Address review feedback for tests

Author: Amanieu

tests/ui/README.md

@@ -1341,6 +1341,10 @@ Generic collection of tests for suggestions, when no more specific directories a
 
 **FIXME**: Some overlap with `tests/ui/did_you_mean/`, that directory should probably be moved under here.
 
+## `tests/ui/supertrait-shadowing/`
+
+Tests for supertrait item shadowing (RFC 3624).
+
 ## `tests/ui/svh/`: Strict Version Hash
 
 Tests on the *Strict Version Hash* (SVH, also known as the "crate hash").

tests/ui/supertrait-shadowing/assoc-const.rs

@@ -1,6 +1,7 @@
 //@ run-pass
 
 #![feature(supertrait_item_shadowing)]
+#![feature(min_generic_const_args)]
 #![allow(dead_code)]
 
 trait A {
@@ -11,12 +12,20 @@ impl<T> A for T {
 }
 
 trait B: A {
-    const CONST: i32;
+    type const CONST: i32;
 }
 impl<T> B for T {
-    const CONST: i32 = 2;
+    type const CONST: i32 = 2;
 }
 
+trait C: B {}
+impl<T> C for T {}
+
 fn main() {
-    assert_eq!(i32::CONST, 2)
+    assert_eq!(i32::CONST, 2);
+    generic::<u32>();
+}
+
+fn generic<T: C<CONST = 2>>() {
+    assert_eq!(T::CONST, 2);
 }

tests/ui/supertrait-shadowing/assoc-const2.rs

@@ -0,0 +1,47 @@
+#![feature(supertrait_item_shadowing)]
+#![allow(dead_code)]
+
+use std::mem::size_of;
+
+trait A {
+    type Assoc;
+}
+impl<X> A for X {
+    type Assoc = i8;
+}
+
+trait B: A {
+    type Assoc;
+}
+impl<X> B for X {
+    type Assoc = i16;
+}
+
+trait C: B {}
+impl<X> C for X {}
+
+fn main() {
+    b_unbound::<u32>();
+    c_unbound::<u32>();
+
+    b_assoc_is_a::<u32>();
+    //~^ ERROR type mismatch resolving `<u32 as B>::Assoc == i8`
+    c_assoc_is_a::<u32>();
+    //~^ ERROR type mismatch resolving `<u32 as B>::Assoc == i8`
+}
+
+fn b_unbound<U: B>() {
+    let _ = size_of::<U::Assoc>();
+}
+
+fn c_unbound<U: C>() {
+    let _ = size_of::<U::Assoc>();
+}
+
+fn b_assoc_is_a<U: B<Assoc = i8>>() {
+    let _ = size_of::<U::Assoc>();
+}
+
+fn c_assoc_is_a<U: C<Assoc = i8>>() {
+    let _ = size_of::<U::Assoc>();
+}

tests/ui/supertrait-shadowing/assoc-const2.run.stdout

@@ -0,0 +1,37 @@
+error[E0271]: type mismatch resolving `<u32 as B>::Assoc == i8`
+  --> $DIR/assoc-type-fail.rs:27:20
+   |
+LL |     b_assoc_is_a::<u32>();
+   |                    ^^^ type mismatch resolving `<u32 as B>::Assoc == i8`
+   |
+note: expected this to be `i8`
+  --> $DIR/assoc-type-fail.rs:17:18
+   |
+LL |     type Assoc = i16;
+   |                  ^^^
+note: required by a bound in `b_assoc_is_a`
+  --> $DIR/assoc-type-fail.rs:41:22
+   |
+LL | fn b_assoc_is_a<U: B<Assoc = i8>>() {
+   |                      ^^^^^^^^^^ required by this bound in `b_assoc_is_a`
+
+error[E0271]: type mismatch resolving `<u32 as B>::Assoc == i8`
+  --> $DIR/assoc-type-fail.rs:29:20
+   |
+LL |     c_assoc_is_a::<u32>();
+   |                    ^^^ type mismatch resolving `<u32 as B>::Assoc == i8`
+   |
+note: expected this to be `i8`
+  --> $DIR/assoc-type-fail.rs:17:18
+   |
+LL |     type Assoc = i16;
+   |                  ^^^
+note: required by a bound in `c_assoc_is_a`
+  --> $DIR/assoc-type-fail.rs:45:22
+   |
+LL | fn c_assoc_is_a<U: C<Assoc = i8>>() {
+   |                      ^^^^^^^^^^ required by this bound in `c_assoc_is_a`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0271`.

