Rollup of 9 pull requests by JonathanBrouwer · Pull Request #154102 · rust-lang/rust

JonathanBrouwer · 2026-03-19T16:09:52Z

Successful merges:

impl restriction lowering #153556 (impl restriction lowering)
bootstrap: Optionally print a backtrace if a command fails #153992 (bootstrap: Optionally print a backtrace if a command fails)
two smaller feature cleanups #154019 (two smaller feature cleanups)
tests: Activate must_not_suspend test for MutexGuard dropped before await #154059 (tests: Activate must_not_suspend test for MutexGuard dropped before await)
Rewrite query_ensure_result. #154075 (Rewrite query_ensure_result.)
Updates derive_where and removes workaround #154082 (Updates derive_where and removes workaround)
Preserve braces around self in use tree pretty printing #154084 (Preserve braces around self in use tree pretty printing)
Insert space after float literal ending with . in pretty printer #154086 (Insert space after float literal ending with . in pretty printer)
Fix whitespace after fragment specifiers in macro pretty printing #154087 (Fix whitespace after fragment specifiers in macro pretty printing)

…wait The test pass in `nightly-2023-09-24` but fail in `nightly-2023-09-23`: $ rustc +nightly-2023-09-23 --edition 2018 tests/ui/lint/must_not_suspend/mutex-guard-dropped-before-await.rs error: `MutexGuard` held across a suspend point, but should not be --> tests/ui/lint/must_not_suspend/mutex-guard-dropped-before-await.rs:13:9 | 13 | let lock = foo.lock().unwrap(); | ^^^^ ... 18 | bar().await; | ----- the value is held across this suspend point |

It currently uses chaining which is concise but hard to read. There are up to four implicit matches occurring after the call to `execute_query_fn`. - The first `map` on `Option<Erased<Result<T, ErrorGuaranteed>>>`. - The second `map` on `Option<Result<T, ErrorGuaranteed>>`. - The third `map` on `Result<T, ErrorGuaranteed>`. - The `unwrap_or` on `Option<Result<(), ErrorGuaranteed>>`. This commit rewrites it to use at most two matches. - An explicit match on `Option<Erased<Result<T, ErrorGuaranteed>>>`. - An explicit match on `Result<T, ErrorGuaranteed>`. This is easier to read. It's also more efficient, though the code isn't hot enough for that to matter.

The AST pretty printer strips braces from single-item `use` sub-groups, simplifying `use foo::{Bar}` to `use foo::Bar`. However, when the single item is `self`, this produces `use foo::self` which is not valid Rust (E0429) — the grammar requires `use foo::{self}`. This affects both `stringify!` and `rustc -Zunpretty=expanded`, causing `cargo expand` output to be unparseable when a crate uses `use path::{self}` imports (a common pattern in the ecosystem). The fix checks whether the single nested item's path starts with `self` before stripping braces. If so, the braces are preserved. Signed-off-by: Andrew V. Teylu <andrew.teylu@vector.com>

When a macro-generating-macro captures fragment specifier tokens (like `$x:ident`) as `tt` metavariables and replays them before a keyword (like `where`), the pretty printer concatenates them into an invalid fragment specifier (e.g. `$x:identwhere` instead of `$x:ident where`). This happens because `tt` captures preserve the original token spacing. When the fragment specifier name (e.g. `ident`) was originally the last token before a closing delimiter, it retains `JointHidden` spacing. The `print_tts` function only checks `space_between` for `Spacing::Alone` tokens, so `JointHidden` tokens skip the space check entirely, causing adjacent identifier-like tokens to merge. The fix adds a check in `print_tts` to insert a space between adjacent identifier-like tokens (identifiers and keywords) regardless of the original spacing, preventing them from being concatenated into invalid tokens. This is similar to the existing `space_between` mechanism that prevents token merging for `Spacing::Alone` tokens, extended to also handle `Joint`/`JointHidden` cases where two identifier-like tokens would merge. Signed-off-by: Andrew V. Teylu <andrew.teylu@vector.com>

The pretty printer was collapsing unsuffixed float literals (like `0.`) with adjacent dot tokens, producing ambiguous or invalid output: - `0. ..45.` (range) became `0...45.` - `0. ..=360.` (inclusive range) became `0...=360.` - `0. .to_string()` (method call) became `0..to_string()` The fix inserts a space after an unsuffixed float literal ending with `.` when it appears as the start expression of a range operator or the receiver of a method call or field access, preventing the trailing dot from merging with the following `.`, `..`, or `..=` token. This is skipped when the expression is already parenthesized, since the closing `)` naturally provides separation. Signed-off-by: Andrew V. Teylu <andrew.teylu@vector.com>

