Add support for postfix yield expressions #138435

eholk · 2025-03-13T00:29:39Z

We've been having a discussion about whether we want postfix yield, or want to stick with prefix yield, or have both. I figured it's easy enough to support both for now and let us play around with them while the feature is still experimental.

This PR treats yield x and x.yield as semantically equivalent. There was a suggestion to make yield x have a () type (so it only works in coroutines with Resume = (). I think that'd be worth trying, either in a later PR, or before this one merges, depending on people's opinions.

#43122

rustbot · 2025-03-13T00:29:43Z

r? @Noratrieb

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eholk · 2025-03-13T00:31:04Z

r? @oli-obk

yoshuawuyts · 2025-03-13T01:24:09Z

link to the relevant Zulip thread

rustbot · 2025-03-13T21:37:49Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

We had a discussion[1] today about whether postfix yield would make sense. It's easy enough to support both in the parser, so we might as well have both and see how people use it while the feature is experimental. [1]: https://rust-lang.zulipchat.com/#narrow/channel/481571-t-lang.2Fgen/topic/postfix-yield/with/505231568

src/tools/rustfmt/src/expr.rs

This involved fixing the span when parsing .yield

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

compiler/rustc_parse/src/parser/expr.rs

Co-authored-by: Travis Cross <[email protected]>

oli-obk · 2025-03-19T15:23:36Z

@bors r+ rollup

bors · 2025-03-19T15:23:39Z

📌 Commit 2bd7f73 has been approved by oli-obk

It is now in the queue for this repository.

Add support for postfix yield expressions We've been having a discussion about whether we want postfix yield, or want to stick with prefix yield, or have both. I figured it's easy enough to support both for now and let us play around with them while the feature is still experimental. This PR treats `yield x` and `x.yield` as semantically equivalent. There was a suggestion to make `yield x` have a `()` type (so it only works in coroutines with `Resume = ()`. I think that'd be worth trying, either in a later PR, or before this one merges, depending on people's opinions. rust-lang#43122

Rollup of 15 pull requests Successful merges: - rust-lang#138321 ([bootstrap] Distribute split debuginfo if present) - rust-lang#138364 (ports the compiler test cases to new rust_intrinsic format) - rust-lang#138410 (Couple mir building cleanups) - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138536 (stable_mir: Add `MutMirVisitor`) - rust-lang#138623 ([bootstrap] Use llvm_runtimes for compiler-rt) - rust-lang#138650 (Optimize `io::Write::write_fmt` for constant strings) - rust-lang#138652 (Reintroduce remote-test support in run-make tests) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138694 (Fix: add ohos target notes) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138709 (Update GCC submodule) - rust-lang#138724 (Check attrs: Don't try to retrieve the name of list stems) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

Add support for postfix yield expressions We've been having a discussion about whether we want postfix yield, or want to stick with prefix yield, or have both. I figured it's easy enough to support both for now and let us play around with them while the feature is still experimental. This PR treats `yield x` and `x.yield` as semantically equivalent. There was a suggestion to make `yield x` have a `()` type (so it only works in coroutines with `Resume = ()`. I think that'd be worth trying, either in a later PR, or before this one merges, depending on people's opinions. rust-lang#43122

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#138435 - eholk:prefix-yield, r=oli-obk Add support for postfix yield expressions We've been having a discussion about whether we want postfix yield, or want to stick with prefix yield, or have both. I figured it's easy enough to support both for now and let us play around with them while the feature is still experimental. This PR treats `yield x` and `x.yield` as semantically equivalent. There was a suggestion to make `yield x` have a `()` type (so it only works in coroutines with `Resume = ()`. I think that'd be worth trying, either in a later PR, or before this one merges, depending on people's opinions. rust-lang#43122

Add support for postfix yield expressions We've been having a discussion about whether we want postfix yield, or want to stick with prefix yield, or have both. I figured it's easy enough to support both for now and let us play around with them while the feature is still experimental. This PR treats `yield x` and `x.yield` as semantically equivalent. There was a suggestion to make `yield x` have a `()` type (so it only works in coroutines with `Resume = ()`. I think that'd be worth trying, either in a later PR, or before this one merges, depending on people's opinions. rust-lang#43122

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned Noratrieb Mar 13, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Mar 13, 2025

rustbot assigned oli-obk and unassigned Noratrieb Mar 13, 2025

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eholk marked this pull request as ready for review March 13, 2025 21:37

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eholk added 4 commits March 14, 2025 12:21

Preserve yield position during pretty printing

1c0916a

Teach rustfmt to handle postfix yield

635eae2

Fix clippy

c5093ac

eholk force-pushed the prefix-yield branch from b0af7f6 to c5093ac Compare March 14, 2025 19:22

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ytmimi reviewed Mar 15, 2025

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ytmimi mentioned this pull request Mar 17, 2025

Add ergonomic ref counting support rust-lang/rustfmt#6512

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Teach rustfmt to handle postfix yield

9b0e7f6

This involved fixing the span when parsing .yield

traviscross reviewed Mar 18, 2025

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compiler/rustc_ast_pretty/src/pprust/state/expr.rs Outdated Show resolved Hide resolved

compiler/rustc_parse/src/parser/expr.rs Outdated Show resolved Hide resolved

eholk and others added 2 commits March 18, 2025 10:50

Apply suggestions from code review

299e5d0

Co-authored-by: Travis Cross <[email protected]>

Refactor YieldKind so postfix yield must have an expression

2bd7f73

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 19, 2025

jieyouxu mentioned this pull request Mar 20, 2025

Rollup of 15 pull requests #138733

Closed

matthiaskrgr mentioned this pull request Mar 20, 2025

Rollup of 8 pull requests #138747

Merged

matthiaskrgr mentioned this pull request Mar 20, 2025

Rollup of 8 pull requests #138760

Merged

bors merged commit d752721 into rust-lang:master Mar 21, 2025
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rustbot added this to the 1.87.0 milestone Mar 21, 2025

dtolnay mentioned this pull request Apr 5, 2025

Implement asymmetrical precedence for closures and jumps #134847

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dtolnay mentioned this pull request Aug 13, 2025

Parse postfix yield syntax dtolnay/syn#1890

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