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https://issues.apache.org/jira/browse/GROOVY-12662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18137396#comment-18137396
]
ASF GitHub Bot commented on GROOVY-12662:
-----------------------------------------
codeconsole opened a new pull request, #3183:
URL: https://github.com/apache/groovy/pull/3183
An implicit-this call in a closure to a method that `Closure` declares was
resolved against every overload of that name, without looking at the arguments:
```groovy
@groovy.transform.TypeChecked
def test() {
Closure<Object> c = { String a, String b -> b == null ? curry(a) : a + b
}
((Closure) c('x', null))('y')
}
```
This fails with "Reference to method is ambiguous. Cannot choose between
Closure#curry(Object[]) and Closure#curry(Object)"; dynamic Groovy returns
`xy`. `rcurry`, `ncurry`, `trampoline()`, `andThenSelf()`, `composeSelf()` and
`leftShift(Closure)` failed the same way, in 4.0.33, 5.0.8 and 6.0.0 too. A
call whose arguments fit no `Closure` overload, such as `memoize('x')` or
`getDelegate(1)` where the owner declares those methods, was bound to the
closure's method (5.0.8 and later): under `@CompileStatic` the closure's method
was called, and under `@TypeChecked` the call failed with a
`GroovyCastException`.
The closure's methods are now chosen with `chooseBestMethod` and the
argument types (the GROOVY-11386 block of
`StaticTypeCheckingVisitor.visitMethodCallExpression`). When none matches, the
call goes through the normal delegate/owner lookup, as
`ClosureMetaClass.invokeMethod` does at run time. Under `DELEGATE_ONLY`,
`ClosureMetaClass` sends `curry`, `ncurry`, `rcurry`, `leftShift` and
`rightShift` to the delegate, and the type checker now does the same
(`CLOSURE_DELEGATE_ONLY_METHODS`); without that, the overload fix would have
bound those calls to the closure.
## Tests
`ClosuresSTCTest.testClosureOverloadedMethods`,
`testClosureMethodWithoutMatchingArguments` and
`testClosureDelegateOnlyCurryAndShiftMethods` fail without the change, in both
`ClosuresSTCTest` and `ClosuresStaticCompileTest`. `groovy.transform.stc.*`,
`org.codehaus.groovy.classgen.asm.sc.*`, `gls.closures.*` and
`groovy.ClosureTest` pass. The Checkstyle and CodeNarc gates pass.
> STC rejects an implicit-this call in a closure to an overloaded Closure
> method, such as curry(x), as ambiguous, and ignores argument types when
> choosing the Closure method
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12662
> URL: https://issues.apache.org/jira/browse/GROOVY-12662
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 4.0.33, 5.0.8, 7.0.0-alpha-1, 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {code:groovy}
> @groovy.transform.TypeChecked // or @CompileStatic
> def test() {
> Closure<Object> c = { String a, String b -> b == null ? curry(a) : a + b }
> ((Closure) c('x', null))('y')
> }
> assert test() == 'xy'
> {code}
> *Actual:*
> {noformat}
> [Static type checking] - Reference to method is ambiguous. Cannot choose
> between [groovy.lang.Closure<V>
> groovy.lang.Closure#curry(java.lang.Object[]), groovy.lang.Closure<V>
> groovy.lang.Closure#curry(java.lang.Object)]
> {noformat}
> *Expected:* 'xy', as in dynamic Groovy, which calls curry(Object) on the
> enclosing closure. rcurry, ncurry, trampoline(), andThenSelf(), composeSelf()
> and leftShift(Closure) fail the same way.
> The selection ignores argument types altogether. If the owner declares
> memoize(String) or getDelegate(int), then memoize('x') or getDelegate(1)
> inside a closure is bound to Closure.memoize() or Closure.getDelegate().
> Under @CompileStatic the closure's method is called. Under @TypeChecked the
> inferred type is wrong, and the call fails with a GroovyCastException.
> Dynamic Groovy calls the owner's method. Under DELEGATE_ONLY,
> ClosureMetaClass sends curry, ncurry, rcurry, leftShift and rightShift to the
> delegate, but the type checker binds them to the closure.
> Cause: for an implicit-this call in a closure, StaticTypeCheckingVisitor
> takes every Closure method of that name (GROOVY-11386) without choosing among
> them by argument type, and never falls back to the delegate or owner when
> none of them accepts the arguments.
> Verified: 4.0.33 (ambiguity only), 5.0.8, 6.0.0 and master.
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