[llvm-objcopy][MachO] Print an error message on use of unsupported options

[seiya]

Summary

It is better to print an error message instead of silently ignoring unsupported options.

As mentioned in https://reviews.llvm.org/D57045, this is not the best solution and we should print which flag is not supported at some time.

[alexander-shaposhnikov]

LGTM

[alexander-shaposhnikov]

llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

20

where is this used btw ?

[seiya]

llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

20

Used in object_error::parse_failed.

llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

 //===- MachOObjcopy.cpp -----------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "MachOObjcopy.h"
 #include "../CopyConfig.h"
 #include "MachOReader.h"
 #include "MachOWriter.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 
 namespace llvm {
 namespace objcopy {
 namespace macho {
 
+using namespace object;
+
+static Error handleArgs(const CopyConfig &Config, Object &Obj) {
+  if (Config.AllowBrokenLinks || !Config.BuildIdLinkDir.empty() ||
+      Config.BuildIdLinkInput || Config.BuildIdLinkOutput ||
+      !Config.SplitDWO.empty() || !Config.SymbolsPrefix.empty() ||
+      !Config.AllocSectionsPrefix.empty() || !Config.AddSection.empty() ||
+      !Config.DumpSection.empty() || !Config.KeepSection.empty() ||
+      !Config.OnlySection.empty() || !Config.SymbolsToGlobalize.empty() ||
+      !Config.SymbolsToKeep.empty() || !Config.SymbolsToLocalize.empty() ||
+      !Config.SymbolsToWeaken.empty() || !Config.SymbolsToKeepGlobal.empty() ||
+      !Config.SectionsToRename.empty() || !Config.SymbolsToRename.empty() ||
+      !Config.UnneededSymbolsToRemove.empty() ||
+      !Config.SetSectionFlags.empty() || !Config.ToRemove.empty() ||
+      Config.ExtractDWO || Config.KeepFileSymbols || Config.LocalizeHidden ||
+      Config.PreserveDates || Config.StripDWO || Config.StripNonAlloc ||
+      Config.StripSections || Config.Weaken || Config.DecompressDebugSections ||
+      Config.StripDebug || Config.StripNonAlloc || Config.StripSections ||
+      Config.StripUnneeded || Config.DiscardMode != DiscardType::None ||
+      !Config.SymbolsToAdd.empty() || Config.EntryExpr) {
+    return createStringError(llvm::errc::invalid_argument,
+                             "option not supported by llvm-objcopy for MachO");
+  }
+
+  return Error::success();
+}
+
 Error executeObjcopyOnBinary(const CopyConfig &Config,
                              object::MachOObjectFile &In, Buffer &Out) {
   MachOReader Reader(In);
   std::unique_ptr<Object> O = Reader.create();
-  assert(O && "Unable to deserialize MachO object");
+  if (!O)
+    return createFileError(
+        Config.InputFilename,
+        createStringError(object_error::parse_failed,
+                          "unable to deserialize MachO object"));
+
+  if (Error E = handleArgs(Config, *O))
+    return createFileError(Config.InputFilename, std::move(E));
+
   MachOWriter Writer(*O, In.is64Bit(), In.isLittleEndian(), Out);
   return Writer.write();
 }
 
 } // end namespace macho
 } // end namespace objcopy
 } // end namespace llvm