Auto merge of #68689 - estebank:where-clause-sugg-missing-fn, r=varkor
When suggesting associated fn with type parameters, include in the structured suggestion Address #50734. ``` error[E0046]: not all trait items implemented, missing: `foo`, `bar`, `baz` --> file.rs:14:1 | 14 | impl TraitA<()> for S { | ^^^^^^^^^^^^^^^^^^^^^ missing `foo`, `bar`, `baz` in implementation | = help: implement the missing item: `fn foo<T>(_: T) -> Self where T: TraitB, TraitB::Item = A { unimplemented!() }` = help: implement the missing item: `fn bar<T>(_: T) -> Self { unimplemented!() }` = help: implement the missing item: `fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: std::marker::Copy { unimplemented!() }` ``` It doesn't work well for associated types with `ty::Predicate::Projection`s as we need to resugar `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`.
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commit
64ea639c12
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@ -2167,8 +2167,77 @@ fn missing_items_err(
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err.emit();
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}
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/// Resugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions.
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fn bounds_from_generic_predicates(
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tcx: TyCtxt<'_>,
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predicates: ty::GenericPredicates<'_>,
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) -> (String, String) {
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let mut types: FxHashMap<Ty<'_>, Vec<DefId>> = FxHashMap::default();
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let mut projections = vec![];
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for (predicate, _) in predicates.predicates {
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debug!("predicate {:?}", predicate);
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match predicate {
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ty::Predicate::Trait(trait_predicate, _) => {
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let entry = types.entry(trait_predicate.skip_binder().self_ty()).or_default();
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let def_id = trait_predicate.skip_binder().def_id();
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if Some(def_id) != tcx.lang_items().sized_trait() {
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// Type params are `Sized` by default, do not add that restriction to the list
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// if it is a positive requirement.
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entry.push(trait_predicate.skip_binder().def_id());
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}
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}
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ty::Predicate::Projection(projection_pred) => {
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projections.push(projection_pred);
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}
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_ => {}
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}
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}
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let generics = if types.is_empty() {
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"".to_string()
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} else {
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format!(
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"<{}>",
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types
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.keys()
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.filter_map(|t| match t.kind {
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ty::Param(_) => Some(t.to_string()),
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// Avoid suggesting the following:
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// fn foo<T, <T as Trait>::Bar>(_: T) where T: Trait, <T as Trait>::Bar: Other {}
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_ => None,
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})
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.collect::<Vec<_>>()
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.join(", ")
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)
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};
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let mut where_clauses = vec![];
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for (ty, bounds) in types {
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for bound in &bounds {
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where_clauses.push(format!("{}: {}", ty, tcx.def_path_str(*bound)));
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}
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}
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for projection in &projections {
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let p = projection.skip_binder();
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// FIXME: this is not currently supported syntax, we should be looking at the `types` and
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// insert the associated types where they correspond, but for now let's be "lazy" and
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// propose this instead of the following valid resugaring:
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// `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`
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where_clauses.push(format!("{} = {}", tcx.def_path_str(p.projection_ty.item_def_id), p.ty));
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}
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let where_clauses = if where_clauses.is_empty() {
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String::new()
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} else {
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format!(" where {}", where_clauses.join(", "))
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};
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(generics, where_clauses)
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}
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/// Return placeholder code for the given function.
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fn fn_sig_suggestion(sig: &ty::FnSig<'_>, ident: Ident) -> String {
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fn fn_sig_suggestion(
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tcx: TyCtxt<'_>,
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sig: &ty::FnSig<'_>,
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ident: Ident,
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predicates: ty::GenericPredicates<'_>,
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) -> String {
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let args = sig
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.inputs()
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.iter()
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@ -2198,12 +2267,17 @@ fn fn_sig_suggestion(sig: &ty::FnSig<'_>, ident: Ident) -> String {
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let output = if !output.is_unit() { format!(" -> {:?}", output) } else { String::new() };
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let unsafety = sig.unsafety.prefix_str();
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let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates);
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// FIXME: this is not entirely correct, as the lifetimes from borrowed params will
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// not be present in the `fn` definition, not will we account for renamed
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// lifetimes between the `impl` and the `trait`, but this should be good enough to
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// fill in a significant portion of the missing code, and other subsequent
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// suggestions can help the user fix the code.
