rust/compiler/rustc_borrowck
Dylan DPC 7537b2036a
Rollup merge of #94375 - WaffleLapkin:copy-suggestion, r=estebank
Adt copy suggestions

Previously we've only suggested adding `Copy` bounds when the type being moved/copied is a type parameter (generic). With this PR we also suggest adding bounds when a type
- Can be copy
- All predicates that need to be satisfied for that are based on type params

i.e. we will suggest `T: Copy` for `Option<T>`, but won't suggest anything for `Option<String>`.

An example:
```rust
fn duplicate<T>(t: Option<T>) -> (Option<T>, Option<T>) {
    (t, t)
}
```
New error (current compiler doesn't provide `help`:):
```text
error[E0382]: use of moved value: `t`
 --> t.rs:2:9
  |
1 | fn duplicate<T>(t: Option<T>) -> (Option<T>, Option<T>) {
  |                 - move occurs because `t` has type `Option<T>`, which does not implement the `Copy` trait
2 |     (t, t)
  |      -  ^ value used here after move
  |      |
  |      value moved here
  |
help: consider restricting type parameter `T`
  |
1 | fn duplicate<T: Copy>(t: Option<T>) -> (Option<T>, Option<T>) {
  |               ++++++
```

Fixes #93623
r? ``````````@estebank``````````
``````````@rustbot`````````` label +A-diagnostics +A-suggestion-diagnostics +C-enhancement

----

I'm not at all sure if this is the right implementation for this kind of suggestion, but it seems to work :')
2022-03-03 01:09:11 +01:00
..
src Rollup merge of #94375 - WaffleLapkin:copy-suggestion, r=estebank 2022-03-03 01:09:11 +01:00
Cargo.toml Update itertools to deduplicate it 2022-01-14 12:33:54 +01:00