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Suggest correct location for lifetime parameters in use

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This commit is contained in:
Esteban Küber 2019-01-12 19:25:03 -08:00
parent db740313e0
commit 28ea03e114
7 changed files with 82 additions and 47 deletions
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52
src/libsyntax/parse/parser.rs
View file

@ -5330,23 +5330,28 @@ impl<'a> Parser<'a> {
/// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
/// possibly including trailing comma.
fn parse_generic_args(&mut self)
-> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
let mut args = Vec::new();
let mut bindings = Vec::new();
let mut seen_type = false;
let mut seen_binding = false;
let mut first_type_or_binding_span: Option<Span> = None;
let mut bad_lifetime_pos = vec![];
let mut last_comma_span = None;
let mut suggestions = vec![];
loop {
if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
// Parse lifetime argument.
args.push(GenericArg::Lifetime(self.expect_lifetime()));
if seen_type || seen_binding {
self.struct_span_err(
self.prev_span,
"lifetime parameters must be declared prior to type parameters"
)
.span_label(self.prev_span, "must be declared prior to type parameters")
.emit();
let remove_sp = last_comma_span.unwrap_or(self.prev_span).to(self.prev_span);
bad_lifetime_pos.push(self.prev_span);
if let Ok(snippet) = self.sess.source_map().span_to_snippet(self.prev_span) {
suggestions.push((remove_sp, String::new()));
suggestions.push((
first_type_or_binding_span.unwrap().shrink_to_lo(),
format!("{}, ", snippet)));
}
}
} else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
// Parse associated type binding.
@ -5354,13 +5359,17 @@ impl<'a> Parser<'a> {
let ident = self.parse_ident()?;
self.bump();
let ty = self.parse_ty()?;
let span = lo.to(self.prev_span);
bindings.push(TypeBinding {
id: ast::DUMMY_NODE_ID,
ident,
ty,
span: lo.to(self.prev_span),
span,
});
seen_binding = true;
if first_type_or_binding_span.is_none() {
first_type_or_binding_span = Some(span);
}
} else if self.check_type() {
// Parse type argument.
let ty_param = self.parse_ty()?;
@ -5375,6 +5384,9 @@ impl<'a> Parser<'a> {
)
.emit();
}
if first_type_or_binding_span.is_none() {
first_type_or_binding_span = Some(ty_param.span);
}
args.push(GenericArg::Type(ty_param));
seen_type = true;
} else {
@ -5383,8 +5395,30 @@ impl<'a> Parser<'a> {
if !self.eat(&token::Comma) {
break
} else {
last_comma_span = Some(self.prev_span);
}
}
if !bad_lifetime_pos.is_empty() {
let mut err = self.struct_span_err(
bad_lifetime_pos.clone(),
"lifetime parameters must be declared prior to type parameters"
);
for sp in &bad_lifetime_pos {
err.span_label(*sp, "must be declared prior to type parameters");
}
if !suggestions.is_empty() {
err.multipart_suggestion_with_applicability(
&format!(
"move the lifetime parameter{} prior to the first type parameter",
if bad_lifetime_pos.len() > 1 { "s" } else { "" },
),
suggestions,
Applicability::MachineApplicable,
);
}
err.emit();
}
Ok((args, bindings))
}

23
src/test/ui/parser/issue-14303-fncall.rs
View file

@ -1,8 +1,17 @@
fn main() {
(0..4)
.map(|x| x * 2)
.collect::<Vec<'a, usize, 'b>>()
//~^ ERROR lifetime parameters must be declared prior to type parameters
//~| ERROR use of undeclared lifetime name
//~| ERROR use of undeclared lifetime name
// can't run rustfix because it doesn't handle multipart suggestions correctly
// compile-flags: -Zborrowck=mir
// we need the above to avoid ast borrowck failure in recovered code
struct S<'a, T> {
a: &'a T,
b: &'a T,
}
fn foo<'a, 'b>(start: &'a usize, end: &'a usize) {
let _x = (*start..*end)
.map(|x| S { a: start, b: end })
.collect::<Vec<S<_, 'a>>>();
//~^ ERROR lifetime parameters must be declared prior to type parameters
}
fn main() {}

