Suggest correct location for lifetime parameters in use
This commit is contained in:
Esteban Küber
parent
db740313e0
commit
28ea03e114
7 changed files with 82 additions and 47 deletions
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@ -5330,23 +5330,28 @@ impl<'a> Parser<'a> {
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/// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
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/// possibly including trailing comma.
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fn parse_generic_args(&mut self)
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-> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
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fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<TypeBinding>)> {
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let mut args = Vec::new();
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let mut bindings = Vec::new();
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let mut seen_type = false;
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let mut seen_binding = false;
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let mut first_type_or_binding_span: Option<Span> = None;
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let mut bad_lifetime_pos = vec![];
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let mut last_comma_span = None;
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let mut suggestions = vec![];
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loop {
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if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
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// Parse lifetime argument.
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args.push(GenericArg::Lifetime(self.expect_lifetime()));
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if seen_type || seen_binding {
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self.struct_span_err(
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self.prev_span,
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"lifetime parameters must be declared prior to type parameters"
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)
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.span_label(self.prev_span, "must be declared prior to type parameters")
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.emit();
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let remove_sp = last_comma_span.unwrap_or(self.prev_span).to(self.prev_span);
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bad_lifetime_pos.push(self.prev_span);
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if let Ok(snippet) = self.sess.source_map().span_to_snippet(self.prev_span) {
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suggestions.push((remove_sp, String::new()));
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suggestions.push((
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first_type_or_binding_span.unwrap().shrink_to_lo(),
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format!("{}, ", snippet)));
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}
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}
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} else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
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// Parse associated type binding.
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@ -5354,13 +5359,17 @@ impl<'a> Parser<'a> {
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let ident = self.parse_ident()?;
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self.bump();
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let ty = self.parse_ty()?;
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let span = lo.to(self.prev_span);
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bindings.push(TypeBinding {
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id: ast::DUMMY_NODE_ID,
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ident,
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ty,
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span: lo.to(self.prev_span),
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span,
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});
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seen_binding = true;
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if first_type_or_binding_span.is_none() {
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first_type_or_binding_span = Some(span);
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}
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} else if self.check_type() {
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// Parse type argument.
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let ty_param = self.parse_ty()?;
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@ -5375,6 +5384,9 @@ impl<'a> Parser<'a> {
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)
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.emit();
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}
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if first_type_or_binding_span.is_none() {
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first_type_or_binding_span = Some(ty_param.span);
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}
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args.push(GenericArg::Type(ty_param));
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seen_type = true;
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} else {
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@ -5383,8 +5395,30 @@ impl<'a> Parser<'a> {
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if !self.eat(&token::Comma) {
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break
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} else {
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last_comma_span = Some(self.prev_span);
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}
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}
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if !bad_lifetime_pos.is_empty() {
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let mut err = self.struct_span_err(
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bad_lifetime_pos.clone(),
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"lifetime parameters must be declared prior to type parameters"
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);
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for sp in &bad_lifetime_pos {
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err.span_label(*sp, "must be declared prior to type parameters");
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}
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if !suggestions.is_empty() {
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err.multipart_suggestion_with_applicability(
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&format!(
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"move the lifetime parameter{} prior to the first type parameter",
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if bad_lifetime_pos.len() > 1 { "s" } else { "" },
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),
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suggestions,
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Applicability::MachineApplicable,
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);
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}
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err.emit();
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}
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Ok((args, bindings))
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}
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@ -1,8 +1,17 @@
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fn main() {
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(0..4)
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.map(|x| x * 2)
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.collect::<Vec<'a, usize, 'b>>()
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//~^ ERROR lifetime parameters must be declared prior to type parameters
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//~| ERROR use of undeclared lifetime name
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//~| ERROR use of undeclared lifetime name
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// can't run rustfix because it doesn't handle multipart suggestions correctly
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// compile-flags: -Zborrowck=mir
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// we need the above to avoid ast borrowck failure in recovered code
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struct S<'a, T> {
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a: &'a T,
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b: &'a T,
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}
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fn foo<'a, 'b>(start: &'a usize, end: &'a usize) {
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let _x = (*start..*end)
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.map(|x| S { a: start, b: end })
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.collect::<Vec<S<_, 'a>>>();
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//~^ ERROR lifetime parameters must be declared prior to type parameters
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}
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fn main() {}
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@ -1,21 +1,12 @@
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error: lifetime parameters must be declared prior to type parameters
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--> $DIR/issue-14303-fncall.rs:4:31
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--> $DIR/issue-14303-fncall.rs:13:29
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LL | .collect::<Vec<'a, usize, 'b>>()
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| ^^ must be declared prior to type parameters
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error[E0261]: use of undeclared lifetime name `'a`
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--> $DIR/issue-14303-fncall.rs:4:20
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LL | .collect::<Vec<S<_, 'a>>>();
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| ^^ must be declared prior to type parameters
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help: move the lifetime parameter prior to the first type parameter
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LL | .collect::<Vec<'a, usize, 'b>>()
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| ^^ undeclared lifetime
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LL | .collect::<Vec<S<'a, _>>>();
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| ^^^ --
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error[E0261]: use of undeclared lifetime name `'b`
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--> $DIR/issue-14303-fncall.rs:4:31
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LL | .collect::<Vec<'a, usize, 'b>>()
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| ^^ undeclared lifetime
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error: aborting due to previous error
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0261`.
