Update src/shader_recompiler/backend/spirv/spirv_emit_context.cpp

This is a format mix-match fix for the MoltenVK SPIRV to MSL conversion error.

src/shader_recompiler/backend/spirv/spirv_emit_context.cpp

@@ -1658,6 +1658,44 @@ void EmitContext::DefineOutputs(const IR::Program& program) {
             if (!info.stores_frag_color[index] && !profile.need_declared_frag_colors) {
                 continue;
             }
+            
+            // MoltenVK/Metal: Use integer output type for integer render targets
+            // Metal requires fragment shader outputs to match render target formats.
+            // On other platforms, always use F32[4] (float vec4) as usual.
+            Id output_type = F32[4];  // Default to float
+            if (runtime_info.is_moltenvk && index < runtime_info.color_formats.size()) {
+                const auto& format = runtime_info.color_formats[index];
+                // Check if the render target format is an integer format
+                const bool is_integer_format = (
+                    format == PixelFormat::R8_UINT || 
+                    format == PixelFormat::R8_SINT ||
+                    format == PixelFormat::R16_UINT || 
+                    format == PixelFormat::R16_SINT ||
+                    format == PixelFormat::R32_UINT || 
+                    format == PixelFormat::R32_SINT ||
+                    format == PixelFormat::R8G8_UINT || 
+                    format == PixelFormat::R8G8_SINT ||
+                    format == PixelFormat::R16G16_UINT || 
+                    format == PixelFormat::R16G16_SINT ||
+                    format == PixelFormat::R32G32_UINT || 
+                    format == PixelFormat::R32G32_SINT ||
+                    format == PixelFormat::R8G8B8A8_UINT || 
+                    format == PixelFormat::R8G8B8A8_SINT ||
+                    format == PixelFormat::R16G16B16A16_UINT || 
+                    format == PixelFormat::R16G16B16A16_SINT ||
+                    format == PixelFormat::R32G32B32A32_UINT || 
+                    format == PixelFormat::R32G32B32A32_SINT ||
+                    format == PixelFormat::A8B8G8R8_UINT || 
+                    format == PixelFormat::A8B8G8R8_SINT
+                );
+                if (is_integer_format) {
+                    output_type = U32[4];  // Use unsigned int vec4 for integer formats
+                }
+            }
+            frag_color[index] = DefineOutput(*this, output_type, std::nullopt);
+            Decorate(frag_color[index], spv::Decoration::Location, index);
+            Name(frag_color[index], fmt::format("frag_color{}", index));
+        }
             frag_color[index] = DefineOutput(*this, F32[4], std::nullopt);
             Decorate(frag_color[index], spv::Decoration::Location, index);
             Name(frag_color[index], fmt::format("frag_color{}", index));