From cd5dcfbf41dc6f40a853b2a207bd3ab0ea0dc0ee Mon Sep 17 00:00:00 2001
From: Jakub Konka <kubkon@jakubkonka.com>
Date: Tue, 28 Jun 2022 09:12:43 +0200
Subject: [PATCH] macho: annotate weak imports when linking with weak
 lib/framework

---
 src/link/MachO.zig      | 18 ++++++++++++++++--
 src/link/MachO/bind.zig |  5 +++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index a406923329..f5e1bf4b4d 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -3117,6 +3117,10 @@ fn resolveSymbolsInDylibs(self: *MachO) !void {
             undef.n_type |= macho.N_EXT;
             undef.n_desc = @intCast(u16, ordinal + 1) * macho.N_SYMBOL_RESOLVER;
 
+            if (dylib.weak) {
+                undef.n_desc |= macho.N_WEAK_REF;
+            }
+
             if (self.unresolved.fetchSwapRemove(resolv.where_index)) |entry| outer_blk: {
                 switch (entry.value) {
                     .none => {},
@@ -5806,11 +5810,16 @@ fn writeDyldInfoData(self: *MachO) !void {
                         },
                         .undef => {
                             const bind_sym = self.undefs.items[resolv.where_index];
+                            var flags: u4 = 0;
+                            if (bind_sym.weakRef()) {
+                                flags |= @truncate(u4, macho.BIND_SYMBOL_FLAGS_WEAK_IMPORT);
+                            }
                             try bind_pointers.append(.{
                                 .offset = binding.offset + base_offset,
                                 .segment_id = match.seg,
-                                .dylib_ordinal = @divExact(@bitCast(i16, bind_sym.n_desc), macho.N_SYMBOL_RESOLVER),
+                                .dylib_ordinal = @divTrunc(@bitCast(i16, bind_sym.n_desc), macho.N_SYMBOL_RESOLVER),
                                 .name = self.getString(bind_sym.n_strx),
+                                .bind_flags = flags,
                             });
                         },
                     }
@@ -5828,11 +5837,16 @@ fn writeDyldInfoData(self: *MachO) !void {
                         },
                         .undef => {
                             const bind_sym = self.undefs.items[resolv.where_index];
+                            var flags: u4 = 0;
+                            if (bind_sym.weakRef()) {
+                                flags |= @truncate(u4, macho.BIND_SYMBOL_FLAGS_WEAK_IMPORT);
+                            }
                             try lazy_bind_pointers.append(.{
                                 .offset = binding.offset + base_offset,
                                 .segment_id = match.seg,
-                                .dylib_ordinal = @divExact(@bitCast(i16, bind_sym.n_desc), macho.N_SYMBOL_RESOLVER),
+                                .dylib_ordinal = @divTrunc(@bitCast(i16, bind_sym.n_desc), macho.N_SYMBOL_RESOLVER),
                                 .name = self.getString(bind_sym.n_strx),
+                                .bind_flags = flags,
                             });
                         },
                     }
diff --git a/src/link/MachO/bind.zig b/src/link/MachO/bind.zig
index 14a5ba3e30..9e34581a23 100644
--- a/src/link/MachO/bind.zig
+++ b/src/link/MachO/bind.zig
@@ -7,6 +7,7 @@ pub const Pointer = struct {
     segment_id: u16,
     dylib_ordinal: ?i64 = null,
     name: ?[]const u8 = null,
+    bind_flags: u4 = 0,
 };
 
 pub fn rebaseInfoSize(pointers: []const Pointer) !u64 {
@@ -73,7 +74,7 @@ pub fn writeBindInfo(pointers: []const Pointer, writer: anytype) !void {
         }
         try writer.writeByte(macho.BIND_OPCODE_SET_TYPE_IMM | @truncate(u4, macho.BIND_TYPE_POINTER));
 
-        try writer.writeByte(macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM); // TODO Sometimes we might want to add flags.
+        try writer.writeByte(macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM | pointer.bind_flags);
         try writer.writeAll(pointer.name.?);
         try writer.writeByte(0);
 
@@ -127,7 +128,7 @@ pub fn writeLazyBindInfo(pointers: []const Pointer, writer: anytype) !void {
             try writer.writeByte(macho.BIND_OPCODE_SET_DYLIB_SPECIAL_IMM | @truncate(u4, @bitCast(u64, pointer.dylib_ordinal.?)));
         }
 
-        try writer.writeByte(macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM); // TODO Sometimes we might want to add flags.
+        try writer.writeByte(macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM | pointer.bind_flags);
         try writer.writeAll(pointer.name.?);
         try writer.writeByte(0);