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https://issues.apache.org/jira/browse/GROOVY-10049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17415661#comment-17415661
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Eric Milles commented on GROOVY-10049:
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Is the regression the parser error? If you replace {{println "$num"}} with
{{println("$num")}} is the STC error still present?
> STC fails when calling a generic method from another generic method
> -------------------------------------------------------------------
>
> Key: GROOVY-10049
> URL: https://issues.apache.org/jira/browse/GROOVY-10049
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Affects Versions: 3.0.8, 4.0.0-alpha-3, 4.0.0-beta-1
> Environment: OpenJDK 8
> Reporter: Lyuben Atanasov
> Assignee: Eric Milles
> Priority: Major
> Fix For: 4.0.0-beta-1
>
> Attachments: screenshot-1.png, screenshot-2.png
>
>
> The static type checker fails to properly determine the return type of a
> generic method when that method is called from another generic method. Here's
> an example:
> {code}
> class Test {
> <T extends Number> Set<T> generateNumbers(Class<T> numberType) {
> // mock return value, needed to demonstrate the issue
> return Collections.emptySet();
> }
> <T extends Number> void printNumbers(Class<T> numberType) {
> generateNumbers(numberType).stream()
> .filter(num -> num.doubleValue() > 0)
> .forEach(num -> println "$num");
> }
>
> }
> {code}
> With static type checking enabled, compilation of this class fails:
> {noformat}
> Script_bbf0c00c9b2872d2a3528c2d80bbaa49.groovy: 10: [Static type checking] -
> Cannot find matching method java.lang.Object#doubleValue(). Please check if
> the declared type is correct and if the method exists.
> @ line 10, column 19.
> .filter(num -> num.doubleValue() > 0)
> {noformat}
> If we call the {{generateNumbers()}} method with a specific class, everything
> works:
> {code}
> class Test {
> <T extends Number> Set<T> generateNumbers(Class<T> numberType) {
> return Collections.emptySet();
> }
> void printNumbers() {
> generateNumbers(Integer).stream()
> .filter(num -> num.doubleValue() > 0)
> .forEach(num -> println "$num");
> }
>
> }
> {code}
> It looks like the static type checker does not properly take into account the
> generic types of the surrounding method and thus fails to determine the type
> of the returned value.
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