From 209a3da4f73ab6dd4182649af8fb7439e9145441 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Fri, 4 Sep 2020 13:00:10 -0700
Subject: [PATCH] provide default implementation of std.log on freestanding

closes #6252
---
 lib/std/log.zig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/std/log.zig b/lib/std/log.zig
index 50bdfdc068..7b677f698a 100644
--- a/lib/std/log.zig
+++ b/lib/std/log.zig
@@ -127,6 +127,10 @@ fn log(
     if (@enumToInt(message_level) <= @enumToInt(level)) {
         if (@hasDecl(root, "log")) {
             root.log(message_level, scope, format, args);
+        } else if (std.Target.current.os.tag == .freestanding) {
+            // On freestanding one must provide a log function; we do not have
+            // any I/O configured.
+            return;
         } else if (builtin.mode != .ReleaseSmall) {
             const held = std.debug.getStderrMutex().acquire();
             defer held.release();