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https://issues.apache.org/jira/browse/GROOVY-7848?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eric Milles reassigned GROOVY-7848:
-----------------------------------
Assignee: Eric Milles
> Closure generic parameters ignored and return types missing from collections
> methods
> ------------------------------------------------------------------------------------
>
> Key: GROOVY-7848
> URL: https://issues.apache.org/jira/browse/GROOVY-7848
> Project: Groovy
> Issue Type: Bug
> Reporter: Dario Bertini
> Assignee: Eric Milles
> Priority: Major
>
> The theme of this ticket is type failures even specifying the correct input
> parameter type in a Closure, specifically these 2 methods fail to compile
> with CompileStatic/TypeChecked:
> {code}
> @CompileStatic
> static List foo(){
> [[1,2], [3,4]].collect{List<Integer> pair -> pair[0]+pair[1]}
> }
> @CompileStatic
> static bar(){
> [[1, 3], [1, 2]].transpose().inject(true){acc, List pair -> acc &&
> pair[0] == pair[1]}
> }
> {code}
> The first is due to the generic parameter Integer apparently being ignored.
> bq. Error:(15, 48) Groovyc: [Static type checking] - Cannot find matching
> method java.lang.Object#plus(java.lang.Object). Please check if the declared
> type is right and if the method exists.
> Ignoring it is just fine when compiling in Dynamic mode, but makes it
> apparently impossible to write a similar Type Safe method
> Apparently, this part of the language is as yet undocumented:
> http://docs.groovy-lang.org/latest/html/documentation/index.html#generics
> The second method instead, has a similar failure to locate Object#getAt(int),
> but the actual error is this one:
> bq. Error:(20, 50) Groovyc: Expected parameter of type java.lang.Object but
> got java.util.List
> Which is imho a bit unhelpful: I'm obviously passing it a List, at runtime...
> and the the Closure parameter type is List, given that I would expect the
> error to be the other way around: expected parameter of type List, but got
> Object
> But the problem is not actually with Closure types, inference or the like...
> I suspect it might simply be an imprecise type specified for transpose()
> result: it should be List<List>, but is instead List (once I understood this
> I simply created an intermedia variable with the explicit type as a
> workaround)
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