[scan-build] fix warnings emitted on LLVM dsymutil code base

[apelete]

Summary

Fix a logic error warning of the type "called C++ object pointer is
null" emitted by Clang Static Analyzer on the following file:

• tools/dsymutil/DwarfLinker.cpp.

Signed-off-by: Apelete Seketeli <[e-mail]>

[llvm-commits]

+Fred

[friss]

Attr can never be null here because one of Loc or Block will be non-null. This looks like a deficiency of the static analyzer. I'd rather initialize Attr in each of the branches of the if above if that helps.

[apelete]

In D19972#422770, @friss wrote:

Attr can never be null here because one of Loc or Block will be non-null. This looks like a deficiency of the static analyzer. I'd rather initialize Attr in each of the branches of the if above if that helps.

Tried initializing Attr in each of the if() branches and it didn't help with the warning.
I guess the warning in this file could be ignored since Attr is expected to never be null.

[JDevlieghere]

Is this still relevant?

tools/dsymutil/DwarfLinker.cpp

if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
     Linker.DIELocs.push_back(Loc);
   } else {
     Block = new (DIEAlloc) DIEBlock;
     Linker.DIEBlocks.push_back(Block);
   }
   Attr = Loc ? static_cast<DIEValueList *>(Loc)
              : static_cast<DIEValueList *>(Block);
 
+  assert(Attr && "DIEValue list needs to be not NULL");
+
   if (Loc)
     Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
                      dwarf::Form(AttrSpec.Form), Loc);
   else
     Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
                      dwarf::Form(AttrSpec.Form), Block);
   ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
   for (auto Byte : Bytes)