exhaustiveness: Explain why a given pattern is considered unreachable #128034

Nadrieril · 2024-07-21T13:41:30Z

This PR tells the user why a given pattern is considered unreachable. I reused the intersection information we were already computing; even though it's incomplete I convinced myself that it is sufficient to always get a set of patterns that cover the unreachable one.

I'm not a fan of the diagnostic messages I came up with, I'm open to suggestions.

Fixes #127870. This is also the other one of the two diagnostic improvements I wanted to do before #122792.

Note: the first commit is an unrelated drive-by tweak.

r? @compiler-errors

Nadrieril · 2024-07-21T13:43:11Z

tests/ui/or-patterns/exhaustiveness-unreachable-pattern.stderr

+LL |         (1 | 2,) => {}
+   |         -------- matches all the values already
 LL |         (1,) => {}
-   |         ^^^^
+   |         ^^^^ unreachable pattern


@estebank do you have a better idea for the message here? I want to express that the pattern above already matches all the values matched by the pattern below but I'm not sure what terminology is appropriate.

What about "unreachable pattern because it is already fully covered by a(n) earlier one(s)"?

or slightly shorter: "unreachable pattern is already fully covered by an earlier one"

I like this. What about the "matches all the values already"?

tests/ui/or-patterns/exhaustiveness-unreachable-pattern.stderr

Nadrieril · 2024-07-21T16:35:01Z

Turns out we can always get a covering set of patterns! I updated the code and added a proof-sketch as to why.

Nadrieril · 2024-07-21T19:21:56Z

@bors try @rust-timer queue

exhaustiveness: Explain why a given pattern is considered unreachable This PR tells the user why a given pattern is considered unreachable. I reused the intersection information we were already computing; even though it's incomplete I convinced myself that it is sufficient to always get a set of patterns that cover the unreachable one. I'm not a fan of the diagnostic messages I came up with, I'm open to suggestions. Fixes rust-lang#127870. This is also the other one of the two diagnostic improvements I wanted to do before rust-lang#122792. Note: the first commit is rust-lang#128015, the second is an unrelated drive-by tweak. r? `@compiler-errors`

bors · 2024-07-21T19:23:07Z

⌛ Trying commit fbc2f03 with merge 49ee7bc...

bors · 2024-07-21T21:12:55Z

☀️ Try build successful - checks-actions
Build commit: 49ee7bc (49ee7bc0950a2e4d6de1d7b8e1dad394785091fe)

rust-timer · 2024-07-21T22:29:25Z

Finished benchmarking commit (49ee7bc): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.5%	[0.1%, 1.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

Results (secondary -2.5%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-2.6%, -2.4%]	2
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 772.021s -> 773.1s (0.14%)
Artifact size: 328.86 MiB -> 328.93 MiB (0.02%)

Nadrieril · 2024-07-24T06:53:14Z

@rustbot ready

compiler/rustc_pattern_analysis/src/pat.rs

compiler-errors · 2024-07-25T15:19:46Z

@bors r+ rollup=never

bors · 2024-07-25T15:19:49Z

📌 Commit 940769a has been approved by compiler-errors

It is now in the queue for this repository.

estebank · 2024-07-25T16:57:59Z

tests/ui/pattern/usefulness/empty-types.min_exh_pats.stderr

@@ -403,18 +456,24 @@ error: unreachable pattern
   |
 LL |         _ => {}
   |         ^
+   |
+   = note: this pattern matches no values because `[!; 3]` is uninhabited


We should look into making this the span label and maybe have the note be a link to an explanation of uninhabited types (!).

estebank · 2024-07-25T16:59:13Z

tests/ui/pattern/usefulness/explain-unreachable-pats.stderr

+LL |         (_, true) => {}
+   |         ^^^^^^^^^ unreachable pattern
+   |
+note: these patterns collectively make the last one unreachable


We're not assured that the unreachable pattern was the last one, so we should tweak the wording of this note message to be something along the lines "these patterns collectively make the other one unreachable" or something.

