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https://issues.apache.org/jira/browse/GROOVY-12535?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18135745#comment-18135745
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Paul King commented on GROOVY-12535:
------------------------------------
I was probably a little unclear when I wrote the Jira description. My goal was
to have more cases work safely rather than just have more errors where safety
was a concern. I'll do another PR which would replace the existing one if it
looks like the behavior we want.
> STC: property-style assignment to a Map<String,String> accepts a GString
> value and stores it unconverted
> --------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12535
> URL: https://issues.apache.org/jira/browse/GROOVY-12535
> Project: Groovy
> Issue Type: Bug
> Reporter: Paul King
> Assignee: Daniel Sun
> Priority: Major
> Fix For: 7.0.0-alpha-1, 6.0.1
>
>
> Under static type checking, a {{GString}} can't be put into a
> {{Map<String,String>}} through {{put}} or the subscript operator; both are
> rejected. Assigning through property notation is accepted, though, and the
> {{GString}} is stored as is:
> {code:groovy}
> @groovy.transform.CompileStatic
> def go() {
> def n = 'ab'
> Map<String,String> m = [:]
> m.k = "$n"
> ((Map) m).values()*.getClass()*.simpleName
> }
> assert go() == ['GStringImpl'] // expected ['String']
> {code}
> ||Form||Result (4.0.29, 6.0.0, master)||
> |{{m.k = "$n"}}|compiles, stores a {{GStringImpl}}|
> |m.with { k = "$n" }|compiles, stores a {{GStringImpl}}|
> |{{m['k'] = "$n"}}|STC error: Cannot call ... putAt ...|
> |{{m.put('k', "$n")}}|STC error: Cannot call ... put(String, String) ...|
> Statically compiled code can't otherwise add a {{GString}} to a collection
> typed for Strings ({{<<}}, {{add}}, {{set}}, {{addAll}}, {{+=}}, {{putAt}}
> and {{put}} are all rejected), so this is the one hole on the write side.
> Later reads that expect a {{String}} can then fail. For example, Java code
> doing {{String s = m.get('k')}} throws {{ClassCastException}}, and
> {{m.get('k').equals('ab')}} is false.
> Expected: either convert the value to a {{String}} at the assignment, as
> Groovy does for {{String s = "$n"}}, or report the same error as {{put}} and
> {{putAt}}. Converting matches the general rule that a {{GString}} becomes a
> {{String}} where one is required, and wouldn't break existing code that
> compiles today.
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