Partial implementation for UFCS trait-less associated paths. #22172

eddyb · 2015-02-11T08:32:08Z

Adds <module::Type>::method support and makes module::Type::method a shorthand for it.
This is most of #16293, except that chaining multiple associated types is not yet supported.
It also fixes #22563 as impls are no longer treated as modules in resolve.

Unfortunately, this is still a [breaking-change]:

If you used a global path to a primitive type, i.e. ::bool, ::i32 etc. - that was a bug I had to fix.
Solution: remove the leading ::.
If you passed explicit impl-side type parameters to an inherent method, e.g.:

struct Foo<T>(T);
impl<A, B> Foo<(A, B)> {
    fn pair(a: A, b: B) -> Foo<(A, B)> { Foo((a, b)) }
}
Foo::<A, B>::pair(a, b)
// Now that is sugar for:
<Foo<A, B>>::pair(a, b)
// Which isn't valid because `Foo` has only one type parameter.
// Solution: replace with:
Foo::<(A, B)>::pair(a, b)
// And, if possible, remove the explicit type param entirely:
Foo::pair(a, b)

If you used the QPath-related AstBuilder methods @hugwijst added in Add QPath construction to ExtCtxt for UFCS support. #21943.
The methods still exist, but QPath was replaced by QSelf, with the actual path stored separately.
Solution: unpack the pair returned by cx.qpath to get the two arguments for cx.expr_qpath.

rust-highfive · 2015-02-11T08:32:21Z

r? @nikomatsakis

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nikomatsakis · 2015-02-11T10:41:32Z

very cool, I will read.

nikomatsakis · 2015-02-13T10:41:49Z

@eddyb sorry for being slow. I spent some time reading into this two days back but yesterday got very busy. I expect to finish up today.

nikomatsakis · 2015-02-13T16:28:43Z

First off, some nits here: nikomatsakis@b6461f0

nikomatsakis · 2015-02-13T16:59:56Z

r+, awesome! But I did have some conditions and comments :)

Conditions:

Nits at nikomatsakis@b6461f0
More new tests! Surely there are new constructions to test here? Some thoughts:
- the fact that inherent takes precedence over trait
- distinction between Trait::method and <Trait>::method
- inherent impls are, I guess, extensively tested already, but there are probably some variations on them that you enable that didn't work right before, right?
- can you rename const-polymorphic-paths to something like ufcs-trait-relative-paths or just anything that begins with ufcs? I'm pretty sure I'd never find it with the current name, and (iiuc) it tests more than just consts.
A comment or two about PartialDef and what the heck depth means (in resolve_path and friends) would be nice.

Comments/Questions:

I still feel like a reworking of resolve and the data structures around resolve (notably, Path and Def) could yield substantially cleaner code, but this seems to be overall a pretty reasonable approach.

One thing I noticed that stuck out at me: in resolve, if parsing a::b::c::d, it seems that you first try to parse the entire path, then you drop segments from the RHS one by one (so next try a::b::c, then a::b, etc) until you find a hit. This seems remarkably inefficient. I am assuming that this was the easiest way to shoehorn this work on top of resolve -- is there a deeper reason for this approach?

I also found the "suppress errors" flag a little bit suboptimal, compared to passing back an error as a result, but it's a relatively minor thing. In general I'd like to see resolution refactored into a "side-effect-free" lookup that returns errors / successful results, leaving it to the caller to decide what to do with those.

I was happy to see you integrated the lookup into probe.

nikomatsakis · 2015-02-18T14:36:01Z

@eddyb ok, so I finished reviewing as of 43bac21. Let's call them concerns, for the most part -- more than nits, but certainly not blockers. Anyway, I'd appreciate clarification about the potential for ICEs etc. I'd like to have a change to look over the patch once you address them -- or tell me why I am wrong --- but promise to make it quick presuming major changes aren't needed.

eddyb · 2015-02-19T01:55:09Z

@bors r=nikomatsakis 7af58b8

bors · 2015-02-19T10:21:18Z

⌛ Testing commit 7af58b8 with merge de86968...

bors · 2015-02-19T10:54:07Z

💔 Test failed - auto-linux-64-x-android-t

bors · 2015-02-19T10:54:07Z

💔 Test failed - auto-mac-32-opt

eddyb · 2015-02-19T11:18:50Z

@bors r=nikomatsakis 6e58a42

bors · 2015-02-19T13:08:31Z

⌛ Testing commit 6e58a42 with merge bf9938f...

bors · 2015-02-19T14:01:33Z

💔 Test failed - auto-mac-64-nopt-t

eddyb · 2015-02-19T20:29:16Z

@bors r=nikomatsakis e979cf4

eddyb · 2015-02-24T12:19:55Z

@bors r=nikomatsakis 0c6d1f3

bors · 2015-02-24T12:38:06Z

⌛ Testing commit 0c6d1f3 with merge f33e2e2...

bors · 2015-02-24T14:45:23Z

💔 Test failed - auto-win-32-nopt-t

Manishearth · 2015-02-24T14:46:41Z

@bors: retry force

Manishearth · 2015-02-24T14:47:42Z

@bors: force

bors · 2015-02-24T14:51:04Z

⌛ Testing commit 0c6d1f3 with merge 695bde9...

bors · 2015-02-24T14:51:06Z

⌛ Testing commit 0c6d1f3 with merge 0b975cb...

bors · 2015-02-24T14:55:51Z

💔 Test failed - auto-win-32-nopt-t

Manishearth · 2015-02-24T15:25:13Z

@bors: retry

bors · 2015-02-24T17:56:10Z

⌛ Testing commit 0c6d1f3 with merge 0bd1565...

