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oriongonzaardi
oriongonza
authored and
ardi
committed
improve parse item fallback
1 parent 4333551 commit b9ddf53

17 files changed

+127
-51
lines changed

‎compiler/rustc_ast_pretty/src/pprust/mod.rs‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -76,6 +76,14 @@ pub fn attribute_to_string(attr: &ast::Attribute) -> String {
7676
State::new().attribute_to_string(attr)
7777
}
7878

79+
pub fn local_to_string(local: &ast::Local) -> String {
80+
State::new().local_to_string(local)
81+
}
82+
83+
pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
84+
State::new().stmt_to_string(stmt)
85+
}
86+
7987
pub fn to_string(f: impl FnOnce(&mut State<'_>)) -> String {
8088
State::to_string(f)
8189
}

‎compiler/rustc_ast_pretty/src/pprust/state.rs‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2076,4 +2076,8 @@ impl<'a> State<'a> {
20762076
pub(crate) fn attribute_to_string(&self, attr: &ast::Attribute) -> String {
20772077
Self::to_string(|s| s.print_attribute(attr))
20782078
}
2079+
2080+
pub(crate) fn local_to_string(&self, local: &ast::Local) -> String {
2081+
Self::to_string(|s| s.print_local_decl(local))
2082+
}
20792083
}

‎compiler/rustc_parse/src/parser/item.rs‎

Lines changed: 84 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
11
use super::diagnostics::{dummy_arg, ConsumeClosingDelim};
22
use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
33
use super::{
4-
AttrWrapper, FollowedByType, ForceCollect, Parser, PathStyle, Trailing, TrailingToken,
4+
AttemptLocalParseRecovery, AttrWrapper, FollowedByType, ForceCollect, Parser, PathStyle,
5+
Trailing, TrailingToken,
56
};
67
use crate::errors::{self, MacroExpandsToAdtField};
78
use crate::fluent_generated as fluent;
@@ -40,6 +41,7 @@ impl<'a> Parser<'a> {
4041
let mod_kind = if self.eat(&token::Semi) {
4142
ModKind::Unloaded
4243
} else {
44+
// mod blocks are parsed recursively
4345
self.expect(&token::OpenDelim(Delimiter::Brace))?;
4446
let (inner_attrs, items, inner_span) =
4547
self.parse_mod(&token::CloseDelim(Delimiter::Brace))?;
@@ -72,28 +74,83 @@ impl<'a> Parser<'a> {
7274
}
7375

7476
if !self.eat(term) {
75-
let token_str = super::token_descr(&self.token);
77+
// The last token should be `term`: either EOF or `}`. If it's not that means that we've had an error
78+
// parsing an item
7679
if !self.maybe_consume_incorrect_semicolon(items.last().map(|x| &**x)) {
77-
let msg = format!("expected item, found {token_str}");
78-
let mut err = self.dcx().struct_span_err(self.token.span, msg);
79-
let span = self.token.span;
80-
if self.is_kw_followed_by_ident(kw::Let) {
81-
err.span_label(
82-
span,
83-
"consider using `const` or `static` instead of `let` for global variables",
84-
);
85-
} else {
86-
err.span_label(span, "expected item")
87-
.note("for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>");
88-
};
89-
return Err(err);
80+
self.fallback_incorrect_item()?;
9081
}
9182
}
9283

9384
let inject_use_span = post_attr_lo.data().with_hi(post_attr_lo.lo());
9485
let mod_spans = ModSpans { inner_span: lo.to(self.prev_token.span), inject_use_span };
9586
Ok((attrs, items, mod_spans))
9687
}
88+
89+
fn fallback_incorrect_item(&mut self) -> PResult<'a, ()> {
90+
let token_str = super::token_descr(&self.token);
91+
let mut err = self
92+
.dcx()
93+
.struct_span_err(self.token.span, format!("expected item, found {token_str}"));
94+
95+
let stmt = match self.parse_full_stmt(AttemptLocalParseRecovery::No) {
96+
Ok(stmt) => stmt,
97+
Err(e) => {
98+
// We don't really care about an error parsing this statement.
99+
e.cancel();
100+
return Err(err);
101+
}
102+
};
103+
104+
if let Some(stmt) = stmt {
105+
let span = stmt.span;
106+
match &stmt.kind {
107+
StmtKind::Let(_) => {
108+
err.span_label(span, "unexpected `let` binding outside of a function")
109+
.help(format!("consider using `const` or `static` instead of `let` for global variables, or put it inside of a function: fn foo() {{ {} }}",
110+
pprust::stmt_to_string(&stmt)));
111+
}
112+
StmtKind::Semi(expr) | StmtKind::Expr(expr) => {
113+
match expr.kind {
114+
ExprKind::Err(_) => {
115+
err.span_label(expr.span, "error parsing this expression");
116+
}
117+
ExprKind::Array(_) => {
118+
// If it's an array it's possible that it's an attribute
119+
// that is missing a `#`.
120+
err.span_label(span, "unexpected array")
121+
.help(
122+
format!("If you wanted an array consider putting it inside a function: fn foo() {{ {} }}",
123+
pprust::expr_to_string(expr)))
124+
.span_help(span.shrink_to_lo(), "If you wanted an attribute consider adding `#`");
125+
}
126+
ExprKind::Unary(UnOp::Not, _) => {
127+
// This might be an inner attribute wihtout #...
128+
err.span_label(span, "unexpected expression");
129+
}
130+
_ => {
131+
err.span_label(span, "unexpected expression").help(format!(
132+
"consider putting it inside a function: fn foo() {{ {} }}",
133+
pprust::expr_to_string(expr)
134+
));
135+
}
136+
};
137+
}
138+
StmtKind::MacCall(_) => {
139+
err.span_label(span, "unexpected macro call at this position");
140+
}
141+
StmtKind::Item(_) => {
142+
err.span_label(span, "unexpected item at this position");
143+
}
144+
StmtKind::Empty => {
145+
unreachable!("should have been handled by maybe_consume_incorrect_semicolon");
146+
}
147+
};
148+
}
149+
150+
err.note("for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>");
151+
152+
return Err(err);
153+
}
97154
}
98155

