Add rules about super and extension types to wildcard spec #3729
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| *The desugared meaning of a super parameter includes a reference to the | ||
| parameter in the initializer list of the enclosing constructor declaration, | ||
| but such references are not possible when the parameter name is a | ||
| wildcard.* |
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This is a funny subtle point, but made sense once I thought about it some more.
| ### Super parameters | ||
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| An occurrence of `super._` as a declaration of a formal parameter in a | ||
| constructor is a compile-time error. |
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Can you also help me visualize this, and maybe the following below, by adding a little code snippet/example?
The words make sense, I just learn better with examples.
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Done. This brings out a slight inconvenience, by the way. I added a commentary paragraph about it.
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@kallentu, we might want to delete the 20 lines just before 'Unused variable warnings', PTAL. |
I would be okay with that. It might be more confusing with that example haha, but thank you for writing it up. |
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OK, done! |
This PR adds rules to the wildcards feature specification about super parameters of the form
super._, and about representation declarations in extension types whose representation variable name is_.In particular,
super._is an error because super parameters that can't be referenced from the initializer list are inherently broken. In contrast,extension type E(int _) {}is allowed: The representation variable name will be_and the formal parameter will be inaccessible (which makes no difference at this time, but will matter if a more general primary constructors feature is introduced).