From 61f6c72bf8ee057541b5554d0553f3c76b6cfdb7 Mon Sep 17 00:00:00 2001
From: Yves Biener <yves.biener@gmx.de>
Date: Wed, 13 Nov 2024 16:49:38 +0100
Subject: [PATCH] mod(layout/Stacks): add comptime checks for correct `Element`
 union typing

---
 src/layout/HStack.zig | 7 ++++++-
 src/layout/VStack.zig | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/layout/HStack.zig b/src/layout/HStack.zig
index 6c47c67..bb5dd7e 100644
--- a/src/layout/HStack.zig
+++ b/src/layout/HStack.zig
@@ -19,8 +19,13 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
         @compileError("Provided type `Element` for `Layout(comptime Event: type, comptime Element: type, comptime Renderer: type)` is not of type `union(enum)`.");
     }
     const Elements = std.ArrayList(Element);
-    // TODO: expect name of field to be corresponding to the type
+    if (!std.mem.eql(u8, @typeInfo(Element).Union.fields[0].name, "layout")) {
+        @compileError("Expected `layout: Layout` to be the first union element, but has name: " ++ @typeInfo(Element).Union.fields[0].name);
+    }
     const LayoutType = @typeInfo(Element).Union.fields[0].type;
+    if (!std.mem.eql(u8, @typeInfo(Element).Union.fields[1].name, "widget")) {
+        @compileError("Expected `widget: Widget` to be the first union element, but has name: " ++ @typeInfo(Element).Union.fields[1].name);
+    }
     const WidgetType = @typeInfo(Element).Union.fields[1].type;
     const Events = std.ArrayList(Event);
     return struct {
diff --git a/src/layout/VStack.zig b/src/layout/VStack.zig
index 273fa9a..7b89062 100644
--- a/src/layout/VStack.zig
+++ b/src/layout/VStack.zig
@@ -19,8 +19,13 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
         @compileError("Provided type `Element` for `Layout(comptime Event: type, comptime Element: type, comptime Renderer: type)` is not of type `union(enum)`.");
     }
     const Elements = std.ArrayList(Element);
-    // TODO: expect name of field to be corresponding to the type
+    if (!std.mem.eql(u8, @typeInfo(Element).Union.fields[0].name, "layout")) {
+        @compileError("Expected `layout: Layout` to be the first union element, but has name: " ++ @typeInfo(Element).Union.fields[0].name);
+    }
     const LayoutType = @typeInfo(Element).Union.fields[0].type;
+    if (!std.mem.eql(u8, @typeInfo(Element).Union.fields[1].name, "widget")) {
+        @compileError("Expected `widget: Widget` to be the first union element, but has name: " ++ @typeInfo(Element).Union.fields[1].name);
+    }
     const WidgetType = @typeInfo(Element).Union.fields[1].type;
     const Events = std.ArrayList(Event);
     return struct {