Wouter Peers created GROOVY-11558:
-------------------------------------
Summary: Method reference treated as closure in method dispatch
Key: GROOVY-11558
URL: https://issues.apache.org/jira/browse/GROOVY-11558
Project: Groovy
Issue Type: Bug
Components: Compiler, Static Type Checker
Affects Versions: 4.0.24
Reporter: Wouter Peers
When passing a method reference to an overloaded method of which one of the
signatures accepts a functional interface. Groovy seems to treat the method ref
as a closure and dispatches to the wrong method signature.
Example:
{code:groovy}
@FunctionalInterface
interface PresenceAware {
boolean isPresent()
}
class Presence {
static boolean isPresent(Object o){
o != null
}
static boolean isPresent(PresenceAware p){
p.isPresent()
}
}
class StringWrapper implements PresenceAware{
private final String s
StringWrapper(String s) {
this.s = s
}
@Override
boolean isPresent() {
return s!= null && !s.empty
}
}
assert !Presence.isPresent(null)
assert Presence.isPresent('')
assert !Presence.isPresent(new StringWrapper(''))
assert Presence.isPresent(Integer.&compare)
// => MissingMethodException (in Groovy v4.0.24)
assert Presence.isPresent(Integer.&valueOf)
// => MethodSelectionException (in Groovy v4.0.24)
{code}
This code runs fine in Groovy v2.4.7—as I would expect, the method references
passed in the last two statements are treated as an Object when dispatching to
Presence::valueOf mehtod.
In Groovy v4.0.24 however the method references seem to be (wrongfully) treated
as closures and are dispatched to Presence::isPresent(PresenceAware) signature.
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