Static type checking fails in Greclipse within closure (closure declared argument types ignored)

[mauromol]

Using Greclipse 4.4.0.v202112282355-e2009.

Consider this Java utility class:

package test70;
import java.util.List;
import java.util.function.BiConsumer;

public class Util {
	public static <T> BiConsumer<String, ? super List<T>> batchFromIndividualPostProcessor(
			final BiConsumer<String, ? super T> postProcessor) {
		return (text, batch) -> {
			for (final T element : batch)
				postProcessor.accept(text, element);
		};
	}
}

and this Groovy class:

package test70
import groovy.transform.CompileStatic

@CompileStatic
class Test70 {
	void foo() {
		Util.batchFromIndividualPostProcessor { String text, Number number ->
			number.toBigDecimal()
		}
	}
}

A compilation error is produced on number.toBigDecimal() because number is detected as Object rather than Number.

Please note that:

• this was compiling fine with some versions of Greclipse ago (cannot say exactly which one now)
• this compiles fine with Gradle/groovyc
• switching to @CompileDynamic makes things work

I have other more complex use cases in my real-world project which I think are related to this same problem. It seems like Greclipse is simply ignoring now the type I'm declaring for closure arguments.

[eric-milles]

I have one fix that will allow you to put in the type arguments explicitly, like:

		Util.<Number>batchFromIndividualPostProcessor { string, number ->
			number.toBigDecimal()
		}

I am still sorting out the parameter type recognition. STC wants to compare the declared types to the inferred types at some point so it can create errors for incompatible types.

[eric-milles]

This will be an issue in Groovy 4, so I have created a ticket to track: https://issues.apache.org/jira/browse/GROOVY-10436