Rollup merge of rust-lang#72572 - JohnTitor:add-tests, r=matthewjasper

Add some regression tests

Closes rust-lang#68532
Closes rust-lang#70121
Closes rust-lang#71042
CC rust-lang#56445

r? @matthewjasper since they (except for rust-lang#71042) are related to rust-lang#72362.

src/test/ui/impl-trait/issue-56445.rs

@@ -0,0 +1,26 @@
+// Regression test for https://github.com/rust-lang/rust/issues/56445#issuecomment-629426939
+// check-pass
+
+#![crate_type = "lib"]
+
+use std::marker::PhantomData;
+
+pub struct S<'a>
+{
+    pub m1: PhantomData<&'a u8>,
+    pub m2: [u8; S::size()],
+}
+
+impl<'a> S<'a>
+{
+    pub const fn size() -> usize { 1 }
+
+    pub fn new() -> Self
+    {
+        Self
+        {
+            m1: PhantomData,
+            m2: [0; Self::size()],
+        }
+    }
+}

src/test/ui/impl-trait/issue-68532.rs

@@ -0,0 +1,13 @@
+// check-pass
+
+pub struct A<'a>(&'a ());
+
+impl<'a> A<'a> {
+    const N: usize = 68;
+
+    pub fn foo(&self) {
+        let _b = [0; Self::N];
+    }
+}
+
+fn main() {}

src/test/ui/pattern/issue-71042-opaquely-typed-constant-used-in-pattern.rs

@@ -0,0 +1,9 @@
+#![feature(impl_trait_in_bindings)]
+#![allow(incomplete_features)]
+
+fn main() {
+    const C: impl Copy = 0;
+    match C {
+        C | _ => {} //~ ERROR: opaque types cannot be used in patterns
+    }
+}

src/test/ui/pattern/issue-71042-opaquely-typed-constant-used-in-pattern.stderr

@@ -0,0 +1,8 @@
+error: opaque types cannot be used in patterns
+  --> $DIR/issue-71042-opaquely-typed-constant-used-in-pattern.rs:7:9
+   |
+LL |         C | _ => {}
+   |         ^
+
+error: aborting due to previous error
+

src/test/ui/type-alias-impl-trait/issue-70121.rs

@@ -0,0 +1,23 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+pub type Successors<'a> = impl Iterator<Item = &'a ()>;
+
+pub fn f<'a>() -> Successors<'a> {
+    None.into_iter()
+}
+
+pub trait Tr {
+    type Item;
+}
+
+impl<'a> Tr for &'a () {
+    type Item = Successors<'a>;
+}
+
+pub fn kazusa<'a>() -> <&'a () as Tr>::Item {
+    None.into_iter()
+}
+
+fn main() {}