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Support inferring&completing Self type in enum/struct/union definitions #1924

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merged 2 commits into from Oct 8, 2019
Merged

Support inferring&completing Self type in enum/struct/union definitions #1924

merged 2 commits into from Oct 8, 2019

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@ice1000
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@ice1000 ice1000 commented Sep 27, 2019

Signed-off-by: ice1000 ice1000kotlin@foxmail.com

An attempt to fix #1908.
This code works, but I believe the implementation is ugly. Please give me suggestions!

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@ice1000 ice1000 commented Sep 27, 2019

I've updated the comment in #1908 with a screenshot.

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@flodiebold flodiebold commented Sep 28, 2019

Note that this should also work for structs; also, Self should refer to the whole type with its type parameters, not just the enum. E.g.:

struct List<T> {
    elem: T,
    next: Option<Box<Self>>,
}

(For a test, I'd shorten that to struct List<T> { next: Self } -- it doesn't matter that this wouldn't compile.)

We already resolve Self in impl blocks, and this is very similar. The Resolver works by having a stack of scopes of various kinds, one of them ImplBlock. When building a Resolver for an impl block, we push such a scope on the stack here. The ImplBlockScope is then handled in a few places in resolve.rs; when resolving Self as a type, we return TypeNs::SelfType. And that's then mainly handled here during type lowering to resolve the target type of the impl.

I think I'd suggest adding an AdtScope(Adt) in the Scope enum, and an AdtSelfType(Adt) in the TypeNs enum. (Note that this is different from the existing TypeNs::Adt, because that one takes type parameters, while Self always gets the type parameters from the definition.) The scope should be handled basically the same way as the impl block scope; we just need to take care to push it in the resolver methods of Struct, Enum and Union. And when handling TypeNs::AdtSelfType in lower.rs, you can just use the ty method to get the definition type.

(Handling the scope here will also mean we'll complete Self in struct/enum definitions, by the way.)

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@ice1000 ice1000 commented Oct 7, 2019

Changed implementation into Scope::AdtSelfScope, please take a look @flodiebold

Signed-off-by: ice1000 <ice1000kotlin@foxmail.com>
crates/ra_hir/src/code_model.rs Outdated Show resolved Hide resolved
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crates/ra_hir/src/ty/infer.rs Outdated Show resolved Hide resolved
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@flodiebold flodiebold commented Oct 8, 2019

Looks good to me apart from what @matklad already wrote! You could add a test for completing Self in this situation (see here).

Feel free to r+ with @matklad's suggestions:

bors delegate+

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@bors bors bot commented Oct 8, 2019

✌️ ice1000 can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

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@ice1000 ice1000 commented Oct 8, 2019

I'm gonna apply the review suggestions locally instead of using GitHub.

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@ice1000 ice1000 commented Oct 8, 2019

I'm very nervous. It's my first time to summon bors for merging a PR.

@ice1000 ice1000 changed the title Support inferring Self type in enum definitions Support inferring&completing Self type in enum/struct/union definitions Oct 8, 2019
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@matklad matklad commented Oct 8, 2019

@ice1000 we have a rather extensive test suite, so the probability that something breaks spectacularly is pretty low :) Just reply with bors r+ comment

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@ice1000 ice1000 commented Oct 8, 2019

Between the darkness and the dawn, a PR bot rises!

bors r+

bors bot added a commit that referenced this issue Oct 8, 2019
1924: Support inferring&completing `Self` type in enum/struct/union definitions r=ice1000 a=ice1000

Signed-off-by: ice1000 <ice1000kotlin@foxmail.com>

An attempt to fix #1908.
This code works, but I believe the implementation is ugly. Please give me suggestions!

Co-authored-by: ice1000 <ice1000kotlin@foxmail.com>
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@bors bors bot commented Oct 8, 2019

@bors bors bot merged commit b043358 into rust-analyzer:master Oct 8, 2019
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@ice1000 ice1000 deleted the sticky-fingers branch Oct 8, 2019
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3 participants