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https://issues.apache.org/jira/browse/GROOVY-12660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18137369#comment-18137369
]
ASF GitHub Bot commented on GROOVY-12660:
-----------------------------------------
codeconsole opened a new pull request, #3181:
URL: https://github.com/apache/groovy/pull/3181
Under `@CompileStatic` with closure packing (`@PackedClosures` or
`-Dgroovy.target.closure.pack=true`), a closure body is hoisted into a method
of the owner class. A call that the type checker resolved against a closure
object then went to the owner:
```groovy
@groovy.transform.CompileStatic
class C {
String toString() { 'C' }
static Object self(@DelegatesTo(value=String, strategy=Closure.TO_SELF)
Closure c) { c.resolveStrategy = Closure.TO_SELF; c() }
Object a() { self { -> toString() } }
// packed: 'C'
Object b() { Closure<String> outer = { -> { -> toString() }() };
[outer(), outer.toString()] } // packed: MissingPropertyException: owner
Object c() { Closure c = { -> memoize() }; c() }
// packed: VerifyError
}
```
Without packing, and in dynamic Groovy, `a()` returns the closure's own
`toString()`, `b()` returns the outer closure's `toString()` twice, and `c()`
returns the memoized closure. Seen in 6.0.0 too.
`StaticTypesClosureWriter.callsClosureMethod` now makes the packing decision
decline when an implicit-this call in the body, nested closures included,
targets a method that `Closure` declares, has the receiver type `Closure` that
STC records under `TO_SELF`, or has the receiver path `"owner"` that STC
records for an enclosing closure. `WARN` and `STRICT` report the reason. Calls
resolved against the owner class still pack.
## Tests
`PackedClosuresTransformTest.closuresCallingObjectMethodsOnAClosureDecline`,
`closuresCallingClosureMethodsDecline` and
`strictModeReportsClosureReceiverDecline` fail without the change. With
`-Pgroovy.target.closure.pack=true`,
`ClosuresStaticCompileTest.testClosureObjectMethodResolveStrategy` now passes.
The packing test classes, `org.codehaus.groovy.classgen.asm.sc.*` and
`groovy.transform.stc.*` pass without the flag; with it, the only failures are
ones that also fail on master and have their own issues. The Checkstyle and
CodeNarc gates pass.
> SC closure packing calls methods resolved against a closure object on the
> owner class (TO_SELF, nested closures, Closure methods)
> ---------------------------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12660
> URL: https://issues.apache.org/jira/browse/GROOVY-12660
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 7.0.0-alpha-1, 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> With closure packing ({{@PackedClosures}} or
> {{-Dgroovy.target.closure.pack=true}}), a statically compiled closure body is
> hoisted into a method of the owner class. Calls that the type checker
> resolved against a closure object are then compiled as if they targeted the
> owner.
> {code:groovy}
> @groovy.transform.CompileStatic
> class C {
> String toString() { 'C' }
> static Object self(@DelegatesTo(value=String, strategy=Closure.TO_SELF)
> Closure c) { c.resolveStrategy = Closure.TO_SELF; c() }
> Object a() { self { -> toString() } }
> Object b() { Closure<String> outer = { -> { -> toString() }() };
> [outer(), outer.toString()] }
> Object c() { Closure c = { -> memoize() }; c() }
> }
> {code}
> *Actual*, with packing:
> * {{a()}} returns {{C}}.
> * {{b()}} throws {{MissingPropertyException: No such property: owner for
> class: C}} (on 6.0.0 it returns {{C}} for the inner call).
> * Loading {{C}} fails with {{VerifyError: Bad type on operand stack ... Type
> 'C' is not assignable to 'groovy/lang/Closure'}}.
> *Expected*, as without packing and in dynamic Groovy: {{a()}} returns the
> closure's own toString(), {{b()}} returns the outer closure's toString()
> twice, {{c()}} returns the memoized closure.
> Cause: the packing decision only checks for delegate-resolved names and for
> the named closure pseudo-properties. It does not decline a call resolved
> against the closure itself: an Object method under TO_SELF, an Object method
> in a nested closure (resolved against the enclosing closure since
> GROOVY-12576), or a method that Closure declares.
> Verified on 6.0.0 and master.
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