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Rollup merge of #69340 - Centril:self-ctor-normalize, r=nikomatsakis
instantiate_value_path: on `SelfCtor`, avoid unconstrained tyvars Fixes #69306. On `Self(...)` (that is, a `Res::SelfCtor`), do not use `self.impl_self_ty(...)`. The problem with that method is that it creates unconstrained inference variables for type parameters in the `impl` (e.g. `impl<T> S0<T>`). These variables then eventually get substituted for something else when they come in contact with the expected type (e.g. `S0<u8>`) or merely the arguments passed to the tuple constructor (e.g. the `0` in `Self(0)`). Instead of using `self.impl_self_ty(...)`, we instead merely use `let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id));` to get the rewritten `res`. r? @eddyb
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‎src/librustc_typeck/check/mod.rs‎

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -5447,9 +5447,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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.unwrap_or(false);
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let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res {
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let ty = self.impl_self_ty(span, impl_def_id).ty;
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let adt_def = ty.ty_adt_def();
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let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id));
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match ty.kind {
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ty::Adt(adt_def, substs) if adt_def.has_ctor() => {
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let variant = adt_def.non_enum_variant();
@@ -5464,7 +5462,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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span,
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"the `Self` constructor can only be used with tuple or unit structs",
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);
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if let Some(adt_def) = adt_def {
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if let Some(adt_def) = ty.ty_adt_def() {
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match adt_def.adt_kind() {
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AdtKind::Enum => {
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err.help("did you mean to use one of the enum's variants?");

‎src/test/ui/issues/issue-69306.rs‎

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@@ -0,0 +1,45 @@
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fn main() {}
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struct S0<T>(T);
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impl<T> S0<T> {
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const C: S0<u8> = Self(0);
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//~^ ERROR mismatched types
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//~| ERROR mismatched types
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fn foo() {
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Self(0);
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//~^ ERROR mismatched types
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}
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}
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// Testing normalization.
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trait Fun {
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type Out;
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}
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impl<T> Fun for S0<T> {
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type Out = Self;
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}
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trait Foo<T> {
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fn foo();
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}
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impl<T> Foo<T> for <S0<T> as Fun>::Out {
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fn foo() {
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Self(0); //~ ERROR mismatched types
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}
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}
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struct S1<T, U>(T, U);
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impl<T> S1<T, u8> {
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const C: S1<u8, u8> = Self(0, 1);
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//~^ ERROR mismatched types
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//~| ERROR mismatched types
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}
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struct S2<T>(T);
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impl<T> S2<T> {
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fn map<U>(x: U) -> S2<U> {
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Self(x)
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//~^ ERROR mismatched types
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//~| ERROR mismatched types
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}
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}

‎src/test/ui/issues/issue-69306.stderr‎

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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:5:28
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|
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LL | impl<T> S0<T> {
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| - this type parameter
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LL | const C: S0<u8> = Self(0);
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| ^ expected type parameter `T`, found integer
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|
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= note: expected type parameter `T`
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found type `{integer}`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:5:23
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|
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LL | impl<T> S0<T> {
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| - this type parameter
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LL | const C: S0<u8> = Self(0);
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| ^^^^^^^ expected `u8`, found type parameter `T`
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|
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= note: expected struct `S0<u8>`
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found struct `S0<T>`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:10:14
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|
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LL | impl<T> S0<T> {
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| - this type parameter
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...
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LL | Self(0);
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| ^ expected type parameter `T`, found integer
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|
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= note: expected type parameter `T`
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found type `{integer}`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:27:14
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|
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LL | impl<T> Foo<T> for <S0<T> as Fun>::Out {
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| - this type parameter
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LL | fn foo() {
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LL | Self(0);
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| ^ expected type parameter `T`, found integer
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|
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= note: expected type parameter `T`
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found type `{integer}`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:33:32
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|
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LL | impl<T> S1<T, u8> {
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| - this type parameter
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LL | const C: S1<u8, u8> = Self(0, 1);
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| ^ expected type parameter `T`, found integer
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|
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= note: expected type parameter `T`
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found type `{integer}`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:33:27
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|
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LL | impl<T> S1<T, u8> {
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| - this type parameter
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LL | const C: S1<u8, u8> = Self(0, 1);
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| ^^^^^^^^^^ expected `u8`, found type parameter `T`
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|
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= note: expected struct `S1<u8, _>`
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found struct `S1<T, _>`
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= help: type parameters must be constrained to match other types
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:41:14
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|
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LL | impl<T> S2<T> {
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| - expected type parameter
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LL | fn map<U>(x: U) -> S2<U> {
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| - found type parameter
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LL | Self(x)
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| ^ expected type parameter `T`, found type parameter `U`
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|
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= note: expected type parameter `T`
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found type parameter `U`
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= note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error[E0308]: mismatched types
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--> $DIR/issue-69306.rs:41:9
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|
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LL | impl<T> S2<T> {
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| - found type parameter
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LL | fn map<U>(x: U) -> S2<U> {
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| - ----- expected `S2<U>` because of return type
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| |
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| expected type parameter
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LL | Self(x)
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| ^^^^^^^ expected type parameter `U`, found type parameter `T`
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|
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= note: expected struct `S2<U>`
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found struct `S2<T>`
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= note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
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= note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
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error: aborting due to 8 previous errors
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For more information about this error, try `rustc --explain E0308`.

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