Add --demangle

Makefile

@@ -12,7 +12,7 @@ LDFLAGS=-L$(TBB_LIBDIR) -Wl,-rpath=$(TBB_LIBDIR) \
 LIBS=-lcrypto -pthread -ltbb -lmimalloc
 OBJS=main.o object_file.o input_sections.o output_chunks.o mapfile.o perf.o \
      linker_script.o archive_file.o output_file.o subprocess.o gc_sections.o \
-     icf.o
+     icf.o symbols.o
 
 mold: $(OBJS)
 	$(CXX) $(CFLAGS) $(OBJS) -o $@ $(LDFLAGS) $(LIBS)

main.cc

@@ -909,6 +909,10 @@ static Config parse_nonpositional_args(std::span<std::string_view> args,
       conf.is_static = true;
     } else if (read_flag(args, "shared")) {
       conf.shared = true;
+    } else if (read_flag(args, "demangle")) {
+      conf.demangle = true;
+    } else if (read_flag(args, "no-demangle")) {
+      conf.demangle = false;
     } else if (read_arg(args, arg, "y") || read_arg(args, arg, "trace-symbol")) {
       conf.trace_symbol.push_back(arg);
     } else if (read_arg(args, arg, "filler")) {

mold.h

@@ -56,6 +56,7 @@ enum class BuildIdKind : u8 { NONE, MD5, SHA1, SHA256, UUID };
 struct Config {
   BuildIdKind build_id = BuildIdKind::NONE;
   bool allow_multiple_definition = false;
+  bool demangle = false;
   bool discard_all = false;
   bool discard_locals = false;
   bool eh_frame_hdr = true;
@@ -299,10 +300,7 @@ public:
   u8 has_copyrel : 1 = false;
 };
 
-inline std::ostream &operator<<(std::ostream &out, const Symbol &sym) {
-  out << sym.name;
-  return out;
-}
+std::ostream &operator<<(std::ostream &out, const Symbol &sym);
 
 //
 // input_sections.cc

symbols.cc

@@ -0,0 +1,20 @@
+#include "mold.h"
+
+#include <cxxabi.h>
+#include <stdlib.h>
+
+std::ostream &operator<<(std::ostream &out, const Symbol &sym) {
+  if (config.demangle) {
+    int status;
+    char *name = abi::__cxa_demangle(std::string(sym.name).c_str(),
+                                     nullptr, 0, &status);
+    if (status == 0) {
+      out << name;
+      free(name);
+      return out;
+    }
+  }
+
+  out << sym.name;
+  return out;
+}