Hm, it may not be the last one in term of spans, but it has to be the last one in terms of match order

estebank · 2024-07-25T16:59:41Z

@Nadrieril thank you for doing this! It's gonna be super helpful.

bors · 2024-07-26T10:51:07Z

⌛ Testing commit 940769a with merge 355efac...

tgross35 · 2024-07-26T11:48:32Z

tests/ui/error-codes/E0001.stderr

+LL |         Some(_) => {/* ... */}
+   |         ------- matches some of the same values
+LL |         None => {/* ... */}
+   |         ---- matches some of the same values
+LL |         _ => {/* ... */}
+   |         ^ collectively making this unreachable


I find the flat line a bit hard to parse, looks more like a separator or a leader to another arrow than an indicator itself. Any specific reason this uses the spatula rather than the forks?

(regardless, this change is wonderful)

I don't know what "spatula" and "forks" mean, I think just used the default principal/non-principal span mechanism in diagnostics

I was being too creative, but

______-- spatula

^^--- fork

I figured it wasn't anything done specifically here. This diagnostic just winds up with more alternating lines of code and ---- than many others, and I think it is somewhat ambiguous whether ---- refers to the line up or down.

Obviously not a big deal since it is just a hint anyway.

I see. It looks a lot clearer with color at least

bors · 2024-07-26T13:11:55Z

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing 355efac to master...

rust-timer · 2024-07-26T14:31:47Z

Finished benchmarking commit (355efac): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.2%	[0.1%, 0.2%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -3.1%, secondary -3.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.1%	[-4.9%, -1.3%]	2
Improvements ✅ (secondary)	-3.1%	[-3.1%, -3.1%]	1
All ❌✅ (primary)	-3.1%	[-4.9%, -1.3%]	2

Cycles

Results (secondary 3.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.0%	[3.0%, 3.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 771.116s -> 771.493s (0.05%)
Artifact size: 328.99 MiB -> 328.96 MiB (-0.01%)

Nadrieril · 2024-07-26T23:16:31Z

@estebank let's chat about this, I can make another PR to tweak the messages

Nadrieril · 2024-07-27T08:38:04Z

Is this worthy of relnotes? I think it's cute

…ording, r=estebank Tweak unreachable lint wording Some tweaks to the notes added in rust-lang#128034. r? `@estebank`

Rollup merge of rust-lang#129281 - Nadrieril:tweak-unreachable-lint-wording, r=estebank Tweak unreachable lint wording Some tweaks to the notes added in rust-lang#128034. r? `@estebank`

