Simplify the `G` in `Diag<'a, G>` by nnethercote · Pull Request #162630 · rust-lang/rust

nnethercote · 2026-09-11T10:24:46Z

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The EmissionGuarantee trait isn't necessary, and just complicates things. Details in individual commits.

r? @oli-obk

rustbot · 2026-09-11T10:24:50Z

HIR ty lowering was modified

cc @fmease

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

cc @fmease

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

The rustc-dev-guide subtree was changed. If your future PRs only touch the subtree, consider submitting them directly to rust-lang/rustc-dev-guide, which is where the document is primarily maintained (and has faster CI).

cc @BoxyUwU, @tshepang

Some changes occurred in match checking

cc @Nadrieril

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustc_macros::diagnostics was changed

cc @TaKO8Ki, @JonathanBrouwer

clippy is developed in its own repository. If possible, consider making this change to rust-lang/rust-clippy instead.

cc @rust-lang/clippy

miri is developed in its own repository. If the Miri part of this change can be broken out, consider making this change to rust-lang/miri instead. However, if Miri needs adjusting for rustc changes, just ignore this message.

cc @rust-lang/miri

Some changes occurred to constck

cc @fee1-dead

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred in const_evaluatable.rs

cc @BoxyUwU

nnethercote · 2026-09-11T10:25:36Z

The first two commits here are definite wins. I'm more ambivalent about the third commit: it makes some things better and some things worse and I'm not sure if it's a good idea overall.

oli-obk

I was initially a bit sceptical about the third commit, but overall I think it's an improvement. The idea of carrying the emission guarantee as a generic param is nice, but ended up not that useful in practice

@bors r+

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rust-bors · 2026-09-11T12:47:11Z

📌 Commit 4377560 has been approved by oli-obk

It is now in the queue for this repository.

oli-obk · 2026-09-11T12:47:42Z

@bors r- I raced my review with other reviews by not checking that something changed oops

rust-bors · 2026-09-11T12:47:47Z

This pull request was unapproved.

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Kobzol · 2026-09-11T13:37:18Z

@bors try @rust-timer queue

Simplify the `G` in `Diag<'a, G>`

rust-bors · 2026-09-11T14:43:42Z

☀️ Try build successful (CI)
Build commit: ecf783e (ecf783ea825f14de5262e03ad65fd0a2d0bfab8b)
Base parent: ca0a647 (ca0a6473ffde01deb7fce24cc04864cf723e14a0)

nnethercote · 2026-09-12T06:07:51Z

@oli-obk: are you ok with the first two commits? I'll do another PR later with the third commit in it and probably some other stuff.

oli-obk · 2026-09-14T08:50:52Z

@bors r+ rollup

rust-bors · 2026-09-14T08:50:56Z

📌 Commit 09bf6de has been approved by oli-obk

It is now in the queue for this repository.

@oli-obk

…-obk Simplify the `G` in `Diag<'a, G>` The `EmissionGuarantee` trait isn't necessary, and just complicates things. Details in individual commits. r? @oli-obk

…uwer Rollup of 11 pull requests Successful merges: - #162752 (`rust-analyzer` subtree update) - #161868 (libtest: never iterate over all tests in `--exact` mode) - #161903 (Fix initialization cycle in `target_config`) - #162240 (Garbage-collect old incremental compilation sessions) - #161675 (document that t-lang does not need involvement for unobservable intrisics) - #162630 (Simplify the `G` in `Diag<'a, G>`) - #162647 (Add regression test for previous overflow evaluating the requirement) - #162703 (regression test for valtree leaf const) - #162723 (Add regression test for unexpected type for constructor) - #162735 (Remove pointless `A: Allocator` bounds in boxed.rs) - #162736 (clean up trivial region constraint filtering)

@oli-obk

…-obk Simplify the `G` in `Diag<'a, G>` The `EmissionGuarantee` trait isn't necessary, and just complicates things. Details in individual commits. r? @oli-obk

…uwer Rollup of 15 pull requests Successful merges: - #162752 (`rust-analyzer` subtree update) - #161903 (Fix initialization cycle in `target_config`) - #162240 (Garbage-collect old incremental compilation sessions) - #162610 (fix tailcall indirect return) - #162634 (Implement semantic analysis for named `Fn` trait params) - #161675 (document that t-lang does not need involvement for unobservable intrisics) - #162160 (turn aligned-in-packed error into lint) - #162504 (Stabilize `unsafe_cell_access`) - #162516 (tidy: Sort multi-line types by treating `>` as a closing bracket) - #162630 (Simplify the `G` in `Diag<'a, G>`) - #162647 (Add regression test for previous overflow evaluating the requirement) - #162703 (regression test for valtree leaf const) - #162723 (Add regression test for unexpected type for constructor) - #162735 (Remove pointless `A: Allocator` bounds in boxed.rs) - #162736 (clean up trivial region constraint filtering)

