Add tests related to normalization in implied bounds

tests/ui/implied-bounds/from-trait-impl.rs

@@ -0,0 +1,24 @@
+// check-pass
+// known-bug: #109628
+
+trait Trait {
+    type Assoc;
+}
+
+impl<X: 'static> Trait for (X,) {
+    type Assoc = ();
+}
+
+struct Foo<T: Trait>(T)
+where
+    T::Assoc: Clone; // any predicate using `T::Assoc` works here
+
+fn func1(foo: Foo<(&str,)>) {
+    let _: &'static str = foo.0.0;
+}
+
+trait TestTrait {}
+
+impl<X> TestTrait for [Foo<(X,)>; 1] {}
+
+fn main() {}

tests/ui/implied-bounds/normalization-nested.lifetime.stderr

@@ -1,18 +1,33 @@
 error[E0759]: `fn` parameter has lifetime `'x` but it needs to satisfy a `'static` lifetime requirement
-  --> $DIR/normalization-nested.rs:35:20
+  --> $DIR/normalization-nested.rs:35:28
    |
-LL | pub fn test<'x>(_: Map<Vec<&'x ()>>, s: &'x str) -> &'static str {
-   |                    ^^^^^^^^^^^^^^^^
-   |                    |
-   |                    this data with lifetime `'x`...
-   |                    ...is used and required to live as long as `'static` here
+LL | pub fn test_wfcheck<'x>(_: Map<Vec<&'x ()>>) {}
+   |                            ^^^^^^^^^^^^^^^^
+   |                            |
+   |                            this data with lifetime `'x`...
+   |                            ...is used and required to live as long as `'static` here
    |
 note: `'static` lifetime requirement introduced by this bound
   --> $DIR/normalization-nested.rs:33:14
    |
 LL |     I::Item: 'static;
    |              ^^^^^^^
 
-error: aborting due to 1 previous error
+error[E0759]: `fn` parameter has lifetime `'x` but it needs to satisfy a `'static` lifetime requirement
+  --> $DIR/normalization-nested.rs:37:29
+   |
+LL | pub fn test_borrowck<'x>(_: Map<Vec<&'x ()>>, s: &'x str) -> &'static str {
+   |                             ^^^^^^^^^^^^^^^^
+   |                             |
+   |                             this data with lifetime `'x`...
+   |                             ...is used and required to live as long as `'static` here
+   |
+note: `'static` lifetime requirement introduced by this bound
+  --> $DIR/normalization-nested.rs:33:14
+   |
+LL |     I::Item: 'static;
+   |              ^^^^^^^
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0759`.

tests/ui/implied-bounds/normalization-nested.rs

@@ -32,7 +32,9 @@ where
     I: Iter,
     I::Item: 'static;
 
-pub fn test<'x>(_: Map<Vec<&'x ()>>, s: &'x str) -> &'static str {
+pub fn test_wfcheck<'x>(_: Map<Vec<&'x ()>>) {}
+
+pub fn test_borrowck<'x>(_: Map<Vec<&'x ()>>, s: &'x str) -> &'static str {
     s
 }
 

tests/ui/implied-bounds/normalization-preserve-equality.borrowck.stderr

@@ -0,0 +1,28 @@
+error: lifetime may not live long enough
+  --> $DIR/normalization-preserve-equality.rs:24:1
+   |
+LL | fn test_borrowck<'a, 'b>(_: (<Equal<'a, 'b> as Trait>::Ty, Equal<'a, 'b>)) {
+   | ^^^^^^^^^^^^^^^^^--^^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |                |   |
+   | |                |   lifetime `'b` defined here
+   | |                lifetime `'a` defined here
+   | requires that `'a` must outlive `'b`
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: lifetime may not live long enough
+  --> $DIR/normalization-preserve-equality.rs:24:1
+   |
+LL | fn test_borrowck<'a, 'b>(_: (<Equal<'a, 'b> as Trait>::Ty, Equal<'a, 'b>)) {
+   | ^^^^^^^^^^^^^^^^^--^^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |                |   |
+   | |                |   lifetime `'b` defined here
+   | |                lifetime `'a` defined here
+   | requires that `'b` must outlive `'a`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+help: `'a` and `'b` must be the same: replace one with the other
+
+error: aborting due to 2 previous errors
+

tests/ui/implied-bounds/normalization-preserve-equality.rs

@@ -0,0 +1,28 @@
+// Both revisions should pass. `borrowck` revision is a bug!
+//
+// revisions: wfcheck borrowck
+// [wfcheck] check-pass
+// [borrowck] check-fail
+// [borrowck] known-bug: #106569
+
+struct Equal<'a, 'b>(&'a &'b (), &'b &'a ()); // implies 'a == 'b
+
+trait Trait {
+    type Ty;
+}
+
+impl<'x> Trait for Equal<'x, 'x> {
+    type Ty = ();
+}
+
+trait WfCheckTrait {}
+
+#[cfg(wfcheck)]
+impl<'a, 'b> WfCheckTrait for (<Equal<'a, 'b> as Trait>::Ty, Equal<'a, 'b>) {}
+
+#[cfg(borrowck)]
+fn test_borrowck<'a, 'b>(_: (<Equal<'a, 'b> as Trait>::Ty, Equal<'a, 'b>)) {
+    let _ = None::<Equal<'a, 'b>>;
+}
+
+fn main() {}