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Fix "missing match arm body" suggestion involving ! #137435

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Merged
bors merged 1 commit into from
Feb 23, 2025
Merged

Fix "missing match arm body" suggestion involving ! #137435

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9 changes: 8 additions & 1 deletion compiler/rustc_ast_passes/src/errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -804,7 +804,14 @@ pub(crate) struct NegativeBoundWithParentheticalNotation {
pub(crate) struct MatchArmWithNoBody {
#[primary_span]
pub span: Span,
#[suggestion(code = " => todo!(),", applicability = "has-placeholders")]
// We include the braces around `todo!()` so that a comma is optional, and we don't have to have
// any logic looking at the arm being replaced if there was a comma already or not for the
// resulting code to be correct.
#[suggestion(
code = " => {{ todo!() }}",
applicability = "has-placeholders",
style = "verbose"
)]
pub suggestion: Span,
}

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3 changes: 2 additions & 1 deletion compiler/rustc_parse/src/parser/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3125,10 +3125,11 @@ impl<'a> Parser<'a> {
let mut result = if armless {
// A pattern without a body, allowed for never patterns.
arm_body = None;
let span = lo.to(this.prev_token.span);
this.expect_one_of(&[exp!(Comma)], &[exp!(CloseBrace)]).map(|x| {
// Don't gate twice
if !pat.contains_never_pattern() {
this.psess.gated_spans.gate(sym::never_patterns, pat.span);
this.psess.gated_spans.gate(sym::never_patterns, span);
}
x
})
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35 changes: 30 additions & 5 deletions tests/ui/feature-gates/feature-gate-never_patterns.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -58,19 +58,34 @@ error: `match` arm with no body
--> $DIR/feature-gate-never_patterns.rs:38:9
|
LL | Some(_)
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) => { todo!() }
| ++++++++++++++

error: `match` arm with no body
--> $DIR/feature-gate-never_patterns.rs:43:9
|
LL | Some(_) if false,
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if false => { todo!() },
| ++++++++++++++

error: `match` arm with no body
--> $DIR/feature-gate-never_patterns.rs:45:9
|
LL | Some(_) if false
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if false => { todo!() }
| ++++++++++++++

error[E0658]: `!` patterns are experimental
--> $DIR/feature-gate-never_patterns.rs:50:13
Expand All @@ -96,13 +111,23 @@ error: `match` arm with no body
--> $DIR/feature-gate-never_patterns.rs:64:9
|
LL | Some(_)
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) => { todo!() }
| ++++++++++++++

error: `match` arm with no body
--> $DIR/feature-gate-never_patterns.rs:70:9
|
LL | Some(_) if false
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if false => { todo!() }
| ++++++++++++++

error: a guard on a never pattern will never be run
--> $DIR/feature-gate-never_patterns.rs:54:19
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7 changes: 6 additions & 1 deletion tests/ui/parser/macro/macro-expand-to-match-arm.stderr
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Expand Up @@ -14,7 +14,12 @@ error: `match` arm with no body
--> $DIR/macro-expand-to-match-arm.rs:14:9
|
LL | arm!(None => {}),
| ^^^^^^^^^^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | arm!(None => {}) => { todo!() },
| ++++++++++++++
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Contributor Author

@estebank estebank Feb 22, 2025

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This isn't great, we'll have to deal with macros somehow :-/


error: aborting due to 2 previous errors

56 changes: 48 additions & 8 deletions tests/ui/parser/match-arm-without-body.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -68,49 +68,89 @@ error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:7:9
|
LL | Some(_)
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) => { todo!() }
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:30:9
|
LL | Some(_) if true
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if true => { todo!() }
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:40:9
|
LL | Some(_) if true,
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if true => { todo!() },
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:45:9
|
LL | Some(_) if true,
| ^^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | Some(_) if true => { todo!() },
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:51:9
|
LL | pat!()
| ^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^
|
help: add a body after the pattern
|
LL | pat!() => { todo!() }
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:56:9
|
LL | pat!(),
| ^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^
|
help: add a body after the pattern
|
LL | pat!() => { todo!() },
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:61:9
|
LL | pat!() if true,
| ^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^^^^^^^^^
|
help: add a body after the pattern
|
LL | pat!() if true => { todo!() },
| ++++++++++++++

error: `match` arm with no body
--> $DIR/match-arm-without-body.rs:72:9
|
LL | pat!(),
| ^^^^^^- help: add a body after the pattern: `=> todo!(),`
| ^^^^^^
|
help: add a body after the pattern
|
LL | pat!() => { todo!() },
| ++++++++++++++

error: aborting due to 13 previous errors

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