deref patterns: bare-bones feature gate and typechecking by Nadrieril · Pull Request #122222 · rust-lang/rust (original) (raw)

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I am restarting the deref patterns experimentation. This introduces a feature gate under the lang-team experimental feature process, with @cramertj as lang-team liaison (it's been a while though, you still ok with this @cramertj?). Tracking issue: #87121.

This is the barest-bones implementation I could think of:

explicit syntax, reusing box <pat> because that saves me a ton of work;
use Deref as a marker trait (instead of a yet-to-design DerefPure);
no support for mutable patterns with DerefMut for now;
MIR lowering will come in the next PR. It's the trickiest part.

My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.

This is in large part salvaged from @fee1-dead's #119467.

r? @compiler-errors

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Mar 9, 2024

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Mar 9, 2024

pls squash as well, ty

regarding the lang team experiment, it may need a new liaison since @cramertj is no longer on T-lang

Ok, I've asked around for a new lang-team liaison

Please, add more tests. I want to see how this is supposed to work. In particular I'd like to see this code in tests:

let a = Rc::new(vec![0]); let x = match a { box x => x, }

let a = Rc::new(vec![0]); let x: &Vec = match &a { box x => x, }

As well as I understand the first example should not compile (because you cannot move out of Rc), but the second - should

These test are not yet possible, because patterns are not lowered correctly to MIR. This is the very first beginnings of implementing the feature, more tests will come in later PRs. (I've just added your examples to my next PR, thank you for them. You are correct about how they should work).

📌 Commit bf7951d has been approved by compiler-errors

It is now in the queue for this repository.

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Mar 20, 2024

Actually

@bors r-

this needs rebasing

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Mar 20, 2024

Co-authored-by: Deadbeef ent3rm4n@gmail.com

📌 Commit 120d357 has been approved by compiler-errors

It is now in the queue for this repository.

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matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Mar 21, 2024

…r=compiler-errors

deref patterns: bare-bones feature gate and typechecking

I am restarting the deref patterns experimentation. This introduces a feature gate under the lang-team experimental feature process, with @cramertj as lang-team liaison (it's been a while though, you still ok with this @cramertj?). Tracking issue: rust-lang#87121.

This is the barest-bones implementation I could think of:

explicit syntax, reusing box <pat> because that saves me a ton of work;
use Deref as a marker trait (instead of a yet-to-design DerefPure);
no support for mutable patterns with DerefMut for now;
MIR lowering will come in the next PR. It's the trickiest part.

My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.

This is in large part salvaged from @fee1-dead's rust-lang#119467.

r? @compiler-errors

workingjubilee added a commit to workingjubilee/rustc that referenced this pull request

Mar 21, 2024

…r=compiler-errors

deref patterns: bare-bones feature gate and typechecking

This is the barest-bones implementation I could think of:

explicit syntax, reusing box <pat> because that saves me a ton of work;
use Deref as a marker trait (instead of a yet-to-design DerefPure);
no support for mutable patterns with DerefMut for now;
MIR lowering will come in the next PR. It's the trickiest part.

My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.

This is in large part salvaged from @fee1-dead's rust-lang#119467.

r? @compiler-errors

bors added a commit to rust-lang-ci/rust that referenced this pull request

Mar 21, 2024

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Mar 21, 2024

…r=compiler-errors

deref patterns: bare-bones feature gate and typechecking

This is the barest-bones implementation I could think of:

explicit syntax, reusing box <pat> because that saves me a ton of work;
use Deref as a marker trait (instead of a yet-to-design DerefPure);
no support for mutable patterns with DerefMut for now;
MIR lowering will come in the next PR. It's the trickiest part.

My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.

This is in large part salvaged from @fee1-dead's rust-lang#119467.

r? @compiler-errors

This was referenced

Mar 21, 2024

bors added a commit to rust-lang-ci/rust that referenced this pull request

Mar 21, 2024

…iaskrgr

Rollup of 8 pull requests

Successful merges:

rust-lang#122222 (deref patterns: bare-bones feature gate and typechecking)
rust-lang#122358 (Don't ICE when encountering bound regions in generator interior type)
rust-lang#122696 (Add bare metal riscv32 target.)
rust-lang#122773 (make "expected paren or brace" error translatable)
rust-lang#122795 (Inherit RUSTC_BOOTSTRAP when testing wasm)
rust-lang#122799 (Replace closures with _ when suggesting fully qualified path for method call)
rust-lang#122801 (Fix misc printing issues in emit=stable_mir)
rust-lang#122806 (Make type_ascribe! not a built-in)

Failed merges:

rust-lang#122771 (add some comments to hir::ModuleItems)

r? @ghost @rustbot modify labels: rollup

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request

Mar 21, 2024

Rollup merge of rust-lang#122222 - Nadrieril:deref-pat-feature-gate, r=compiler-errors

deref patterns: bare-bones feature gate and typechecking

This is the barest-bones implementation I could think of:

explicit syntax, reusing box <pat> because that saves me a ton of work;
use Deref as a marker trait (instead of a yet-to-design DerefPure);
no support for mutable patterns with DerefMut for now;
MIR lowering will come in the next PR. It's the trickiest part.

My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.

This is in large part salvaged from @fee1-dead's rust-lang#119467.

r? @compiler-errors

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Mar 21, 2024

…r=Nadrieril

Implement macro-based deref!() syntax for deref patterns

Stop using box PAT syntax for deref patterns, and instead use a perma-unstable macro.

Blocked on rust-lang#122222

r? @Nadrieril

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request

Mar 21, 2024

Rollup merge of rust-lang#122793 - compiler-errors:deref-pat-syntax, r=Nadrieril

Implement macro-based deref!() syntax for deref patterns

Stop using box PAT syntax for deref patterns, and instead use a perma-unstable macro.

Blocked on rust-lang#122222

r? @Nadrieril

Labels

F-deref_patterns

`#![feature(deref_patterns)]`

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