From 275917345237b79761a0692dbc7d47080cd4c8b5 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Fri, 24 May 2024 11:58:57 -0700
Subject: [PATCH] zig build: lock stderr while executing the build runner

---
 src/main.zig | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/main.zig b/src/main.zig
index 3369fa4c21..ac8a483d17 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -5151,7 +5151,12 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
             child.stdout_behavior = .Inherit;
             child.stderr_behavior = .Inherit;
 
-            const term = try child.spawnAndWait();
+            const term = t: {
+                std.debug.lockStdErr();
+                defer std.debug.unlockStdErr();
+                break :t try child.spawnAndWait();
+            };
+
             switch (term) {
                 .Exited => |code| {
                     if (code == 0) return cleanExit();