[SR-13655] "Inconsistently imported as implementation-only" diagnostic unclear

[beccadax]

Previous ID	SR-13655
Radar	rdar://problem/69979002
Original Reporter	@beccadax
Type	Improvement

Additional Detail from JIRA

Votes	1
Component/s	Compiler
Labels	Improvement, DiagnosticsQoI, TypeChecker
Assignee	None
Priority	Medium

md5: ad3dc1f93ade7ed3d2867519b11c7d1e

Issue Description:

If some files have normal imports and others have implementation-only imports for the same module, we ignore the @_implementationOnly attribute and emit warnings about the inconsistency. However, the warnings are vague and sound like they could just be some sort of style complaint:

warning: 'SomeModule' inconsistently imported as implementation-only

These warnings should clearly indicate that we are ignoring the @_implementationOnly attribute on other import statements because of this import. Perhaps something like:

warning: other imports of 'SomeModule' will not be implementation-only because this import does not use '@_implementationOnly'

It may also make sense to customize the fix-its for this diagnostic in IDE mode—we could have one fix-it which adds @_implementationOnly wherever it's missing, and another that removes it wherever it's present.

[typesanitizer]

@swift-ci create

[bimawa]

Also, can we move up warning level to error? Because it is really critical moment for SPM Frameworks.

[ncooke3]

Hi @bimawa, in case it wasn't considered, you could try passing the -warnings-as-errors flag to surface this warning as an error. Granted, this would turn all warnings into errors, but it could still be helpful in your use case– in the event you didn't already consider this.