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [rust](https://github.com/rust-lang/rust) | minor | `1.81.0` -> `1.82.0` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>rust-lang/rust (rust)</summary> ### [`v1.82.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1820-2024-10-17) [Compare Source](rust-lang/rust@1.81.0...1.82.0) \========================== <a id="1.82.0-Language"></a> ## Language - [Don't make statement nonterminals match pattern nonterminals](rust-lang/rust#120221) - [Patterns matching empty types can now be omitted in common cases](rust-lang/rust#122792) - [Enforce supertrait outlives obligations when using trait impls](rust-lang/rust#124336) - [`addr_of(_mut)!` macros and the newly stabilized `&raw (const|mut)` are now safe to use with all static items](rust-lang/rust#125834) - [size_of_val_raw: for length 0 this is safe to call](rust-lang/rust#126152) - [Reorder trait bound modifiers *after* `for<...>` binder in trait bounds](rust-lang/rust#127054) - [Stabilize opaque type precise capturing (RFC 3617)](rust-lang/rust#127672) - [Stabilize `&raw const` and `&raw mut` operators (RFC 2582)](rust-lang/rust#127679) - [Stabilize unsafe extern blocks (RFC 3484)](rust-lang/rust#127921) - [Stabilize nested field access in `offset_of!`](rust-lang/rust#128284) - [Do not require `T` to be live when dropping `[T; 0]`](rust-lang/rust#128438) - [Stabilize `const` operands in inline assembly](rust-lang/rust#128570) - [Stabilize floating-point arithmetic in `const fn`](rust-lang/rust#128596) - [Stabilize explicit opt-in to unsafe attributes](rust-lang/rust#128771) - [Document NaN bit patterns guarantees](rust-lang/rust#129559) <a id="1.82.0-Compiler"></a> ## Compiler - [Promote riscv64gc-unknown-linux-musl to tier 2](rust-lang/rust#122049) - [Promote Mac Catalyst targets `aarch64-apple-ios-macabi` and `x86_64-apple-ios-macabi` to Tier 2, and ship them with rustup](rust-lang/rust#126450) - [Add tier 3 NuttX based targets for RISC-V and ARM](rust-lang/rust#127755) - [Add tier 3 powerpc-unknown-linux-muslspe target](rust-lang/rust#127905) - [Improved diagnostics to explain why a pattern is unreachable](rust-lang/rust#128034) - [The compiler now triggers the unreachable code warning properly for async functions that don't return/are `-> !`](rust-lang/rust#128443) - [Promote `aarch64-apple-darwin` to Tier 1](rust-lang/rust#128592) - [Add Trusty OS target `aarch64-unknown-trusty` and `armv7-unknown-trusty` as tier 3 targets](rust-lang/rust#129490) - [Promote `wasm32-wasip2` to Tier 2.](rust-lang/rust#126967) <a id="1.82.0-Libraries"></a> ## Libraries - [Generalize `{Rc,Arc}::make_mut()` to `Path`, `OsStr`, and `CStr`.](rust-lang/rust#126877) <a id="1.82.0-Stabilized-APIs"></a> ## Stabilized APIs - [`std::thread::Builder::spawn_unchecked`](https://doc.rust-lang.org/stable/std/thread/struct.Builder.html#method.spawn_unchecked) - [`std::str::CharIndices::offset`](https://doc.rust-lang.org/nightly/std/str/struct.CharIndices.html#method.offset) - [`std::option::Option::is_none_or`](https://doc.rust-lang.org/nightly/std/option/enum.Option.html#method.is_none_or) - [`[T]::is_sorted`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.is_sorted) - [`[T]::is_sorted_by`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.is_sorted_by) - [`[T]::is_sorted_by_key`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.is_sorted_by_key) - [`Iterator::is_sorted`](https://doc.rust-lang.org/nightly/std/iter/trait.Iterator.html#method.is_sorted) - [`Iterator::is_sorted_by`](https://doc.rust-lang.org/nightly/std/iter/trait.Iterator.html#method.is_sorted_by) - [`Iterator::is_sorted_by_key`](https://doc.rust-lang.org/nightly/std/iter/trait.Iterator.html#method.is_sorted_by_key) - [`std::future::Ready::into_inner`](https://doc.rust-lang.org/nightly/std/future/struct.Ready.html#method.into_inner) - [`std::iter::repeat_n`](https://doc.rust-lang.org/nightly/std/iter/fn.repeat_n.html) - [`impl<T: Clone> DoubleEndedIterator for Take<Repeat<T>>`](https://doc.rust-lang.org/nightly/std/iter/struct.Take.html#impl-DoubleEndedIterator-for-Take%3CRepeat%3CT%3E%3E) - [`impl<T: Clone> ExactSizeIterator for Take<Repeat<T>>`](https://doc.rust-lang.org/nightly/std/iter/struct.Take.html#impl-ExactSizeIterator-for-Take%3CRepeat%3CT%3E%3E) - [`impl<T: Clone> ExactSizeIterator for Take<RepeatWith<T>>`](https://doc.rust-lang.org/nightly/std/iter/struct.Take.html#impl-ExactSizeIterator-for-Take%3CRepeatWith%3CF%3E%3E) - [`impl Default for std::collections::binary_heap::Iter`](https://doc.rust-lang.org/nightly/std/collections/binary_heap/struct.Iter.html#impl-Default-for-Iter%3C'\_,+T%3E) - [`impl Default for std::collections::btree_map::RangeMut`](https://doc.rust-lang.org/nightly/std/collections/btree_map/struct.RangeMut.html#impl-Default-for-RangeMut%3C'\_,+K,+V%3E) - [`impl Default for std::collections::btree_map::ValuesMut`](https://doc.rust-lang.org/nightly/std/collections/btree_map/struct.ValuesMut.html#impl-Default-for-ValuesMut%3C'\_,+K,+V%3E) - [`impl Default for