99156
pub(super) type ItemInfo = (Ident, ItemKind);
@@ -2312,10 +2369,18 @@ impl<'a> Parser<'a> {
23122369
vis: &Visibility,
23132370
case: Case,
23142371
) -> PResult<'a, (Ident, FnSig, Generics, Option<P<Block>>)> {
2372+
// Let's have an example function
2373+
// const unsafe fn <'a, T> foo(arg: &'a T) -> i32
2374+
// where T: Send {
2375+
// 1+1
2376+
// }
2377+
23152378
let fn_span = self.token.span;
2316-
let header = self.parse_fn_front_matter(vis, case)?; // `const ... fn`
2379+
let header = self.parse_fn_front_matter(vis, case)?; // `const unsafe`
23172380
let ident = self.parse_ident()?; // `foo`
2318-
let mut generics = self.parse_generics()?; // `<'a, T, ...>`
2381+
let mut generics = self.parse_generics()?; // `<'a, T>`
2382+
2383+
// (arg: &'a T) -> i32
23192384
let decl = match self.parse_fn_decl(
23202385
fn_parse_mode.req_name,
23212386
AllowPlus::Yes,
@@ -2332,10 +2397,10 @@ impl<'a> Parser<'a> {
23322397
}
23332398
}
23342399
};
2335-
generics.where_clause = self.parse_where_clause()?; // `where T: Ord`
2400+
generics.where_clause = self.parse_where_clause()?; // `where T: Send`
23362401

23372402
let mut sig_hi = self.prev_token.span;
2338-
let body = self.parse_fn_body(attrs, &ident, &mut sig_hi, fn_parse_mode.req_body)?; // `;` or `{ ... }`.
2403+
let body = self.parse_fn_body(attrs, &ident, &mut sig_hi, fn_parse_mode.req_body)?; // `{ 1+1 }` but could also be `;`
23392404
let fn_sig_span = sig_lo.to(sig_hi);
23402405
Ok((ident, FnSig { header, decl, span: fn_sig_span }, generics, body))
23412406
}

‎tests/ui/fn/keyword-order.stderr‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,9 @@ error: expected item, found keyword `pub`
1010
--> $DIR/keyword-order.rs:3:9
1111
|
1212
LL | default pub const async unsafe extern fn err() {}
13-
| ^^^ expected item
13+
| ^^^--------------------------------------
14+
| |
15+
| unexpected item at this position
1416
|
1517
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
1618

‎tests/ui/parser/default-unmatched.stderr‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,9 +10,7 @@ error: expected item, found reserved keyword `do`
1010
--> $DIR/default-unmatched.rs:3:13
1111
|
1212
LL | default do
13-
| ^^ expected item
14-
|
15-
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
13+
| ^^
1614

1715
error: aborting due to 2 previous errors
1816

‎tests/ui/parser/help-set-edition-ice-122130.stderr‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -13,9 +13,7 @@ error: expected item, found `"owned_box"`
1313
--> $DIR/help-set-edition-ice-122130.rs:2:9
1414
|
1515
LL | s#[c"owned_box"]
16-
| ^^^^^^^^^^^ expected item
17-
|
18-
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
16+
| ^^^^^^^^^^^
1917

2018
error: aborting due to 2 previous errors
2119

‎tests/ui/parser/impl-parsing.stderr‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -34,9 +34,7 @@ error: expected item, found keyword `unsafe`
3434
--> $DIR/impl-parsing.rs:9:9
3535
|
3636
LL | default unsafe FAIL
37-
| ^^^^^^ expected item
38-
|
39-
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
37+
| ^^^^^^
4038

4139
error: aborting due to 6 previous errors
4240

‎tests/ui/parser/issues/issue-101477-enum.stderr‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,9 +10,7 @@ error: expected item, found `==`
1010
--> $DIR/issue-101477-enum.rs:6:7
1111
|
1212
LL | B == 2
13-
| ^^ expected item
14-
|
15-
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
13+
| ^^
1614

1715
error: aborting due to 2 previous errors
1816

‎tests/ui/parser/issues/issue-113110-non-item-at-module-root.stderr‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2,8 +2,9 @@ error: expected item, found `5`
22
--> $DIR/issue-113110-non-item-at-module-root.rs:1:2
33
|
44
LL | 5
5-
| ^ expected item
5+
| ^ unexpected expression
66
|
7+
= help: consider putting it inside a function: fn foo() { 5 }
78
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
89

910
error: aborting due to 1 previous error

‎tests/ui/parser/issues/issue-17904-2.stderr‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -2,9 +2,7 @@ error: expected item, found keyword `where`
22
--> $DIR/issue-17904-2.rs:1:24
33
|
44
LL | struct Bar<T> { x: T } where T: Copy
5-
| ^^^^^ expected item
6-
|
7-
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
5+
| ^^^^^
86

97
error: aborting due to 1 previous error
108

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