fix startup procedure for async WinMain

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/std/start.zig b/lib/std/start.zig
index 29b254c0f9..a3cc3d00a8 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -511,9 +511,9 @@ inline fn initEventLoopAndCallWinMain() std.os.windows.INT {
             };
             defer loop.deinit();
 
-            var result: u8 = undefined;
-            var frame: @Frame(callMainAsync) = undefined;
-            _ = @asyncCall(&frame, &result, callMainAsync, .{loop});
+            var result: std.os.windows.INT = undefined;
+            var frame: @Frame(callWinMainAsync) = undefined;
+            _ = @asyncCall(&frame, &result, callWinMainAsync, .{loop});
             loop.run();
             return result;
         }
@@ -532,6 +532,14 @@ fn callMainAsync(loop: *std.event.Loop) callconv(.Async) u8 {
     return callMain();
 }
 
+fn callWinMainAsync(loop: *std.event.Loop) callconv(.Async) std.os.windows.INT {
+    // This prevents the event loop from terminating at least until main() has returned.
+    // TODO This shouldn't be needed here; it should be in the event loop code.
+    loop.beginOneEvent();
+    defer loop.finishOneEvent();
+    return call_wWinMain();
+}
+
 // This is not marked inline because it is called with @asyncCall when
 // there is an event loop.
 pub fn callMain() u8 {