Merge pull request #6990 from kubkon/system-linker-hack

Re-enable system linker hack

build.zig

@@ -396,8 +396,8 @@ fn configureStage2(b: *Builder, exe: anytype, ctx: Context, need_cpp_includes: b
                 try addCxxKnownPath(b, ctx, exe, "libstdc++.a", null, need_cpp_includes);
                 exe.linkSystemLibrary("pthread");
                 // TODO LLD cannot perform this link.
+                // Set ZIG_SYSTEM_LINKER_HACK env var to use system linker ld instead.
                 // See https://github.com/ziglang/zig/issues/1535
-                exe.enableSystemLinkerHack();
             } else |err| switch (err) {
                 error.RequiredLibraryNotFound => {
                     // System compiler, not gcc.

lib/std/build.zig

@@ -1237,7 +1237,6 @@ pub const LibExeObjStep = struct {
     packages: ArrayList(Pkg),
     build_options_contents: std.ArrayList(u8),
     build_options_artifact_args: std.ArrayList(BuildOptionArtifactArg),
-    system_linker_hack: bool = false,
 
     object_src: []const u8,
 
@@ -1898,10 +1897,6 @@ pub const LibExeObjStep = struct {
         self.exec_cmd_args = args;
     }
 
-    pub fn enableSystemLinkerHack(self: *LibExeObjStep) void {
-        self.system_linker_hack = true;
-    }
-
     fn linkLibraryOrObject(self: *LibExeObjStep, other: *LibExeObjStep) void {
         self.step.dependOn(&other.step);
         self.link_objects.append(LinkObject{ .OtherStep = other }) catch unreachable;
@@ -2283,10 +2278,6 @@ pub const LibExeObjStep = struct {
             }
         }
 
-        if (self.system_linker_hack) {
-            try zig_args.append("--system-linker-hack");
-        }
-
         if (self.valgrind_support) |valgrind_support| {
             if (valgrind_support) {
                 try zig_args.append("-fvalgrind");

src/Compilation.zig

@@ -472,13 +472,22 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             break :blk false;
         };
 
-        const syslibroot = if (build_options.have_llvm and comptime std.Target.current.isDarwin()) outer: {
-            const path = if (use_lld and options.is_native_os and options.target.isDarwin()) inner: {
-                const syslibroot_path = try std.zig.system.getSDKPath(arena);
-                break :inner syslibroot_path;
-            } else null;
-            break :outer path;
-        } else null;
+        const DarwinOptions = struct {
+            syslibroot: ?[]const u8 = null,
+            system_linker_hack: bool = false,
+        };
+
+        const darwin_options: DarwinOptions = if (build_options.have_llvm and comptime std.Target.current.isDarwin()) outer: {
+            const opts: DarwinOptions = if (use_lld and options.is_native_os and options.target.isDarwin()) inner: {
+                const syslibroot = try std.zig.system.getSDKPath(arena);
+                const system_linker_hack = std.os.getenv("ZIG_SYSTEM_LINKER_HACK") != null;
+                break :inner .{
+                    .syslibroot = syslibroot,
+                    .system_linker_hack = system_linker_hack,
+                };
+            } else .{};
+            break :outer opts;
+        } else .{};
 
         const link_libc = options.link_libc or target_util.osRequiresLibC(options.target);
 
@@ -775,13 +784,14 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .optimize_mode = options.optimize_mode,
             .use_lld = use_lld,
             .use_llvm = use_llvm,
+            .system_linker_hack = darwin_options.system_linker_hack,
             .link_libc = link_libc,
             .link_libcpp = options.link_libcpp,
             .objects = options.link_objects,
             .frameworks = options.frameworks,
             .framework_dirs = options.framework_dirs,
             .system_libs = system_libs,
-            .syslibroot = syslibroot,
+            .syslibroot = darwin_options.syslibroot,
             .lib_dirs = options.lib_dirs,
             .rpath_list = options.rpath_list,
             .strip = strip,

src/link.zig

@@ -57,6 +57,9 @@ pub const Options = struct {
     /// other objects.
     /// Otherwise (depending on `use_lld`) this link code directly outputs and updates the final binary.
     use_llvm: bool,
+    /// Darwin-only. If this is true, `use_llvm` is true, and `is_native_os` is true, this link code will
+    /// use system linker `ld` instead of the LLD.
+    system_linker_hack: bool,
     link_libc: bool,
     link_libcpp: bool,
     function_sections: bool,

src/link/MachO.zig

@@ -532,11 +532,19 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
         // Create an LLD command line and invoke it.
         var argv = std.ArrayList([]const u8).init(self.base.allocator);
         defer argv.deinit();
+
+        // TODO https://github.com/ziglang/zig/issues/6971
+        // Note that there is no need to check if running natively since we do that already
+        // when setting `system_linker_hack` in Compilation struct.
+        if (self.base.options.system_linker_hack) {
+            try argv.append("ld");
+        } else {
             // Even though we're calling LLD as a library it thinks the first argument is its own exe name.
             try argv.append("lld");
 
             try argv.append("-error-limit");
             try argv.append("0");
+        }
 
         try argv.append("-demangle");
 
@@ -703,6 +711,28 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
             Compilation.dump_argv(argv.items);
         }
 
+        // TODO https://github.com/ziglang/zig/issues/6971
+        // Note that there is no need to check if running natively since we do that already
+        // when setting `system_linker_hack` in Compilation struct.
+        if (self.base.options.system_linker_hack) {
+            const result = try std.ChildProcess.exec(.{ .allocator = self.base.allocator, .argv = argv.items });
+            defer {
+                self.base.allocator.free(result.stdout);
+                self.base.allocator.free(result.stderr);
+            }
+            if (result.stdout.len != 0) {
+                std.log.warn("unexpected LD stdout: {}", .{result.stdout});
+            }
+            if (result.stderr.len != 0) {
+                std.log.warn("unexpected LD stderr: {}", .{result.stderr});
+            }
+            if (result.term != .Exited or result.term.Exited != 0) {
+                // TODO parse this output and surface with the Compilation API rather than
+                // directly outputting to stderr here.
+                std.debug.print("{}", .{result.stderr});
+                return error.LDReportedFailure;
+            }
+        } else {
             const new_argv = try arena.allocSentinel(?[*:0]const u8, argv.items.len, null);
             for (argv.items) |arg, i| {
                 new_argv[i] = try arena.dupeZ(u8, arg);
@@ -741,6 +771,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
                 std.log.warn("unexpected LLD stderr: {}", .{stderr_context.data.items});
             }
         }
+    }
 
     if (!self.base.options.disable_lld_caching) {
         // Update the file with the digest. If it fails we can continue; it only