std::collections::vec_deque::Iter`](https://doc.rust-lang.org/nightly/std/collections/vec_deque/struct.Iter.html#impl-Default-for-Iter%3C'\_,+T%3E) - [`impl Default for std::collections::vec_deque::IterMut`](https://doc.rust-lang.org/nightly/std/collections/vec_deque/struct.IterMut.html#impl-Default-for-IterMut%3C'\_,+T%3E) - [`Rc<T>::new_uninit`](https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.new_uninit) - [`Rc<T>::assume_init`](https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.assume_init) - [`Rc<[T]>::new_uninit_slice`](https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.new_uninit_slice) - [`Rc<[MaybeUninit<T>]>::assume_init`](https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.assume_init-1) - [`Arc<T>::new_uninit`](https://doc.rust-lang.org/nightly/std/sync/struct.Arc.html#method.new_uninit) - [`Arc<T>::assume_init`](https://doc.rust-lang.org/nightly/std/sync/struct.Arc.html#method.assume_init) - [`Arc<[T]>::new_uninit_slice`](https://doc.rust-lang.org/nightly/std/sync/struct.Arc.html#method.new_uninit_slice) - [`Arc<[MaybeUninit<T>]>::assume_init`](https://doc.rust-lang.org/nightly/std/sync/struct.Arc.html#method.assume_init-1) - [`Box<T>::new_uninit`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html#method.new_uninit) - [`Box<T>::assume_init`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html#method.assume_init) - [`Box<[T]>::new_uninit_slice`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html#method.new_uninit_slice) - [`Box<[MaybeUninit<T>]>::assume_init`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html#method.assume_init-1) - [`core::arch::x86_64::_bextri_u64`](https://doc.rust-lang.org/stable/core/arch/x86\_64/fn.\_bextri_u64.html) - [`core::arch::x86_64::_bextri_u32`](https://doc.rust-lang.org/stable/core/arch/x86\_64/fn.\_bextri_u32.html) - [`core::arch::x86::_mm_broadcastsi128_si256`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_broadcastsi128\_si256.html) - [`core::arch::x86::_mm256_stream_load_si256`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm256\_stream_load_si256.html) - [`core::arch::x86::_tzcnt_u16`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_tzcnt_u16.html) - [`core::arch::x86::_mm_extracti_si64`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_extracti_si64.html) - [`core::arch::x86::_mm_inserti_si64`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_inserti_si64.html) - [`core::arch::x86::_mm_storeu_si16`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_storeu_si16.html) - [`core::arch::x86::_mm_storeu_si32`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_storeu_si32.html) - [`core::arch::x86::_mm_storeu_si64`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_storeu_si64.html) - [`core::arch::x86::_mm_loadu_si16`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_loadu_si16.html) - [`core::arch::x86::_mm_loadu_si32`](https://doc.rust-lang.org/stable/core/arch/x86/fn.\_mm_loadu_si32.html) - [`core::arch::wasm32::u8x16_relaxed_swizzle`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u8x16\_relaxed_swizzle.html) - [`core::arch::wasm32::i8x16_relaxed_swizzle`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i8x16\_relaxed_swizzle.html) - [`core::arch::wasm32::i32x4_relaxed_trunc_f32x4`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i32x4\_relaxed_trunc_f32x4.html) - [`core::arch::wasm32::u32x4_relaxed_trunc_f32x4`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u32x4\_relaxed_trunc_f32x4.html) - [`core::arch::wasm32::i32x4_relaxed_trunc_f64x2_zero`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i32x4\_relaxed_trunc_f64x2\_zero.html) - [`core::arch::wasm32::u32x4_relaxed_trunc_f64x2_zero`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u32x4\_relaxed_trunc_f64x2\_zero.html) - [`core::arch::wasm32::f32x4_relaxed_madd`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f32x4\_relaxed_madd.html) - [`core::arch::wasm32::f32x4_relaxed_nmadd`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f32x4\_relaxed_nmadd.html) - [`core::arch::wasm32::f64x2_relaxed_madd`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f64x2\_relaxed_madd.html) - [`core::arch::wasm32::f64x2_relaxed_nmadd`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f64x2\_relaxed_nmadd.html) - [`core::arch::wasm32::i8x16_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i8x16\_relaxed_laneselect.html) - [`core::arch::wasm32::u8x16_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u8x16\_relaxed_laneselect.html) - [`core::arch::wasm32::i16x8_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i16x8\_relaxed_laneselect.html) - [`core::arch::wasm32::u16x8_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u16x8\_relaxed_laneselect.html) - [`core::arch::wasm32::i32x4_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i32x4\_relaxed_laneselect.html) - [`core::arch::wasm32::u32x4_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u32x4\_relaxed_laneselect.html) - [`core::arch::wasm32::i64x2_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i64