On E0277 be clearer about implicit `Sized` bounds on type params and assoc types #120323

estebank · 2024-01-24T21:29:49Z

error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
   --> f100.rs:2:33
    |
2   |     let _ = std::mem::size_of::<[i32]>();
    |                                 ^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `[i32]`
note: required by an implicit `Sized` bound in `std::mem::size_of`
   --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22
    |
312 | pub const fn size_of<T>() -> usize {
    |                      ^ required by the implicit `Sized` requirement on this type parameter in `size_of`

Fix #120178.

rustbot · 2024-01-24T21:29:57Z

r? @b-naber

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estebank · 2024-01-25T01:24:32Z

This change as is affects incremental compilation, making the change fn foo<T>() {} to fn foo<T: Sized>() {} now be picked up as a change. Haven't looked at the incr compilation machinery in a while, so I'm not sure how long it might take me to fix that.

Edit: figured out what the issue is. My change now only adds the implicit Sized obligation if there isn't an explicit one already. When testing incr comp, the first few cases use a flag to ignore spans, but because the predicate list doesn't change (there's always 1 Sized obligation, and it doesn't have Span state), adding an explicit Sized bound doesn't trigger a recompilation requirement (as long as spans are ignored).

fmease · 2024-01-26T02:13:44Z

I will review this tomorrow together with your other PR :)

r? fmease

compiler/rustc_hir_analysis/src/astconv/bounds.rs

tests/ui/associated-types/issue-20005.stderr

fmease

Thanks a lot!

fmease · 2024-01-30T22:19:35Z

@bors r+ rollup

bors · 2024-01-30T22:19:38Z

📌 Commit 43fdb12 has been approved by fmease

It is now in the queue for this repository.

On E0277 be clearer about implicit `Sized` bounds on type params and assoc types ``` error[E0277]: the size for values of type `[i32]` cannot be known at compilation time --> f100.rs:2:33 | 2 | let _ = std::mem::size_of::<[i32]>(); | ^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[i32]` note: required by an implicit `Sized` bound in `std::mem::size_of` --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22 | 312 | pub const fn size_of<T>() -> usize { | ^ required by the implicit `Sized` requirement on this bound in `size_of` ``` Fix rust-lang#120178.

Rollup of 12 pull requests Successful merges: - rust-lang#120207 (check `RUST_BOOTSTRAP_CONFIG` in `profile_user_dist` test) - rust-lang#120321 (pattern_analysis: cleanup the contexts) - rust-lang#120323 (On E0277 be clearer about implicit `Sized` bounds on type params and assoc types) - rust-lang#120355 (document `FromIterator for Vec` allocation behaviors) - rust-lang#120396 (Account for unbounded type param receiver in suggestions) - rust-lang#120430 (std: thread_local::register_dtor fix proposal for FreeBSD.) - rust-lang#120435 (Suggest name value cfg when only value is used for check-cfg) - rust-lang#120470 (Mark "unused binding" suggestion as maybe incorrect) - rust-lang#120472 (Make duplicate lang items fatal) - rust-lang#120490 (Don't hash lints differently to non-lints.) - rust-lang#120495 (Remove the `abi_amdgpu_kernel` feature) - rust-lang#120501 (rustdoc: Correctly handle attribute merge if this is a glob reexport) Failed merges: - rust-lang#120346 (hir: Refactor getters for owner nodes) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2024-01-31T08:29:19Z

☔ The latest upstream changes (presumably #120346) made this pull request unmergeable. Please resolve the merge conflicts.

…assoc types ``` error[E0277]: the size for values of type `[i32]` cannot be known at compilation time --> f100.rs:2:33 | 2 | let _ = std::mem::size_of::<[i32]>(); | ^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[i32]` note: required by an implicit `Sized` bound in `std::mem::size_of` --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22 | 312 | pub const fn size_of<T>() -> usize { | ^ required by the implicit `Sized` requirement on this bound in `size_of` ``` Fix rust-lang#120178.

Given the previous change to add implicit `Sized` bounds only if there isn't already an explicit `Sized` bound, now the incr comp machinery doesn't consider adding the explicit bound as being dirty, as long as `-Zincremental-ignore-spans` is set.

fmease · 2024-02-01T16:25:10Z

@bors r+

bors · 2024-02-01T16:25:12Z

📌 Commit 8b0ab54 has been approved by fmease

It is now in the queue for this repository.

bors · 2024-02-01T16:25:13Z

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

On E0277 be clearer about implicit `Sized` bounds on type params and assoc types ``` error[E0277]: the size for values of type `[i32]` cannot be known at compilation time --> f100.rs:2:33 | 2 | let _ = std::mem::size_of::<[i32]>(); | ^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[i32]` note: required by an implicit `Sized` bound in `std::mem::size_of` --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22 | 312 | pub const fn size_of<T>() -> usize { | ^ required by the implicit `Sized` requirement on this bound in `size_of` ``` Fix rust-lang#120178.

estebank · 2024-02-01T22:39:14Z

@bors r=fmease

bors · 2024-02-01T22:39:17Z

📌 Commit 0df6dfd has been approved by fmease

It is now in the queue for this repository.

