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Rollup merge of rust-lang#122217 - estebank:issue-119685, r=fmease
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Handle str literals written with `'` lexed as lifetime

Given `'hello world'` and `'1 str', provide a structured suggestion for a valid string literal:

```
error[E0762]: unterminated character literal
  --> $DIR/lex-bad-str-literal-as-char-3.rs:2:26
   |
LL |     println!('hello world');
   |                          ^^^^
   |
help: if you meant to write a `str` literal, use double quotes
   |
LL |     println!("hello world");
   |              ~           ~
```
```
error[E0762]: unterminated character literal
  --> $DIR/lex-bad-str-literal-as-char-1.rs:2:20
   |
LL |     println!('1 + 1');
   |                    ^^^^
   |
help: if you meant to write a `str` literal, use double quotes
   |
LL |     println!("1 + 1");
   |              ~     ~
```

Fix rust-lang#119685.
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workingjubilee authored Mar 24, 2024
2 parents 5277cfd + f4d30b1 commit 0e1a3de
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2 changes: 1 addition & 1 deletion compiler/rustc_infer/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,7 @@ infer_lifetime_param_suggestion_elided = each elided lifetime in input position
infer_meant_byte_literal = if you meant to write a byte literal, prefix with `b`
infer_meant_char_literal = if you meant to write a `char` literal, use single quotes
infer_meant_str_literal = if you meant to write a `str` literal, use double quotes
infer_meant_str_literal = if you meant to write a string literal, use double quotes
infer_mismatched_static_lifetime = incompatible lifetime on type
infer_more_targeted = {$has_param_name ->
[true] `{$param_name}`
Expand Down
13 changes: 5 additions & 8 deletions compiler/rustc_infer/src/errors/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1339,15 +1339,12 @@ pub enum TypeErrorAdditionalDiags {
span: Span,
code: String,
},
#[suggestion(
infer_meant_str_literal,
code = "\"{code}\"",
applicability = "machine-applicable"
)]
#[multipart_suggestion(infer_meant_str_literal, applicability = "machine-applicable")]
MeantStrLiteral {
#[primary_span]
span: Span,
code: String,
#[suggestion_part(code = "\"")]
start: Span,
#[suggestion_part(code = "\"")]
end: Span,
},
#[suggestion(
infer_consider_specifying_length,
Expand Down
14 changes: 4 additions & 10 deletions compiler/rustc_infer/src/infer/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2079,16 +2079,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// If a string was expected and the found expression is a character literal,
// perhaps the user meant to write `"s"` to specify a string literal.
(ty::Ref(_, r, _), ty::Char) if r.is_str() => {
if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span) {
if let Some(code) =
code.strip_prefix('\'').and_then(|s| s.strip_suffix('\''))
{
suggestions.push(TypeErrorAdditionalDiags::MeantStrLiteral {
span,
code: escape_literal(code),
})
}
}
suggestions.push(TypeErrorAdditionalDiags::MeantStrLiteral {
start: span.with_hi(span.lo() + BytePos(1)),
end: span.with_lo(span.hi() - BytePos(1)),
})
}
// For code `if Some(..) = expr `, the type mismatch may be expected `bool` but found `()`,
// we try to suggest to add the missing `let` for `if let Some(..) = expr`
Expand Down
11 changes: 10 additions & 1 deletion compiler/rustc_lexer/src/cursor.rs
Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ impl<'a> Cursor<'a> {
/// If requested position doesn't exist, `EOF_CHAR` is returned.
/// However, getting `EOF_CHAR` doesn't always mean actual end of file,
/// it should be checked with `is_eof` method.
pub(crate) fn first(&self) -> char {
pub fn first(&self) -> char {
// `.next()` optimizes better than `.nth(0)`
self.chars.clone().next().unwrap_or(EOF_CHAR)
}
Expand All @@ -59,6 +59,15 @@ impl<'a> Cursor<'a> {
iter.next().unwrap_or(EOF_CHAR)
}

/// Peeks the third symbol from the input stream without consuming it.
pub fn third(&self) -> char {
// `.next()` optimizes better than `.nth(1)`
let mut iter = self.chars.clone();
iter.next();
iter.next();
iter.next().unwrap_or(EOF_CHAR)
}

