[GROOVY-11363] Bootstrap method error for method reference used with a primitive literal

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.21, 5.0.0-alpha-8, 4.0.21
• Fix Version/s: 3.0.22, 5.0.0-alpha-9, 4.0.22
• Assignee: Eric Milles
• Reporter: Paul King
• Created: 23/Apr/24 02:07
• Updated: 24/Apr/24 16:36
• Resolved: 24/Apr/24 15:09

Description

This code:

import groovy.transform.CompileStatic
import java.util.function.Supplier

@CompileStatic
Supplier<String> method() {
    5::toString
}

method().get()

Fails with this error:

java.lang.BootstrapMethodError: bootstrap method initialization exception
	at java.base/java.lang.invoke.BootstrapMethodInvoker.invoke(BootstrapMethodInvoker.java:188)
	at java.base/java.lang.invoke.CallSite.makeSite(CallSite.java:315)
	at java.base/java.lang.invoke.MethodHandleNatives.linkCallSiteImpl(MethodHandleNatives.java:281)
	at java.base/java.lang.invoke.MethodHandleNatives.linkCallSite(MethodHandleNatives.java:271)
	at ConsoleScript9.method(ConsoleScript9:6)
        ...
Caused by: java.lang.invoke.LambdaConversionException: Type mismatch in captured lambda parameter 0: expecting int, found class java.lang.Object

It seems like 3.0.x versions are unaffected and 4.0.13 was the first version exhibiting this behavior.

My initial expectation is that the wrapper type/boxed version should be used.

See also:
https://stackoverflow.com/questions/78369048/groovy3-how-to-get-java-lambdas-instead-of-closures