23
src/test/ui/parser/issue-14303-fncall.stderr
View file

@ -1,21 +1,12 @@
error: lifetime parameters must be declared prior to type parameters
--> $DIR/issue-14303-fncall.rs:4:31
--> $DIR/issue-14303-fncall.rs:13:29
|
LL | .collect::<Vec<'a, usize, 'b>>()
| ^^ must be declared prior to type parameters
error[E0261]: use of undeclared lifetime name `'a`
--> $DIR/issue-14303-fncall.rs:4:20
LL | .collect::<Vec<S<_, 'a>>>();
| ^^ must be declared prior to type parameters
help: move the lifetime parameter prior to the first type parameter
|
LL | .collect::<Vec<'a, usize, 'b>>()
| ^^ undeclared lifetime
LL | .collect::<Vec<S<'a, _>>>();
| ^^^ --
error[E0261]: use of undeclared lifetime name `'b`
--> $DIR/issue-14303-fncall.rs:4:31
|
LL | .collect::<Vec<'a, usize, 'b>>()
| ^^ undeclared lifetime
error: aborting due to previous error
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0261`.

1
src/test/ui/parser/issue-14303-path.rs
View file

@ -9,6 +9,5 @@ mod foo {
fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
//~^ ERROR lifetime parameters must be declared prior to type parameters
//~| ERROR lifetime parameters must be declared prior to type parameters
fn main() {}

14
src/test/ui/parser/issue-14303-path.stderr
View file

@ -2,13 +2,13 @@ error: lifetime parameters must be declared prior to type parameters
--> $DIR/issue-14303-path.rs:10:40
|
LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
| ^^ must be declared prior to type parameters
error: lifetime parameters must be declared prior to type parameters
--> $DIR/issue-14303-path.rs:10:44
| ^^ ^^ must be declared prior to type parameters
| |
| must be declared prior to type parameters
help: move the lifetime parameters prior to the first type parameter
|
LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
| ^^ must be declared prior to type parameters
LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, 'b, 'c, T>) {}
| ^^^ ^^^ --
error: aborting due to 2 previous errors
error: aborting due to previous error

2
src/test/ui/traits/trait-object-vs-lifetime.rs
View file

@ -1,8 +1,6 @@
// A few contrived examples where lifetime should (or should not) be parsed as an object type.
// Lifetimes parsed as types are still rejected later by semantic checks.
// compile-flags: -Z continue-parse-after-error
struct S<'a, T>(&'a u8, T);
fn main() {

14
src/test/ui/traits/trait-object-vs-lifetime.stderr
View file

@ -1,29 +1,33 @@
error: lifetime parameters must be declared prior to type parameters
--> $DIR/trait-object-vs-lifetime.rs:16:25
--> $DIR/trait-object-vs-lifetime.rs:14:25
|
LL | let _: S<'static +, 'static>;
| ^^^^^^^ must be declared prior to type parameters
help: move the lifetime parameter prior to the first type parameter
|
LL | let _: S<'static, 'static +>;
| ^^^^^^^^ --
error[E0224]: at least one non-builtin trait is required for an object type
--> $DIR/trait-object-vs-lifetime.rs:11:23
--> $DIR/trait-object-vs-lifetime.rs:9:23
|
LL | let _: S<'static, 'static +>;
| ^^^^^^^^^
error[E0107]: wrong number of lifetime arguments: expected 1, found 2
--> $DIR/trait-object-vs-lifetime.rs:13:23
--> $DIR/trait-object-vs-lifetime.rs:11:23
|
LL | let _: S<'static, 'static>;
| ^^^^^^^ unexpected lifetime argument
error[E0107]: wrong number of type arguments: expected 1, found 0
--> $DIR/trait-object-vs-lifetime.rs:13:12
--> $DIR/trait-object-vs-lifetime.rs:11:12
|
LL | let _: S<'static, 'static>;
| ^^^^^^^^^^^^^^^^^^^ expected 1 type argument
error[E0224]: at least one non-builtin trait is required for an object type
--> $DIR/trait-object-vs-lifetime.rs:16:14
--> $DIR/trait-object-vs-lifetime.rs:14:14
|
LL | let _: S<'static +, 'static>;
| ^^^^^^^^^