[jira] [Created] (GROOVY-10054) STC: Cannot infer lambda parameter types for a Stream Collector in a generic method

["Lyuben Atanasov (Jira)" <ji...@apache.org>]

Lyuben Atanasov created GROOVY-10054:
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             Summary: STC: Cannot infer lambda parameter types for a Stream Collector in a generic method
                 Key: GROOVY-10054
                 URL: https://issues.apache.org/jira/browse/GROOVY-10054
             Project: Groovy
          Issue Type: Bug
          Components: Static Type Checker
         Environment: OpenJDK8
            Reporter: Lyuben Atanasov


This is a follow-up for GROOVY-10049. After the issue there had been fixed I was able to progress further with a chain of Stream method calls. However, the fix doesn't seem to cover the following case:
{code}
import java.util.stream.Collectors;

class Test {

	static interface Named {
		String getName();
	}

	<T extends Named> Map<String, List<T>> group(Set<T> namedObjects) {
		return namedObjects.stream()
			.collect(Collectors.groupingBy(named -> named.getName()));
	}
	
}
{code}
With static type checking enabled, an error is produced:
{noformat}
Script_ce61a645759c941d687680111f9bedbd.groovy: 11: [Static type checking] - Cannot find matching method java.lang.Object#getName(). Please check if the declared type is correct and if the method exists.
 @ line 11, column 44.
   ollectors.groupingBy(named -> named.getN
{noformat}

The difference between this issue and GROOVY-10049 is that the lambda passed here is not directly assigned to a Stream method. Of course, the issue is probably not limited to Collectors, but this is how I am able to reproduce it.
I've tested this against https://github.com/apache/groovy/commit/e07f0112c5eff8d9c6828bd0ddb69e4b7f7cc1d6



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