config: change quick terminal size C layout to tagged union

include/ghostty.h

@@ -455,11 +455,16 @@ typedef enum {
   GHOSTTY_QUICK_TERMINAL_SIZE_NONE,
   GHOSTTY_QUICK_TERMINAL_SIZE_PERCENTAGE,
   GHOSTTY_QUICK_TERMINAL_SIZE_PIXELS,
-} ghostty_quick_terminal_size_e;
+} ghostty_quick_terminal_size_tag_e;
+
+typedef union {
+  float percentage;
+  uint32_t pixels;
+} ghostty_quick_terminal_size_value_u;
 
 typedef struct {
-  ghostty_quick_terminal_size_e type;
-  uint32_t value;
+  ghostty_quick_terminal_size_tag_e tag;
+  ghostty_quick_terminal_size_value_u value;
 } ghostty_quick_terminal_size_s;
 
 typedef struct {

macos/Ghostty.xcodeproj/project.pbxproj

@@ -490,7 +490,6 @@
 		A55B7BB429B6F4410055DE60 /* Ghostty */ = {
 			isa = PBXGroup;
 			children = (
-				A5BB78B82DF9D8CE009AC3FA /* QuickTerminalSize.swift */,
 				A55B7BB729B6F53A0055DE60 /* Package.swift */,
 				A55B7BBB29B6FC330055DE60 /* SurfaceView.swift */,
 				A5333E212B5A2128008AEFF7 /* SurfaceView_AppKit.swift */,
@@ -640,6 +639,7 @@
 				CFBB5FE92D231E5000FD62EE /* QuickTerminalSpaceBehavior.swift */,
 				A5CBD0632CA122E70017A1AE /* QuickTerminalPosition.swift */,
 				A52FFF562CA90481000C6A5B /* QuickTerminalScreen.swift */,
+				A5BB78B82DF9D8CE009AC3FA /* QuickTerminalSize.swift */,
 				A5CBD05F2CA0C9080017A1AE /* QuickTerminalWindow.swift */,
 			);
 			path = QuickTerminal;

macos/Sources/Features/QuickTerminal/QuickTerminalSize.swift

@@ -19,16 +19,13 @@ struct QuickTerminalSize {
         case pixels(UInt32)
 
         init?(from cStruct: ghostty_quick_terminal_size_s) {
-            switch cStruct.type {
+            switch cStruct.tag {
             case GHOSTTY_QUICK_TERMINAL_SIZE_NONE:
                 return nil
             case GHOSTTY_QUICK_TERMINAL_SIZE_PERCENTAGE:
-                let floatValue = withUnsafePointer(to: cStruct.value) { ptr in
-                    ptr.withMemoryRebound(to: Float.self, capacity: 1) { $0.pointee }
-                }
-                self = .percentage(floatValue)
+                self = .percentage(cStruct.value.percentage)
             case GHOSTTY_QUICK_TERMINAL_SIZE_PIXELS:
-                self = .pixels(cStruct.value)
+                self = .pixels(cStruct.value.pixels)
             default:
                 return nil
             }

src/config/Config.zig

@@ -7200,25 +7200,36 @@ pub const QuickTerminalSize = struct {
 
     /// C API structure for QuickTerminalSize
     pub const C = extern struct {
-        primary: CSize,
-        secondary: CSize,
-    };
+        primary: C.Size,
+        secondary: C.Size,
 
-    pub const CSize = extern struct {
-        type: Type,
-        value: u32,
+        pub const Size = extern struct {
+            tag: Tag,
+            value: Value,
 
-        pub const Type = enum(u8) { none, percentage, pixels };
+            pub const Tag = enum(u8) { none, percentage, pixels };
 
-        pub const none: CSize = .{ .type = .none, .value = 0 };
+            pub const Value = extern union {
+                percentage: f32,
+                pixels: u32,
+            };
 
-        fn percentage(v: f32) CSize {
-            return .{ .type = .percentage, .value = @bitCast(v) };
-        }
+            pub const none: C.Size = .{ .tag = .none, .value = undefined };
 
-        fn pixels(v: u32) CSize {
-            return .{ .type = .pixels, .value = v };
-        }
+            pub fn percentage(v: f32) C.Size {
+                return .{
+                    .tag = .percentage,
+                    .value = .{ .percentage = v },
+                };
+            }
+
+            pub fn pixels(v: u32) C.Size {
+                return .{
+                    .tag = .pixels,
+                    .value = .{ .pixels = v },
+                };
+            }
+        };
     };
 
     pub fn cval(self: QuickTerminalSize) C {