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fix code to suggest ; on parse error

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This commit is contained in:
Elliot Bobrow 2021-07-24 10:58:55 -07:00
parent b543e0dc03
commit e0995a5a8d
6 changed files with 118 additions and 64 deletions
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114
compiler/rustc_parse/src/parser/diagnostics.rs
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@ -242,6 +242,63 @@ impl<'a> Parser<'a> {
expected.sort_by_cached_key(|x| x.to_string());
expected.dedup();
let sm = self.sess.source_map();
let msg = format!("expected `;`, found {}", super::token_descr(&self.token));
let appl = Applicability::MachineApplicable;
if expected.contains(&TokenType::Token(token::Semi)) {
if self.token.span == DUMMY_SP || self.prev_token.span == DUMMY_SP {
// Likely inside a macro, can't provide meaningful suggestions.
} else if !sm.is_multiline(self.prev_token.span.until(self.token.span)) {
// The current token is in the same line as the prior token, not recoverable.
} else if [token::Comma, token::Colon].contains(&self.token.kind)
&& self.prev_token.kind == token::CloseDelim(token::Paren)
{
// Likely typo: The current token is on a new line and is expected to be
// `.`, `;`, `?`, or an operator after a close delimiter token.
//
// let a = std::process::Command::new("echo")
// .arg("1")
// ,arg("2")
// ^
// https://github.com/rust-lang/rust/issues/72253
} else if self.look_ahead(1, |t| {
t == &token::CloseDelim(token::Brace)
|| t.can_begin_expr() && t.kind != token::Colon
}) && [token::Comma, token::Colon].contains(&self.token.kind)
{
// Likely typo: `,` → `;` or `:` → `;`. This is triggered if the current token is
// either `,` or `:`, and the next token could either start a new statement or is a
// block close. For example:
//
// let x = 32:
// let y = 42;
self.bump();
let sp = self.prev_token.span;
self.struct_span_err(sp, &msg)
.span_suggestion_short(sp, "change this to `;`", ";".to_string(), appl)
.emit();
return Ok(false);
} else if self.look_ahead(0, |t| {
t == &token::CloseDelim(token::Brace)
|| (
t.can_begin_expr() && t != &token::Semi && t != &token::Pound
// Avoid triggering with too many trailing `#` in raw string.
)
}) {
// Missing semicolon typo. This is triggered if the next token could either start a
// new statement or is a block close. For example:
//
// let x = 32
// let y = 42;
let sp = self.prev_token.span.shrink_to_hi();
self.struct_span_err(sp, &msg)
.span_label(self.token.span, "unexpected token")
.span_suggestion_short(sp, "add `;` here", ";".to_string(), appl)
.emit();
return Ok(false);
}
}
let expect = tokens_to_string(&expected[..]);
let actual = super::token_descr(&self.token);
let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
@ -303,7 +360,6 @@ impl<'a> Parser<'a> {
return Err(err);
}
let sm = self.sess.source_map();
if self.prev_token.span == DUMMY_SP {
// Account for macro context where the previous span might not be
// available to avoid incorrect output (#54841).
@ -1144,62 +1200,6 @@ impl<'a> Parser<'a> {
if self.eat(&token::Semi) {
return Ok(());
}
let sm = self.sess.source_map();
let msg = format!("expected `;`, found {}", super::token_descr(&self.token));
let appl = Applicability::MachineApplicable;
if self.token.span == DUMMY_SP || self.prev_token.span == DUMMY_SP {
// Likely inside a macro, can't provide meaningful suggestions.
return self.expect(&token::Semi).map(drop);
} else if !sm.is_multiline(self.prev_token.span.until(self.token.span)) {
// The current token is in the same line as the prior token, not recoverable.
} else if [token::Comma, token::Colon].contains(&self.token.kind)
&& self.prev_token.kind == token::CloseDelim(token::Paren)
{
// Likely typo: The current token is on a new line and is expected to be
// `.`, `;`, `?`, or an operator after a close delimiter token.
//
// let a = std::process::Command::new("echo")
// .arg("1")
// ,arg("2")
// ^
// https://github.com/rust-lang/rust/issues/72253
self.expect(&token::Semi)?;
return Ok(());
} else if self.look_ahead(1, |t| {
t == &token::CloseDelim(token::Brace) || t.can_begin_expr() && t.kind != token::Colon
}) && [token::Comma, token::Colon].contains(&self.token.kind)
{
// Likely typo: `,` → `;` or `:` → `;`. This is triggered if the current token is
// either `,` or `:`, and the next token could either start a new statement or is a
// block close. For example:
//
// let x = 32:
// let y = 42;
self.bump();
let sp = self.prev_token.span;
self.struct_span_err(sp, &msg)
.span_suggestion_short(sp, "change this to `;`", ";".to_string(), appl)
.emit();
return Ok(());
} else if self.look_ahead(0, |t| {
t == &token::CloseDelim(token::Brace)
|| (
t.can_begin_expr() && t != &token::Semi && t != &token::Pound
// Avoid triggering with too many trailing `#` in raw string.
)
}) {
// Missing semicolon typo. This is triggered if the next token could either start a
// new statement or is a block close. For example:
//
// let x = 32
// let y = 42;
let sp = self.prev_token.span.shrink_to_hi();
self.struct_span_err(sp, &msg)
.span_label(self.token.span, "unexpected token")
.span_suggestion_short(sp, "add `;` here", ";".to_string(), appl)
.emit();
return Ok(());
}
self.expect(&token::Semi).map(drop) // Error unconditionally
}