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Make some parser structured suggestions verbose and tweak their wording #159667

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Merged
rust-bors merged 2 commits into from
Jul 24, 2026
Merged

Make some parser structured suggestions verbose and tweak their wording #159667

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7372202
Make some parser structured suggestions verbose
estebank Jul 21, 2026
1b7ae04
Tweak code and diagnostic formatting and messages
estebank Jul 21, 2026
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2 changes: 1 addition & 1 deletion compiler/rustc_parse/src/lexer/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -987,7 +987,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
let lo = start + BytePos(possible_offset);
let hi = lo + BytePos(found_terminators);
let span = self.mk_sp(lo, hi);
err.span_suggestion(
err.span_suggestion_verbose(
span,
"consider terminating the string here",
"#".repeat(n_hashes as usize),
Expand Down
10 changes: 5 additions & 5 deletions compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -162,7 +162,7 @@ pub(crate) fn emit_unescape_error(
);
} else {
if mode == Mode::Str || mode == Mode::Char {
diag.span_suggestion(
diag.span_suggestion_verbose(
full_lit_span,
"if you meant to write a literal backslash (perhaps escaping in a regular expression), consider a raw string literal",
format!("r\"{lit}\""),
Expand Down Expand Up @@ -204,7 +204,7 @@ pub(crate) fn emit_unescape_error(
// Note: the \\xHH suggestions are not given for raw byte string
// literals, because they are araw and so cannot use any escapes.
if (c as u32) <= 0xFF && mode != Mode::RawByteStr {
err.span_suggestion(
err.span_suggestion_verbose(
span,
format!(
"if you meant to use the unicode code point for {c:?}, use a \\xHH escape"
Expand All @@ -217,7 +217,7 @@ pub(crate) fn emit_unescape_error(
} else if mode != Mode::RawByteStr {
let mut utf8 = String::new();
utf8.push(c);
err.span_suggestion(
err.span_suggestion_verbose(
span,
format!("if you meant to use the UTF-8 encoding of {c:?}, use \\xHH escapes"),
utf8.as_bytes()
Expand Down Expand Up @@ -313,7 +313,7 @@ fn foreign_escape_suggestion(
err_span: Span,
) {
if escaped_char == "?" {
diag.span_suggestion(
diag.span_suggestion_verbose(
err_span,
"if you meant to write a literal question mark, don't escape the character",
"?",
Expand All @@ -336,7 +336,7 @@ fn foreign_escape_suggestion(
_ => return,
};

diag.span_suggestion(
diag.span_suggestion_verbose(
escape_span,
format!("if you meant to write {name}, use a hex escape"),
format!("x{hex}"),
Expand Down
24 changes: 16 additions & 8 deletions compiler/rustc_parse/src/parser/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -597,7 +597,7 @@ impl<'a> Parser<'a> {
.iter()
.any(|tok| matches!(tok, TokenType::FatArrow | TokenType::CloseBrace))
{
err.span_suggestion(
err.span_suggestion_verbose(
self.token.span,
"you might have meant to write a \"greater than or equal to\" comparison",
">=",
Expand Down Expand Up @@ -942,7 +942,7 @@ impl<'a> Parser<'a> {
count += 1;
}
err.span(span);
err.span_suggestion(
err.span_suggestion_verbose(
span,
format!("remove the extra `#`{}", pluralize!(count)),
"",
Expand Down Expand Up @@ -2062,7 +2062,15 @@ impl<'a> Parser<'a> {
Applicability::MachineApplicable,
);
}
err.span_suggestion(lo.shrink_to_lo(), format!("{prefix}you can still access the deprecated `try!()` macro using the \"raw identifier\" syntax"), "r#", Applicability::MachineApplicable);
err.span_suggestion_verbose(
lo.shrink_to_lo(),
format!(
"{prefix}you can still access the deprecated `try!()` macro using the \
\"raw identifier\" syntax"
),
"r#",
Applicability::MachineApplicable,
);
let guar = err.emit();
Ok(self.mk_expr_err(lo.to(hi), guar))
} else {
Expand Down Expand Up @@ -2243,7 +2251,7 @@ impl<'a> Parser<'a> {
let ident = self.parse_ident_common(true).unwrap();
let span = pat.span.with_hi(ident.span.hi());

