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Rollup merge of rust-lang#49268 - ordovicia:dotdot-pattern-diag, r=pe…
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…trochenkov

Better diagnostics for '..' pattern fragment not in the last position

Fixes rust-lang#49257.
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frewsxcv authored Mar 23, 2018
2 parents 759ebda + 347b9d6 commit 9e0d0ff
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8 changes: 7 additions & 1 deletion src/libsyntax/parse/parser.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3672,7 +3672,13 @@ impl<'a> Parser<'a> {
if self.token != token::CloseDelim(token::Brace) {
let token_str = self.this_token_to_string();
let mut err = self.fatal(&format!("expected `{}`, found `{}`", "}", token_str));
err.span_label(self.span, "expected `}`");
if self.token == token::Comma { // Issue #49257
err.span_label(self.span,
"`..` must be in the last position, \
and cannot have a trailing comma");
} else {
err.span_label(self.span, "expected `}`");
}
return Err(err);
}
etc = true;
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23 changes: 23 additions & 0 deletions src/test/ui/issue-49257.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Test for #49257:
// emits good diagnostics for `..` pattern fragments not in the last position.

#![allow(unused)]

struct Point { x: u8, y: u8 }

fn main() {
let p = Point { x: 0, y: 0 };
let Point { .., y } = p; //~ ERROR expected `}`, found `,`
//~| ERROR pattern does not mention field `x`
//~| ERROR pattern does not mention field `y`
}
21 changes: 21 additions & 0 deletions src/test/ui/issue-49257.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
error: expected `}`, found `,`
--> $DIR/issue-49257.rs:20:19
|
LL | let Point { .., y } = p; //~ ERROR expected `}`, found `,`
| ^ `..` must be in the last position, and cannot have a trailing comma

error[E0027]: pattern does not mention field `x`
--> $DIR/issue-49257.rs:20:9
|
LL | let Point { .., y } = p; //~ ERROR expected `}`, found `,`
| ^^^^^^^^^^^^^^^ missing field `x`

error[E0027]: pattern does not mention field `y`
--> $DIR/issue-49257.rs:20:9
|
LL | let Point { .., y } = p; //~ ERROR expected `}`, found `,`
| ^^^^^^^^^^^^^^^ missing field `y`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0027`.

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