tests/ui/supertrait-shadowing/assoc-type-fail.rs

@@ -0,0 +1,45 @@
+//@ normalize-stderr: "assoc_type_predicates\[[^\]]+\]" -> "assoc_type_predicates[HASH]"
+
+#![feature(rustc_attrs)]
+#![feature(supertrait_item_shadowing)]
+#![allow(dead_code)]
+
+trait A {
+    type Assoc;
+}
+impl<T> A for T {
+    type Assoc = i8;
+}
+
+trait B: A {
+    type Assoc;
+}
+impl<T> B for T {
+    type Assoc = i16;
+}
+
+trait C: B {}
+impl<T> C for T {}
+
+#[rustc_dump_predicates]
+fn a_bound<T: A<Assoc = i8>>() {}
+//~^ ERROR rustc_dump_predicates
+//~| NOTE TraitPredicate(<T as std::marker::Sized>
+//~| NOTE TraitPredicate(<T as A>
+//~| NOTE A::Assoc
+
+#[rustc_dump_predicates]
+fn b_bound<T: B<Assoc = i16>>() {}
+//~^ ERROR rustc_dump_predicates
+//~| NOTE TraitPredicate(<T as std::marker::Sized>
+//~| NOTE TraitPredicate(<T as B>
+//~| NOTE B::Assoc
+
+#[rustc_dump_predicates]
+fn c_bound<T: C<Assoc = i16>>() {}
+//~^ ERROR rustc_dump_predicates
+//~| NOTE TraitPredicate(<T as std::marker::Sized>
+//~| NOTE TraitPredicate(<T as C>
+//~| NOTE B::Assoc
+
+fn main() {}

tests/ui/supertrait-shadowing/assoc-type-fail.stderr

@@ -0,0 +1,32 @@
+error: rustc_dump_predicates
+  --> $DIR/assoc-type-predicates.rs:25:1
+   |
+LL | fn a_bound<T: A<Assoc = i8>>() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: Binder { value: TraitPredicate(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: TraitPredicate(<T as A>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: ProjectionPredicate(AliasTerm { args: [T/#0], kind: ProjectionTy { def_id: DefId(0:4 ~ assoc_type_predicates[HASH]::A::Assoc) }, .. }, Term::Ty(i8)), bound_vars: [] }
+
+error: rustc_dump_predicates
+  --> $DIR/assoc-type-predicates.rs:32:1
+   |
+LL | fn b_bound<T: B<Assoc = i16>>() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: Binder { value: TraitPredicate(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: TraitPredicate(<T as B>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: ProjectionPredicate(AliasTerm { args: [T/#0], kind: ProjectionTy { def_id: DefId(0:9 ~ assoc_type_predicates[HASH]::B::Assoc) }, .. }, Term::Ty(i16)), bound_vars: [] }
+
+error: rustc_dump_predicates
+  --> $DIR/assoc-type-predicates.rs:39:1
+   |
+LL | fn c_bound<T: C<Assoc = i16>>() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: Binder { value: TraitPredicate(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: TraitPredicate(<T as C>, polarity:Positive), bound_vars: [] }
+   = note: Binder { value: ProjectionPredicate(AliasTerm { args: [T/#0], kind: ProjectionTy { def_id: DefId(0:9 ~ assoc_type_predicates[HASH]::B::Assoc) }, .. }, Term::Ty(i16)), bound_vars: [] }
+
+error: aborting due to 3 previous errors
+

tests/ui/supertrait-shadowing/assoc-type-predicates.rs

@@ -7,17 +7,17 @@
 use std::mem::size_of;
 
 trait A {
-    type T;
+    type Assoc;
 }
 impl<T> A for T {
-    type T = i8;
+    type Assoc = i8;
 }
 
 trait B: A {
-    type T;
+    type Assoc;
 }
 impl<T> B for T {
-    type T = i16;
+    type Assoc = i16;
 }
 
 trait C: B {}
@@ -28,20 +28,26 @@ fn main() {
     generic2::<u32>();
     generic3::<u32>();
     generic4::<u32>();
+    generic5::<u32>();
 }
 
-fn generic<U: B>() {
-    println!("{}", size_of::<U::T>());
+fn generic<T: B>() {
+    assert_eq!(size_of::<T::Assoc>(), 2);
 }
 
-fn generic2<U: A<T = i8>>() {
-    println!("{}", size_of::<U::T>());
+fn generic2<T: A<Assoc = i8>>() {
+    assert_eq!(size_of::<T::Assoc>(), 1);
 }
 
-fn generic3<U: B<T = i16>>() {
-    println!("{}", size_of::<U::T>());
+fn generic3<T: B<Assoc = i16>>() {
+    assert_eq!(size_of::<T::Assoc>(), 2);
 }
 
-fn generic4<U: C<T = i16>>() {
-    println!("{}", size_of::<U::T>());
+fn generic4<T: C<Assoc = i16>>() {
+    assert_eq!(size_of::<T::Assoc>(), 2);
+}
+
+fn generic5<T: B>() {
+    assert_eq!(size_of::<<T as A>::Assoc>(), 1);
+    assert_eq!(size_of::<<T as B>::Assoc>(), 2);
 }