From 9e23e1d16c77d05ab0b4c2bcc861f2aaf4ad5c16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Mon, 5 May 2025 14:58:13 +0200
Subject: [PATCH] compiler: Define __FreeBSD_version when targeting FreeBSD
 libc.

---
 src/Compilation.zig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 0a63d29e13..bd7d5221e7 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -5852,6 +5852,15 @@ pub fn addCCArgs(
                     try argv.append(
                         try std.fmt.allocPrint(arena, "-D_WIN32_WINNT=0x{x:0>4}", .{minver}),
                     );
+                } else if (target.isFreeBSDLibC()) {
+                    // https://docs.freebsd.org/en/books/porters-handbook/versions
+                    const min_ver = target.os.version_range.semver.min;
+                    try argv.append(try std.fmt.allocPrint(arena, "-D__FreeBSD_version={d}", .{
+                        // We don't currently respect the minor and patch components. This wouldn't be particularly
+                        // helpful because our abilists file only tracks major FreeBSD releases, so the link-time stub
+                        // symbols would be inconsistent with header declarations.
+                        min_ver.major * 100_000,
+                    }));
                 }
             }