Thread Expected<...> up from libObject’s getType() for symbols to allow llvm-objdump to produce a good error message.

Produce another specific error message for a malformed Mach-O file when a symbol’s
section index is more than the number of sections.  The existing test case in test/Object/macho-invalid.test
for macho-invalid-section-index-getSectionRawName now reports the error with the message indicating
that a symbol at a specific index has a bad section index and that bad section index value.

Again converting interfaces to Expected<> from ErrorOr<> does involve
touching a number of places. Where the existing code reported the error with a
string message or an error code it was converted to do the same.

Also there some were bugs in the existing code that did not deal with the
old ErrorOr<> return values.  So now with Expected<> since they must be
checked and the error handled, I added a TODO and a comment:
"// TODO: Actually report errors helpfully" and a call something like
consumeError(NameOrErr.takeError()) so the buggy code will not crash
since needed to deal with the Error.

llvm-svn: 268298
diff --git a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
index 8d00c90..9e14e69 100644
--- a/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
+++ b/llvm/tools/llvm-readobj/ARMWinEHPrinter.cpp
@@ -198,9 +198,9 @@
 ErrorOr<object::SymbolRef> Decoder::getSymbol(const COFFObjectFile &COFF,
                                               uint64_t VA, bool FunctionOnly) {
   for (const auto &Symbol : COFF.symbols()) {
-    ErrorOr<SymbolRef::Type> Type = Symbol.getType();
-    if (std::error_code EC = Type.getError())
-      return EC;
+    Expected<SymbolRef::Type> Type = Symbol.getType();
+    if (!Type)
+      return errorToErrorCode(Type.takeError());
     if (FunctionOnly && *Type != SymbolRef::ST_Function)
       continue;
 
@@ -648,9 +648,12 @@
 
     SW.printString("ExceptionRecord", formatSymbol(*Name, Address));
 
-    ErrorOr<section_iterator> SIOrErr = XDataRecord->getSection();
-    if (!SIOrErr)
+    Expected<section_iterator> SIOrErr = XDataRecord->getSection();
+    if (!SIOrErr) {
+      // TODO: Actually report errors helpfully.
+      consumeError(SIOrErr.takeError());
       return false;
+    }
     section_iterator SI = *SIOrErr;
 
     return dumpXDataRecord(COFF, *SI, FunctionAddress, Address);