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Fix the issue of typo of comma in arm parsing #141077

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Fix the issue of typo of comma in arm parsing #141077

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54 changes: 36 additions & 18 deletions compiler/rustc_parse/src/parser/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3311,26 +3311,44 @@ impl<'a> Parser<'a> {
let sm = this.psess.source_map();
if let Ok(expr_lines) = sm.span_to_lines(expr_span)
&& let Ok(arm_start_lines) = sm.span_to_lines(arm_start_span)
&& arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
&& expr_lines.lines.len() == 2
{
// We check whether there's any trailing code in the parse span,
// if there isn't, we very likely have the following:
//
// X | &Y => "y"
// | -- - missing comma
// | |
// | arrow_span
// X | &X => "x"
// | - ^^ self.token.span
// | |
// | parsed until here as `"y" & X`
err.span_suggestion_short(
arm_start_span.shrink_to_hi(),
"missing a comma here to end this `match` arm",
",",
Applicability::MachineApplicable,
);
if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col {
// We check whether there's any trailing code in the parse span,
// if there isn't, we very likely have the following:
//
// X | &Y => "y"
// | -- - missing comma
// | |
// | arrow_span
// X | &X => "x"
// | - ^^ self.token.span
// | |
// | parsed until here as `"y" & X`
err.span_suggestion_short(
arm_start_span.shrink_to_hi(),
"missing a comma here to end this `match` arm",
",",
Applicability::MachineApplicable,
);
} else if arm_start_lines.lines[0].end_col + rustc_span::CharPos(1)
== expr_lines.lines[0].end_col
{
// similar to the above, but we may typo a `.` or `/` at the end of the line
let comma_span = arm_start_span
.shrink_to_hi()
.with_hi(arm_start_span.hi() + rustc_span::BytePos(1));
if let Ok(res) = sm.span_to_snippet(comma_span)
&& (res == "." || res == "/")
{
err.span_suggestion_short(
comma_span,
"you might have meant to write a `,` to end this `match` arm",
",",
Applicability::MachineApplicable,
);
}
}
}
} else {
err.span_label(
Expand Down
24 changes: 24 additions & 0 deletions tests/ui/parser/match-arm-comma-typo-issue-140991.fixed
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
//@ run-rustfix

pub enum Foo {
X, Y
}

pub fn typo1(foo: Foo) -> Foo {
use Foo::*;
match foo {
X => Y,
Y => X, //~ ERROR expected one of
}
}

pub fn typo2(foo: Foo) -> Foo {
use Foo::*;
match foo {
X => Y,
Y => X, //~ ERROR expected one of
}
}


fn main() { }
24 changes: 24 additions & 0 deletions tests/ui/parser/match-arm-comma-typo-issue-140991.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
//@ run-rustfix

pub enum Foo {
X, Y
}

pub fn typo1(foo: Foo) -> Foo {
use Foo::*;
match foo {
X => Y.
Y => X, //~ ERROR expected one of
}
}

pub fn typo2(foo: Foo) -> Foo {
use Foo::*;
match foo {
X => Y/
Y => X, //~ ERROR expected one of
}
}


fn main() { }
26 changes: 26 additions & 0 deletions tests/ui/parser/match-arm-comma-typo-issue-140991.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
error: expected one of `(`, `,`, `.`, `::`, `?`, `}`, or an operator, found `=>`
--> $DIR/match-arm-comma-typo-issue-140991.rs:11:11
|
LL | Y => X,
| ^^ expected one of 7 possible tokens
|
help: you might have meant to write a `,` to end this `match` arm
|
LL - X => Y.
LL + X => Y,
|

error: expected one of `!`, `,`, `.`, `::`, `?`, `{`, `}`, or an operator, found `=>`
--> $DIR/match-arm-comma-typo-issue-140991.rs:19:11
|
LL | Y => X,
| ^^ expected one of 8 possible tokens
|
help: you might have meant to write a `,` to end this `match` arm
|
LL - X => Y/
LL + X => Y,
|

error: aborting due to 2 previous errors

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