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Fix let_chains and if_let_guard feature flags
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@c410-f3r
c410-f3r committed Jan 22, 2022
1 parent ecf7299 commit cbb0fff
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Showing 5 changed files with 112 additions and 23 deletions.
20 changes: 17 additions & 3 deletions compiler/rustc_parse/src/parser/expr.rs
View file
Expand Up @@ -2383,16 +2383,30 @@ impl<'a> Parser<'a> {
}

pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
fn check_let_expr(expr: &Expr) -> (bool, bool) {
match expr.kind {
ExprKind::Binary(_, ref lhs, ref rhs) => {
let lhs_rslt = check_let_expr(lhs);
let rhs_rslt = check_let_expr(rhs);
(lhs_rslt.0 || rhs_rslt.0, false)
}
ExprKind::Let(..) => (true, true),
_ => (false, true),
}
}
let attrs = self.parse_outer_attributes()?;
self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
let lo = this.token.span;
let pat = this.parse_pat_allow_top_alt(None, RecoverComma::Yes, RecoverColon::Yes)?;
let guard = if this.eat_keyword(kw::If) {
let if_span = this.prev_token.span;
let cond = this.parse_expr()?;
if let ExprKind::Let(..) = cond.kind {
// Remove the last feature gating of a `let` expression since it's stable.
this.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
let (has_let_expr, does_not_have_bin_op) = check_let_expr(&cond);
if has_let_expr {
if does_not_have_bin_op {
// Remove the last feature gating of a `let` expression since it's stable.
this.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
}
let span = if_span.to(cond.span);
this.sess.gated_spans.gate(sym::if_let_guard, span);
}
Expand Down
13 changes: 9 additions & 4 deletions src/test/ui/rfc-2294-if-let-guard/feature-gate.rs
View file
Expand Up @@ -14,10 +14,12 @@ fn _if_let_guard() {
//~^ ERROR `let` expressions in this position are unstable

() if true && let 0 = 1 => {}
//~^ ERROR `let` expressions in this position are unstable
//~^ ERROR `if let` guards are experimental
//~| ERROR `let` expressions in this position are unstable

() if let 0 = 1 && true => {}
//~^ ERROR `let` expressions in this position are unstable
//~^ ERROR `if let` guards are experimental
//~| ERROR `let` expressions in this position are unstable

() if (let 0 = 1) && true => {}
//~^ ERROR `let` expressions in this position are unstable
Expand All @@ -30,14 +32,17 @@ fn _if_let_guard() {
//~| ERROR `let` expressions in this position are unstable

() if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
//~^ ERROR `let` expressions in this position are unstable
//~^ ERROR `if let` guards are experimental
//~| ERROR `let` expressions in this position are unstable
//~| ERROR `let` expressions in this position are unstable
//~| ERROR `let` expressions in this position are unstable
//~| ERROR `let` expressions in this position are unstable
//~| ERROR `let` expressions in this position are unstable

() if let Range { start: _, end: _ } = (true..true) && false => {}
//~^ ERROR `let` expressions in this position are unstable
//~^ ERROR `if let` guards are experimental
//~| ERROR `let` expressions in this position are unstable

