Merge #999

999: Implement automatic `NativeClass` registration via inventory. Implement mix-ins. r=chitoyuu a=chitoyuu

## Implement automatic NativeClass registration via inventory

This adds the optional `inventory` feature, which allows `NativeClass` types to be automatically registered on supported platforms (everything that OSS Godot currently supports except WASM).

Run-time diagnostic functions are added to help debug missing registration problems that are highly likely to arise when porting `inventory`-enabled projects to WASM.

An internal `cfg_ex` attribute macro is added to help manage cfg conditions.

Close #350. Note that the standalone registration attribute syntax proposed by the original issue isn't implemented, for the limited usefulness -- there are much fewer cases where manual `NativeClass` impls are necessary thanks to all the improvements since the original issue.

## Implement mix-in `#[methods]` blocks

Adds the `#[methods(mixin = "Name")]` syntax for declaring mix-in blocks. Mix-in blocks have a many-to-many relationship with `NativeClass` types. Both `impl Type` and `impl Trait for Type` blocks are accepted.

The argument name is changed from `as` in the original proposal to `mixin`, because we might still want to keep universal `#[methods]` blocks in the future for ease of use with WASM. `#[methods(mixin)]` makes a lot more sense for a future auto-registered mixin block than `#[methods(as /* as what? */)]`.

All mix-in blocks have to be manually registered for gdnative v0.11.x. Some difficulty was encountered when trying to make auto-mixins compatible with existing code. It might still be possible with some tricks like autoref-specialization, but that might be too much effort given that we likely want to re-design much of the hierarchy for 0.12.

Close #984.

## Allow `#[register_with]` for `#[monomorphize]`

Enables `#[monomorphize]` to take the same standalone `#[register_with]` attribute as `#[derive(NativeClass)]`. This is chosen for short term consistency, but will probably change in a later version w/ #848, which might not still get implemented for a fair bit of time.


Co-authored-by: Chitose Yuuzaki <chitoyuu@potatoes.gay>

Author: bors[bot]

.github/workflows/full-ci.yml

@@ -277,20 +277,38 @@ jobs:
             godot: "3.5.1-stable"
             postfix: ' (ptrcall)'
             build_args: '--features ptrcall'
+          - rust: stable
+            godot: "3.5.1-stable"
+            postfix: ' (inventory)'
+            build_args: '--features inventory'
+          - rust: stable
+            godot: "3.5.1-stable"
+            postfix: ' (inventory)'
+            # Limiting no-manual-register tests to stable as to not slow down CI too far -- if inventory is
+            # working across all 3 Rust versions, this is likely to be as well.
+            build_args: '--features inventory,no-manual-register'
           - rust: nightly
             godot: "3.5.1-stable"
             postfix: ' (nightly)'
           - rust: nightly
             godot: "3.5.1-stable"
             postfix: ' (nightly, ptrcall)'
             build_args: '--features ptrcall'
+          - rust: nightly
+            godot: "3.5.1-stable"
+            postfix: ' (nightly, inventory)'
+            build_args: '--features inventory'
           - rust: '1.63'
             godot: "3.5.1-stable"
             postfix: ' (msrv 1.63)'
           - rust: '1.63'
             godot: "3.5.1-stable"
             postfix: ' (msrv 1.63, ptrcall)'
             build_args: '--features ptrcall'
+          - rust: '1.63'
+            godot: "3.5.1-stable"
+            postfix: ' (msrv 1.63, inventory)'
+            build_args: '--features inventory'
 
           # Test with oldest supported engine version
           - rust: stable

check.sh

@@ -62,7 +62,8 @@ function findGodot() {
     fi
 }
 
-features="gdnative/async,gdnative/serde"
+features="gdnative/async,gdnative/serde,gdnative/inventory"
+itest_toggled_features="no-manual-register"
 cmds=()
 
 for arg in "${args[@]}"; do
@@ -81,6 +82,9 @@ for arg in "${args[@]}"; do
         cmds+=("cargo build --manifest-path test/Cargo.toml --features $features")
         cmds+=("cp target/debug/*gdnative_test* test/project/lib/")
         cmds+=("$godotBin --path test/project")
+        cmds+=("cargo build --manifest-path test/Cargo.toml --features $features,$itest_toggled_features")
+        cmds+=("cp target/debug/*gdnative_test* test/project/lib/")
+        cmds+=("$godotBin --path test/project")
         ;;
     doc)
         cmds+=("cargo doc --lib -p gdnative --no-deps --features $features")

gdnative-core/Cargo.toml

@@ -30,6 +30,7 @@ libc = "0.2"
 once_cell = "1"
 parking_lot = "0.12"
 serde = { version = "1", features = ["derive"], optional = true }
+inventory = { version = "0.3", optional = true }
 
