[GROOVY-10648] Compile error during static compilation (missing type derivation?)

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5.17, 3.0.11
• Fix Version/s: 3.0.12, 2.5.22
• Component/s: Compiler
• Environment: Gradle, Windows
• Assignee: Eric Milles
• Reporter: Chris Briem
• Created: 03/Jun/22 21:05
• Updated: 11/Mar/23 19:58
• Resolved: 04/Jun/22 15:07

Description

Hi all!

The following code doesn't compile on my machine with Groovy 3.0.11. But it does compile with 3.0.10 and 4.0.2:

@CompileStatic
class TestClass2 {
    def <T extends Number> Set<T> fill(Iterable<T> a_consumable) {
        Set<T> result = new HashSet<>()
        a_consumable.forEach { result.add(it) }
        return result
    }
}

The compilation fails with the following output:

9: [Static type checking] - Cannot call java.util.HashSet <T>#add(T) with arguments [java.lang.Object]

Expected behavior:
AFAICT, this code should compile, as the type of it can be derived.

Additional remarks:
Interestingly, the code compiles if I replace {{ <T extends Number> }} with just {{ <T> }}. An explicit cast also helps. So workaround is easy.

If you need more info, feel free to ask!

Issue Links

• is related to: GROOVY-10049 STC fails when calling a generic method from another generic method
• is related to: GROOVY-10436 STC: closure parameter type-checking: declared vs inferred