@Urgau

…wering, r=petrochenkov `impl` restriction lowering This PR is linked to a [GSoC proposal](https://github.com/rust-lang/google-summer-of-code?tab=readme-ov-file#implementing-impl-and-mut-restrictions) and is part of the progress toward implementing `impl` restrictions proposed in [RFC 3323](https://rust-lang.github.io/rfcs/3323-restrictions.html). This PR implements path resolution for `impl` restrictions. The resolution is performed in `rustc_resolve/src/late.rs` using `smart_resolve_path`. This PR also checks whether the restricted module or crate is an ancestor. If it is not, it emits a restriction-specific counterpart to visibility’s `AncestorOnly` error. r? @Urgau cc @jhpratt

… r=jieyouxu,kobzol bootstrap: Optionally print a backtrace if a command fails I found this quite useful for debugging why a command was failing eagerly (it turns out that `.delay_failure()` is ignored if `fail_fast` is enabled).

two smaller feature cleanups Remove an unneeded feature gate for a private macro and sort the used features correctly by whether they are language or library features.

…ooeo tests: Activate `must_not_suspend` test for `MutexGuard` dropped before `await` After bisect it turns out that the test passes in `nightly-2023-09-24` but fails in `nightly-2023-09-23`: $ rustc +nightly-2023-09-23 --edition 2018 tests/ui/lint/must_not_suspend/mutex-guard-dropped-before-await.rs error: `MutexGuard` held across a suspend point, but should not be --> tests/ui/lint/must_not_suspend/mutex-guard-dropped-before-await.rs:13:9 | 13 | let lock = foo.lock().unwrap(); | ^^^^ ... 18 | bar().await; | ----- the value is held across this suspend point | That leaves us with <details> <summary>git log e4133ba..13e6f24 --no-merges --oneline </summary> bffb346 Make test more robust to opts. 44ac8dc Remove GeneratorWitness and rename GeneratorWitnessMIR. 855a75b Remove useless wrapper. baa64b0 Remove dead error code. 6aa1268 Bless clippy. d989e14 Bless mir-opt 211d2ed Bless tests. 286502c Enable drop_tracking_mir by default. a626caa Revert duplication of tests. ff03204 Fold lifetimes before substitution. 9450b75 Do not construct def_path_str for MustNotSuspend. 58ef3a0 diagnostics: simpler 83556 handling by bailing out 79d6853 Check types live across yields in generators too c21867f Check that closure's by-value captures are sized d3dea30 Point at cause of expectation of `break` value when possible 4ed4913 Merge `ExternProviders` into the general `Providers` struct 2ba911c Have a single struct for queries and hook 9090ed8 Fix test on targets with crt-static default 5db9a5e Update cargo 9defc97 Add tracing instrumentation, just like queries automatically add it 2157f31 Add a way to decouple the implementation and the declaration of a TyCtxt method. d5ec9af Add test to guard against VecDeque optimization regression 3799af3 diagnostics: avoid mismatch between variance index and hir generic 34c248d compiletest: load supports-xray from target spec 64e27cb compiletest: load supported sanitizers from target spec bc7bb3c compiletest: use builder pattern to construct Config in tests </details> of which 286502c (rust-lang#107421) seems most likely. I can't find an existing test except the "inactive" one, so let's simply activate it. Closes rust-lang#89562 which is where the activated test comes from. The test was originally added in rust-lang#89826. Tracking issue: - rust-lang#83310

@Zalathar

…esult, r=Zalathar Rewrite `query_ensure_result`. It currently uses chaining which is concise but hard to read. There are up to four implicit matches occurring after the call to `execute_query_fn`. - The first `map` on `Option<Erased<Result<T, ErrorGuaranteed>>>`. - The second `map` on `Option<Result<T, ErrorGuaranteed>>`. - The third `map` on `Result<T, ErrorGuaranteed>`. - The `unwrap_or` on `Option<Result<(), ErrorGuaranteed>>`. This commit rewrites it to use at most two matches. - An explicit match on `Option<Erased<Result<T, ErrorGuaranteed>>>`. - An explicit match on `Result<T, ErrorGuaranteed>`. This is easier to read. It's also more efficient, though the code isn't hot enough for that to matter. r? @Zalathar

Updates derive_where and removes workaround Updates dependency on `derive-where` that fixes issue ModProg/derive-where#136 and removes the following workaround: ``` // FIXME(derive-where#136): Need to use separate `derive_where` for // `Copy` and `Ord` to prevent the emitted `Clone` and `PartialOrd` // impls from incorrectly relying on `T: Copy` and `T: Ord`. ``` r? lcnr

