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From "Eric Milles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GROOVY-9064) STC: explicit declared variable type ignored in favor of assigned value type(s)
Date Mon, 08 Apr 2019 14:41:00 GMT

    [ https://issues.apache.org/jira/browse/GROOVY-9064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16812477#comment-16812477
] 

Eric Milles commented on GROOVY-9064:
-------------------------------------

Flow typing combined with generics has been a major source of confusion and compiler errors
for our teams.  {{List}} vs {{LinkedList}} is not a problem; {{List<Object>>}} vs.
{{List<Serializable<?>>}} or some other weird LUB or union type is problematic.

> STC: explicit declared variable type ignored in favor of assigned value type(s)
> -------------------------------------------------------------------------------
>
>                 Key: GROOVY-9064
>                 URL: https://issues.apache.org/jira/browse/GROOVY-9064
>             Project: Groovy
>          Issue Type: Improvement
>            Reporter: Eric Milles
>            Priority: Major
>
> Follow up to GROOVY-9058.  Consider the following:
> {code:groovy}
> List getSomeRows() { ... }
> @groovy.transform.CompileStatic
> void meth() {
>   List<Object[]> rows = getSomeRows()
>   rows.each { row ->
>     def col = row[0]
>   }
> }
> {code}
> The inferred type of {{rows}} is {{List}} and not {{List<Object[]>}} even though
the assignment cleared type checking.  This causes the inferred type of {{row}} to be {{Object}}
instead of {{Object[]}}.
> Similarly, {{List<String> list = []}} infers as {{ArrayList<String>}} instead
of the explicit declared type, and {{Map<String, ?> map = [:]}} infers to {{LinkedHasMap<...>}}
instead of the declared type.  In general, I think as long as the assignment is compatible,
the variable should retain its explicitly declared type regardless of assignments.



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