…uwer Rollup of 16 pull requests Successful merges: - #162762 (Subtree sync for rustc_codegen_cranelift) - #162752 (`rust-analyzer` subtree update) - #161903 (Fix initialization cycle in `target_config`) - #162240 (Garbage-collect old incremental compilation sessions) - #162610 (fix tailcall indirect return) - #162634 (Implement semantic analysis for named `Fn` trait params) - #161675 (document that t-lang does not need involvement for unobservable intrisics) - #162160 (turn aligned-in-packed error into lint) - #162504 (Stabilize `unsafe_cell_access`) - #162516 (tidy: Sort multi-line types by treating `>` as a closing bracket) - #162630 (Simplify the `G` in `Diag<'a, G>`) - #162647 (Add regression test for previous overflow evaluating the requirement) - #162703 (regression test for valtree leaf const) - #162723 (Add regression test for unexpected type for constructor) - #162735 (Remove pointless `A: Allocator` bounds in boxed.rs) - #162736 (clean up trivial region constraint filtering)

@oli-obk

Rollup merge of #162630 - nnethercote:simplify-Diag-G, r=oli-obk Simplify the `G` in `Diag<'a, G>` The `EmissionGuarantee` trait isn't necessary, and just complicates things. Details in individual commits. r? @oli-obk

@oli-obk

…-obk Simplify the `G` in `Diag<'a, G>` The `EmissionGuarantee` trait isn't necessary, and just complicates things. Details in individual commits. r? @oli-obk

…uwer Rollup of 16 pull requests Successful merges: - rust-lang/rust#162762 (Subtree sync for rustc_codegen_cranelift) - rust-lang/rust#162752 (`rust-analyzer` subtree update) - rust-lang/rust#161903 (Fix initialization cycle in `target_config`) - rust-lang/rust#162240 (Garbage-collect old incremental compilation sessions) - rust-lang/rust#162610 (fix tailcall indirect return) - rust-lang/rust#162634 (Implement semantic analysis for named `Fn` trait params) - rust-lang/rust#161675 (document that t-lang does not need involvement for unobservable intrisics) - rust-lang/rust#162160 (turn aligned-in-packed error into lint) - rust-lang/rust#162504 (Stabilize `unsafe_cell_access`) - rust-lang/rust#162516 (tidy: Sort multi-line types by treating `>` as a closing bracket) - rust-lang/rust#162630 (Simplify the `G` in `Diag<'a, G>`) - rust-lang/rust#162647 (Add regression test for previous overflow evaluating the requirement) - rust-lang/rust#162703 (regression test for valtree leaf const) - rust-lang/rust#162723 (Add regression test for unexpected type for constructor) - rust-lang/rust#162735 (Remove pointless `A: Allocator` bounds in boxed.rs) - rust-lang/rust#162736 (clean up trivial region constraint filtering)

Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in rust-lang#162630 (comment)

Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in #162630 (comment)

Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in rust-lang#162630 (comment)

Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in #162630 (comment)

Rollup merge of #163083 - nnethercote:rm-Diag-G, r=oli-obk Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in #162630 (comment)

Remove `G` generic param from `Diag<'_, G>` The benefits are outweighed by the costs. Details in invidual commits. some minor earlier discussion about this change in rust-lang/rust#162630 (comment)

rustbot assigned oli-obk Sep 11, 2026

ada4a reviewed Sep 11, 2026

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Comment thread compiler/rustc_ast_lowering/src/lib.rs Outdated

RalfJung reviewed Sep 11, 2026

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Comment thread compiler/rustc_errors/src/diagnostic.rs Outdated

RalfJung reviewed Sep 11, 2026

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Comment thread compiler/rustc_errors/src/diagnostic.rs Outdated

oli-obk approved these changes Sep 11, 2026

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rust-bors Bot pushed a commit that referenced this pull request Sep 11, 2026

Auto merge of #162630 - nnethercote:simplify-Diag-G, r=<try>

ecf783e

Simplify the `G` in `Diag<'a, G>`

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 12, 2026

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JonathanBrouwer mentioned this pull request Sep 14, 2026

Rollup of 11 pull requests #162755

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JonathanBrouwer mentioned this pull request Sep 14, 2026

Rollup of 15 pull requests #162764

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JonathanBrouwer mentioned this pull request Sep 14, 2026

Rollup of 16 pull requests #162767

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rust-bors Bot merged commit 305d36b into rust-lang:main Sep 14, 2026
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rustbot added this to the 1.100.0 milestone Sep 14, 2026

nnethercote deleted the simplify-Diag-G branch September 14, 2026 21:53

oli-obk mentioned this pull request Sep 21, 2026

Remove G generic param from Diag<'_, G> #163083

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