Preserve braces around `self` in use tree pretty printing The AST pretty printer strips braces from single-item `use` sub-groups, simplifying `use foo::{Bar}` to `use foo::Bar`. However, when the single item is `self`, this produces `use foo::self` which is not valid Rust (E0429) — the grammar requires `use foo::{self}`. This affects both `stringify!` and `rustc -Zunpretty=expanded`, causing `cargo expand` output to be unparseable when a crate uses `use path::{self}` imports (a common pattern in the ecosystem). The fix checks whether the single nested item's path starts with `self` before stripping braces. If so, the braces are preserved. ## Example **before** (`rustc 1.96.0-nightly (3b1b0ef 2026-03-11)`): ```rust #![feature(prelude_import)] //@ pp-exact //@ edition:2021 #![allow(unused_imports)] extern crate std; #[prelude_import] use std::prelude::rust_2021::*; // Braces around `self` must be preserved, because `use foo::self` is not valid Rust. use std::io::self; use std::fmt::{self, Debug}; fn main() {} ``` **after** (this branch): ```rust #![feature(prelude_import)] //@ pp-exact //@ edition:2021 #![allow(unused_imports)] extern crate std; #[prelude_import] use std::prelude::rust_2021::*; // Braces around `self` must be preserved, because `use foo::self` is not valid Rust. use std::io::{self}; use std::fmt::{self, Debug}; fn main() {} ``` Notice the `use std::io::self` (invalid, E0429) in the before becomes `use std::io::{self}` in the after.

…ivooeo Insert space after float literal ending with `.` in pretty printer The pretty printer was collapsing unsuffixed float literals (like `0.`) with adjacent dot tokens, producing ambiguous or invalid output: - `0. ..45.` (range) became `0...45.` - `0. ..=360.` (inclusive range) became `0...=360.` - `0. .to_string()` (method call) became `0..to_string()` The fix inserts a space after an unsuffixed float literal ending with `.` when it appears as the start expression of a range operator or the receiver of a method call or field access, preventing the trailing dot from merging with the following `.`, `..`, or `..=` token. This is skipped when the expression is already parenthesized, since the closing `)` naturally provides separation. ## Example **before** (`rustc 1.96.0-nightly (3b1b0ef 2026-03-11)`): ```rust #![feature(prelude_import)] #![no_std] extern crate std; #[prelude_import] use ::std::prelude::rust_2015::*; //@ pp-exact fn main() { let _ = 0...45.; let _ = 0...=360.; let _ = 0...; let _ = 0..to_string(); } ``` **after** (this branch): ```rust #![feature(prelude_import)] #![no_std] extern crate std; #[prelude_import] use ::std::prelude::rust_2015::*; //@ pp-exact fn main() { let _ = 0. ..45.; let _ = 0. ..=360.; let _ = 0. ..; let _ = 0. .to_string(); } ``` Notice `0...45.` (ambiguous — looks like deprecated `...` inclusive range) becomes `0. ..45.` (clear: float `0.` followed by range `..`). Similarly `0..to_string()` (parsed as range) becomes `0. .to_string()` (method call on float).

…space, r=Kivooeo Fix whitespace after fragment specifiers in macro pretty printing When a macro-generating-macro captures fragment specifier tokens (like `$x:ident`) as `tt` metavariables and replays them before a keyword (like `where`), the pretty printer concatenates them into an invalid fragment specifier (e.g. `$x:identwhere` instead of `$x:ident where`). This happens because `tt` captures preserve the original token spacing. When the fragment specifier name (e.g. `ident`) was originally the last token before a closing delimiter, it retains `JointHidden` spacing. The `print_tts` function only checks `space_between` for `Spacing::Alone` tokens, so `JointHidden` tokens skip the space check entirely, causing adjacent identifier-like tokens to merge. The fix adds a check in `print_tts` to insert a space between adjacent identifier-like tokens (identifiers and keywords) regardless of the original spacing, preventing them from being concatenated into invalid tokens. This is similar to the existing `space_between` mechanism that prevents token merging for `Spacing::Alone` tokens, extended to also handle `Joint`/`JointHidden` cases where two identifier-like tokens would merge. ## Example **before** (`rustc 1.96.0-nightly (3b1b0ef 2026-03-11)`): ```rust #![feature(prelude_import)] #![no_std] extern crate std; #[prelude_import] use ::std::prelude::rust_2015::*; //@ pretty-mode:expanded //@ pp-exact:macro-fragment-specifier-whitespace.pp // Test that fragment specifier names in macro definitions are properly // separated from the following keyword/identifier token when pretty-printed. // This is a regression test for a bug where `$x:ident` followed by `where` // was pretty-printed as `$x:identwhere` (an invalid fragment specifier). macro_rules! outer { ($d:tt $($params:tt)*) => { #[macro_export] macro_rules! inner { ($($params)* where $d($rest:tt)*) => {}; } }; } #[macro_export] macro_rules! inner { ($x:identwhere $ ($rest : tt)*) => {}; } fn main() {} ``` **after** (this branch): ```rust #![feature(prelude_import)] #![no_std] extern crate std; #[prelude_import] use ::std::prelude::rust_2015::*; //@ pretty-mode:expanded //@ pp-exact:macro-fragment-specifier-whitespace.pp // Test that fragment specifier names in macro definitions are properly // separated from the following keyword/identifier token when pretty-printed. // This is a regression test for a bug where `$x:ident` followed by `where` // was pretty-printed as `$x:identwhere` (an invalid fragment specifier). macro_rules! outer { ($d:tt $($params:tt)*) => { #[macro_export] macro_rules! inner { ($($params)* where $d($rest:tt)*) => {}; } }; } #[macro_export] macro_rules! inner { ($x:ident where $ ($rest : tt)*) => {}; } fn main() {} ``` Notice the `$x:identwhere` in the before — an invalid fragment specifier that causes a hard parse error. The after correctly separates it as `$x:ident where`.