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format!("{}fn {}({}){} {{ unimplemented!() }}", unsafety, ident, args, output)
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format!(
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"{}fn {}{}({}){}{} {{ todo!() }}",
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unsafety, ident, generics, args, output, where_clauses
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)
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}
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/// Return placeholder code for the given associated item.
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@ -2216,7 +2290,12 @@ fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String {
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// late-bound regions, and we don't want method signatures to show up
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// `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
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// regions just fine, showing `fn(&MyType)`.
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fn_sig_suggestion(tcx.fn_sig(assoc.def_id).skip_binder(), assoc.ident)
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fn_sig_suggestion(
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tcx,
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tcx.fn_sig(assoc.def_id).skip_binder(),
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assoc.ident,
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tcx.predicates_of(assoc.def_id),
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)
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}
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ty::AssocKind::Type => format!("type {} = Type;", assoc.ident),
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// FIXME(type_alias_impl_trait): we should print bounds here too.
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@ -29,7 +29,7 @@ error[E0046]: not all trait items implemented, missing: `fmt`
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LL | impl std::fmt::Display for MyType4 {}
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `fmt` in implementation
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= help: implement the missing item: `fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> { unimplemented!() }`
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= help: implement the missing item: `fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> { todo!() }`
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error: aborting due to 4 previous errors
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@ -4,7 +4,7 @@ error[E0046]: not all trait items implemented, missing: `partial_cmp`
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LL | impl PartialOrd for Thing {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^ missing `partial_cmp` in implementation
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= help: implement the missing item: `fn partial_cmp(&self, _: &Rhs) -> std::option::Option<std::cmp::Ordering> { unimplemented!() }`
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= help: implement the missing item: `fn partial_cmp(&self, _: &Rhs) -> std::option::Option<std::cmp::Ordering> { todo!() }`
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error: aborting due to previous error
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@ -6,7 +6,7 @@ LL | impl m1::X for X {
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= help: implement the missing item: `const CONSTANT: u32 = 42;`
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= help: implement the missing item: `type Type = Type;`
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= help: implement the missing item: `fn method(&self, _: std::string::String) -> <Self as m1::X>::Type { unimplemented!() }`
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= help: implement the missing item: `fn method(&self, _: std::string::String) -> <Self as m1::X>::Type { todo!() }`
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error: aborting due to previous error
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@ -64,7 +64,7 @@ error[E0046]: not all trait items implemented, missing: `fmt`
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LL | impl Debug for FooTypeForMethod {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `fmt` in implementation
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= help: implement the missing item: `fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> { unimplemented!() }`
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= help: implement the missing item: `fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> { todo!() }`
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error: aborting due to 8 previous errors
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@ -0,0 +1,21 @@
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// run-rustfix
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trait TraitB {
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type Item;
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}
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trait TraitA<A> {
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type Type;
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fn bar<T>(_: T) -> Self;
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fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: Copy;
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}
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struct S;
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struct Type;
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impl TraitA<()> for S { //~ ERROR not all trait items implemented
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fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: std::marker::Copy { todo!() }
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fn bar<T>(_: T) -> Self { todo!() }
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type Type = Type;
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}
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fn main() {}
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@ -0,0 +1,18 @@
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// run-rustfix
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trait TraitB {
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type Item;
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}
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trait TraitA<A> {
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type Type;
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fn bar<T>(_: T) -> Self;
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fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: Copy;
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}
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struct S;
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struct Type;
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impl TraitA<()> for S { //~ ERROR not all trait items implemented
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}
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fn main() {}
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@ -0,0 +1,16 @@
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error[E0046]: not all trait items implemented, missing: `Type`, `bar`, `baz`
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--> $DIR/missing-assoc-fn-applicable-suggestions.rs:15:1
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LL | type Type;
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| ---------- `Type` from trait
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LL | fn bar<T>(_: T) -> Self;
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| ------------------------ `bar` from trait
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LL | fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: Copy;
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| ------------------------------------------------------------------- `baz` from trait
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...
