[WIP] [let_chains, 4/N] Introduce hir::ExprKind::Let
#68577
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
disallowed positions is checked in ast_validation in next commit
rust-highfive
added
the
S-waiting-on-review
Centril
commented
Jan 27, 2020
| } | ||
|
|
||
| /// Emits an error banning the `let` expression provided in the given location. | ||
| fn ban_let_expr(&self, expr: &'a Expr) { |
There was a problem hiding this comment.
It's probably a better idea to move this to feature gating under e.g. #![feature(let_expr)] so that we can test ::Let more than what let_chains alone would allow. We could also move that, or the ast_validation logic, out of this PR and land it separately.
| @@ -513,33 +513,6 @@ warning: the feature `let_chains` is incomplete and may cause the compiler to cr | |||
| LL | #![feature(let_chains)] // Avoid inflating `.stderr` with overzealous gates in this test. | |||
| | ^^^^^^^^^^ | |||
|
|
|||
| error[E0658]: `match` is not allowed in a `const` | |||
There was a problem hiding this comment.
::Let can result in switching on the discriminant, like or-patterns. Alone however, it is not control flow. That said, we should probably gate let p = s here too?
|
@bors try @rust-timer queue |
|
Awaiting bors try build completion |
|
⌛ Trying commit 6ed41a8 with merge 460f28a6daf1e5ebd90eb84972688220a0f03b6a... |
|
The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
|
Some notes that seem important:
struct D(usize);
impl Drop for D {
fn drop(&mut self) {
dbg!(self.0);
}
}
fn main() {
if let Some(d) = Some(D(0)) {
D(1);
}
D(2);
let mut x = Some(D(3));
while let Some(d) = x.take() {
D(4);
}
D(5);
}should result in: [src/main.rs:5] self.0 = 1
[src/main.rs:5] self.0 = 0
[src/main.rs:5] self.0 = 2
[src/main.rs:5] self.0 = 4
[src/main.rs:5] self.0 = 3
[src/main.rs:5] self.0 = 5That is: Note to self: Add a test for this!
match let Some(d) = Some(D(0)) {
// borrowck doesn't understand that `true` and the pattern matching conincide.
true => D(1),
_ => {} // make sure `d` is not available here.
}
D(2);
|
|
☀️ Try build successful - checks-azure |
|
Queued 460f28a6daf1e5ebd90eb84972688220a0f03b6a with parent 8a79d08, future comparison URL. |
JohnCSimon
added
S-waiting-on-author
|
@Centril any updates? |
|
Closing this for now. I'll need to think some more about how to make progress here. |
voidc
added a commit
to voidc/rust
that referenced
this pull request
Nov 11, 2020
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Aug 16, 2021
Introduce `hir::ExprKind::Let` - Take 2 Builds on rust-lang#68577 and depends on rust-lang#79328. cc rust-lang#53667
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Introduces
hir::ExprKind::Let(&Pat<'_>, &Expr<'_>). That is, this introduceslet pat = exprexpressions.For now, this is very much WIP and probably depends on #67668 to remove the hacks in HAIR / region / generator_interior, but I thought it would be useful to have this open for discussion purposes and so that I can check perf.
cc #53667.
r? @matthewjasper cc @oli-obk