JonathanBrouwer · 2026-03-19T16:10:00Z

@bors r+ rollup=never p=5

rust-bors · 2026-03-19T16:10:03Z

📌 Commit 6f3b14a has been approved by JonathanBrouwer

It is now in the queue for this repository.

JonathanBrouwer · 2026-03-19T16:10:03Z

Trying commonly failed jobs
@bors try jobs=test-various,x86_64-gnu-aux,x86_64-gnu-llvm-21-3,x86_64-msvc-1,aarch64-apple,x86_64-mingw-1

Rollup of 9 pull requests try-job: test-various try-job: x86_64-gnu-aux try-job: x86_64-gnu-llvm-21-3 try-job: x86_64-msvc-1 try-job: aarch64-apple try-job: x86_64-mingw-1

…uwer Rollup of 9 pull requests Successful merges: - #153556 (`impl` restriction lowering) - #153992 (bootstrap: Optionally print a backtrace if a command fails) - #154019 (two smaller feature cleanups) - #154059 (tests: Activate `must_not_suspend` test for `MutexGuard` dropped before `await`) - #154075 (Rewrite `query_ensure_result`.) - #154082 (Updates derive_where and removes workaround) - #154084 (Preserve braces around `self` in use tree pretty printing) - #154086 (Insert space after float literal ending with `.` in pretty printer) - #154087 (Fix whitespace after fragment specifiers in macro pretty printing)

JonathanBrouwer · 2026-03-19T18:03:46Z

@bors yield

rust-bors · 2026-03-19T18:03:51Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/23309250340

The next pull request likely to be tested is #154092.

rust-bors · 2026-03-19T19:33:43Z

☀️ Try build successful (CI)
Build commit: ff095ca (ff095cab03d3e4a84507a419248108303c7bedaf, parent: 1f7f8ea0721a3b1eb73e6c6d25cccb371434b320)

…uwer Rollup of 9 pull requests Successful merges: - #153556 (`impl` restriction lowering) - #153992 (bootstrap: Optionally print a backtrace if a command fails) - #154019 (two smaller feature cleanups) - #154059 (tests: Activate `must_not_suspend` test for `MutexGuard` dropped before `await`) - #154075 (Rewrite `query_ensure_result`.) - #154082 (Updates derive_where and removes workaround) - #154084 (Preserve braces around `self` in use tree pretty printing) - #154086 (Insert space after float literal ending with `.` in pretty printer) - #154087 (Fix whitespace after fragment specifiers in macro pretty printing)

rust-bors · 2026-03-19T21:25:42Z

💔 Test for 185535d failed: CI. Failed job:

auto - aarch64-gnu (web logs, enhanced plaintext logs)

rust-log-analyzer · 2026-03-19T21:31:35Z

The job aarch64-gnu failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] rustc_hash test:false 0.041
[RUSTC-TIMING] similar test:false 1.264
   Compiling tidy v0.1.0 (/checkout/src/tools/tidy)

Session terminated, killing shell...::group::Clock drift check
  local time: Thu Mar 19 21:25:00 UTC 2026
##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
  network time: Thu, 19 Mar 2026 21:25:00 GMT
##[endgroup]
 ...killed.

JonathanBrouwer · 2026-03-19T21:32:11Z

@bors retry
Yet another certified github moment

rust-bors · 2026-03-19T21:37:38Z

This pull request was unapproved due to being closed.

cyrgani and others added 20 commits March 17, 2026 09:27

remove internal_impls_macro feature

aa7d812

move features into the correct section

e350a56

bootstrap: Optionally print a backtrace if a command fails

c8a2c46

Updates derive_where and removes workaround

bef4b47

Resolve paths for impl restrictions using smart_resolve_path

cec0a68

Add UI tests for path resolution errors of impl restrictions

4a60dae

Rollup merge of rust-lang#154019 - cyrgani:feature-clean, r=joboet

65c7618

two smaller feature cleanups Remove an unneeded feature gate for a private macro and sort the used features correctly by whether they are language or library features.

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Rollup of 9 pull requests - #154102

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