_ => {}
}
}
Expand Down
72 changes: 56 additions & 16 deletions src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
View file
@@ -1,5 +1,5 @@
error: no rules expected the token `let`
--> $DIR/feature-gate.rs:64:15
--> $DIR/feature-gate.rs:69:15
|
LL | macro_rules! use_expr {
| --------------------- when calling this macro
Expand All @@ -18,7 +18,47 @@ LL | () if let 0 = 1 => {}
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:60:12
--> $DIR/feature-gate.rs:16:12
|
LL | () if true && let 0 = 1 => {}
| ^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:20:12
|
LL | () if let 0 = 1 && true => {}
| ^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:34:12
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:42:12
|
LL | () if let Range { start: _, end: _ } = (true..true) && false => {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:65:12
|
LL | () if let 0 = 1 => {}
| ^^^^^^^^^^^^
Expand Down Expand Up @@ -55,7 +95,7 @@ LL | () if true && let 0 = 1 => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:19:15
--> $DIR/feature-gate.rs:20:15
|
LL | () if let 0 = 1 && true => {}
| ^^^^^^^^^
Expand All @@ -64,7 +104,7 @@ LL | () if let 0 = 1 && true => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:22:16
--> $DIR/feature-gate.rs:24:16
|
LL | () if (let 0 = 1) && true => {}
| ^^^^^^^^^
Expand All @@ -73,7 +113,7 @@ LL | () if (let 0 = 1) && true => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:25:24
--> $DIR/feature-gate.rs:27:24
|
LL | () if true && (let 0 = 1) => {}
| ^^^^^^^^^
Expand All @@ -82,7 +122,7 @@ LL | () if true && (let 0 = 1) => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:28:16
--> $DIR/feature-gate.rs:30:16
|
LL | () if (let 0 = 1) && (let 0 = 1) => {}
| ^^^^^^^^^
Expand All @@ -91,7 +131,7 @@ LL | () if (let 0 = 1) && (let 0 = 1) => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:28:31
--> $DIR/feature-gate.rs:30:31
|
LL | () if (let 0 = 1) && (let 0 = 1) => {}
| ^^^^^^^^^
Expand All @@ -100,7 +140,7 @@ LL | () if (let 0 = 1) && (let 0 = 1) => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:32:15
--> $DIR/feature-gate.rs:34:15
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^
Expand All @@ -109,7 +149,7 @@ LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:32:28
--> $DIR/feature-gate.rs:34:28
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^
Expand All @@ -118,7 +158,7 @@ LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:32:42
--> $DIR/feature-gate.rs:34:42
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^
Expand All @@ -127,7 +167,7 @@ LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:32:55
--> $DIR/feature-gate.rs:34:55
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^
Expand All @@ -136,7 +176,7 @@ LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:32:68
--> $DIR/feature-gate.rs:34:68
|
LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
| ^^^^^^^^^
Expand All @@ -145,7 +185,7 @@ LL | () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:39:15
--> $DIR/feature-gate.rs:42:15
|
LL | () if let Range { start: _, end: _ } = (true..true) && false => {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -154,7 +194,7 @@ LL | () if let Range { start: _, end: _ } = (true..true) && false => {}
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:54:16
--> $DIR/feature-gate.rs:59:16
|
LL | use_expr!((let 0 = 1 && 0 == 0));
| ^^^^^^^^^
Expand All @@ -163,14 +203,14 @@ LL | use_expr!((let 0 = 1 && 0 == 0));
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error[E0658]: `let` expressions in this position are unstable
--> $DIR/feature-gate.rs:56:16
--> $DIR/feature-gate.rs:61:16
|
LL | use_expr!((let 0 = 1));
| ^^^^^^^^^
|
= note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error: aborting due to 19 previous errors
error: aborting due to 23 previous errors

For more information about this error, try `rustc --explain E0658`.
8 changes: 8 additions & 0 deletions src/test/ui/rfc-2497-if-let-chains/issue-93150.rs
View file
@@ -0,0 +1,8 @@
fn main() {
match true {
_ if let true = true && true => {}
//~^ ERROR `if let` guards are
//~| ERROR `let` expressions in this
_ => {}
}
}
22 changes: 22 additions & 0 deletions src/test/ui/rfc-2497-if-let-chains/issue-93150.stderr
View file
@@ -0,0 +1,22 @@
error[E0658]: `if let` guards are experimental
--> $DIR/issue-93150.rs:3:11
|
LL | _ if let true = true && true => {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
= help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`

error[E0658]: `let` expressions in this position are unstable
--> $DIR/issue-93150.rs:3:14
|
LL | _ if let true = true && true => {}
| ^^^^^^^^^^^^^^^
|
= note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
= help: add `#![feature(let_chains)]` to the crate attributes to enable

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.

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