A few build issues on macOS

[lhoward]

% xcodebuild -version
Xcode 14.2
Build version 14C18

A couple of build issues.

Firstly, assumption that Vulkan is installed in /usr/local but brew installs them into /opt/homebrew. This is probably related to the fact that the setup-vulkan-macOS Makefile target (in SwiftVulkan) doesn't work because the apenngrace/vulkan/vulkan-sdk cask cannot be found. Instead I used the regular Homebrew install, which didn't even seem to compile (not all headers were installed, had to hand-edit vulkan_core.h to remove H264/5 dependencies).

Then I ran into an issue where SDL_KeyCode couldn't be used as a dictionary key in virtualKeyMap.

diff --git a/Sources/FirebladePAL/Platform/SDL/SDLKeys.swift b/Sources/FirebladePAL/Platform/SDL/SDLKeys.swift
index ee13545..717f611 100644
--- a/Sources/FirebladePAL/Platform/SDL/SDLKeys.swift
+++ b/Sources/FirebladePAL/Platform/SDL/SDLKeys.swift
@@ -9,6 +9,8 @@
 
     @_implementationOnly import SDL2
 
+    extension SDL_KeyCode: Hashable {}
+
     extension KeyCode {
         public init?(scancode: UInt) {
             guard let keyCode = Self.physicalKeyMap[SDL_Scancode(rawValue: SDL_Scancode.RawValue(scancode))] else {

fixed it.

Then building a package that depends on it, I got:

Building for debugging...
ld: warning: Could not find or use auto-linked library 'vulkan'
Undefined symbols for architecture arm64:
  "_vkCreateInstance", referenced from:
      _$s12FirebladePAL19SDLVLKWindowSurfaceC14createInstance6layers10extensionss13OpaquePointerVSaySSG_AItKFZAHSRySPys4Int8VGSgGKXEfU_AhNKXEfU_ in SDLVLKWindowSurface.swift.o
  "_vkDestroySurfaceKHR", referenced from:
      _$s12FirebladePAL19SDLVLKWindowSurfaceC7destroyyyF in SDLVLKWindowSurface.swift.o
ld: symbol(s) not found for architecture arm64
ld: warning: Could not find or use auto-linked library 'vulkan'
Undefined symbols for architecture arm64:
  "_vkCreateInstance", referenced from:
      _$s12FirebladePAL19SDLVLKWindowSurfaceC14createInstance6layers10extensionss13OpaquePointerVSaySSG_AItKFZAHSRySPys4Int8VGSgGKXEfU_AhNKXEfU_ in SDLVLKWindowSurface.swift.o
  "_vkDestroySurfaceKHR", referenced from:
      _$s12FirebladePAL19SDLVLKWindowSurfaceC7destroyyyF in SDLVLKWindowSurface.swift.o
ld: symbol(s) not found for architecture arm64

even after sym-linking libvulkan.dylib from /opt/homebrew/lib into /usr/local/lib.

diff --git a/Package.swift b/Package.swift
index 16ae1a4..3654af0 100644
--- a/Package.swift
+++ b/Package.swift
@@ -122,7 +122,8 @@ let package = Package(
                 .vulkan,
                 .nfd,
             ],
-            swiftSettings: swiftSettings
+            swiftSettings: swiftSettings,
+            linkerSettings: [.unsafeFlags(["-L/opt/homebrew/lib","-lvulkan"])]
         ),
         .target(
             name: "CPUBackendDemoApp",

fixed that.

Finally, I also needed to make the SDL dependency on SDL instead of SDL2.

After all of this, it builds and tests pass, although VulkanBackendDemoApp does trap with:

FirebladePAL/SDLWindow.swift:79: Fatal error: vkInstanceCreationFailed(__C.VkResult(rawValue: -6))