/// Checks if there is nothing more to consume.
pub(crate) fn is_eof(&self) -> bool {
self.chars.as_str().is_empty()
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_parse/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -568,7 +568,7 @@ parse_more_than_one_char = character literal may only contain one codepoint
.remove_non = consider removing the non-printing characters
.use_double_quotes = if you meant to write a {$is_byte ->
[true] byte string
*[false] `str`
*[false] string
} literal, use double quotes
parse_multiple_skipped_lines = multiple lines skipped by escaped newline
Expand Down Expand Up @@ -833,6 +833,7 @@ parse_unknown_prefix = prefix `{$prefix}` is unknown
.label = unknown prefix
.note = prefixed identifiers and literals are reserved since Rust 2021
.suggestion_br = use `br` for a raw byte string
.suggestion_str = if you meant to write a string literal, use double quotes
.suggestion_whitespace = consider inserting whitespace here
parse_unknown_start_of_token = unknown start of token: {$escaped}
Expand Down
22 changes: 21 additions & 1 deletion compiler/rustc_parse/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1987,6 +1987,17 @@ pub enum UnknownPrefixSugg {
style = "verbose"
)]
Whitespace(#[primary_span] Span),
#[multipart_suggestion(
parse_suggestion_str,
applicability = "maybe-incorrect",
style = "verbose"
)]
MeantStr {
#[suggestion_part(code = "\"")]
start: Span,
#[suggestion_part(code = "\"")]
end: Span,
},
}

#[derive(Diagnostic)]
Expand Down Expand Up @@ -2198,12 +2209,21 @@ pub enum MoreThanOneCharSugg {
ch: String,
},
#[suggestion(parse_use_double_quotes, code = "{sugg}", applicability = "machine-applicable")]
Quotes {
QuotesFull {
#[primary_span]
span: Span,
is_byte: bool,
sugg: String,
},
#[multipart_suggestion(parse_use_double_quotes, applicability = "machine-applicable")]
Quotes {
#[suggestion_part(code = "{prefix}\"")]
start: Span,
#[suggestion_part(code = "\"")]
end: Span,
is_byte: bool,
prefix: &'static str,
},
}

#[derive(Subdiagnostic)]
Expand Down
57 changes: 52 additions & 5 deletions compiler/rustc_parse/src/lexer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ pub(crate) fn parse_token_trees<'psess, 'src>(
cursor,
override_span,
nbsp_is_whitespace: false,
last_lifetime: None,
};
let (stream, res, unmatched_delims) =
tokentrees::TokenTreesReader::parse_all_token_trees(string_reader);
Expand Down Expand Up @@ -105,6 +106,10 @@ struct StringReader<'psess, 'src> {
/// in this file, it's safe to treat further occurrences of the non-breaking
/// space character as whitespace.
nbsp_is_whitespace: bool,

/// Track the `Span` for the leading `'` of the last lifetime. Used for
/// diagnostics to detect possible typo where `"` was meant.
last_lifetime: Option<Span>,
}

impl<'psess, 'src> StringReader<'psess, 'src> {
Expand All @@ -130,6 +135,18 @@ impl<'psess, 'src> StringReader<'psess, 'src> {

debug!("next_token: {:?}({:?})", token.kind, self.str_from(start));

if let rustc_lexer::TokenKind::Semi
| rustc_lexer::TokenKind::LineComment { .. }
| rustc_lexer::TokenKind::BlockComment { .. }
| rustc_lexer::TokenKind::CloseParen
| rustc_lexer::TokenKind::CloseBrace
| rustc_lexer::TokenKind::CloseBracket = token.kind
{
// Heuristic: we assume that it is unlikely we're dealing with an unterminated
// string surrounded by single quotes.
self.last_lifetime = None;
}

// Now "cook" the token, converting the simple `rustc_lexer::TokenKind` enum into a
// rich `rustc_ast::TokenKind`. This turns strings into interned symbols and runs
// additional validation.
Expand Down Expand Up @@ -247,6 +264,7 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
// expansion purposes. See #12512 for the gory details of why
// this is necessary.
let lifetime_name = self.str_from(start);
self.last_lifetime = Some(self.mk_sp(start, start + BytePos(1)));
if starts_with_number {
let span = self.mk_sp(start, self.pos);
self.dcx().struct_err("lifetimes cannot start with a number")
Expand Down Expand Up @@ -395,10 +413,21 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
match kind {
rustc_lexer::LiteralKind::Char { terminated } => {
if !terminated {
self.dcx()
let mut err = self
.dcx()
.struct_span_fatal(self.mk_sp(start, end), "unterminated character literal")
.with_code(E0762)
.emit()
.with_code(E0762);
if let Some(lt_sp) = self.last_lifetime {
err.multipart_suggestion(
"if you meant to write a string literal, use double quotes",
vec![
(lt_sp, "\"".to_string()),
(self.mk_sp(start, start + BytePos(1)), "\"".to_string()),
],
Applicability::MaybeIncorrect,
);
}
err.emit()
}
self.cook_unicode(token::Char, Mode::Char, start, end, 1, 1) // ' '
}
Expand Down Expand Up @@ -669,15 +698,33 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
let expn_data = prefix_span.ctxt().outer_expn_data();

