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https://issues.apache.org/jira/browse/GROOVY-12756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18143321#comment-18143321
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ASF GitHub Bot commented on GROOVY-12756:
-----------------------------------------
codeconsole commented on PR #3289:
URL: https://github.com/apache/groovy/pull/3289#issuecomment-6812919027
Thanks. 2ceac52315 applies the same rule to a field initializer and to
`this.f` / `other.f`: when the target is a parameterized `Class` and the value
is not a `Class`, the target type is used. A `Class` value still goes through
the generic check, so `Class<?>` to `Class<? extends CharSequence>` is still
rejected in all three places, and the test now covers that.
I also replaced the `Object o = Integer` lines with an `Object` parameter,
because, as you pointed out, the flow typing made the local a `Class<Integer>`.
Without the change the test fails on the `String` and `Type` lines and on the
three new writes. `STCAssignmentTest`, `AssignmentsStaticCompileTest`,
`groovy.transform.stc.*`, `org.codehaus.groovy.classgen.asm.sc.*` and
`groovy.bugs.*` pass.
> 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}}.
> Pull request: https://github.com/apache/groovy/pull/3289
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