Prevent "<no match>" reports by StronglyTypeTime

[Stephan202]

This fix prevents reports such as the following, which are hard to debug for users:

[INFO] /path/to/some/File.java: [<no match>] <no match>
    (see <no match>)

[cushon]

Thanks for the fix. I think this is a more general problem with the handling of NO_MATCH that affects other checks, and that we should handle it here:

error-prone/check_api/src/main/java/com/google/errorprone/VisitorState.java

Line 266 in 3006a97

public void reportMatch(Description description) {

instead of here:

error-prone/check_api/src/main/java/com/google/errorprone/scanner/Scanner.java

Line 124 in 3006a97

if (description == null || description == Description.NO_MATCH) {

Any concerns with that change? (I can make the edit when importing, I just want to check if you see any reasons not do that.) Thanks!

[Stephan202]

I think that's a good suggestion, and indeed I wondered about this. But then I noticed that several existing plugins follow the current pattern, so I assumed that there was a reason for not handling NO_MATCH at such a "deep" level.

But now that I think about it a bit more, the suggested change makes a lot of sense: NO_MATCH is owned by Description, so in a sense NO_MATCH is to Description what empty is to Optional. Since VisitorState explicitly handles Description it is thus reasonable that it also handles NO_MATCH .

For reference, if you make that change then the following callers can also be simplified:

error-prone/core/src/main/java/com/google/errorprone/bugpatterns/ExpectedExceptionChecker.java

Lines 112 to 115 in 704e8a1

	Description description = scanBlock(tree, block, state);
	if (description != NO_MATCH) {
	state.reportMatch(description);
	}

error-prone/core/src/main/java/com/google/errorprone/bugpatterns/threadsafety/GuardedByChecker.java

Lines 206 to 209 in 3c0c609

	if (description == null || description == NO_MATCH) {
	return;
	}
	state.reportMatch(description);

error-prone/core/src/main/java/com/google/errorprone/bugpatterns/MockitoCast.java

Lines 180 to 183 in a91042e

	Description description = matchMethodInvocation(node, state.withPath(getCurrentPath()));
	if (description != Description.NO_MATCH) {
	state.reportMatch(description);
	}