if expn_data.edition >= Edition::Edition2021 {
let mut silence = false;
// In Rust 2021, this is a hard error.
let sugg = if prefix == "rb" {
Some(errors::UnknownPrefixSugg::UseBr(prefix_span))
} else if expn_data.is_root() {
Some(errors::UnknownPrefixSugg::Whitespace(prefix_span.shrink_to_hi()))
if self.cursor.first() == '\''
&& let Some(start) = self.last_lifetime
&& self.cursor.third() != '\''
{
// An "unclosed `char`" error will be emitted already, silence redundant error.
silence = true;
Some(errors::UnknownPrefixSugg::MeantStr {
start,
end: self.mk_sp(self.pos, self.pos + BytePos(1)),
})
} else {
Some(errors::UnknownPrefixSugg::Whitespace(prefix_span.shrink_to_hi()))
}
} else {
None
};
self.dcx().emit_err(errors::UnknownPrefix { span: prefix_span, prefix, sugg });
let err = errors::UnknownPrefix { span: prefix_span, prefix, sugg };
if silence {
self.dcx().create_err(err).delay_as_bug();
} else {
self.dcx().emit_err(err);
}
} else {
// Before Rust 2021, only emit a lint for migration.
self.psess.buffer_lint_with_diagnostic(
Expand Down
20 changes: 15 additions & 5 deletions compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
Original file line number Diff line number Diff line change
Expand Up @@ -95,11 +95,21 @@ pub(crate) fn emit_unescape_error(
}
escaped.push(c);
}
let sugg = format!("{prefix}\"{escaped}\"");
MoreThanOneCharSugg::Quotes {
span: full_lit_span,
is_byte: mode == Mode::Byte,
sugg,
if escaped.len() != lit.len() || full_lit_span.is_empty() {
let sugg = format!("{prefix}\"{escaped}\"");
MoreThanOneCharSugg::QuotesFull {
span: full_lit_span,
is_byte: mode == Mode::Byte,
sugg,
}
} else {
MoreThanOneCharSugg::Quotes {
start: full_lit_span
.with_hi(full_lit_span.lo() + BytePos((prefix.len() + 1) as u32)),
end: full_lit_span.with_lo(full_lit_span.hi() - BytePos(1)),
is_byte: mode == Mode::Byte,
prefix,
}
}
});
dcx.emit_err(UnescapeError::MoreThanOneChar {
Expand Down
12 changes: 6 additions & 6 deletions tests/ui/inference/str-as-char.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ error: character literal may only contain one codepoint
LL | let _: &str = '"""';
| ^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let _: &str = "\"\"\"";
| ~~~~~~~~
Expand All @@ -15,18 +15,18 @@ error: character literal may only contain one codepoint
LL | let _: &str = '\"\"\"';
| ^^^^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let _: &str = "\"\"\"";
| ~~~~~~~~
| ~ ~

error: character literal may only contain one codepoint
--> $DIR/str-as-char.rs:10:19
|
LL | let _: &str = '"\"\"\\"\\"';
| ^^^^^^^^^^^^^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let _: &str = "\"\"\\"\\"\\\"";
| ~~~~~~~~~~~~~~~~~~~~
Expand All @@ -39,10 +39,10 @@ LL | let _: &str = 'a';
| |
| expected due to this
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let _: &str = "a";
| ~~~
| ~ ~

error: aborting due to 4 previous errors

Expand Down
4 changes: 2 additions & 2 deletions tests/ui/issues/issue-23589.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,10 @@ error[E0308]: mismatched types
LL | let v: Vec(&str) = vec!['1', '2'];
| ^^^ expected `&str`, found `char`
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let v: Vec(&str) = vec!["1", '2'];
| ~~~
| ~ ~

error: aborting due to 2 previous errors

Expand Down
4 changes: 2 additions & 2 deletions tests/ui/lexer/lex-bad-char-literals-2.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,10 @@ error: character literal may only contain one codepoint
LL | 'nope'
| ^^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | "nope"
| ~~~~~~
| ~ ~

error: aborting due to 1 previous error

8 changes: 4 additions & 4 deletions tests/ui/lexer/lex-bad-char-literals-3.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,21 +4,21 @@ error: character literal may only contain one codepoint
LL | static c: char = '●●';
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | static c: char = "●●";
| ~~~~
| ~ ~

error: character literal may only contain one codepoint
--> $DIR/lex-bad-char-literals-3.rs:5:20
|
LL | let ch: &str = '●●';
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let ch: &str = "●●";
| ~~~~
| ~ ~

error: aborting due to 2 previous errors

8 changes: 4 additions & 4 deletions tests/ui/lexer/lex-bad-char-literals-5.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,21 +4,21 @@ error: character literal may only contain one codepoint
LL | static c: char = '\x10\x10';
| ^^^^^^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | static c: char = "\x10\x10";
| ~~~~~~~~~~
| ~ ~

error: character literal may only contain one codepoint
--> $DIR/lex-bad-char-literals-5.rs:5:20
|
LL | let ch: &str = '\x10\x10';
| ^^^^^^^^^^
|
help: if you meant to write a `str` literal, use double quotes
help: if you meant to write a string literal, use double quotes
|
LL | let ch: &str = "\x10\x10";
| ~~~~~~~~~~
| ~ ~

error: aborting due to 2 previous errors

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