On E0277 be clearer about implicit `Sized` bounds on type params and assoc types ``` error[E0277]: the size for values of type `[i32]` cannot be known at compilation time --> f100.rs:2:33 | 2 | let _ = std::mem::size_of::<[i32]>(); | ^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[i32]` note: required by an implicit `Sized` bound in `std::mem::size_of` --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22 | 312 | pub const fn size_of<T>() -> usize { | ^ required by the implicit `Sized` requirement on this bound in `size_of` ``` Fix rust-lang#120178.

…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#119759 (Add FileCheck annotations to dataflow-const-prop tests) - rust-lang#120323 (On E0277 be clearer about implicit `Sized` bounds on type params and assoc types) - rust-lang#120473 (Only suggest removal of `as_*` and `to_` conversion methods on E0308) - rust-lang#120520 (Some cleanups around diagnostic levels.) - rust-lang#120540 (add test for try-block-in-match-arm) - rust-lang#120547 (`#![feature(inline_const_pat)]` is no longer incomplete) - rust-lang#120552 (Correctly check `never_type` feature gating) - rust-lang#120555 (put pnkfelix (me) back on the review queue.) - rust-lang#120556 (Improve the diagnostics for unused generic parameters) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#119759 (Add FileCheck annotations to dataflow-const-prop tests) - rust-lang#120323 (On E0277 be clearer about implicit `Sized` bounds on type params and assoc types) - rust-lang#120473 (Only suggest removal of `as_*` and `to_` conversion methods on E0308) - rust-lang#120540 (add test for try-block-in-match-arm) - rust-lang#120547 (`#![feature(inline_const_pat)]` is no longer incomplete) - rust-lang#120552 (Correctly check `never_type` feature gating) - rust-lang#120555 (put pnkfelix (me) back on the review queue.) - rust-lang#120556 (Improve the diagnostics for unused generic parameters) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#120323 - estebank:issue-120178, r=fmease On E0277 be clearer about implicit `Sized` bounds on type params and assoc types ``` error[E0277]: the size for values of type `[i32]` cannot be known at compilation time --> f100.rs:2:33 | 2 | let _ = std::mem::size_of::<[i32]>(); | ^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `[i32]` note: required by an implicit `Sized` bound in `std::mem::size_of` --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22 | 312 | pub const fn size_of<T>() -> usize { | ^ required by the implicit `Sized` requirement on this bound in `size_of` ``` Fix rust-lang#120178.

… r=estebank Make sure to insert `Sized` bound first into clauses list rust-lang#120323 made it so that we don't insert an implicit `Sized` bound whenever we see an *explicit* `Sized` bound. However, since the code that inserts implicit sized bounds puts the bound as the *first* in the list, that means that it had the **side-effect** of possibly meaning we check `Sized` *after* checking other trait bounds. If those trait bounds result in ambiguity or overflow or something, it may change how we winnow candidates. (**edit: SEE** rust-lang#123303) This is likely the cause for the regression in rust-lang#123279 (comment), since the impl... ```rust impl<T: Job + Sized> AsJob for T { // <----- changing this to `Sized + Job` or just `Job` (which turns into `Sized + Job`) will FIX the issue. } ``` ...looks incredibly suspicious. Fixes [after beta-backport] rust-lang#123279. Alternative is to revert rust-lang#120323. I don't have a strong opinion about this, but think it may be nice to keep the diagnostic changes around.

Rollup merge of rust-lang#123302 - compiler-errors:sized-bound-first, r=estebank Make sure to insert `Sized` bound first into clauses list rust-lang#120323 made it so that we don't insert an implicit `Sized` bound whenever we see an *explicit* `Sized` bound. However, since the code that inserts implicit sized bounds puts the bound as the *first* in the list, that means that it had the **side-effect** of possibly meaning we check `Sized` *after* checking other trait bounds. If those trait bounds result in ambiguity or overflow or something, it may change how we winnow candidates. (**edit: SEE** rust-lang#123303) This is likely the cause for the regression in rust-lang#123279 (comment), since the impl... ```rust impl<T: Job + Sized> AsJob for T { // <----- changing this to `Sized + Job` or just `Job` (which turns into `Sized + Job`) will FIX the issue. } ``` ...looks incredibly suspicious. Fixes [after beta-backport] rust-lang#123279. Alternative is to revert rust-lang#120323. I don't have a strong opinion about this, but think it may be nice to keep the diagnostic changes around.

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Nadrieril mentioned this pull request Jan 31, 2024

Rollup of 12 pull requests #120519

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estebank added 2 commits February 1, 2024 03:31

review comment: change wording

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matthiaskrgr mentioned this pull request Feb 1, 2024

Rollup of 9 pull requests #120560

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fix rebase

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matthiaskrgr mentioned this pull request Feb 1, 2024

Rollup of 9 pull requests #120561

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matthiaskrgr mentioned this pull request Feb 4, 2024

Rollup of 8 pull requests #120649

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bors merged commit 6af0458 into rust-lang:master Feb 5, 2024

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regression: trait bound is not satisfied #123279

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Make sure to insert Sized bound first into clauses list #123302

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On E0277 be clearer about implicit `Sized` bounds on type params and assoc types #120323

On E0277 be clearer about implicit `Sized` bounds on type params and assoc types #120323

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On E0277 be clearer about implicit Sized bounds on type params and assoc types #120323

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On E0277 be clearer about implicit `Sized` bounds on type params and assoc types #120323

On E0277 be clearer about implicit `Sized` bounds on type params and assoc types #120323

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