[Support] Make ErrorAsOutParameter take an Error* rather than an Error&.

This allows ErrorAsOutParameter to work better with "optional" errors. For
example, consider a function where for certain input values it is known that
the function can't fail. This can now be written as:

Result foo(Arg X, Error *Err) {
  ErrorAsOutParameter EAO(Err);

  if (<Error Condition>) {
    if (Err)
      *Err = <report error>;
    else
      llvm_unreachable("Unexpected failure!");
  }
}

Rather than having to construct an ErrorAsOutParameter under every conditional
where Err is known to be non-null.

llvm-svn: 276430

1 files changed, 3 insertions, 4 deletions

diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 6d0330d52ec..84ef358344d 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -108,16 +108,15 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
     : Parent(Parent) {
   if (!Start)
     return;
+  ErrorAsOutParameter ErrAsOutParam(Err);
 
   uint64_t Size = sizeof(ArchiveMemberHeader);
   Data = StringRef(Start, Size);
   if (!isThinMember()) {
     Expected<uint64_t> MemberSize = getRawSize();
     if (!MemberSize) {
-      if (Err) {
-        ErrorAsOutParameter ErrAsOutParam(*Err);
+      if (Err)
         *Err = MemberSize.takeError();
-      }
       return;
     }
     Size += MemberSize.get();
@@ -299,7 +298,7 @@ void Archive::setFirstRegular(const Child &C) {
 
 Archive::Archive(MemoryBufferRef Source, Error &Err)
     : Binary(Binary::ID_Archive, Source) {
-  ErrorAsOutParameter ErrAsOutParam(Err);
+  ErrorAsOutParameter ErrAsOutParam(&Err);
   StringRef Buffer = Data.getBuffer();
   // Check for sufficient magic.
   if (Buffer.startswith(ThinMagic)) {