Fix schema implementation for slice references

Also fix the schema test that was never running.

src/schema.rs

@@ -210,7 +210,7 @@ impl<T: Schema, E: Schema> Schema for Result<T, E> {
     };
 }
 
-impl<T: Schema> Schema for &'_ T {
+impl<T: Schema + ?Sized> Schema for &'_ T {
     const SCHEMA: &'static NamedType = T::SCHEMA;
 }
 

tests/schema.rs

@@ -1,6 +1,6 @@
-#![cfg(feature = "derive")]
+#![cfg(feature = "experimental-derive")]
 
-use postcard::schema::{NamedType, NamedValue, NamedVariant, Schema, SdmTy, Varint};
+use postcard::experimental::schema::{NamedType, NamedValue, NamedVariant, Schema, SdmTy, Varint};
 
 const U8_SCHEMA: NamedType = NamedType {
     name: "u8",
@@ -40,7 +40,13 @@ struct Outer {
     b: u64,
     c: u8,
     d: Inner,
-    e: [u8; 10],
+    e: [u8; 3],
+}
+
+#[allow(unused)]
+#[derive(Schema)]
+struct Slice<'a> {
+    x: &'a [u8],
 }
 
 #[test]
@@ -97,11 +103,28 @@ fn test_struct_serialize() {
                     name: "e",
                     ty: &NamedType {
                         name: "[T; N]",
-                        ty: &SdmTy::Seq(&U8_SCHEMA),
+                        ty: &SdmTy::Tuple(&[&U8_SCHEMA, &U8_SCHEMA, &U8_SCHEMA]),
                     }
                 }
             ]),
         },
         Outer::SCHEMA
     );
 }
+
+#[test]
+fn test_slice_serialize() {
+    assert_eq!(
+        &NamedType {
+            name: "Slice",
+            ty: &SdmTy::Struct(&[&NamedValue {
+                name: "x",
+                ty: &NamedType {
+                    name: "&[T]",
+                    ty: &SdmTy::Seq(&U8_SCHEMA)
+                }
+            },]),
+        },
+        Slice::SCHEMA
+    );
+}