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@ -9,6 +9,5 @@ mod foo {
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fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
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//~^ ERROR lifetime parameters must be declared prior to type parameters
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//~| ERROR lifetime parameters must be declared prior to type parameters
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fn main() {}
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@ -2,13 +2,13 @@ error: lifetime parameters must be declared prior to type parameters
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--> $DIR/issue-14303-path.rs:10:40
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LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
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| ^^ must be declared prior to type parameters
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error: lifetime parameters must be declared prior to type parameters
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--> $DIR/issue-14303-path.rs:10:44
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| ^^ ^^ must be declared prior to type parameters
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| |
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| must be declared prior to type parameters
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help: move the lifetime parameters prior to the first type parameter
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LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, T, 'b, 'c>) {}
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| ^^ must be declared prior to type parameters
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LL | fn bar<'a, 'b, 'c, T>(x: foo::X<'a, 'b, 'c, T>) {}
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| ^^^ ^^^ --
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error: aborting due to 2 previous errors
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error: aborting due to previous error
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@ -1,8 +1,6 @@
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// A few contrived examples where lifetime should (or should not) be parsed as an object type.
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// Lifetimes parsed as types are still rejected later by semantic checks.
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// compile-flags: -Z continue-parse-after-error
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struct S<'a, T>(&'a u8, T);
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fn main() {
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@ -1,29 +1,33 @@
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error: lifetime parameters must be declared prior to type parameters
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--> $DIR/trait-object-vs-lifetime.rs:16:25
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--> $DIR/trait-object-vs-lifetime.rs:14:25
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LL | let _: S<'static +, 'static>;
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| ^^^^^^^ must be declared prior to type parameters
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help: move the lifetime parameter prior to the first type parameter
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LL | let _: S<'static, 'static +>;
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| ^^^^^^^^ --
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error[E0224]: at least one non-builtin trait is required for an object type
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--> $DIR/trait-object-vs-lifetime.rs:11:23
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--> $DIR/trait-object-vs-lifetime.rs:9:23
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LL | let _: S<'static, 'static +>;
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| ^^^^^^^^^
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error[E0107]: wrong number of lifetime arguments: expected 1, found 2
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--> $DIR/trait-object-vs-lifetime.rs:13:23
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--> $DIR/trait-object-vs-lifetime.rs:11:23
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LL | let _: S<'static, 'static>;
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| ^^^^^^^ unexpected lifetime argument
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error[E0107]: wrong number of type arguments: expected 1, found 0
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--> $DIR/trait-object-vs-lifetime.rs:13:12
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--> $DIR/trait-object-vs-lifetime.rs:11:12
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LL | let _: S<'static, 'static>;
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| ^^^^^^^^^^^^^^^^^^^ expected 1 type argument
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error[E0224]: at least one non-builtin trait is required for an object type
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--> $DIR/trait-object-vs-lifetime.rs:16:14
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--> $DIR/trait-object-vs-lifetime.rs:14:14
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LL | let _: S<'static +, 'static>;
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| ^^^^^^^^^
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