handle elision in async fn correctly #63499
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| // Test using `&Self` explicitly: | ||
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| // FIXME(#63388). This behavior *ought* to, but does not, |
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ick, that's pretty gnarly, though I suppose backwards-compatible (since we just disallow it, rather than misinterpreting it)
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Yeah...roughly what I was thinking. Not entirely sure this PR is the right thing to do. I'm just assuming that a more correct fix will take more time -- but I think we should definitely not just leave the code like this long term.
cramertj
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src/librustc/hir/lowering.rs
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| // lifetime from `&self` (same for `&mut self`). This | ||
| // will always be the first one we define. | ||
| hir::ImplicitSelfKind::ImmRef | hir::ImplicitSelfKind::MutRef => | ||
| get_elided_lt_replacement( |
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IMO this call is somewhat cleaner when inlined:
let (_span, param) = self.lifetimes_to_define[lifetime_count_before_args];
LtReplacement::Some(param)
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r=me. This is... not wonderful, but it seems like a clear and simple fix for the most common case. |
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I'm seeing some test failures that suggest that my assumption that |
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@cramertj this is ready for re-review |
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We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
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jackh726
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Centril
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Aug 12, 2019
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Aug 12, 2019
| @@ -2622,9 +2570,18 @@ impl<'a> LoweringContext<'a> { | |||
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| self.allocate_hir_id_counter(opaque_ty_node_id); | |||
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| let input_lifetimes_count = self.in_scope_lifetimes.len() + self.lifetimes_to_define.len(); | |||
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This is pretty clever and probably deserves a comment-- that in_scope_lifetimes contains all the non-elided lifetime names in scope, and lifetimes_to_define says how many lifetimes we have been paired with CreateParameter, so the last lifetime_params.len() - (in_scope_lifetimes + lifetimes_to_define) elements of lifetime_params are all elided lifetimes. Obviously the way I just worded it is probably even more confusing than just reading the code, but I think some explanation would be helpful.
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r=me with comment-- this seems better than the |
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@cramertj is that comment roughly what you had in mind? |
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Looks great, thanks! @bors r+ |
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📌 Commit ad214fe has been approved by |
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@bors r=cramertj |
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📌 Commit d7c7c52 has been approved by |
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@bors p=18 |
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…elision-self-mut-self, r=cramertj
handle elision in async fn correctly
We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
Fixes rust-lang#63388
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Rollup of 11 pull requests Successful merges: - #62760 (Deduplicate error messages in `librsctc_mir`) - #62849 (typeck: Prohibit RPIT types that inherit lifetimes) - #63383 (`async fn` lifetime elision tests) - #63421 (Implement Clone, Display for ascii::EscapeDefault) - #63459 (syntax: account for CVarArgs being in the argument list.) - #63475 (Bring back suggestion for splitting `<-` into `< -`) - #63485 (ci: move mirrors to their standalone bucket) - #63486 (Document `From` trait for `BinaryHeap`) - #63488 (improve DiagnosticBuilder docs) - #63493 (Remove unneeded comment in src/libcore/hash/mod.rs) - #63499 (handle elision in async fn correctly) Failed merges: r? @ghost
|
Failed in #63515 (comment), @bors r- |
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@bors r=cramertj |
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📌 Commit 18d69c8 has been approved by |
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…elision-self-mut-self, r=cramertj
handle elision in async fn correctly
We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
Fixes rust-lang#63388
Centril
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Aug 14, 2019
…elision-self-mut-self, r=cramertj
handle elision in async fn correctly
We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
Fixes rust-lang#63388
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Rollup of 17 pull requests Successful merges: - #62760 (Deduplicate error messages in `librsctc_mir`) - #62849 (typeck: Prohibit RPIT types that inherit lifetimes) - #63383 (`async fn` lifetime elision tests) - #63421 (Implement Clone, Display for ascii::EscapeDefault) - #63459 (syntax: account for CVarArgs being in the argument list.) - #63475 (Bring back suggestion for splitting `<-` into `< -`) - #63485 (ci: move mirrors to their standalone bucket) - #63486 (Document `From` trait for `BinaryHeap`) - #63488 (improve DiagnosticBuilder docs) - #63493 (Remove unneeded comment in src/libcore/hash/mod.rs) - #63499 (handle elision in async fn correctly) - #63501 (use `ParamName` to track in-scope lifetimes instead of Ident) - #63508 (Do not ICE when synthesizing spans falling inside unicode chars) - #63511 (ci: add a check for clock drift) - #63512 (Provide map_ok and map_err method for Poll<Option<Result<T, E>>>) - #63529 (RELEASES.md: ? is one of three Kleene operators) - #63530 (Fix typo in error message.) Failed merges: r? @ghost
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Rollup of 17 pull requests Successful merges: - #62760 (Deduplicate error messages in `librsctc_mir`) - #62849 (typeck: Prohibit RPIT types that inherit lifetimes) - #63383 (`async fn` lifetime elision tests) - #63421 (Implement Clone, Display for ascii::EscapeDefault) - #63459 (syntax: account for CVarArgs being in the argument list.) - #63475 (Bring back suggestion for splitting `<-` into `< -`) - #63485 (ci: move mirrors to their standalone bucket) - #63486 (Document `From` trait for `BinaryHeap`) - #63488 (improve DiagnosticBuilder docs) - #63493 (Remove unneeded comment in src/libcore/hash/mod.rs) - #63499 (handle elision in async fn correctly) - #63501 (use `ParamName` to track in-scope lifetimes instead of Ident) - #63508 (Do not ICE when synthesizing spans falling inside unicode chars) - #63511 (ci: add a check for clock drift) - #63512 (Provide map_ok and map_err method for Poll<Option<Result<T, E>>>) - #63529 (RELEASES.md: ? is one of three Kleene operators) - #63530 (Fix typo in error message.) Failed merges: r? @ghost
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…amertj
Stabilize `async_await` in Rust 1.39.0
Here we stabilize:
- free and inherent `async fn`s,
- the `<expr>.await` expression form,
- and the `async move? { ... }` block form.
Closes rust-lang#62149.
Closes rust-lang#50547.
All the blockers are now closed.
<details>
- [x] FCP in rust-lang#62149
- [x] rust-lang#61949; PR in rust-lang#62849.
- [x] rust-lang#62517; PR in rust-lang#63376.
- [x] rust-lang#63225; PR in rust-lang#63501
- [x] rust-lang#63388; PR in rust-lang#63499
- [x] rust-lang#63500; PR in rust-lang#63501
- [x] rust-lang#62121 (comment)
- [x] Some tests for control flow (PR rust-lang#63387):
- `?`
- `return` in `async` blocks
- `break`
- [x] rust-lang#61775 (comment), i.e. tests for rust-lang#60944 with `async fn`s instead). PR in rust-lang#63383
</details>
r? @cramertj
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We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate
'_in the case of elided lifetimes from the outputs.Example:
becomes
Fixes #63388