add regression test for bug fixed by lazy values

closes #624

Author: andrewrk

test/stage1/behavior.zig

@@ -32,6 +32,7 @@ comptime {
     _ = @import("behavior/bugs/394.zig");
     _ = @import("behavior/bugs/421.zig");
     _ = @import("behavior/bugs/529.zig");
+    _ = @import("behavior/bugs/624.zig");
     _ = @import("behavior/bugs/655.zig");
     _ = @import("behavior/bugs/656.zig");
     _ = @import("behavior/bugs/679.zig");

test/stage1/behavior/bugs/624.zig

@@ -0,0 +1,23 @@
+const std = @import("std");
+const expect = std.testing.expect;
+
+const TestContext = struct {
+    server_context: *ListenerContext,
+};
+
+const ListenerContext = struct {
+    context_alloc: *ContextAllocator,
+};
+
+const ContextAllocator = MemoryPool(TestContext);
+
+fn MemoryPool(comptime T: type) type {
+    return struct {
+        n: usize,
+    };
+}
+
+test "foo" {
+    var allocator = ContextAllocator{ .n = 10 };
+    expect(allocator.n == 10);
+}