Merge pull request #1321 from godot-rust/qol/object-arg-lifetime

FFI: make `AsArg` internals safer to use

Author: Bromeon

godot-core/src/meta/args/as_arg.rs

@@ -10,7 +10,7 @@ use std::ffi::CStr;
 use crate::builtin::{GString, NodePath, StringName, Variant};
 use crate::meta::sealed::Sealed;
 use crate::meta::traits::{GodotFfiVariant, GodotNullableFfi};
-use crate::meta::{CowArg, GodotType, ObjectArg, ToGodot};
+use crate::meta::{CowArg, FfiArg, GodotType, ObjectArg, ToGodot};
 use crate::obj::{bounds, Bounds, DynGd, Gd, GodotClass, Inherits};
 
 /// Implicit conversions for arguments passed to Godot APIs.
@@ -97,13 +97,14 @@ where
 
     /// FFI-optimized argument conversion that may use `FfiObject` when beneficial.
     ///
-    /// Defaults to calling `into_arg()`, which always works, but might be an `Owned` for a conservative approach (e.g. object upcast).
+    /// Defaults to calling `into_arg()` and wrapping in `FfiArg::Cow()`, which always works, but might be an `Owned` for a conservative
+    /// approach (e.g. object upcast).
     #[doc(hidden)]
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, T>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, T>
     where
         Self: 'arg,
     {
-        self.into_arg()
+        FfiArg::Cow(self.into_arg())
     }
 }
 
@@ -157,13 +158,12 @@ where
         }
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, Gd<Base>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, Gd<Base>>
     where
         Self: 'arg,
     {
-        // SAFETY: ObjectArg exists only during FFI call.
-        let arg = unsafe { ObjectArg::from_gd(self) };
-        CowArg::FfiObject(arg)
+        let arg = ObjectArg::from_gd(self);
+        FfiArg::FfiObject(arg)
     }
 }
 
@@ -190,13 +190,12 @@ where
         }
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, DynGd<Base, D>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, DynGd<Base, D>>
     where
         Self: 'arg,
     {
-        // SAFETY: ObjectArg exists only during FFI call.
-        let arg = unsafe { ObjectArg::from_gd(self) };
-        CowArg::FfiObject(arg)
+        let arg = ObjectArg::from_gd(self);
+        FfiArg::FfiObject(arg)
     }
 }
 
@@ -215,7 +214,7 @@ where
         AsArg::into_arg(gd_ref)
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, Gd<Base>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, Gd<Base>>
     where
         Self: 'arg,
     {
@@ -244,13 +243,12 @@ where
         }
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, Option<Gd<Base>>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, Option<Gd<Base>>>
     where
         Self: 'arg,
     {
-        // SAFETY: ObjectArg exists only during FFI call.
-        let arg = unsafe { ObjectArg::from_option_gd(self) };
-        CowArg::FfiObject(arg)
+        let arg = ObjectArg::from_option_gd(self);
+        FfiArg::FfiObject(arg)
     }
 }
 
@@ -268,13 +266,12 @@ where
         CowArg::Owned(Some(self.clone().upcast::<Base>()))
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, Option<Gd<Base>>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, Option<Gd<Base>>>
     where
         Self: 'arg,
     {
-        // SAFETY: ObjectArg exists only during FFI call.
-        let arg = unsafe { ObjectArg::from_gd(self) };
-        CowArg::FfiObject(arg)
+        let arg = ObjectArg::from_gd(self);
+        FfiArg::FfiObject(arg)
     }
 }
 
@@ -293,7 +290,7 @@ where
         AsArg::into_arg(gd_ref)
     }
 
-    fn into_ffi_arg<'arg>(self) -> CowArg<'arg, Option<Gd<Base>>>
+    fn into_ffi_arg<'arg>(self) -> FfiArg<'arg, Option<Gd<Base>>>
     where
         Self: 'arg,
     {
@@ -614,7 +611,7 @@ impl ArgPassing for ByObject {
     type Output<'r, T: 'r> = &'r T;
 
     type FfiOutput<'f, T>
-        = ObjectArg
+        = ObjectArg<'f>
     where
         T: GodotType + 'f;
 
@@ -627,13 +624,13 @@ impl ArgPassing for ByObject {
         value.to_godot().clone()
     }
 
-    fn ref_to_ffi<T>(value: &T) -> ObjectArg
+    fn ref_to_ffi<T>(value: &T) -> ObjectArg<'_>
     where
         T: ToGodot<Pass = Self>,
         T::Via: GodotType,
     {
         let obj_ref: &T::Via = value.to_godot(); // implements GodotType.
-        unsafe { obj_ref.as_object_arg() }
+        obj_ref.as_object_arg()
     }
 }