Rollup merge of #154425 - ujjwalvishwakarma2006:migrate-transmute-tests, r=Kivooeo,Teapot4195

Migrate transmute tests

I have made the following changes in this PR:

- `tests/ui/issues/issue-23477.rs` ➝ `tests/ui/transmute/transmute-slice-to-dst.rs`
- `tests/ui/issues/issue-28625.{rs,stderr}` ➝ `tests/ui/transmute/transmute-associated-type-to-slice.{rs,stderr}`

The reason I changed the trait name from `trait Bar` to `trait MyTrait` and `type Bar` to `type MyType` is that the same name (i.e., `Bar`) for the trait and associated type was making it harder to follow the test. It was confusing for me, at least.

r? Kivooeo

tests/ui/issues/issue-28625.rs

@@ -1,22 +0,0 @@
-//@ normalize-stderr: "\d+ bits" -> "N bits"
-
-trait Bar {
-    type Bar;
-}
-
-struct ArrayPeano<T: Bar> {
-    data: T::Bar,
-}
-
-fn foo<T>(a: &ArrayPeano<T>) -> &[T] where T: Bar {
-    unsafe { std::mem::transmute(a) } //~ ERROR cannot transmute between types of different sizes
-}
-
-impl Bar for () {
-    type Bar = ();
-}
-
-fn main() {
-    let x: ArrayPeano<()> = ArrayPeano { data: () };
-    foo(&x);
-}

tests/ui/transmute/transmute-associated-type-to-slice.rs

@@ -0,0 +1,23 @@
+//! regression test for <https://github.com/rust-lang/rust/issues/28625>
+//@ normalize-stderr: "\d+ bits" -> "N bits"
+
+trait MyTrait {
+    type MyType;
+}
+
+struct ArrayPeano<T: MyTrait> {
+    data: T::MyType,
+}
+
+fn foo<T>(a: &ArrayPeano<T>) -> &[T] where T: MyTrait {
+    unsafe { std::mem::transmute(a) } //~ ERROR cannot transmute between types of different sizes
+}
+
+impl MyTrait for () {
+    type MyType = ();
+}
+
+fn main() {
+    let x: ArrayPeano<()> = ArrayPeano { data: () };
+    foo(&x);
+}

tests/ui/transmute/transmute-associated-type-to-slice.stderr

@@ -1,5 +1,5 @@
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/issue-28625.rs:12:14
+  --> $DIR/transmute-associated-type-to-slice.rs:13:14
    |
 LL |     unsafe { std::mem::transmute(a) }
    |              ^^^^^^^^^^^^^^^^^^^

tests/ui/transmute/transmute-slice-to-dst.rs

@@ -1,3 +1,4 @@
+//! regression test for <https://github.com/rust-lang/rust/issues/23477>
 //@ build-pass
 //@ compile-flags: -g