Unused import doesn't handle export

[johnniwinther]

The unused import warning doesn't handle exports. For instance if a declaration is imported both from its declaring library and a reexporting library, neither import is flags a unused even when one of them could be removed.

I've created a CL that show some of the cases.

[scheglov]

I think this might be intentional.
If we don't know for sure what to refer, we choose to not have a preference.

sdk/pkg/analyzer/lib/src/error/imports_verifier.dart

Lines 199 to 212 in 846c5bb

	var firstSet = tracker.elementsOf2(firstElement);
	var secondSet = tracker.elementsOf2(secondElement);
	// The second must provide all elements of the first.
	if (!secondSet.containsAll(firstSet)) {
	continue;
	}
	// The second must provide strictly more than the first.
	if (!(secondSet.length > firstSet.length)) {
	continue;
	}
	var firstElementUri = firstElement.uri;

[bwilkerson]

@srawlins Who implemented a lot of this support, in case he remembers anything useful.

[srawlins]

I believe you're looking for "redundant imports." See #44569. I specced this out a lifetime ago, go/dart-redundant-imports.