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bishabosha opened this issue Nov 5, 2019 · 1 comment · Fixed by #9487
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Prevent extending java.lang.Enum except from an enum #7499

bishabosha opened this issue Nov 5, 2019 · 1 comment · Fixed by #9487
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@bishabosha
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bishabosha commented Nov 5, 2019 •
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as detailed in lampepfl/dotty-feature-requests#73, extending java.lang.Enum from a class is forbidden in Java, as Java enums are only guaranteed typesafe when created from its enum construct, additionally, the super call to java/lang/Enum."<init>":(Ljava/lang/String;I)V is synthesised by javac and the constructor is not exposed to Java source programs.

We should do the same in Dotty - extending java.lang.Enum should not be permitted apart from in an enum.

We should also support the old scala 2 way of extending java.lang.Enum with 3.0-migration
@bishabosha bishabosha mentioned this issue Nov 5, 2019
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@ekrich
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ekrich commented Nov 7, 2019

Linking for reference - #7174

@bishabosha bishabosha mentioned this issue Jun 11, 2020
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TheElectronWill added a commit to TheElectronWill/dotty that referenced this issue Aug 3, 2020
@TheElectronWill
Fix scala#7499: prevent extending jl.Enum except from an enum
44c4800
TheElectronWill added a commit to TheElectronWill/dotty that referenced this issue Aug 3, 2020
@TheElectronWill
Fix scala#7499: prevent extending jl.Enum except from an enum
75989e3
@TheElectronWill TheElectronWill linked a pull request Aug 3, 2020 that will close this issue
Fix #7499: Prevent extending java.lang.Enum except from an enum #9487
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TheElectronWill added a commit to TheElectronWill/dotty that referenced this issue Aug 7, 2020
@TheElectronWill
Fix scala#7499, fix scala#7174: prevent extending jl.Enum except from…
e0e0f36 
… an enum
TheElectronWill added a commit that referenced this issue Aug 7, 2020
@TheElectronWill
Merge pull request #9487 from TheElectronWill/prevent-extend-java-enum
1af1f46 
Fix #7499: Prevent extending java.lang.Enum except from an enum
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Fix #7499: Prevent extending java.lang.Enum except from an enum TheElectronWill/dotty
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@ekrich @bishabosha