err.span_suggestion(
err.span_suggestion_verbose(
span,
"declare the type after the parameter binding",
"<identifier>: <type>",
Expand Down Expand Up @@ -2641,7 +2649,7 @@ impl<'a> Parser<'a> {
Ok((expr, _)) => {
// Find a mistake like `MyTrait<Assoc == S::Assoc>`.
if snapshot.token == token::EqEq {
err.span_suggestion(
err.span_suggestion_verbose(
snapshot.token.span,
"if you meant to use an associated type binding, replace `==` with `=`",
"=",
Expand All @@ -2655,7 +2663,7 @@ impl<'a> Parser<'a> {
&& matches!(expr.kind, ExprKind::Path(..))
{
// Find a mistake like "foo::var:A".
err.span_suggestion(
err.span_suggestion_verbose(
snapshot.token.span,
"write a path separator here",
"::",
Expand Down Expand Up @@ -2938,7 +2946,7 @@ impl<'a> Parser<'a> {
Applicability::MachineApplicable,
);
if let CommaRecoveryMode::EitherTupleOrPipe = rt {
err.span_suggestion(
err.span_suggestion_verbose(
comma_span,
"...or a vertical bar to match on alternatives",
" |",
Expand Down Expand Up @@ -2975,7 +2983,7 @@ impl<'a> Parser<'a> {
&& (self.expected_token_types.contains(TokenType::Gt)
|| matches!(self.token.kind, token::Literal(..)))
{
err.span_suggestion(
err.span_suggestion_verbose(
maybe_lt.span,
"remove the `<` to write an exclusive range",
"",
Expand Down
13 changes: 9 additions & 4 deletions compiler/rustc_parse/src/parser/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1699,7 +1699,12 @@ impl<'a> Parser<'a> {
// directly adjacent (i.e. '=<')
if maybe_eq_tok == TokenKind::Eq && maybe_eq_tok.span.hi() == lt_span.lo() {
let eq_lt = maybe_eq_tok.span.to(lt_span);
err.span_suggestion(eq_lt, "did you mean", "<=", Applicability::Unspecified);
err.span_suggestion_verbose(
eq_lt,
"you might have meant to write a \"less than or equal to\" comparison",
"<=",
Applicability::Unspecified,
);
}
err
})?;
Expand Down Expand Up @@ -2755,7 +2760,7 @@ impl<'a> Parser<'a> {
&& let maybe_let = self.look_ahead(1, |t| t.clone())
&& maybe_let.is_keyword(kw::Let)
{
err.span_suggestion(
err.span_suggestion_verbose(
self.prev_token.span,
"consider removing this semicolon to parse the `let` as part of the same chain",
"",
Expand All @@ -2767,7 +2772,7 @@ impl<'a> Parser<'a> {
} else {
// Look for usages of '=>' where '>=' might be intended
if maybe_fatarrow == token::FatArrow {
err.span_suggestion(
err.span_suggestion_verbose(
maybe_fatarrow.span,
"you might have meant to write a \"greater than or equal to\" comparison",
">=",
Expand Down Expand Up @@ -3381,7 +3386,7 @@ impl<'a> Parser<'a> {
if let Err(mut err) = this.expect(exp!(FatArrow)) {
// We might have a `=>` -> `=` or `->` typo (issue #89396).
if is_almost_fat_arrow {
err.span_suggestion(
err.span_suggestion_verbose(
this.token.span,
"use a fat arrow to start a match arm",
"=>",
Expand Down
