reflect: allow compilation of boxed trait objects

Add a hidden `compile_boxed` function to CompileShader to support this. This is to allow Box<dyn CompileReflectShader> to work.

librashader-reflect/src/back/mod.rs

@@ -36,6 +36,16 @@ pub trait CompileShader<T: OutputTarget> {
         self,
         options: Self::Options,
     ) -> Result<ShaderCompilerOutput<T::Output, Self::Context>, ShaderCompileError>;
+
+    /// Consume the object and return the compiled output of the shader.
+    ///
+    /// This is an internal implementation detail for stable building without TAIT,
+    /// to allow delegation when Self is unsized (i.e. dyn CompileReflectShader).
+    #[doc(hidden)]
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<T::Output, Self::Context>, ShaderCompileError>;
 }
 
 /// Marker trait for combinations of targets and compilations that can be reflected and compiled
@@ -81,6 +91,13 @@ where
     ) -> Result<ShaderCompilerOutput<E::Output, Self::Context>, ShaderCompileError> {
         self.backend.compile(options)
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<E::Output, Self::Context>, ShaderCompileError> {
+        self.backend.compile(options)
+    }
 }
 
 /// A trait for reflectable compilations that can be transformed
@@ -124,6 +141,39 @@ where
     }
 }
 
+impl<T: ReflectShader + ?Sized> ReflectShader for Box<T> {
+    fn reflect(
+        &mut self,
+        pass_number: usize,
+        semantics: &ShaderSemantics,
+    ) -> Result<ShaderReflection, ShaderReflectError> {
+        (**self).reflect(pass_number, semantics)
+    }
+}
+
+impl<O, T> CompileShader<T> for Box<O>
+where
+    O: CompileShader<T> + ?Sized,
+    T: OutputTarget,
+{
+    type Options = O::Options;
+    type Context = O::Context;
+
+    fn compile(
+        self,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<T::Output, Self::Context>, ShaderCompileError> {
+        O::compile_boxed(self, options)
+    }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<T::Output, Self::Context>, ShaderCompileError> {
+        self.compile(options)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::front::{Glslang, ShaderInputCompiler};

librashader-reflect/src/back/msl.rs

@@ -1,5 +1,5 @@
 use crate::back::targets::MSL;
-use crate::back::{CompileReflectShader, CompileShader, CompilerBackend, FromCompilation};
+use crate::back::{CompileReflectShader, CompilerBackend, FromCompilation};
 use crate::error::ShaderReflectError;
 use crate::front::SpirvCompilation;
 use crate::reflect::cross::msl::MslReflect;
@@ -29,8 +29,7 @@ impl FromCompilation<SpirvCompilation, SpirvCross> for MSL {
     type Target = MSL;
     type Options = Option<self::MslVersion>;
     type Context = CrossMslContext;
-    type Output = impl CompileShader<Self::Target, Options = Self::Options, Context = Self::Context>
-        + ReflectShader;
+    type Output = impl CompileReflectShader<Self::Target, SpirvCompilation, SpirvCross>;
 
     fn from_compilation(
         compile: SpirvCompilation,

librashader-reflect/src/back/spirv.rs

@@ -1,5 +1,7 @@
 use crate::back::targets::SPIRV;
-use crate::back::{CompileShader, CompilerBackend, FromCompilation, ShaderCompilerOutput};
+use crate::back::{
+    CompileReflectShader, CompileShader, CompilerBackend, FromCompilation, ShaderCompilerOutput,
+};
 use crate::error::{ShaderCompileError, ShaderReflectError};
 use crate::front::SpirvCompilation;
 use crate::reflect::cross::glsl::GlslReflect;
@@ -20,8 +22,7 @@ impl FromCompilation<SpirvCompilation, SpirvCross> for SPIRV {
     type Target = SPIRV;
     type Options = Option<()>;
     type Context = ();
-    type Output = impl CompileShader<Self::Target, Options = Self::Options, Context = Self::Context>
-        + ReflectShader;
+    type Output = impl CompileReflectShader<Self::Target, SpirvCompilation, SpirvCross>;
 
     fn from_compilation(
         compile: SpirvCompilation,
@@ -86,8 +87,7 @@ impl FromCompilation<SpirvCompilation, Naga> for SPIRV {
     type Target = SPIRV;
     type Options = NagaSpirvOptions;
     type Context = NagaSpirvContext;
-    type Output = impl CompileShader<Self::Target, Options = Self::Options, Context = Self::Context>
-        + ReflectShader;
+    type Output = impl CompileReflectShader<Self::Target, SpirvCompilation, Naga>;
 
     fn from_compilation(
         compile: SpirvCompilation,

librashader-reflect/src/reflect/cross/glsl.rs

@@ -165,4 +165,11 @@ impl CompileShader<GLSL> for CrossReflect<targets::Glsl> {
             },
         })
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<String, Self::Context>, ShaderCompileError> {
+        <CrossReflect<targets::Glsl> as CompileShader<GLSL>>::compile(*self, options)
+    }
 }

librashader-reflect/src/reflect/cross/hlsl.rs

@@ -128,4 +128,11 @@ impl CompileShader<HLSL> for CrossReflect<targets::Hlsl> {
             },
         })
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<String, Self::Context>, ShaderCompileError> {
+        <CrossReflect<targets::Hlsl> as CompileShader<HLSL>>::compile(*self, options)
+    }
 }

librashader-reflect/src/reflect/naga/msl.rs

@@ -146,6 +146,13 @@ impl CompileShader<MSL> for NagaReflect {
             },
         })
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<String, Self::Context>, ShaderCompileError> {
+        <NagaReflect as CompileShader<MSL>>::compile(*self, options)
+    }
 }
 
 #[cfg(test)]

librashader-reflect/src/reflect/naga/spirv.rs

@@ -51,4 +51,11 @@ impl CompileShader<SPIRV> for NagaReflect {
             },
         })
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<Vec<u32>, Self::Context>, ShaderCompileError> {
+        <NagaReflect as CompileShader<SPIRV>>::compile(*self, options)
+    }
 }

librashader-reflect/src/reflect/naga/wgsl.rs

@@ -38,4 +38,11 @@ impl CompileShader<WGSL> for NagaReflect {
             },
         })
     }
+
+    fn compile_boxed(
+        self: Box<Self>,
+        options: Self::Options,
+    ) -> Result<ShaderCompilerOutput<String, Self::Context>, ShaderCompileError> {
+        <NagaReflect as CompileShader<WGSL>>::compile(*self, options)
+    }
 }