MRI delete command

[dmikulin]

Summary

A far-from-perfect attempt at MRI delete command.
llvm-ar is not very well set up to handle multiple types of commands in the same script...
Need to add a test case.

[Bigcheese]

I'm not sure about this one. I've added Rafael as a reviewer as he's on the blame for most of this code.

[dmikulin]

llvm-ar supports only a subset of MRI commands, that's why 'delete' as implemented here only works for a specific use case: deleting members added with 'addlib' or 'addmod' commands during archive creation.

[dmikulin]

Changed the implementation to avoid writing the archive twice.

[dmikulin]

Changed deleteMember() to erase_if()

llvm/test/tools/llvm-ar/mri-delete.test

+RUN: yaml2obj %S/Inputs/elf.yaml -o %t.o
+RUN: rm -f %t.ar
+
+RUN: echo "create %t.ar" > %t.mri
+RUN: echo "addmod %t.o" >> %t.mri
+RUN: echo "addmod %S/Inputs/elf.yaml" >> %t.mri
+RUN: echo "delete %t.o" >> %t.mri
+RUN: echo "save" >> %t.mri
+RUN: echo "end" >> %t.mri
+
+RUN: llvm-ar -M < %t.mri
+RUN: llvm-ar tv %t.ar | FileCheck %s
+
+CHECK-NOT: mri-delete.test{{.*}}.o

llvm/tools/llvm-ar/llvm-ar.cpp

Expected<NewArchiveMember> NMOrErr =
       NewArchiveMember::getOldMember(M, Deterministic);
   failIfError(NMOrErr.takeError());
   if (Pos == -1)
     Members.push_back(std::move(*NMOrErr));
   else
     Members[Pos] = std::move(*NMOrErr);
 }
 
+static void deleteMember(std::vector<NewArchiveMember> &Members,
+                         StringRef FileName) {
+  StringRef MemberName = sys::path::filename(FileName);
+  for (auto Member = Members.begin(); Member != Members.end();) {
+    if (Member->MemberName == MemberName)
+      Member = Members.erase(Member);
+    else
+      ++Member;
+  }
+}
+
 enum InsertAction {
   IA_AddOldMember,
   IA_AddNewMember,
   IA_Delete,
   IA_MoveOldMember,
   IA_MoveNewMember
 };
 
if (!shouldCreateArchive(Operation)) {
     }
   }
 
   performOperation(Operation, nullptr, nullptr, NewMembers);
   return 0;
 }
 
 static void runMRIScript() {
-  enum class MRICommand { AddLib, AddMod, Create, Save, End, Invalid };
+  enum class MRICommand { AddLib, AddMod, Create, Delete, Save, End, Invalid };
 
   ErrorOr<std::unique_ptr<MemoryBuffer>> Buf = MemoryBuffer::getSTDIN();
   failIfError(Buf.getError());
   const MemoryBuffer &Ref = *Buf.get();
   bool Saved = false;
   std::vector<NewArchiveMember> NewMembers;
   std::vector<std::unique_ptr<MemoryBuffer>> ArchiveBuffers;
   std::vector<std::unique_ptr<object::Archive>> Archives;
 
   for (line_iterator I(Ref, /*SkipBlanks*/ true, ';'), E; I != E; ++I) {
     StringRef Line = *I;
     StringRef CommandStr, Rest;
     std::tie(CommandStr, Rest) = Line.split(' ');
     Rest = Rest.trim();
     if (!Rest.empty() && Rest.front() == '"' && Rest.back() == '"')
       Rest = Rest.drop_front().drop_back();
     auto Command = StringSwitch<MRICommand>(CommandStr.lower())
                        .Case("addlib", MRICommand::AddLib)
                        .Case("addmod", MRICommand::AddMod)
                        .Case("create", MRICommand::Create)
+                       .Case("delete", MRICommand::Delete)
                        .Case("save", MRICommand::Save)
                        .Case("end", MRICommand::End)
                        .Default(MRICommand::Invalid);
 
     switch (Command) {
     case MRICommand::AddLib: {
       auto BufOrErr = MemoryBuffer::getFile(Rest, -1, false);
       failIfError(BufOrErr.getError(), "Could not open library");
for (line_iterator I(Ref, /*SkipBlanks*/ true, ';'), E; I != E; ++I) {
     case MRICommand::Create:
       Create = true;
       if (!ArchiveName.empty())
         fail("Editing multiple archives not supported");
       if (Saved)
         fail("File already saved");
       ArchiveName = Rest;
       break;
+    case MRICommand::Delete:
+      deleteMember(NewMembers, Rest);
+      break;
     case MRICommand::Save:
       Saved = true;
       break;
     case MRICommand::End:
       break;
     case MRICommand::Invalid:
       fail("Unknown command: " + CommandStr);
     }