bjoernager/rust
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Suggest i += 1 when we see i++ or ++i

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Camelid 2021-03-25 21:04:03 -07:00 • committed by Noah Lev
parent 6970f88db3
commit 5d9cd4b851
3 changed files with 122 additions and 0 deletions
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43
compiler/rustc_parse/src/parser/diagnostics.rs
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@ -1882,6 +1882,49 @@ impl<'a> Parser<'a> {
self.sess.expr_parentheses_needed(&mut err, *sp);
}
err.span_label(span, "expected expression");
if self.prev_token.kind == TokenKind::BinOp(token::Plus)
&& self.token.kind == TokenKind::BinOp(token::Plus)
&& self.look_ahead(1, |t| !t.is_lit())
{
let span = self.prev_token.span.to(self.token.span);
err.note("Rust has no dedicated increment operator");
err.span_suggestion_verbose(
span,
"try using `+= 1` instead",
" += 1".into(),
Applicability::Unspecified,
);
} else if self.token.kind == TokenKind::BinOp(token::Plus)
&& self.look_ahead(1, |t| t.kind == TokenKind::BinOp(token::Plus))
&& self.look_ahead(2, |t| !t.is_lit())
{
let target_span = self.look_ahead(2, |t| t.span);
let left_brace_span = target_span.shrink_to_lo();
let pre_span = self.token.span.to(self.look_ahead(1, |t| t.span));
let post_span = target_span.shrink_to_hi();
err.note("Rust has no dedicated increment operator");
if self.prev_token.kind == TokenKind::Semi {
err.multipart_suggestion(
"try using `+= 1` instead",
vec![(pre_span, String::new()), (post_span, " += 1".into())],
Applicability::MachineApplicable,
);
} else if let Ok(target_snippet) = self.span_to_snippet(target_span) {
err.multipart_suggestion(
"try using `+= 1` instead",
vec![
(left_brace_span, "{ ".to_string()),
(pre_span, String::new()),
(post_span, format!(" += 1; {} }}", target_snippet)),
],
Applicability::MachineApplicable,
);
} else {
err.span_help(pre_span.to(target_span), "try using `+= 1` instead");
}
}
err
}