@hugwijst

Adds `<module::Type>::method` support and makes `module::Type::method` a shorthand for it. This is most of #16293, except that chaining multiple associated types is not yet supported. It also fixes #22563 as `impl`s are no longer treated as modules in resolve. Unfortunately, this is still a *[breaking-change]*: * If you used a global path to a primitive type, i.e. `::bool`, `::i32` etc. - that was a bug I had to fix. Solution: remove the leading `::`. * If you passed explicit `impl`-side type parameters to an inherent method, e.g.: ```rust struct Foo<T>(T); impl<A, B> Foo<(A, B)> { fn pair(a: A, b: B) -> Foo<(A, B)> { Foo((a, b)) } } Foo::<A, B>::pair(a, b) // Now that is sugar for: <Foo<A, B>>::pair(a, b) // Which isn't valid because `Foo` has only one type parameter. // Solution: replace with: Foo::<(A, B)>::pair(a, b) // And, if possible, remove the explicit type param entirely: Foo::pair(a, b) ``` * If you used the `QPath`-related `AstBuilder` methods @hugwijst added in #21943. The methods still exist, but `QPath` was replaced by `QSelf`, with the actual path stored separately. Solution: unpack the pair returned by `cx.qpath` to get the two arguments for `cx.expr_qpath`.

bors · 2015-02-24T20:48:50Z

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-32-nopt-t, auto-win-32-opt, auto-win-64-nopt-t, auto-win-64-opt

Now possible thanks to rust-lang/rust#22172

rust-highfive assigned nikomatsakis Feb 11, 2015

eddyb force-pushed the almost-there branch from 6cb01ea to e76176b Compare February 11, 2015 19:01

eddyb force-pushed the almost-there branch from 71ac4be to 88fcf83 Compare February 13, 2015 10:53

eddyb mentioned this pull request Feb 16, 2015

Redefining built-in types does not work #20427

Closed

eddyb force-pushed the almost-there branch from 88fcf83 to 46cddac Compare February 17, 2015 10:26

eddyb changed the title ~~Desugar module::Type::method to <module::Type>::method.~~ Partial implementation for UFCS trait-less associated paths. Feb 17, 2015

eddyb force-pushed the almost-there branch 3 times, most recently from b7dd4cc to 43bac21 Compare February 17, 2015 17:29

This was referenced Feb 18, 2015

Permit T::Item based on bounds that appear in where clauses #22512

Merged

Resolve shorthand projections (T::A-style associated type paths) based solely on type, instead of a Def #22519

Open

eddyb force-pushed the almost-there branch 2 times, most recently from dc4043a to 7af58b8 Compare February 19, 2015 01:54

eddyb force-pushed the almost-there branch from 6e58a42 to e979cf4 Compare February 19, 2015 20:28

eddyb added 6 commits February 24, 2015 14:16

Fix fallout from correct stability handling in UFCS.

866a5ee

Fix fallout from allowing impls outside of the type's definition module.

9ac0736

Update trans/save's span hacks for fully qualified UFCS paths.

f0efa2d

rustc_typeck: unify the impl type with the UFCS path prefix type.

8501c9d

Fix fallout from rebasing.

72d5f39

syntax: update pretty-printer for the <T>::method shorthand.

0c6d1f3

eddyb force-pushed the almost-there branch from 4b59f96 to 0c6d1f3 Compare February 24, 2015 12:19

pnkfelix mentioned this pull request Feb 24, 2015

Avoid cat_expr Erred notes when already in error state. #22767

Merged

bors merged commit 0c6d1f3 into rust-lang:master Feb 24, 2015

eddyb deleted the almost-there branch February 24, 2015 20:52

pnkfelix mentioned this pull request Feb 24, 2015

Projecting <Type as Trait>::N should check that N is part of Trait #22731

Closed

SSheldon added a commit to SSheldon/rust-objc that referenced this pull request Feb 27, 2015

Removed lots of type annotations.

6069aed

Now possible thanks to rust-lang/rust#22172

SSheldon added a commit to SSheldon/rust-objc-foundation that referenced this pull request Mar 23, 2015

Removed lots of type annotations.

dec0d9c

Now possible thanks to rust-lang/rust#22172

SSheldon added a commit to SSheldon/rust-objc-id that referenced this pull request May 2, 2015

Removed lots of type annotations.

602d2d1

Now possible thanks to rust-lang/rust#22172

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Partial implementation for UFCS trait-less associated paths. #22172

Partial implementation for UFCS trait-less associated paths. #22172

eddyb commented Feb 11, 2015

rust-highfive commented Feb 11, 2015

nikomatsakis commented Feb 11, 2015

nikomatsakis commented Feb 13, 2015

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bors commented Feb 24, 2015

Partial implementation for UFCS trait-less associated paths. #22172

Partial implementation for UFCS trait-less associated paths. #22172

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eddyb commented Feb 11, 2015

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