x2\_relaxed_laneselect.html) - [`core::arch::wasm32::u64x2_relaxed_laneselect`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u64x2\_relaxed_laneselect.html) - [`core::arch::wasm32::f32x4_relaxed_min`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f32x4\_relaxed_min.html) - [`core::arch::wasm32::f32x4_relaxed_max`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f32x4\_relaxed_max.html) - [`core::arch::wasm32::f64x2_relaxed_min`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f64x2\_relaxed_min.html) - [`core::arch::wasm32::f64x2_relaxed_max`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.f64x2\_relaxed_max.html) - [`core::arch::wasm32::i16x8_relaxed_q15mulr`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i16x8\_relaxed_q15mulr.html) - [`core::arch::wasm32::u16x8_relaxed_q15mulr`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u16x8\_relaxed_q15mulr.html) - [`core::arch::wasm32::i16x8_relaxed_dot_i8x16_i7x16`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i16x8\_relaxed_dot_i8x16\_i7x16.html) - [`core::arch::wasm32::u16x8_relaxed_dot_i8x16_i7x16`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u16x8\_relaxed_dot_i8x16\_i7x16.html) - [`core::arch::wasm32::i32x4_relaxed_dot_i8x16_i7x16_add`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.i32x4\_relaxed_dot_i8x16\_i7x16\_add.html) - [`core::arch::wasm32::u32x4_relaxed_dot_i8x16_i7x16_add`](https://doc.rust-lang.org/nightly/core/arch/wasm32/fn.u32x4\_relaxed_dot_i8x16\_i7x16\_add.html) These APIs are now stable in const contexts: - [`std::task::Waker::from_raw`](https://doc.rust-lang.org/nightly/std/task/struct.Waker.html#method.from_raw) - [`std::task::Context::from_waker`](https://doc.rust-lang.org/nightly/std/task/struct.Context.html#method.from_waker) - [`std::task::Context::waker`](https://doc.rust-lang.org/nightly/std/task/struct.Context.html#method.waker) - [`$integer::from_str_radix`](https://doc.rust-lang.org/nightly/std/primitive.u32.html#method.from_str_radix) - [`std::num::ParseIntError::kind`](https://doc.rust-lang.org/nightly/std/num/struct.ParseIntError.html#method.kind) <a id="1.82.0-Cargo"></a> ## Cargo - [feat: Add `info` cargo subcommand](rust-lang/cargo#14141) <a id="1.82.0-Compatibility-Notes"></a> ## Compatibility Notes - We now [disallow setting some built-in cfgs via the command-line](rust-lang/rust#126158) with the newly added [`explicit_builtin_cfgs_in_flags`](https://doc.rust-lang.org/rustc/lints/listing/deny-by-default.html#explicit-builtin-cfgs-in-flags) lint in order to prevent incoherent state, eg. `windows` cfg active but target is Linux based. The appropriate [`rustc` flag](https://doc.rust-lang.org/rustc/command-line-arguments.html) should be used instead. - The standard library has a new implementation of `binary_search` which is significantly improves performance ([#128254](rust-lang/rust#128254)). However when a sorted slice has multiple values which compare equal, the new implementation may select a different value among the equal ones than the old implementation. - [illumos/Solaris now sets `MSG_NOSIGNAL` when writing to sockets](rust-lang/rust#128259). This avoids killing the process with SIGPIPE when writing to a closed socket, which matches the existing behavior on other UNIX targets. - [Removes a problematic hack that always passed the --whole-archive linker flag for tests, which may cause linker errors for code accidentally relying on it.](rust-lang/rust#128400) - The WebAssembly target features `multivalue` and `reference-types` are now both enabled by default. These two features both have subtle changes implied for generated WebAssembly binaries. For the `multivalue` feature, WebAssembly target support has changed when upgrading to LLVM 19. Support for generating functions with multiple returns no longer works and `-Ctarget-feature=+multivalue` has a different meaning than it did in LLVM 18 and prior. There is no longer any supported means to generate a module that has a function with multiple returns in WebAssembly from Rust source code. For the `reference-types` feature the encoding of immediates in the `call_indirect`, a commonly used instruction by the WebAssembly backend, has changed. Validators and parsers which don't understand the `reference-types` proposal will no longer accept modules produced by LLVM due to this change in encoding of immediates. Additionally these features being enabled are encoded in the `target_features` custom section and may affect downstream tooling such as `wasm-opt` consuming the module. Generating a WebAssembly module that disables default features requires `-Zbuild-std` support from Cargo and more information can be found at [rust-lang/rust#128511](rust-lang/rust#128511). - [Rust now raises unsafety errors for union patterns in parameter-position](rust-lang/rust#130531) <a id="1.82.0-Internal-Changes"></a> ## Internal Changes These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Update to LLVM 19](rust-lang/rust#127513) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