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LL | impl TraitA<()> for S {
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| ^^^^^^^^^^^^^^^^^^^^^ missing `Type`, `bar`, `baz` in implementation
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0046`.
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@ -0,0 +1,22 @@
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trait TraitB {
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type Item;
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}
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trait TraitA<A> {
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fn foo<T: TraitB<Item = A>>(_: T) -> Self;
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fn bar<T>(_: T) -> Self;
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fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: Copy;
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fn bat<T: TraitB<Item: Copy>>(_: T) -> Self; //~ ERROR associated type bounds are unstable
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}
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struct S;
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impl TraitA<()> for S { //~ ERROR not all trait items implemented
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}
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use std::iter::FromIterator;
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struct X;
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impl FromIterator<()> for X { //~ ERROR not all trait items implemented
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}
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fn main() {}
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@ -0,0 +1,36 @@
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error[E0658]: associated type bounds are unstable
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--> $DIR/missing-assoc-fn.rs:9:22
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LL | fn bat<T: TraitB<Item: Copy>>(_: T) -> Self;
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| ^^^^^^^^^^
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= note: for more information, see https://github.com/rust-lang/rust/issues/52662
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= help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
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error[E0046]: not all trait items implemented, missing: `foo`, `bar`, `baz`, `bat`
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--> $DIR/missing-assoc-fn.rs:14:1
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LL | fn foo<T: TraitB<Item = A>>(_: T) -> Self;
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| ------------------------------------------ `foo` from trait
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LL | fn bar<T>(_: T) -> Self;
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| ------------------------ `bar` from trait
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LL | fn baz<T>(_: T) -> Self where T: TraitB, <T as TraitB>::Item: Copy;
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| ------------------------------------------------------------------- `baz` from trait
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LL | fn bat<T: TraitB<Item: Copy>>(_: T) -> Self;
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| -------------------------------------------- `bat` from trait
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...
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LL | impl TraitA<()> for S {
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| ^^^^^^^^^^^^^^^^^^^^^ missing `foo`, `bar`, `baz`, `bat` in implementation
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error[E0046]: not all trait items implemented, missing: `from_iter`
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--> $DIR/missing-assoc-fn.rs:19:1
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LL | impl FromIterator<()> for X {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `from_iter` in implementation
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= help: implement the missing item: `fn from_iter<T>(_: T) -> Self where T: std::iter::IntoIterator, std::iter::IntoIterator::Item = A { todo!() }`
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error: aborting due to 3 previous errors
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Some errors have detailed explanations: E0046, E0658.
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For more information about an error, try `rustc --explain E0046`.
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@ -7,13 +7,13 @@ trait T {
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mod foo {
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use super::T;
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impl T for () { fn bar(&self, _: &usize, _: &usize) -> usize { unimplemented!() }
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unsafe fn foo(_: &usize, _: &usize) -> usize { unimplemented!() }
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impl T for () { fn bar(&self, _: &usize, _: &usize) -> usize { todo!() }
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unsafe fn foo(_: &usize, _: &usize) -> usize { todo!() }
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} //~ ERROR not all trait items
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impl T for usize { //~ ERROR not all trait items
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fn bar(&self, _: &usize, _: &usize) -> usize { unimplemented!() }
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unsafe fn foo(_: &usize, _: &usize) -> usize { unimplemented!() }
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fn bar(&self, _: &usize, _: &usize) -> usize { todo!() }
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unsafe fn foo(_: &usize, _: &usize) -> usize { todo!() }
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}
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}
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