Scott Murphy Heiberg created GROOVY-12599:
---------------------------------------------
Summary: STC accepts a Closure<R> value passed to or returned as a
functional interface whose method does not return R
Key: GROOVY-12599
URL: https://issues.apache.org/jira/browse/GROOVY-12599
Project: Groovy
Issue Type: Bug
Affects Versions: 5.0.8, 4.0.33, 6.0.0
Reporter: Scott Murphy Heiberg
{code:groovy}
import java.util.function.Supplier
@groovy.transform.CompileStatic // or @TypeChecked
class C {
static String take(Supplier<String> s) { s.get().toLowerCase() }
static Supplier<String> make() { Closure<Integer> c = { 1 }; c }
static void main(args) {
Closure<Integer> c = { 1 }
take(c)
make().get().toLowerCase()
}
}
{code}
Actual: the code compiles. Under static compilation both calls throw
{noformat}
java.lang.ClassCastException: class java.lang.Integer cannot be cast to class
java.lang.String
{noformat}
(MissingMethodException under @TypeChecked). The same happens for an instance
of a non-generic subclass such as {{class D extends Closure<Integer>}} passed
as the argument.
Expected: compile errors, as for a closure literal ("Cannot return value of
type int for closure expecting java.lang.String"):
{noformat}
Cannot call C#take(java.util.function.Supplier<java.lang.String>) with
arguments [groovy.lang.Closure<java.lang.Integer>]
Cannot return value of type groovy.lang.Closure<java.lang.Integer> for method
returning java.util.function.Supplier<java.lang.String>
{noformat}
For a method argument,
StaticTypeCheckingSupport.typeCheckMethodArgumentWithGenerics accepts any
Closure for a SAM-type parameter and assumes the return type was checked
earlier. That is only true for a closure literal. For a return statement,
generics are compared only when the value's type implements the return type,
which Closure does not for most SAM types.
Seen in 4.0.33, 5.0.8 and 6.0.0.
--
This message was sent by Atlassian Jira
(v10.3.26#10030026)
