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https://issues.apache.org/jira/browse/GROOVY-8342?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16645251#comment-16645251
]
Eric Milles commented on GROOVY-8342:
-------------------------------------
{{StaticTypeCheckingVisitor}} seems to have a handle on the generics. When
visiting method {{testListMethod}}, it does manage to understand the link
between {{E}} and {{Integer}}.
{code:java}
protected ClassNode inferReturnTypeGenerics(
ClassNode receiver,
MethodNode method,
Expression arguments,
GenericsType[] explicitTypeHints) {
...
// resolvedPlaceholders: {E=java.lang.Integer}
// returnType: java.util.Optional <[LE;> -> java.util.Optional <T
extends java.lang.Object>
return applyGenericsContext(resolvedPlaceholders, returnType);
}
{code}
> Static compilation error with a method returning an array in a type parameter
> -----------------------------------------------------------------------------
>
> Key: GROOVY-8342
> URL: https://issues.apache.org/jira/browse/GROOVY-8342
> Project: Groovy
> Issue Type: Bug
> Components: Static compilation
> Reporter: M. Justin
> Priority: Major
>
> A compilation error occurs when using static compilation and attempting to
> assign the result of a method that returns a parameterized argument that
> contains an array in the type parameter. The equivalent Java code has no
> issues.
> Here is a specific example:
> {code}@CompileStatic
> class ArrayGenericsIssue {
> static void main(String[] args) {
> Optional<Integer[]> value = testArrayMethod(1) //This fails to compile
> }
> static <E> Optional<E[]> testArrayMethod(E ignored) {
> return Optional.empty()
> }
> }{code}
> The error returned is:
> {code}Error:(11, 33) Groovyc: [Static type checking] - Incompatible generic
> argument types. Cannot assign java.util.Optional <E[]> to: java.util.Optional
> <Integer[]>{code}
> The expected behavior is that this code would compile and run successfully
> with @CompileStatic enabled.
> Note that equivalent code with a non-array generic parameter works just fine:
> {code}
> static void main(String[] args) {
> Optional<List<Integer>> value = testListMethod(1)
> }
> static <E> Optional<List<E>> testListMethod(E ignored) {
> return Optional.empty()
> }
> {code}
> Additionally, there is no compilation issue if the value is cast:
> {code}Optional<Integer[]> value = (Optional<Integer[]>)
> testArrayMethod(1){code}
> For some context, I'm running into this issue when working with
> [jOOQ|https://www.jooq.org/], as some of its API involves working with array
> type parameters.
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