Make IPDBSession::getGlobalScope a non-const method

[amccarth]

Summary

There doesn't seem to be a compelling reason why this method should be const other than it was possible with the DIA implementation. The native session is going to act as a symbol factory and cache. This could be acheived with mutable (and the existing const_cast), but it seems cleaner to accept that this method affects the state of the session.

This change eliminates an existing const_cast.

llvm/include/llvm/DebugInfo/PDB/DIA/DIASession.h

public:
 
   static Error createFromPdb(StringRef Path,
                              std::unique_ptr<IPDBSession> &Session);
   static Error createFromExe(StringRef Path,
                              std::unique_ptr<IPDBSession> &Session);
 
   uint64_t getLoadAddress() const override;
   void setLoadAddress(uint64_t Address) override;
-  std::unique_ptr<PDBSymbolExe> getGlobalScope() const override;
+  std::unique_ptr<PDBSymbolExe> getGlobalScope() override;
   std::unique_ptr<PDBSymbol> getSymbolById(uint32_t SymbolId) const override;
 
   std::unique_ptr<PDBSymbol>
   findSymbolByAddress(uint64_t Address, PDB_SymType Type) const override;
 
   std::unique_ptr<IPDBEnumLineNumbers>
   findLineNumbers(const PDBSymbolCompiland &Compiland,
                   const IPDBSourceFile &File) const override;

llvm/include/llvm/DebugInfo/PDB/IPDBSession.h

 /// IPDBSession defines an interface used to provide a context for querying
 /// debug information from a debug data source (for example, a PDB).
 class IPDBSession {
 public:
   virtual ~IPDBSession();
 
   virtual uint64_t getLoadAddress() const = 0;
   virtual void setLoadAddress(uint64_t Address) = 0;
-  virtual std::unique_ptr<PDBSymbolExe> getGlobalScope() const = 0;
+  virtual std::unique_ptr<PDBSymbolExe> getGlobalScope() = 0;
   virtual std::unique_ptr<PDBSymbol> getSymbolById(uint32_t SymbolId) const = 0;
 
   template <typename T>
   std::unique_ptr<T> getConcreteSymbolById(uint32_t SymbolId) const {
     return unique_dyn_cast_or_null<T>(getSymbolById(SymbolId));
   }
 
   virtual std::unique_ptr<PDBSymbol>

llvm/include/llvm/DebugInfo/PDB/Native/NativeSession.h

public:
 
   static Error createFromPdb(StringRef Path,
                              std::unique_ptr<IPDBSession> &Session);
   static Error createFromExe(StringRef Path,
                              std::unique_ptr<IPDBSession> &Session);
 
   uint64_t getLoadAddress() const override;
   void setLoadAddress(uint64_t Address) override;
-  std::unique_ptr<PDBSymbolExe> getGlobalScope() const override;
+  std::unique_ptr<PDBSymbolExe> getGlobalScope() override;
   std::unique_ptr<PDBSymbol> getSymbolById(uint32_t SymbolId) const override;
 
   std::unique_ptr<PDBSymbol>
   findSymbolByAddress(uint64_t Address, PDB_SymType Type) const override;
 
   std::unique_ptr<IPDBEnumLineNumbers>
   findLineNumbers(const PDBSymbolCompiland &Compiland,
                   const IPDBSourceFile &File) const override;

llvm/lib/DebugInfo/PDB/DIA/DIASession.cpp

uint64_t DIASession::getLoadAddress() const {
   bool success = (S_OK == Session->get_loadAddress(&LoadAddress));
   return (success) ? LoadAddress : 0;
 }
 
 void DIASession::setLoadAddress(uint64_t Address) {
   Session->put_loadAddress(Address);
 }
 
-std::unique_ptr<PDBSymbolExe> DIASession::getGlobalScope() const {
+std::unique_ptr<PDBSymbolExe> DIASession::getGlobalScope() {
   CComPtr<IDiaSymbol> GlobalScope;
   if (S_OK != Session->get_globalScope(&GlobalScope))
     return nullptr;
 
   auto RawSymbol = llvm::make_unique<DIARawSymbol>(*this, GlobalScope);
   auto PdbSymbol(PDBSymbol::create(*this, std::move(RawSymbol)));
   std::unique_ptr<PDBSymbolExe> ExeSymbol(
       static_cast<PDBSymbolExe *>(PdbSymbol.release()));

llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp

Error NativeSession::createFromExe(StringRef Path,
                                    std::unique_ptr<IPDBSession> &Session) {
   return make_error<RawError>(raw_error_code::feature_unsupported);
 }
 
 uint64_t NativeSession::getLoadAddress() const { return 0; }
 
 void NativeSession::setLoadAddress(uint64_t Address) {}
 
-std::unique_ptr<PDBSymbolExe> NativeSession::getGlobalScope() const {
-  auto RawSymbol =
-      llvm::make_unique<NativeExeSymbol>(const_cast<NativeSession &>(*this));
+std::unique_ptr<PDBSymbolExe> NativeSession::getGlobalScope() {
+  auto RawSymbol = llvm::make_unique<NativeExeSymbol>(*this);
   auto PdbSymbol(PDBSymbol::create(*this, std::move(RawSymbol)));
   std::unique_ptr<PDBSymbolExe> ExeSymbol(
       static_cast<PDBSymbolExe *>(PdbSymbol.release()));
   return ExeSymbol;
 }
 
 std::unique_ptr<PDBSymbol>
 NativeSession::getSymbolById(uint32_t SymbolId) const {
   return nullptr;
 }
 

llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp

#define MOCK_SYMBOL_ACCESSOR(Func)                                             \
   decltype(std::declval<IPDBRawSymbol>().Func()) Func() const override {       \
     typedef decltype(IPDBRawSymbol::Func()) ReturnType;                        \
     return ReturnType();                                                       \
   }
 
 class MockSession : public IPDBSession {
   uint64_t getLoadAddress() const override { return 0; }
   void setLoadAddress(uint64_t Address) override {}
-  std::unique_ptr<PDBSymbolExe> getGlobalScope() const override {
-    return nullptr;
-  }
+  std::unique_ptr<PDBSymbolExe> getGlobalScope() override { return nullptr; }
   std::unique_ptr<PDBSymbol> getSymbolById(uint32_t SymbolId) const override {
     return nullptr;
   }
   std::unique_ptr<IPDBSourceFile>
   getSourceFileById(uint32_t SymbolId) const override {
     return nullptr;
   }