Scott Murphy Heiberg created GROOVY-12755:
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Summary: STC: e.getClass() is typed Class<?>, so since
GROOVY-12714 it is rejected where a Class<? extends T> is expected
Key: GROOVY-12755
URL: https://issues.apache.org/jira/browse/GROOVY-12755
Project: Groovy
Issue Type: Bug
Components: Static Type Checker
Affects Versions: 6.0.1, 7.0.0-alpha-1
Reporter: Scott Murphy Heiberg
JLS 4.3.2 gives a call {{e.getClass()}} the type {{Class<? extends |T|>}},
where {{|T|}} is the erasure of the static type of {{e}}. Static type checking
types it with the declared return type of {{Object#getClass()}}, {{Class<?>}}.
Until GROOVY-12714 the wildcard check accepted {{Class<?>}} where a {{Class<?
extends T>}} was expected. Since GROOVY-12714 (GROOVY_6_0_X and master) it is
rejected:
{code:groovy}
@groovy.transform.CompileStatic
class C {
interface Store {}
static <T> T with(Class<? extends Store> type, Closure<T> body) {
body.call() }
static class Adapter { Adapter(Class<? extends Store> type) {} }
static Object viaMethod(Store store) { with(store.getClass()) { 1 } }
static Object viaProperty(Store store) { with(store.class) { 1 } }
static Object viaConstructor(Store store) { new Adapter(store.getClass()) }
static Class<? extends Store> viaReturn(Store store) { store.getClass() }
}
{code}
{noformat}
[Static type checking] - Cannot call <T> C#with(java.lang.Class<? extends
C.Store>, groovy.lang.Closure<T>) with arguments [java.lang.Class<?>,
groovy.lang.Closure]
[Static type checking] - Cannot call <T> C#with(java.lang.Class<? extends
C.Store>, groovy.lang.Closure<T>) with arguments [java.lang.Class<?>,
groovy.lang.Closure]
[Static type checking] - Cannot call C$Adapter#<init>(java.lang.Class<? extends
C.Store>) with arguments [java.lang.Class<?>]
[Static type checking] - Incompatible generic argument types. Cannot assign
java.lang.Class<?> to: java.lang.Class<? extends C.Store>
{noformat}
javac accepts the equivalent Java. Grails no longer compiles against
GROOVY_6_0_X: it passes {{datastore.getClass()}} to a {{Class<? extends
Datastore>}} parameter and {{registrar.getClass()}} to a {{Class<? extends
BeanRegistrar>}} one
(https://github.com/apache/grails-core/actions/runs/42702095261).
Typing {{e.getClass()}} and {{e.class}} as {{Class<? extends |T|>}} makes more
calls pass an upper-bounded wildcard for a bounded type parameter, such as
{{foo(list.class)}} for {{<T extends List<Integer>> foo(Class<T>)}}, which
GROOVY-12754 rejected. So this depends on GROOVY-12754.
The inferred type of {{list.class}} for a raw {{List list}} changes from
{{Class<? extends Object>}} to {{Class<? extends List>}}, and the GROOVY-5415
error for {{a.bar(this.getClass())}} now names {{Class<? extends ClassB>}}; the
two tests that assert those types are updated.
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