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Improve diagnostics for parenthesized type arguments
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wutchzone committed Mar 9, 2024
1 parent 1c580bc commit 2648a13
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Showing 7 changed files with 160 additions and 2 deletions.
86 changes: 84 additions & 2 deletions compiler/rustc_parse/src/parser/path.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
use super::{Parser, Restrictions, TokenType};
use crate::errors::PathSingleColon;
use crate::parser::{CommaRecoveryMode, RecoverColon, RecoverComma};
use crate::{errors, maybe_whole};
use ast::token::IdentIsRaw;
use rustc_ast::ptr::P;
Expand All @@ -10,7 +11,7 @@ use rustc_ast::{
AssocConstraintKind, BlockCheckMode, GenericArg, GenericArgs, Generics, ParenthesizedArgs,
Path, PathSegment, QSelf,
};
use rustc_errors::{Applicability, PResult};
use rustc_errors::{Applicability, Diag, PResult};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{BytePos, Span};
use std::mem;
Expand Down Expand Up @@ -373,7 +374,38 @@ impl<'a> Parser<'a> {
.into()
} else {
// `(T, U) -> R`
let (inputs, _) = self.parse_paren_comma_seq(|p| p.parse_ty())?;

let prev_token_before_parsing = self.prev_token.clone();
let token_before_parsing = self.token.clone();
let mut snapshot = None;
if self.may_recover()
&& prev_token_before_parsing.kind == token::ModSep
&& (style == PathStyle::Expr && self.token.can_begin_expr()
|| style == PathStyle::Pat && self.token.can_begin_pattern())
{
snapshot = Some(self.create_snapshot_for_diagnostic());
}

let (inputs, _) = match self.parse_paren_comma_seq(|p| p.parse_ty()) {
Ok(output) => output,
Err(mut error) if prev_token_before_parsing.kind == token::ModSep => {
error.span_label(
prev_token_before_parsing.span.to(token_before_parsing.span),
"while parsing this parenthesized list of type arguments starting here",
);

if let Some(mut snapshot) = snapshot {
snapshot.recover_fn_call_leading_path_sep(
style,
prev_token_before_parsing,
&mut error,
)
}

return Err(error);
}
Err(error) => return Err(error),
};
let inputs_span = lo.to(self.prev_token.span);
let output =
self.parse_ret_ty(AllowPlus::No, RecoverQPath::No, RecoverReturnSign::No)?;
Expand All @@ -399,6 +431,56 @@ impl<'a> Parser<'a> {
}
}

/// Recover `$path::(...)` as `$path(...)`.
///
/// ```ignore (diagnostics)
/// foo::(420, "bar")
/// ^^ remove extra separator to make the function call
/// // or
/// match x {
/// Foo::(420, "bar") => { ... },
/// ^^ remove extra separator to turn this into tuple struct pattern
/// _ => { ... },
/// }
/// ```
fn recover_fn_call_leading_path_sep(
&mut self,
style: PathStyle,
prev_token_before_parsing: Token,
error: &mut Diag<'_>,
) {
if ((style == PathStyle::Expr && self.parse_paren_comma_seq(|p| p.parse_expr()).is_ok())
|| (style == PathStyle::Pat
&& self
.parse_paren_comma_seq(|p| {
p.parse_pat_allow_top_alt(
None,
RecoverComma::No,
RecoverColon::No,
CommaRecoveryMode::LikelyTuple,
)
})
.is_ok()))
&& !matches!(self.token.kind, token::ModSep | token::RArrow)
{
error.span_suggestion_verbose(
prev_token_before_parsing.span,
format!(
"consider removing the `::` here to {}",
match style {
PathStyle::Expr => "call the expresion",
PathStyle::Pat => "turn this into a tuple struct pattern",
_ => {
return;
}
}
),
"",
Applicability::MaybeIncorrect,
);
}
}

/// Parses generic args (within a path segment) with recovery for extra leading angle brackets.
/// For the purposes of understanding the parsing logic of generic arguments, this function
/// can be thought of being the same as just calling `self.parse_angle_args()` if the source
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
fn main() {
foo::( //~ HELP: consider removing the `::` here to call the expresion
//~^ NOTE: while parsing this parenthesized list of type arguments starting
bar(x, y, z),
bar(x, y, z),
bar(x, y, z),
bar(x, y, z),
bar(x, y, z),
bar(x, y, z),
bar(x, y, z),
baz("test"), //~ ERROR: expected type, found `"test"`
//~^ NOTE: expected type
)
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
error: expected type, found `"test"`
--> $DIR/diagnostics-parenthesized-type-arguments-issue-120892-1.rs:11:9
|
LL | foo::(
| --- while parsing this parenthesized list of type arguments starting here
...
LL | baz("test"),
| ^^^^^^ expected type
|
help: consider removing the `::` here to call the expresion
|
LL - foo::(
LL + foo(
|

error: aborting due to 1 previous error

Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
fn main() {
foo::/* definitely not harmful comment */(123, "foo") -> (u32); //~ ERROR: expected type, found `123`
//~^ NOTE: while parsing this parenthesized list of type arguments starting
//~^^ NOTE: expected type
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
error: expected type, found `123`
--> $DIR/diagnostics-parenthesized-type-arguments-issue-120892-2.rs:2:45
|
LL | foo::/* definitely not harmful comment */(123, "foo") -> (u32);
| ---------------------------------------^^^ expected type
| |
| while parsing this parenthesized list of type arguments starting here

error: aborting due to 1 previous error

Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
struct Foo(u32, u32);
impl Foo {
fn foo(&self) {
match *self {
Foo::(1, 2) => {}, //~ HELP: consider removing the `::` here to turn this into a tuple struct pattern
//~^ NOTE: while parsing this parenthesized list of type arguments starting
//~^^ ERROR: expected type, found `1`
//~^^^ NOTE: expected type
_ => {},
}
}
}

fn main() {}
Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
error: expected type, found `1`
--> $DIR/diagnostics-parenthesized-type-arguments-issue-120892-3.rs:5:19
|
LL | Foo::(1, 2) => {},
| ---^ expected type
| |
| while parsing this parenthesized list of type arguments starting here
|
help: consider removing the `::` here to turn this into a tuple struct pattern
|
LL - Foo::(1, 2) => {},
LL + Foo(1, 2) => {},
|

error: aborting due to 1 previous error

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