 [dev-dependencies]
 gdnative = { path = "../gdnative" } # for doc-tests

gdnative-core/src/core_types/byte_array.rs

@@ -14,7 +14,7 @@ godot_test!(
         let original_read = {
             let read = arr.read();
             assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7], read.as_slice());
-            read.clone()
+            read
         };
 
         let mut cow_arr = arr.new_ref();

gdnative-core/src/core_types/color_array.rs

@@ -23,7 +23,7 @@ godot_test!(
                 Color::from_rgb(0.0, 1.0, 0.0),
                 Color::from_rgb(0.0, 0.0, 1.0),
             ], read.as_slice());
-            read.clone()
+            read
         };
 
         let mut cow_arr = arr.new_ref();

gdnative-core/src/core_types/error.rs

@@ -1,6 +1,7 @@
 use crate::sys;
 
 /// Error codes used in various Godot APIs.
+#[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(u32)]
@@ -65,6 +66,7 @@ impl GodotError {
     /// `err` should be a valid value for `GodotError`.
     #[inline]
     #[doc(hidden)]
+    #[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
     pub unsafe fn result_from_sys(err: sys::godot_error) -> Result<(), Self> {
         if err == sys::godot_error_GODOT_OK {
             return Ok(());

gdnative-core/src/core_types/float32_array.rs

@@ -16,7 +16,7 @@ godot_test!(
             for (n, i) in read.as_slice().iter().enumerate() {
                 assert_relative_eq!(n as f32, i);
             }
-            read.clone()
+            read
         };
 
         let mut cow_arr = arr.new_ref();
@@ -30,7 +30,7 @@ godot_test!(
         }
 
         for i in 0..8 {
-            assert_relative_eq!(i as f32 * 2., cow_arr.get(i as i32));
+            assert_relative_eq!(i as f32 * 2., cow_arr.get(i));
         }
 
         // the write shouldn't have affected the original array

gdnative-core/src/core_types/int32_array.rs

@@ -14,7 +14,7 @@ godot_test!(
         let original_read = {
             let read = arr.read();
             assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7], read.as_slice());
-            read.clone()
+            read
         };
 
         let mut cow_arr = arr.new_ref();
@@ -28,7 +28,7 @@ godot_test!(
         }
 
         for i in 0..8 {
-            assert_eq!(i * 2, cow_arr.get(i as i32));
+            assert_eq!(i * 2, cow_arr.get(i));
         }
 
         // the write shouldn't have affected the original array

gdnative-core/src/core_types/string_array.rs

@@ -23,7 +23,7 @@ godot_test!(
                 GodotString::from("bar"),
                 GodotString::from("baz"),
             ], read.as_slice());
-            read.clone()
+            read
         };
 
         let mut cow_arr = arr.new_ref();

gdnative-core/src/core_types/variant.rs

@@ -166,6 +166,7 @@ decl_variant_type!(
 );
 
 impl VariantType {
+    #[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
     #[doc(hidden)]
     #[inline]
     pub fn from_sys(v: sys::godot_variant_type) -> VariantType {
@@ -182,6 +183,7 @@ impl VariantType {
     }
 }
 
+#[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
 #[repr(u32)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum CallError {
@@ -198,6 +200,7 @@ pub enum CallError {
 }
 
 impl CallError {
+    #[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
     #[inline]
     fn from_sys(v: sys::godot_variant_call_error_error) -> Result<(), CallError> {
         if v == sys::godot_variant_call_error_error_GODOT_CALL_ERROR_CALL_OK {
@@ -230,6 +233,7 @@ impl std::fmt::Display for CallError {
 impl std::error::Error for CallError {}
 
 /// Godot variant operator kind.
+#[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
 #[repr(u32)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum VariantOperator {
@@ -269,6 +273,7 @@ pub enum VariantOperator {
     In = sys::godot_variant_operator_GODOT_VARIANT_OP_IN as u32,
 }
 
+#[allow(clippy::unnecessary_cast)] // False positives: casts necessary for cross-platform
 impl VariantOperator {
     const MAX: u32 = sys::godot_variant_operator_GODOT_VARIANT_OP_MAX as u32;