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Nadrieril commented Jul 21, 2024

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Nadrieril force-pushed the explain-unreachable branch from 6cf3c4c to 1b18b16 Compare July 21, 2024 16:34

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Nadrieril added 3 commits July 24, 2024 08:02

Move rustc-specific entrypoint to the rustc module

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Add some tests

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Explain why a given pattern is considered unreachable

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Nadrieril force-pushed the explain-unreachable branch from fbc2f03 to 6d2a803 Compare July 24, 2024 06:40

Improve "covered_by_many" error

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Nadrieril force-pushed the explain-unreachable branch from 6d2a803 to 940769a Compare July 24, 2024 06:46

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This was referenced Jul 26, 2024

Stabilize min_exhaustive_patterns #122792

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Emit a warning if a match is too complex #122685

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Nadrieril deleted the explain-unreachable branch July 26, 2024 23:15

traviscross added the relnotes Marks issues that should be documented in the release notes of the next release. label Jul 27, 2024

Nadrieril mentioned this pull request Aug 19, 2024

Tweak unreachable lint wording #129281

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Tracking issue for release notes of #128034: exhaustiveness: Explain why a given pattern is considered unreachable #129574

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exhaustiveness: Explain why a given pattern is considered unreachable #128034

exhaustiveness: Explain why a given pattern is considered unreachable #128034

Nadrieril commented Jul 21, 2024 •

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exhaustiveness: Explain why a given pattern is considered unreachable #128034

exhaustiveness: Explain why a given pattern is considered unreachable #128034

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rust-timer commented Jul 21, 2024

Overall result: ❌✅ regressions and improvements - no action needed

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rust-timer commented Jul 26, 2024

Overall result: ❌ regressions - no action needed

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