[llvm-pdbdump] Rewrite dumper using visitor pattern.

This increases the flexibility of how to dump different
symbol types -- necessary for context-sensitive formatting of
symbol types -- and also improves the modularity by allowing
the dumping to be implemented in the actual dumper, as opposed
to in the PDB library.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230184 91177308-0d34-0410-b5e6-96231b3b80d8

lib/DebugInfo/PDB/PDBSymbol.cpp

@@ -42,6 +42,7 @@
 #include "llvm/DebugInfo/PDB/PDBSymbolTypeVTableShape.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolUnknown.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolUsingNamespace.h"
+#include "llvm/DebugInfo/PDB/PDBSymDumper.h"
 #include <memory>
 #include <utility>
 
@@ -100,6 +101,12 @@ PDBSymbol::create(const IPDBSession &PDBSession,
   }
 }
 
+#define TRY_DUMP_TYPE(Type)                                                    \
+  if (const Type *DerivedThis = dyn_cast<Type>(this))                          \
+    Dumper.dump(OS, Indent, *DerivedThis);
+
+#define ELSE_TRY_DUMP_TYPE(Type, Dumper) else TRY_DUMP_TYPE(Type, Dumper)
+
 void PDBSymbol::defaultDump(raw_ostream &OS, int Indent,
                             PDB_DumpLevel Level) const {
   RawSymbol->dump(OS, Indent, Level);