Initial demonstration of ResourceKey::type_id

See unicode-org#570

Author: sffc

provider/core/Cargo.toml

@@ -36,6 +36,9 @@ std = ["icu_locid/std"]
 provider_serde = ["serde", "erased-serde"]
 macros = ["icu_provider_macros"]
 
+# The "expressive_keys" feature enables type checking of resource keys.
+expressive_keys = []
+
 [dependencies]
 icu_locid = { version = "0.3", path = "../../components/locid" }
 tinystr = { version = "0.4.10", features = ["alloc"], default-features = false }

provider/core/src/data_provider/test.rs

@@ -19,7 +19,7 @@ use crate::yoke;
 // JSON string. It also exercises most of the data provider code paths.
 
 /// Key for HelloAlt, used for testing mismatched types
-const HELLO_ALT_KEY: ResourceKey = crate::resource_key!(Core, "helloalt", 1);
+const HELLO_ALT_KEY: ResourceKey = crate::resource_key!(Core, HelloAlt, "helloalt", 1);
 
 /// A data struct serialization-compatible with HelloWorldV1 used for testing mismatched types
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Yokeable, ZeroCopyFrom)]

provider/core/src/hello_world.rs

@@ -18,8 +18,8 @@ use icu_locid::LanguageIdentifier;
 use litemap::LiteMap;
 
 pub mod key {
-    use crate::resource::ResourceKey;
-    pub const HELLO_WORLD_V1: ResourceKey = resource_key!(Core, "helloworld", 1);
+    use super::*;
+    pub const HELLO_WORLD_V1: ResourceKey = resource_key!(Core, HelloWorldV1, "helloworld", 1);
 }
 
 /// A struct containing "Hello World" in the requested language.

provider/core/src/lib.rs

@@ -103,6 +103,7 @@
 //! [`impl_dyn_provider!`]: impl_dyn_provider
 
 #![cfg_attr(not(any(test, feature = "std")), no_std)]
+#![feature(const_type_id)]
 
 extern crate alloc;
 

provider/core/src/resource.rs

@@ -79,6 +79,8 @@ pub struct ResourceKey {
     pub category: ResourceCategory,
     pub sub_category: TinyStr16,
     pub version: u16,
+    #[cfg(feature = "expressive_keys")]
+    pub type_id: core::any::TypeId,
 }
 
 /// Shortcut to construct a const resource identifier.
@@ -104,21 +106,29 @@ pub struct ResourceKey {
 /// ```
 #[macro_export]
 macro_rules! resource_key {
-    ($category:ident, $sub_category:literal, $version:tt) => {
-        $crate::resource_key!($crate::ResourceCategory::$category, $sub_category, $version)
+    ($category:ident, $struct_type:ty, $sub_category:literal, $version:tt) => {
+        $crate::resource_key!(
+            $crate::ResourceCategory::$category,
+            $struct_type,
+            $sub_category,
+            $version
+        )
     };
-    (x, $pu:literal, $sub_category:literal, $version:tt) => {
+    (x, $pu:literal, $struct_type:ty, $sub_category:literal, $version:tt) => {
         $crate::resource_key!(
             $crate::ResourceCategory::PrivateUse($crate::internal::tinystr4!($pu)),
+            $struct_type,
             $sub_category,
             $version
         )
     };
-    ($category:expr, $sub_category:literal, $version:tt) => {
+    ($category:path, $struct_type:ty, $sub_category:literal, $version:tt) => {
         $crate::ResourceKey {
             category: $category,
             sub_category: $crate::internal::tinystr16!($sub_category),
             version: $version,
+            #[cfg(feature = "expressive_keys")]
+            type_id: core::any::TypeId::of::<$struct_type>(),
         }
     };
 }
@@ -410,23 +420,24 @@ mod tests {
     fn get_key_test_cases() -> [KeyTestCase; 4] {
         [
             KeyTestCase {
-                resc_key: resource_key!(Core, "cardinal", 1),
+                resc_key: resource_key!(Core, (), "cardinal", 1),
                 expected: "core/cardinal@1",
             },
             KeyTestCase {
                 resc_key: ResourceKey {
                     category: ResourceCategory::PrivateUse(tinystr4!("priv")),
                     sub_category: tinystr::tinystr16!("cardinal"),
                     version: 1,
+                    type_id: core::any::TypeId::of::<()>(),
                 },
                 expected: "x-priv/cardinal@1",
             },
             KeyTestCase {
-                resc_key: resource_key!(Core, "maxlengthsubcatg", 1),
+                resc_key: resource_key!(Core, (), "maxlengthsubcatg", 1),
                 expected: "core/maxlengthsubcatg@1",
             },
             KeyTestCase {
-                resc_key: resource_key!(Core, "cardinal", 65535),
+                resc_key: resource_key!(Core, (),"cardinal", 65535),
                 expected: "core/cardinal@65535",
             },
         ]

provider/core/tests/sizes.rs

@@ -8,4 +8,4 @@ use static_assertions::const_assert_eq;
 const_assert_eq!(8, core::mem::size_of::<ResourceCategory>());
 const_assert_eq!(16, core::mem::size_of::<tinystr::TinyStr16>());
 const_assert_eq!(4, core::mem::size_of::<u32>());
-const_assert_eq!(32, core::mem::size_of::<ResourceKey>());
+const_assert_eq!(40, core::mem::size_of::<ResourceKey>());