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Also expand weak alias tys inside consts inside expand_weak_alias_tys #124990

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merged 1 commit into from
May 15, 2024

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@fmease fmease commented May 10, 2024

Ever since #121344 has been merged, I couldn't let go of the fear that I might've slipped a tiny bug into rustc (:P).

Checking the type flags of the Const is strictly more correct than only checking the ones of the Const's Ty. I don't think it's possible to trigger an ICE rn (i.e., one of the two bug!("unexpected weak alias type") I added in branches where expand_weak_alias_tys should've expanded all weak alias tys) because presently const exprs aren't allowed to capture late-bound vars. To be future-proof however, we should iron this out.

A possible reproducer would be the following if I'm not mistaken (currently fails to compile due to the aforementioned restriction):

#![feature(lazy_type_alias, adt_const_params, generic_const_exprs)]

type F = for<'a> fn(A<{ S::<Weak<'a>>(loop {}) }>) -> &'a ();

type A<const N: S<Weak<'static>>> = ();

#[derive(PartialEq, Eq, std::marker::ConstParamTy)]
struct S<T>(T);

type Weak<'a> = &'a ();

Whether a late-bound region should actually be considered constrained by a const expr is a separate question — one which we don't need to answer until / unless we actually allow them in such contexts (probable answer: only inside the return exprs of a block but not inside the stmts).

r? oli-obk (he's not available rn but that's fine) or types or compiler

@fmease fmease added the F-lazy_type_alias `#![feature(lazy_type_alias)]` label May 10, 2024
@rustbot 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 May 10, 2024
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r? compiler-errors @bors r+ rollup

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bors commented May 15, 2024

📌 Commit 35a5be2 has been approved by compiler-errors

It is now in the queue for this repository.

@bors 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 May 15, 2024
bors added a commit to rust-lang-ci/rust that referenced this pull request May 15, 2024
…iaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#124990 (Also expand weak alias tys inside consts inside `expand_weak_alias_tys`)
 - rust-lang#125108 (coverage: `CoverageIdsInfo::mcdc_bitmap_bytes` is never needed)
 - rust-lang#125132 (Add `on_unimplemented" typo suggestions)
 - rust-lang#125135 (Fix the dedup error because of spans from suggestion)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 03ff673 into rust-lang:master May 15, 2024
6 checks passed
@rustbot rustbot added this to the 1.80.0 milestone May 15, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request May 15, 2024
Rollup merge of rust-lang#124990 - fmease:expand-weak-aliases-within-cts, r=compiler-errors

Also expand weak alias tys inside consts inside `expand_weak_alias_tys`

Ever since rust-lang#121344 has been merged, I couldn't let go of the fear that I might've slipped a tiny bug into rustc (:P).

Checking the type flags of the `Const` is strictly more correct than only checking the ones of the `Const`'s `Ty`. I don't think it's possible to trigger an ICE rn (i.e., one of the two `bug!("unexpected weak alias type")` I added in branches where `expand_weak_alias_tys` should've expanded *all* weak alias tys) because presently const exprs aren't allowed to capture late-bound vars. To be future-proof however, we should iron this out.

A possible reproducer would be the following if I'm not mistaken (currently fails to compile due to the aforementioned restriction):

```rs
#![feature(lazy_type_alias, adt_const_params, generic_const_exprs)]

type F = for<'a> fn(A<{ S::<Weak<'a>>(loop {}) }>) -> &'a ();

type A<const N: S<Weak<'static>>> = ();

#[derive(PartialEq, Eq, std::marker::ConstParamTy)]
struct S<T>(T);

type Weak<'a> = &'a ();
```

Whether a late-bound region should actually be considered constrained by a const expr is a separate question — one which we don't need to answer until / unless we actually allow them in such contexts (probable answer: only inside the return exprs of a block but not inside the stmts).

