cross compiled macos binaries with LLD which depend on TLS fail at runtime

[andrewrk]

threadlocal var x: i32 = 1;
test "tls macos cross compile" {
    x += 1;
}

$ ./zig test test.zig
(ok)
$ ./zig test test.zig -target x86_64-macosx
dyld: Symbol not found: __tlv_bootstrap

[andrewrk]

I think this ultimately comes down to a deficiency in LLD. See #1535

[daurnimator]

(continuing from ziglang/zig-bootstrap#38): I think this may be caused by a too low OSX version. I can find similar issues elsewhere where wrong/low OSX version leads to Symbol not found: __tlv_bootstrap, e.g. rust-lang/rust#10842

Can you try passing -macosx_version_min 10.7.0 to lld?

[andrewrk]

Can you try passing -macosx_version_min 10.7.0 to lld?

We do that here:

zig/src/link/MachO.zig

Lines 598 to 614 in 2eee058

	switch (target.os.tag) {
	.macos => {
	try argv.append("-macosx_version_min");
	},
	.ios, .tvos, .watchos => switch (target.cpu.arch) {
	.i386, .x86_64 => {
	try argv.append("-ios_simulator_version_min");
	},
	else => {
	try argv.append("-iphoneos_version_min");
	},
	},
	else => unreachable,
	}
	const ver = target.os.version_range.semver.min;
	const version_string = try std.fmt.allocPrint(arena, "{d}.{d}.{d}", .{ ver.major, ver.minor, ver.patch });
	try argv.append(version_string);

[kubkon]

Just an FYI that this one was fixed for cross-compiling C and Zig sources (C++ is still not in the clear) in #7318; however, ultimately this is a deficiency in LLD so I'm inclined to leave the issue open until LLD acknowledges and fixes it, or our self-hosted linker is up to the job.

[andrewrk]

The plan to address this issue is #8727. Once that is done, this issue can be closed as well.

[kubkon]

I will only add that cross-compilation is now exclusively handled by zig ld which handles TLVs properly on both x86_64 and arm64 architectures.

[kubkon]

Given that we no longer rely on LLD when targeting macOS, I'm closing this issue regardless of whether it's been fixed in upstream since it's irrelevant for zig.