that have @if attributes that require the ignore tag).

[myitcv]

So the proposal here is that to ignore a file we use the @if build attribute with the ignore tag?

@if(ignore)

x: 5

[rogpeppe]

Yes. Actually, not quite, because I believe file-level attributes only apply when there's a package clause, so the correct phrasing would be:

@if(ignore)

package foo

x: 5

[rogpeppe]

One interesting question here is whether CUE files without a package directive should have their dependencies considered by cue mod tidy. Should they really be considered as "part" of the module in that sense?

[myitcv]

Should they really be considered as "part" of the module in that sense?

When evaluating such a file, is cue.mod/module.cue used to resolve the dependencies? I believe the answer is yes, and thus I think the answer to your question should also be yes.

[myitcv]

@rogpeppe - has the change to ignore @if(ignore) files been made already along with the recent changes to fix consideration of @if and _test.cue files in dependencies?

[rogpeppe]

@rogpeppe - has the change to ignore @if(ignore) files been made already along with the recent changes to fix consideration of @if and _test.cue files in dependencies?

No, it had not.

But after online discussion, we've gone with a separate @ignore() attribute for this functionality. See https://cuelang.org/cl/1198249