49 changes: 29 additions & 20 deletions compiler/rustc_parse/src/parser/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -601,7 +601,7 @@ impl<'a> Parser<'a> {
&& let [segment] = path.segments.as_slice()
&& edit_distance("macro_rules", &segment.ident.to_string(), 2).is_some()
{
err.span_suggestion(
err.span_suggestion_verbose(
path.span,
"perhaps you meant to define a macro",
"macro_rules",
Expand All @@ -626,13 +626,16 @@ impl<'a> Parser<'a> {
let mut err = self.dcx().struct_span_err(end.span, msg);
if end.is_doc_comment() {
err.span_label(end.span, "this doc comment doesn't document anything");
} else if self.token == TokenKind::Semi {
err.span_suggestion_verbose(
self.token.span,
"consider removing this semicolon",
"",
Applicability::MaybeIncorrect,
);
} else {
err.span_label(end.span, "expected an item after this");
if self.token == TokenKind::Semi {
err.span_suggestion_verbose(
self.token.span,
"remove the semicolon after the attribute",
"",
Applicability::MaybeIncorrect,
);
}
}
if let [.., penultimate, _] = attrs {
err.span_label(start.span.to(penultimate.span), "other attributes here");
Expand Down Expand Up @@ -2429,16 +2432,19 @@ impl<'a> Parser<'a> {
&inherited_vis,
Case::Insensitive,
) {
Ok(_) => {
self.dcx().struct_span_err(
Ok(_) => self
.dcx()
.struct_span_err(
lo.to(self.prev_token.span),
format!("functions are not allowed in {adt_ty} definitions"),
)
.with_help(
"unlike in C++, Java, and C#, functions are declared in `impl` blocks",
)
.with_help("see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information")
}
.with_help(
"see https://doc.rust-lang.org/book/ch05-03-method-syntax.html \
for more information",
),
Err(err) => {
err.cancel();
self.restore_snapshot(snapshot);
Expand Down Expand Up @@ -2474,14 +2480,17 @@ impl<'a> Parser<'a> {
.map_err(|err| err.cancel())
&& self.token == TokenKind::Colon
{
err.span_suggestion(
err.span_suggestion_verbose(
removal_span,
"remove this `let` keyword",
"remove the `let` keyword",
String::new(),
Applicability::MachineApplicable,
);
err.note("the `let` keyword is not allowed in `struct` fields");
err.note("see <https://doc.rust-lang.org/book/ch05-01-defining-structs.html> for more information");
err.note(
"see <https://doc.rust-lang.org/book/ch05-01-defining-structs.html> \
for more information",
);
err.emit();
return Ok(ident);
} else {
Expand Down Expand Up @@ -2632,7 +2641,7 @@ impl<'a> Parser<'a> {
vec![(open, "{".to_string()), (close, '}'.to_string())],
Applicability::MaybeIncorrect,
);
err.span_suggestion(
err.span_suggestion_verbose(
span.with_neighbor(self.token.span).shrink_to_hi(),
"add a semicolon",
';',
Expand Down Expand Up @@ -3248,7 +3257,7 @@ impl<'a> Parser<'a> {
.span_to_snippet(original_sp)
.expect("Span extracted directly from keyword should always work");

