This handles using deref patterns to choose the correct match arm. This
does not handle bindings or guards.
Co-authored-by: Deadbeef <ent3rm4n@gmail.com>
For ref pattern in func param, the mutability suggestion has to apply to the binding.
For example: `fn foo(&x: &i32)` -> `fn foo(&(mut x): &i32)`
fixes#122415
never patterns: suggest `!` patterns on non-exhaustive matches
When a match is non-exhaustive we now suggest never patterns whenever it makes sense.
r? ``@compiler-errors``
Detect calls to .clone() on T: !Clone types on borrowck errors
When encountering a lifetime error on a type that *holds* a type that doesn't implement `Clone`, explore the item's body for potential calls to `.clone()` that are only cloning the reference `&T` instead of `T` because `T: !Clone`. If we find this, suggest `T: Clone`.
```
error[E0502]: cannot borrow `*list` as mutable because it is also borrowed as immutable
--> $DIR/clone-on-ref.rs:7:5
|
LL | for v in list.iter() {
| ---- immutable borrow occurs here
LL | cloned_items.push(v.clone())
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
LL | }
LL | list.push(T::default());
| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL |
LL | drop(cloned_items);
| ------------ immutable borrow later used here
|
help: consider further restricting this bound
|
LL | fn foo<T: Default + Clone>(list: &mut Vec<T>) {
| +++++++
```
```
error[E0505]: cannot move out of `x` because it is borrowed
--> $DIR/clone-on-ref.rs:23:10
|
LL | fn qux(x: A) {
| - binding `x` declared here
LL | let a = &x;
| -- borrow of `x` occurs here
LL | let b = a.clone();
| ------- this call doesn't do anything, the result is still `&A` because `A` doesn't implement `Clone`
LL | drop(x);
| ^ move out of `x` occurs here
LL |
LL | println!("{b:?}");
| ----- borrow later used here
|
help: consider annotating `A` with `#[derive(Clone)]`
|
LL + #[derive(Clone)]
LL | struct A;
|
```
Fix#48677.
match lowering: don't collect test alternatives ahead of time
I'm very happy with this one. Before this, when sorting candidates into the possible test branches, we manually computed `usize` indices to determine in which branch each candidate goes. To make this work we had a first pass that collected the possible alternatives we'd have to deal with, and a second pass that actually sorts the candidates.
In this PR, I replace `usize` indices with a dedicated enum. This makes `sort_candidates` easier to follow, and we don't need the first pass anymore.
r? ``@matthewjasper``
Add new `pattern_complexity` attribute to add possibility to limit and check recursion in pattern matching
Needed for https://github.com/rust-lang/rust-analyzer/issues/9528.
This PR adds a new attribute only available when running rust testsuite called `pattern_complexity` which allows to set the maximum recursion for the pattern matching. It is quite useful to ensure the complexity doesn't grow, like in `tests/ui/pattern/usefulness/issue-118437-exponential-time-on-diagonal-match.rs`.
r? `@Nadrieril`
match lowering: Lower bindings in a predictable order
After the recent refactorings, we can now lower bindings in a truly predictable order. The order in https://github.com/rust-lang/rust/pull/120214 was an improvement but not very clear. With this PR, we lower bindings from left to right, with the special case that `x @ pat` is traversed as `pat @ x` (i.e. `x` is lowered after any bindings in `pat`).
This description only applies in the absence of or-patterns. Or-patterns make everything complicated, because the binding place depends on the subpattern. Until I have a better idea I leave them to be handled in whatever weird order arises from today's code.
r? `@matthewjasper`
Before, the SwitchInt cases were computed in two passes: if the first
pass accepted e.g. 0..=5 and then 1, the second pass would not accept
0..=5 anymore because 1 would be listed in the SwitchInt options.
Now there's a single pass, so if we sort 0..=5 we must take care to not
sort a subsequent 1.
When a `Local` is fully parsed, but not followed by a `;`, keep the `:` span
arround and mention it. If the type could continue being parsed as an
expression, suggest replacing the `:` with a `=`.
```
error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
--> file.rs:2:32
|
2 | let _: std::env::temp_dir().join("foo");
| - ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
| |
| while parsing the type for `_`
| help: use `=` if you meant to assign
```
Fix#119665.
mark `min_exhaustive_patterns` as complete
This is step 1 and 2 of my [proposal](https://github.com/rust-lang/rust/issues/119612#issuecomment-1918097361) to move `min_exhaustive_patterns` forward. The vast majority of in-tree use cases of `exhaustive_patterns` are covered by `min_exhaustive_patterns`. There are a few cases that still require `exhaustive_patterns` in tests and they're all behind references.
r? ``@ghost``
Make `min_exhaustive_patterns` match `exhaustive_patterns` better
Split off from https://github.com/rust-lang/rust/pull/120742.
There remained two edge cases where `min_exhaustive_patterns` wasn't behaving like `exhaustive_patterns`. This fixes them, and tests the feature in a bunch more cases. I essentially went through all uses of `exhaustive_patterns` to see which ones would be interesting to compare between the two features.
r? `@compiler-errors`
Rollup of 9 pull requests
Successful merges:
- #119592 (resolve: Unload speculatively resolved crates before freezing cstore)
- #120103 (Make it so that async-fn-in-trait is compatible with a concrete future in implementation)
- #120206 (hir: Make sure all `HirId`s have corresponding HIR `Node`s)
- #120214 (match lowering: consistently lower bindings deepest-first)
- #120688 (GVN: also turn moves into copies with projections)
- #120702 (docs: also check the inline stmt during redundant link check)
- #120727 (exhaustiveness: Prefer "`0..MAX` not covered" to "`_` not covered")
- #120734 (Add `SubdiagnosticMessageOp` as a trait alias.)
- #120739 (improve pretty printing for associated items in trait objects)
r? `@ghost`
`@rustbot` modify labels: rollup
exhaustiveness: Prefer "`0..MAX` not covered" to "`_` not covered"
There was an exception when reporting integer ranges as missing, it's been there for as long as I can remember. This PR removes it. I think it's nicer to report "`0..MAX` not covered" than "`_` not covered". This also makes it consistent with enums, where we report individual enum variants in this case (as showcased in the rest of the `empty-match.rs` test).
r? ``@estebank``
