[Mach-O] wip

macho/main.cc

@@ -113,9 +113,11 @@ static bool compare_chunks(const Chunk *a, const Chunk *b) {
 static void create_synthetic_chunks(Context &ctx) {
   for (ObjectFile *file : ctx.objs) {
     for (std::unique_ptr<InputSection> &isec : file->sections) {
-      for (std::unique_ptr<Subsection> &subsec : isec->subsections)
-        isec->osec.add_subsec(subsec.get());
-      isec->osec.hdr.attr |= isec->hdr.attr;
+      if (isec) {
+        for (std::unique_ptr<Subsection> &subsec : isec->subsections)
+          isec->osec.add_subsec(subsec.get());
+        isec->osec.hdr.attr |= isec->hdr.attr;
+      }
     }
   }
 
@@ -300,12 +302,16 @@ int main(int argc, char **argv) {
 
   create_synthetic_chunks(ctx);
 
+  for (ObjectFile *file : ctx.objs)
+    file->check_duplicate_symbols(ctx);
+
   for (i64 i = 0; i < ctx.segments.size(); i++)
     ctx.segments[i]->seg_idx = i + 1;
 
   for (ObjectFile *file : ctx.objs)
-    for (std::unique_ptr<InputSection> &sec : file->sections)
-      sec->scan_relocations(ctx);
+    for (std::unique_ptr<InputSection> &isec : file->sections)
+      if (isec)
+        isec->scan_relocations(ctx);
 
   export_symbols(ctx);
   i64 output_size = assign_offsets(ctx);

macho/mold.h

@@ -76,6 +76,7 @@ public:
   void resolve_lazy_symbols(Context &ctx);
   std::vector<ObjectFile *> mark_live_objects(Context &ctx);
   void convert_common_symbols(Context &ctx);
+  void check_duplicate_symbols(Context &ctx);
 
   Relocation read_reloc(Context &ctx, const MachSection &hdr, MachRel r);
 

macho/object-file.cc

@@ -40,10 +40,17 @@ void ObjectFile::parse(Context &ctx) {
         if (mach_sec[i].get_segname() == "__LD" &&
             mach_sec[i].get_sectname() == "__compact_unwind") {
           unwind_sec = &mach_sec[i];
-        } else {
-          sections.push_back(
-            std::make_unique<InputSection>(ctx, *this, mach_sec[i]));
+          sections.push_back(nullptr);
+          continue;
         }
+
+        if (mach_sec[i].attr & S_ATTR_DEBUG) {
+          sections.push_back(nullptr);
+          continue;
+        }
+
+        sections.push_back(
+          std::make_unique<InputSection>(ctx, *this, mach_sec[i]));
       }
       break;
     }
@@ -88,7 +95,8 @@ void ObjectFile::parse(Context &ctx) {
   }
 
   for (std::unique_ptr<InputSection> &sec : sections)
-    sec->parse_relocations(ctx);
+    if (sec)
+      sec->parse_relocations(ctx);
 
   if (unwind_sec)
     parse_compact_unwind(ctx, *unwind_sec);
@@ -314,7 +322,17 @@ void ObjectFile::convert_common_symbols(Context &ctx) {
       sym.value = 0;
       sym.is_common = false;
     }
-  }  
+  }
+}
+
+void ObjectFile::check_duplicate_symbols(Context &ctx) {
+  for (i64 i = 0; i < syms.size(); i++) {
+    Symbol &sym = *syms[i];
+    MachSym &msym = mach_syms[i];
+    if (!msym.is_undef() && !msym.is_common() && sym.file != this)
+      Error(ctx) << "duplicate symbol: " << *this << ": " << *sym.file
+                 << ": " << sym;
+  }
 }
 
 InputSection *ObjectFile::get_common_sec(Context &ctx) {

macho/output-chunks.cc

@@ -911,10 +911,12 @@ void DataInCodeSection::compute_size(Context &ctx) {
     std::span<DataInCodeEntry> entries = file->data_in_code_entries;
 
     for (i64 i = 0; !entries.empty() && i < file->sections.size(); i++) {
-      InputSection &sec = *file->sections[i];
+      std::unique_ptr<InputSection> &isec = file->sections[i];
+      if (!isec)
+        continue;
 
-      for (i64 j = 0; !entries.empty() && j < sec.subsections.size(); j++) {
-        Subsection &subsec = *sec.subsections[j];
+      for (i64 j = 0; !entries.empty() && j < isec->subsections.size(); j++) {
+        Subsection &subsec = *isec->subsections[j];
         DataInCodeEntry &ent = entries[0];
 
         if (subsec.input_addr + subsec.input_size < ent.offset)

test/macho/duplicate-error.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+set -e
+cd $(dirname $0)
+mold=`pwd`/../../ld64.mold
+echo -n "Testing $(basename -s .sh $0) ... "
+t=$(pwd)/../../out/test/macho/$(basename -s .sh $0)
+mkdir -p $t
+
+cat <<EOF | cc -o $t/a.o -c -xc -
+void hello() {}
+EOF
+
+cat <<EOF | cc -o $t/b.o -c -xc -
+void hello() {}
+int main() {}
+EOF
+
+! clang -fuse-ld=$mold -o $t/exe $t/a.o $t/b.o 2> $t/log || false
+grep -q 'duplicate symbol: .*/b.o: .*/a.o: _hello' $t/log
+
+echo OK