From b1b8321fa493f63cae5f2dc7302ca1b20fcd4ea9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20Partheym=C3=BCller?= <s.partheymueller@initics.de>
Date: Wed, 8 Feb 2023 11:40:19 +0100
Subject: [PATCH] change comptime access to typeInfo of load function to
 satisfy compiler / use function pointer in order to make @field() work

---
 zig-ecs/src/resources/assets.zig | 25 ++++++++++++++-----------
 zig-ecs/src/resources/cache.zig  | 16 ++++++++--------
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/zig-ecs/src/resources/assets.zig b/zig-ecs/src/resources/assets.zig
index 3b6a6e2..6481783 100644
--- a/zig-ecs/src/resources/assets.zig
+++ b/zig-ecs/src/resources/assets.zig
@@ -37,8 +37,8 @@ pub const Assets = struct {
         return self.get(ReturnType(loader, true)).load(id, loader);
     }
 
-    fn ReturnType(comptime loader: anytype, strip_ptr: bool) type {
-        var ret = @typeInfo(@TypeOf(@field(loader, "load"))).BoundFn.return_type.?;
+    fn ReturnType(comptime loader: anytype, comptime strip_ptr: bool) type {
+        var ret = @typeInfo(@typeInfo(@TypeOf(@field(loader, "load"))).Pointer.child).Fn.return_type.?;
         if (strip_ptr) {
             return std.meta.Child(ret);
         }
@@ -47,9 +47,6 @@ pub const Assets = struct {
 };
 
 test "assets" {
-    // zig v0.10.0: Compilation Error
-    // error: no field named 'load' in struct 'resources.assets.test.assets.ThingLoadArgs'
-
     const Thing = struct {
         fart: i32,
         pub fn deinit(self: *@This()) void {
@@ -65,13 +62,19 @@ test "assets" {
     };
 
     const OtherThingLoadArgs = struct {
-        pub fn load(_: @This()) *OtherThing {
+        // Use actual field "load" as function pointer to avoid zig v0.10.0
+        // compiler error: "error: no field named 'load' in struct '...'"
+        load: *const fn (_: @This()) *OtherThing,
+        pub fn loadFn(_: @This()) *OtherThing {
             return std.testing.allocator.create(OtherThing) catch unreachable;
         }
     };
 
     const ThingLoadArgs = struct {
-        pub fn load(_: @This()) *Thing {
+        // Use actual field "load" as function pointer to avoid zig v0.10.0
+        // compiler error: "error: no field named 'load' in struct '...'"
+        load: *const fn (_: @This()) *Thing,
+        pub fn loadFn(_: @This()) *Thing {
             return std.testing.allocator.create(Thing) catch unreachable;
         }
     };
@@ -79,16 +82,16 @@ test "assets" {
     var assets = Assets.init(std.testing.allocator);
     defer assets.deinit();
 
-    _ = assets.get(Thing).load(6, ThingLoadArgs{});
+    _ = assets.get(Thing).load(6, ThingLoadArgs{ .load = ThingLoadArgs.loadFn });
     try std.testing.expectEqual(assets.get(Thing).size(), 1);
 
-    _ = assets.load(4, ThingLoadArgs{});
+    _ = assets.load(4, ThingLoadArgs{ .load = ThingLoadArgs.loadFn });
     try std.testing.expectEqual(assets.get(Thing).size(), 2);
 
-    _ = assets.get(OtherThing).load(6, OtherThingLoadArgs{});
+    _ = assets.get(OtherThing).load(6, OtherThingLoadArgs{ .load = OtherThingLoadArgs.loadFn });
     try std.testing.expectEqual(assets.get(OtherThing).size(), 1);
 
-    _ = assets.load(8, OtherThingLoadArgs{});
+    _ = assets.load(8, OtherThingLoadArgs{ .load = OtherThingLoadArgs.loadFn });
     try std.testing.expectEqual(assets.get(OtherThing).size(), 2);
 
     assets.get(OtherThing).clear();
diff --git a/zig-ecs/src/resources/cache.zig b/zig-ecs/src/resources/cache.zig
index 0d8fbd8..2195973 100644
--- a/zig-ecs/src/resources/cache.zig
+++ b/zig-ecs/src/resources/cache.zig
@@ -42,12 +42,12 @@ pub fn Cache(comptime T: type) type {
             self.safe_deinit(self);
         }
 
-        pub fn load(self: *@This(), id: u32, comptime loader: anytype) @typeInfo(@TypeOf(@field(loader, "load"))).BoundFn.return_type.? {
+        pub fn load(self: *@This(), id: u32, comptime loader: anytype) @typeInfo(@typeInfo(@TypeOf(@field(loader, "load"))).Pointer.child).Fn.return_type.? {
             if (self.resources.get(id)) |resource| {
                 return resource;
             }
 
-            var resource = loader.load();
+            var resource = loader.load(loader);
             _ = self.resources.put(id, resource) catch unreachable;
             return resource;
         }
@@ -82,9 +82,6 @@ pub fn Cache(comptime T: type) type {
 }
 
 test "cache" {
-    // zig v0.10.0: Compilation Error
-    // error: no field named 'load' in struct 'resources.cache.test.cache.ThingLoadArgs'
-
     const utils = @import("../ecs/utils.zig");
 
     const Thing = struct {
@@ -95,7 +92,10 @@ test "cache" {
     };
 
     const ThingLoadArgs = struct {
-        pub fn load(self: @This()) *Thing {
+        // Use actual field "load" as function pointer to avoid zig v0.10.0
+        // compiler error: "error: no field named 'load' in struct '...'"
+        load: *const fn (self: @This()) *Thing,
+        pub fn loadFn(self: @This()) *Thing {
             _ = self;
             return std.testing.allocator.create(Thing) catch unreachable;
         }
@@ -104,8 +104,8 @@ test "cache" {
     var cache = Cache(Thing).init(std.testing.allocator);
     defer cache.deinit();
 
-    _ = cache.load(utils.hashString("my/id"), ThingLoadArgs{});
-    _ = cache.load(utils.hashString("another/id"), ThingLoadArgs{});
+    _ = cache.load(utils.hashString("my/id"), ThingLoadArgs{ .load = ThingLoadArgs.loadFn });
+    _ = cache.load(utils.hashString("another/id"), ThingLoadArgs{ .load = ThingLoadArgs.loadFn });
     try std.testing.expectEqual(cache.size(), 2);
 
     cache.remove(utils.hashString("my/id"));