r? oli-obk (he's not available rn but that's fine) or types or compiler
@fmease fmease deleted the expand-weak-aliases-within-cts branch May 15, 2024 08:33
celinval added a commit to celinval/rust-dev that referenced this pull request Jun 4, 2024
Update Rust toolchain from nightly-2024-05-15 to nightly-2024-05-16
without any other source changes.
This is an automatically generated pull request. If any of the CI checks
fail, manual intervention is required. In such a case, review the
changes at https://github.com/rust-lang/rust from
rust-lang@8387315
up to
rust-lang@1871252.
The log for this commit range is:
rust-lang@1871252fc8 Auto merge of
rust-lang#125164 - fmease:rollup-s5vwzlg, r=fmease
rust-lang@734a109998 Rollup merge of
rust-lang#125159 - fmease:allow-unauth-labels-l-pg-z, r=jieyouxu
rust-lang@601e5d199f Rollup merge of
rust-lang#125154 - FractalFir:fnabi_doc, r=compiler-errors
rust-lang@09156291e5 Rollup merge of
rust-lang#125146 - Oneirical:panic-impl, r=jieyouxu
rust-lang@80f991e09b Rollup merge of
rust-lang#125142 - GuillaumeGomez:migrate-rustdoc-themes, r=jieyouxu
rust-lang@c5b17ec9d2 Rollup merge of
rust-lang#125003 - RalfJung:aligned_alloc, r=cuviper
rust-lang@257d222e4b Improved the
documentation of the FnAbi struct
rust-lang@72a48fc68c Allow
unauthenticated users to modify `L-*`, `PG-*` and `-Z*` labels
rust-lang@b21b74b5e6 Auto merge of
rust-lang#125134 - compiler-errors:negative-traits-are-not-notable, r=fmease
rust-lang@a7484d2e49 fix tidy
rust-lang@cae17ff42b rewrite
panic-impl-transitive
rust-lang@ade234d574 Auto merge of
rust-lang#125144 - fmease:rollup-4uft293, r=fmease
rust-lang@8d38f2fb11 Rollup merge of
rust-lang#125137 - RalfJung:mir-sh, r=scottmcm
rust-lang@2659ff3882 Rollup merge of
rust-lang#125104 - Oneirical:test6, r=jieyouxu
rust-lang@4f7d9d4ad8 Rollup merge of
rust-lang#125038 - ivan-shrimp:checked_sub, r=joboet
rust-lang@2804d4223b Rollup merge of
rust-lang#125027 - Oneirical:c-test-with-remove, r=jieyouxu
rust-lang@2e70bea168 Rollup merge of
rust-lang#124975 - lu-zero:move_file, r=clubby789
rust-lang@3873a74f8a Rollup merge of
rust-lang#124307 - reitermarkus:escape-debug-size-hint-inline, r=joboet
rust-lang@3cb0030fe9 Auto merge of
rust-lang#123413 - petrochenkov:delegmulti2, r=fmease
rust-lang@c765480efe Migrate
`run-make/rustdoc-themes` to new rmake
rust-lang@c87ae947eb Add new `htmldocck`
function to `run-make-support`
rust-lang@a71c3ffce9 Auto merge of
rust-lang#125032 - compiler-errors:crash-dump-dir, r=onur-ozkan
rust-lang@0afd50e852 MIR operators:
clarify Shl/Shr handling of negative offsets
rust-lang@44fa5fd39a Auto merge of
rust-lang#125136 - matthiaskrgr:rollup-ljm15m3, r=matthiaskrgr
rust-lang@5f1a120ee5 Rollup merge of
rust-lang#125135 - chenyukang:yukang-fix-116502, r=compiler-errors
rust-lang@f7c2934420 Rollup merge of
rust-lang#125132 - mejrs:diag, r=compiler-errors
rust-lang@a8ff937b07 Rollup merge of
rust-lang#125108 - Zalathar:info-bitmap-bytes, r=nnethercote
rust-lang@03ff673dcc Rollup merge of
rust-lang#124990 - fmease:expand-weak-aliases-within-cts, r=compiler-errors
rust-lang@75895f59b0 Fix the dedup error
because of spans from suggestion
rust-lang@9e7aff7945 Auto merge of
rust-lang#125031 - Oneirical:dynamic-libs, r=jieyouxu
rust-lang@8994840f7e rustdoc: Negative
impls are not notable
rust-lang@91a3f04a3f fix the test
rust-lang@0160bff4b1 Auto merge of
rust-lang#125084 - Jules-Bertholet:fix-125058, r=Nadrieril
rust-lang@c30b41012d delegation:
Implement list delegation
rust-lang@18d7411719 Add
`on_unimplemented" typo suggestions
rust-lang@81f7e54962 Port issue-11908 to
rmake
rust-lang@1f61cc3078 port
no-cdylib-as-rdylib test
rust-lang@b1e5e5161a remove cxx_flags
rust-lang@1f5837ae25 rewrite
c-link-to-rust-staticlib
rust-lang@5cc020d3df avoid using
aligned_alloc; posix_memalign is better-behaved
rust-lang@c81be68fb4 coverage: Remove
confusing comments from `CoverageKind`
rust-lang@bfadc3a9b9 coverage:
`CoverageIdsInfo::mcdc_bitmap_bytes` is never needed
rust-lang@fe8f66e4bc `rustc_hir_typeck`:
Account for `skipped_ref_pats` in `expr_use_visitor`
rust-lang@4db00fe229 Use an helper to
move the files
rust-lang@7fde7308bf reverse condition in
`uN::checked_sub`
rust-lang@848f3c2c6e Make crashes dump
mir to build dir
rust-lang@35a5be2833 Also expand weak
alias tys inside consts inside `expand_weak_alias_tys`
rust-lang@4edf12d33e Improve escape
methods.
rust-lang@16981ba406 Avoid panicking
branch in `EscapeIterInner`.
rust-lang@e3fc97be2b Inline
`EscapeDebug::size_hint`.

Co-authored-by: celinval <[email protected]>
Co-authored-by: Zyad Hassan <[email protected]>
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