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stabilize never type - #155499

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WaffleLapkin:stabilize-never-type
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stabilize never type#155499
WaffleLapkin wants to merge 18 commits into
rust-lang:mainfrom
WaffleLapkin:stabilize-never-type

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@WaffleLapkin WaffleLapkin commented Apr 18, 2026 •
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52270233795_5979a3174d_b

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Experiments

Closes #35121
Closes #148922

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@rustbot rustbot added A-rustdoc-js Area: Rustdoc's JS front-end A-rustdoc-json Area: Rustdoc JSON backend A-rustdoc-search Area: Rustdoc's search feature S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-clippy Relevant to the Clippy team. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. T-rust-analyzer Relevant to the rust-analyzer team, which will review and decide on the PR/issue. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. T-rustdoc-frontend Relevant to the rustdoc-frontend team, which will review and decide on the web UI/UX output. labels Apr 18, 2026
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WaffleLapkin marked this pull request as draft April 18, 2026 22:14
@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 18, 2026
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WaffleLapkin commented Apr 18, 2026

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@bors try

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rust-bors Bot pushed a commit that referenced this pull request Apr 18, 2026
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Auto merge of #155499 - WaffleLapkin:stabilize-never-type, r=<try>
1c4199d 
[experiment][0] nya
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☀️ Try build successful (CI)
Build commit: 1c4199d (1c4199da70f816f2239f41c55168ff75a3663718, parent: b2f1ccf524a3a4cf9c34545167cc23b659cf1cbd)

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WaffleLapkin force-pushed the stabilize-never-type branch from 2895d33 to 3e8df8d Compare April 19, 2026 01:05
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WaffleLapkin commented Apr 19, 2026

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@craterbot check p=1 crates=https://crater-reports.s3.amazonaws.com/pr-154887/retry-regressed-list.txt

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craterbot commented Apr 19, 2026

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👌 Experiment pr-155499 created and queued.
🤖 Automatically detected try build 1c4199d
⚠️ Try build based on commit 2895d33, but latest commit is 3e8df8d. Did you forget to make a new try build?
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

@craterbot craterbot added S-waiting-on-crater Status: Waiting on a crater run to be completed. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 19, 2026
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🚧 Experiment pr-155499 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

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🎉 Experiment pr-155499 is completed!
📊 3277 regressed and 0 fixed (9024 total)
📊 1149 spurious results on the retry-regressed-list.txt, consider a retry1 if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

Footnotes

  1. re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-155499/retry-regressed-list.txt ↩

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@jmg-duarte jmg-duarte mentioned this pull request Aug 12, 2026
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@matthiaskrgr matthiaskrgr mentioned this pull request Aug 12, 2026
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@WaffleLapkin
Set never type fallback to always be !
8261788
@WaffleLapkin
stabilize the never type (!)
313a800
@WaffleLapkin
fixup clippy::empty_enums
2f570b4
@WaffleLapkin
remove #![feature(never_type)] from the compiler
04c8a38 
The reason `rustc_ast_ir` and `rustc_pattern_analysis` have nested
`cfg_attr`s is so that they don't mention `cfg(bootstrap)` when nightly
or rustc cargo feature turned on. If you don't do it like that, they stop
compiling on stable (or rather, they emit unexpected cfg warnings...).
@WaffleLapkin
remove #![feature(never_type)] from tests
d2192b6
@WaffleLapkin
remove #![feature(never_type)] from library
9b42e86
@WaffleLapkin
remove #![feature(never_type)] from tools
b8cb137
@WaffleLapkin
bless tests
f8b8490
@WaffleLapkin
bless mir-opt tests
1a99dc7
@WaffleLapkin
update tests which depended on never fallback to ()
752ad22
@WaffleLapkin
remove dependency_on_unit_never_type_fallback lint
b2a7e4c
@WaffleLapkin
remove stray stderr files
9a622cf 
??? why wasn't this detected by compiletest ???
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

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@rustbot rustbot added the WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) label Aug 14, 2026
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⚠️ Warning ⚠️

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A-rustdoc-js Area: Rustdoc's JS front-end A-rustdoc-json Area: Rustdoc JSON backend A-rustdoc-search Area: Rustdoc's search feature disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. I-lang-radar Items that are on lang's radar and will need eventual work or consideration. needs-fcp This change is insta-stable, or significant enough to need a team FCP to proceed. needs-reference-pr This language change needs an approved Reference PR to proceed. S-blocked Status: Blocked on something else such as an RFC or other implementation work. T-clippy Relevant to the Clippy team. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-lang Relevant to the language team T-libs Relevant to the library team, which will review and decide on the PR/issue. T-rust-analyzer Relevant to the rust-analyzer team, which will review and decide on the PR/issue. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. T-rustdoc-frontend Relevant to the rustdoc-frontend team, which will review and decide on the web UI/UX output. to-announce Announce this issue on triage meeting WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver)

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Successfully merging this pull request may close these issues.

Tracking Issue for never type fallback change Tracking issue for promoting ! to a type (RFC 1216)