Thread Expected<...> up from libObject’s getName() 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
string index is past the end of the string table.  The existing test case in test/Object/macho-invalid.test
for macho-invalid-symbol-name-past-eof now reports the error with the message indicating
that a symbol at a specific index has a bad sting index and that bad string 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.  There is some
code for this that could be factored into a routine but I would like to leave that for
the code owners post-commit to do as they want for handling an llvm::Error.  An
example of how this could be done is shown in the diff in
lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h which had a Check() routine
already for std::error_code so I added one like it for llvm::Error .

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.

Note there fixes needed to lld that goes along with this that I will commit right after this.
So expect lld not to built after this commit and before the next one.

llvm-svn: 266919

1 files changed, 8 insertions, 3 deletions

diff --git a/llvm/tools/llvm-readobj/MachODumper.cpp b/llvm/tools/llvm-readobj/MachODumper.cpp
index 8bd09b62a1f..2faf36842ed 100644
--- a/llvm/tools/llvm-readobj/MachODumper.cpp
+++ b/llvm/tools/llvm-readobj/MachODumper.cpp
@@ -541,8 +541,9 @@ void MachODumper::printRelocation(const MachOObjectFile *Obj,
   if (IsExtern) {
     symbol_iterator Symbol = Reloc.getSymbol();
     if (Symbol != Obj->symbol_end()) {
-      ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
-      error(TargetNameOrErr.getError());
+      Expected<StringRef> TargetNameOrErr = Symbol->getName();
+      if (!TargetNameOrErr)
+        error(errorToErrorCode(TargetNameOrErr.takeError()));
       TargetName = *TargetNameOrErr;
     }
   } else if (!IsScattered) {
@@ -605,7 +606,11 @@ void MachODumper::printDynamicSymbols() {
 
 void MachODumper::printSymbol(const SymbolRef &Symbol) {
   StringRef SymbolName;
-  if (ErrorOr<StringRef> SymbolNameOrErr = Symbol.getName())
+  Expected<StringRef> SymbolNameOrErr = Symbol.getName();
+  if (!SymbolNameOrErr) {
+    // TODO: Actually report errors helpfully.
+    consumeError(SymbolNameOrErr.takeError());
+  } else
     SymbolName = *SymbolNameOrErr;
 
   MachOSymbol MOSymbol;