[
https://issues.apache.org/jira/browse/GROOVY-11508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17892872#comment-17892872
]
Eric Milles commented on GROOVY-11508:
--------------------------------------
"Also, since GROOVY-5106 breaks backwards compatibility with Groovy 3.x, it
would make sense for this to be a warning in Groovy 4 & a restriction in Groovy
5 instead."
Since this checking was introduced in 4.0.0, the error was the correct choice
IMO. There have been 23 point fixes since... So I have a different take on
the criticality.
I will have a look at "abstract static" methods and static members referencing
type vars in traits for Eclipse IDE integration. Not too sure how I can
represent these things to the Java model -- the parallel would be the stubs
that the Groovy compiler generates in joint compilation mode.
> Multiple traits with related generic types cannot be used
> ---------------------------------------------------------
>
> Key: GROOVY-11508
> URL: https://issues.apache.org/jira/browse/GROOVY-11508
> Project: Groovy
> Issue Type: Bug
> Components: Compiler
> Affects Versions: 4.0.0
> Reporter: James Daugherty
> Assignee: Eric Milles
> Priority: Major
> Attachments: screenshot-1.png, screenshot-2.png, screenshot-3.png
>
>
> When updating Grails from Groovy 3.x to 4.x we discovered that GROOVY-5106
> prevents us from updating to Groovy 4 for the
> [grails-data-mapping|https://github.com/grails/grails-data-mapping] (GORM)
> project. Groovy-5106 does not take into account relationships between
> generic types and groovy does not support inheritance in generic types on
> traits so we have no workable solution for using Groovy 4.
>
> For example, the following is not possible in Groovy 4:
> {code:java}
> class Parent extends GormEntity<Parent> {
> }
> class Child extends GormEntity<Child> {
> }
> class GormEntity<? extends GormEntity> { // ? extends GormEntity is not
> allowed
> }{code}
>
> We have documented the impacts of this issue on the grails-data-mapping
> project here: [https://github.com/grails/grails-data-mapping/issues/1811]
> We have discovered that the original change could be reverted and continue to
> work with the latest Java & Groovy.
>
> For Grails Data Mapping (GORM), there is support for inheritance between a
> Parent & Child domain object. This is often implemented like this:
> {code:java}
> class Parent extends GormEntity<Parent> {
> }
> class Child extends GormEntity<Child> {
> }
> trait GormEntity<D> { // Simplified for this ticket
> static D get(Serializable id)
>
> static List<D> getAll()
> }
> {code}
> This allows someone to do the following in code:
> {code:java}
> Parent.get(1L) // Will find either a Child or Parent
> Child.get(1L) // Will find only child types{code}
>
> Since Groovy-5106 does not take into account inheritance, can this change be
> reverted or changed to a warning until inheritance is taken into account?
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
