From 2f240d0819b99999964ad2cee9193dc3d7b1df28 Mon Sep 17 00:00:00 2001
From: Harold <edwards.harold@pm.me>
Date: Sat, 15 Nov 2025 13:50:15 +0100
Subject: [PATCH] std.Build.Step.Compile: add support for '-z defs' flag

---
 lib/std/Build/Step/Compile.zig | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/std/Build/Step/Compile.zig b/lib/std/Build/Step/Compile.zig
index 85257b9560..7dd9c17273 100644
--- a/lib/std/Build/Step/Compile.zig
+++ b/lib/std/Build/Step/Compile.zig
@@ -135,6 +135,9 @@ link_z_common_page_size: ?u64 = null,
 /// Maximum page size
 link_z_max_page_size: ?u64 = null,
 
+/// Force a fatal error if any undefined symbols remain.
+link_z_defs: bool = false,
+
 /// (Darwin) Install name for the dylib
 install_name: ?[]const u8 = null,
 
@@ -1550,6 +1553,10 @@ fn getZigArgs(compile: *Compile, fuzz: bool) ![][]const u8 {
         try zig_args.append("-z");
         try zig_args.append(b.fmt("max-page-size={d}", .{size}));
     }
+    if (compile.link_z_defs) {
+        try zig_args.append("-z");
+        try zig_args.append("defs");
+    }
 
     if (compile.libc_file) |libc_file| {
         try zig_args.append("--libc");