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https://issues.apache.org/jira/browse/GROOVY-12756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18142148#comment-18142148
]
ASF GitHub Bot commented on GROOVY-12756:
-----------------------------------------
codeconsole opened a new pull request, #3289:
URL: https://github.com/apache/groovy/pull/3289
https://issues.apache.org/jira/browse/GROOVY-12756
Anything can be assigned to a `Class`, `String` or `Boolean` variable: the
value is converted at run time, so `Class c = 'java.lang.String'` loads the
class. Since GROOVY-12714, static type checking rejects that when the
variable's type has a type argument, even `Class<?>`, while the same assignment
to a raw `Class` still compiles:
```groovy
Class raw = type // compiles
Class<?> any = type // a java.lang.reflect.Type: error
Class<String> string = 'java.lang.String' // error
Class<? extends Number> number = object // an Object: error
```
```
[Static type checking] - Incompatible generic argument types. Cannot assign
java.lang.reflect.Type to: java.lang.Class<?>
```
Grails no longer compiles against GROOVY_6_0_X because of this:
`AbstractStructuredBindingEditor` assigns `actualTypeArguments[0]`, a `Type`,
to its `Class<T> targetType`.
For such a variable `getResultType` returned the variable's type.
GROOVY-12714 made it keep the type of the value when the variable is a
parameterized `Class`, so that `Class<?>` is not accepted for `Class<? extends
CharSequence>`. When the value is not a `Class` there are no type arguments to
compare, and `checkTypeGenerics` reported the value's type as an incompatible
generic argument. The type of the value is now kept only when it is a `Class`,
so a `Class` value is still checked against the type arguments.
`STCAssignmentTest`, and so `AssignmentsStaticCompileTest`, gets the three
forms and the `Class<?>` to `Class<? extends CharSequence>` case that must stay
an error. The test fails without the change.
Please also apply this to GROOVY_6_0_X, where the change applies cleanly.
> STC: since GROOVY-12714 a value that is not a Class cannot be assigned to a
> parameterized Class variable
> --------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12756
> URL: https://issues.apache.org/jira/browse/GROOVY-12756
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Affects Versions: 7.0.0-alpha-1, 6.0.1
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> Anything can be assigned to a variable of type {{Class}}, {{String}} or
> {{Boolean}}: the value is converted at run time, so {{Class c =
> 'java.lang.String'}} loads the class. That still compiles for a raw
> {{Class}}. Since GROOVY-12714 (GROOVY_6_0_X and master) static type checking
> rejects it when the variable's type has a type argument, even {{Class<?>}}:
> {code:groovy}
> import java.lang.reflect.ParameterizedType
> import java.lang.reflect.Type
> @groovy.transform.CompileStatic
> abstract class Editor<T> {
> final Class<T> targetType
> Editor() {
> Type[] types = ((ParameterizedType)
> getClass().genericSuperclass).actualTypeArguments
> targetType = types[0]
> }
> }
> @groovy.transform.CompileStatic
> void test(Type type, Object object) {
> Class raw = type // compiles
> Class<?> any = type // error
> Class<String> string = 'java.lang.String' // error
> Class<? extends Number> number = object // error
> }
> {code}
> {noformat}
> [Static type checking] - Incompatible generic argument types. Cannot assign
> java.lang.reflect.Type to: java.lang.Class<T>
> [Static type checking] - Incompatible generic argument types. Cannot assign
> java.lang.reflect.Type to: java.lang.Class<?>
> [Static type checking] - Incompatible generic argument types. Cannot assign
> java.lang.String to: java.lang.Class<java.lang.String>
> [Static type checking] - Incompatible generic argument types. Cannot assign
> java.lang.Object to: java.lang.Class<? extends java.lang.Number>
> {noformat}
> All of these compiled on GROOVY_6_0_X before GROOVY-12714 (a5d10dd198). The
> first is {{AbstractStructuredBindingEditor}} in Grails, which no longer
> compiles against GROOVY_6_0_X.
> For an assignment to a {{Class}}, {{String}} or {{Boolean}} variable,
> {{getResultType}} returned the variable's type. GROOVY-12714 made it keep the
> type of the value when the variable is a parameterized {{Class}}, so that
> {{Class<?>}} is no longer accepted for {{Class<? extends CharSequence>}}.
> That is right when the value is a {{Class}}. When it is not, there are no
> type arguments to compare, and {{checkTypeGenerics}} reports the value's type
> as an incompatible generic argument.
> The value's type should be kept only when it is a {{Class}}.
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