Add conversion traits for unified type casts:

* `Reinterpret`
* `TryReinterpret`
* `ReinterpretInner`
* `TryReinterpretInner`

.github/workflows/rust.yml

@@ -78,6 +78,16 @@ jobs:
     - run: cargo miri test --verbose --all-features
     - run: cd derive && rm -fr target && cargo miri test --verbose --all-features
 
+  ui-test:
+    name: Test compiler errors
+    runs-on: ubuntu-latest
+    steps:
+    - uses: hecrj/setup-rust-action@v1
+      with:
+        rust-version: stable
+    - uses: actions/checkout@v3
+    - run: cargo test -p uitest
+
   sanitizer-test:
     name: Test with -Zsanitizer=${{ matrix.sanitizer }}
     runs-on: ubuntu-latest

.gitignore

@@ -8,3 +8,4 @@ Cargo.lock
 
 /derive/target/
 /derive/.vscode/
+/uitest/wip/

Cargo.toml

@@ -11,6 +11,9 @@ edition = "2018"
 license = "Zlib OR Apache-2.0 OR MIT"
 exclude = ["/pedantic.bat"]
 
+[workspace]
+members = ["uitest", "derive"]
+
 [features]
 # In v2 we'll fix these names to be more "normal".
 derive = ["bytemuck_derive"]
@@ -19,8 +22,12 @@ extern_crate_std = ["extern_crate_alloc"]
 zeroable_maybe_uninit = []
 zeroable_atomics = []
 min_const_generics = []
-wasm_simd = [] # Until >= 1.54.0 is MSRV this is an off-by-default feature.
-aarch64_simd = [] # Until >= 1.59.0 is MSRV this is an off-by-default feature.
+
+# Off-by-default until bytemuck's MSRV is raised.
+wasm_simd = [] # Requires MSRV >= 1.54.0.
+unified_cast = [] # Requires MSRV >= 1.57.0.
+aarch64_simd = [] # Requires MSRV >= 1.59.0.
+non_null_slice_cast = [] # Requires MSRV >= 1.63.0.
 
 # Do not use if you can avoid it, because this is unsound.
 unsound_ptr_pod_impl = []
@@ -42,6 +49,8 @@ features = [
   "zeroable_atomics",
   "min_const_generics",
   "wasm_simd",
+  "unified_cast",
+  "non_null_slice_cast",
 ]
 
 [package.metadata.playground]
@@ -54,4 +63,6 @@ features = [
   "zeroable_atomics",
   "min_const_generics",
   "wasm_simd",
+  "unified_cast",
+  "non_null_slice_cast",
 ]