err.span_suggestion(
err.span_suggestion_verbose(
self.token_uninterpolated_span(),
format!("`{original_kw}` already used earlier, remove this one"),
"",
Expand All @@ -3263,7 +3272,7 @@ impl<'a> Parser<'a> {
let misplaced_qual_sp = self.token_uninterpolated_span();
let misplaced_qual = self.span_to_snippet(misplaced_qual_sp).unwrap();

err.span_suggestion(
err.span_suggestion_verbose(
correct_pos_sp.to(misplaced_qual_sp),
format!("`{misplaced_qual}` must come before `{current_qual}`"),
format!("{misplaced_qual} {current_qual}"),
Expand All @@ -3287,7 +3296,7 @@ impl<'a> Parser<'a> {

// There was no explicit visibility
if matches!(orig_vis.kind, VisibilityKind::Inherited) {
err.span_suggestion(
err.span_suggestion_verbose(
sp_start.to(self.prev_token.span),
format!("visibility `{vs}` must come before `{snippet}`"),
format!("{vs} {snippet}"),
Expand All @@ -3296,7 +3305,7 @@ impl<'a> Parser<'a> {
}
// There was an explicit visibility
else {
err.span_suggestion(
err.span_suggestion_verbose(
current_vis.span,
"there is already a visibility modifier, remove one",
"",
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_parse/src/parser/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1805,7 +1805,7 @@ impl<'a> Parser<'a> {
format!("the {kind_desc} was parsed as having {op_desc} binary expression"),
);

err.span_suggestion(
err.span_suggestion_verbose(
lhs_end_span,
format!("you may have meant to write a `;` to terminate the {kind_desc} earlier"),
";",
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_parse/src/parser/path.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -817,13 +817,13 @@ impl<'a> Parser<'a> {
.dcx()
.struct_span_err(after_eq.to(before_next), "missing type to the right of `=`");
if matches!(self.token.kind, token::Comma | token::Gt) {
err.span_suggestion(
err.span_suggestion_verbose(
self.psess.source_map().next_point(eq_span).to(before_next),
"to constrain the associated type, add a type after `=`",
" TheType",
Applicability::HasPlaceholders,
);
err.span_suggestion(
err.span_suggestion_verbose(
prev_token_span.shrink_to_hi().to(before_next),
format!("remove the `=` if `{ident}` is a type"),
"",
Expand Down
11 changes: 7 additions & 4 deletions tests/ui/async-await/in-trait/bad-signatures.stderr
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Expand Up @@ -8,10 +8,13 @@ error: expected one of `:`, `@`, or `|`, found keyword `self`
--> $DIR/bad-signatures.rs:5:23
|
LL | async fn bar(&abc self);
| -----^^^^
| | |
| | expected one of `:`, `@`, or `|`
| help: declare the type after the parameter binding: `<identifier>: <type>`
| ^^^^ expected one of `:`, `@`, or `|`
|
help: declare the type after the parameter binding
|
LL - async fn bar(&abc self);
LL + async fn bar(<identifier>: <type>);
|

error: aborting due to 2 previous errors

10 changes: 6 additions & 4 deletions tests/ui/async-await/no-async-const.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,12 +2,14 @@ error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `const
--> $DIR/no-async-const.rs:4:11
|
LL | pub async const fn x() {}
| ------^^^^^
| | |
| | expected one of `extern`, `fn`, `safe`, or `unsafe`
| help: `const` must come before `async`: `const async`
| ^^^^^ expected one of `extern`, `fn`, `safe`, or `unsafe`
|
= note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
help: `const` must come before `async`
|
LL - pub async const fn x() {}
LL + pub const async fn x() {}
|

error: functions cannot be both `const` and `async`
--> $DIR/no-async-const.rs:4:5
Expand Down
20 changes: 12 additions & 8 deletions tests/ui/async-await/no-unsafe-async.stderr
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Expand Up @@ -2,23 +2,27 @@ error: expected one of `extern` or `fn`, found keyword `async`
--> $DIR/no-unsafe-async.rs:7:12
|
LL | unsafe async fn g() {}
| -------^^^^^
| | |
| | expected one of `extern` or `fn`
| help: `async` must come before `unsafe`: `async unsafe`
| ^^^^^ expected one of `extern` or `fn`
|
= note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
help: `async` must come before `unsafe`
|
LL - unsafe async fn g() {}
LL + async unsafe fn g() {}
|

error: expected one of `extern` or `fn`, found keyword `async`
--> $DIR/no-unsafe-async.rs:11:8
|
LL | unsafe async fn f() {}
| -------^^^^^
| | |
| | expected one of `extern` or `fn`
| help: `async` must come before `unsafe`: `async unsafe`
| ^^^^^ expected one of `extern` or `fn`
|
= note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`
help: `async` must come before `unsafe`
|
LL - unsafe async fn f() {}
LL + async unsafe fn f() {}
|

error: aborting due to 2 previous errors

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