Add null-pointer checks when accessing a TypeSystem's SymbolFile

A type system is not guaranteed to have a symbol file. This patch adds null-pointer checks so we don't crash when trying to access a type system's symbol file.

Reviewed By: aprantl, teemperor

Differential Revision: https://reviews.llvm.org/D101539

lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp

@@ -534,8 +534,12 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
     auto type_def = llvm::dyn_cast<PDBSymbolTypeTypedef>(&type);
     assert(type_def);
 
+    SymbolFile *symbol_file = m_ast.GetSymbolFile();
+    if (!symbol_file)
+      return nullptr;
+
     lldb_private::Type *target_type =
-        m_ast.GetSymbolFile()->ResolveTypeUID(type_def->getTypeId());
+        symbol_file->ResolveTypeUID(type_def->getTypeId());
     if (!target_type)
       return nullptr;
 
@@ -609,8 +613,13 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
       auto arg = arg_enum->getChildAtIndex(arg_idx);
       if (!arg)
         break;
+
+      SymbolFile *symbol_file = m_ast.GetSymbolFile();
+      if (!symbol_file)
+        return nullptr;
+
       lldb_private::Type *arg_type =
-          m_ast.GetSymbolFile()->ResolveTypeUID(arg->getSymIndexId());
+          symbol_file->ResolveTypeUID(arg->getSymIndexId());
       // If there's some error looking up one of the dependent types of this
       // function signature, bail.
       if (!arg_type)
@@ -621,8 +630,12 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
     lldbassert(arg_list.size() <= num_args);
 
     auto pdb_return_type = func_sig->getReturnType();
+    SymbolFile *symbol_file = m_ast.GetSymbolFile();
+    if (!symbol_file)
+      return nullptr;
+
     lldb_private::Type *return_type =
-        m_ast.GetSymbolFile()->ResolveTypeUID(pdb_return_type->getSymIndexId());
+        symbol_file->ResolveTypeUID(pdb_return_type->getSymIndexId());
     // If there's some error looking up one of the dependent types of this
     // function signature, bail.
     if (!return_type)
@@ -654,10 +667,13 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
     if (uint64_t size = array_type->getLength())
       bytes = size;
 
+    SymbolFile *symbol_file = m_ast.GetSymbolFile();
+    if (!symbol_file)
+      return nullptr;
+
     // If array rank > 0, PDB gives the element type at N=0. So element type
     // will parsed in the order N=0, N=1,..., N=rank sequentially.
-    lldb_private::Type *element_type =
-        m_ast.GetSymbolFile()->ResolveTypeUID(element_uid);
+    lldb_private::Type *element_type = symbol_file->ResolveTypeUID(element_uid);
     if (!element_type)
       return nullptr;
 
@@ -711,7 +727,12 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
   case PDB_SymType::PointerType: {
     auto *pointer_type = llvm::dyn_cast<PDBSymbolTypePointer>(&type);
     assert(pointer_type);
-    Type *pointee_type = m_ast.GetSymbolFile()->ResolveTypeUID(
+
+    SymbolFile *symbol_file = m_ast.GetSymbolFile();
+    if (!symbol_file)
+      return nullptr;
+
+    Type *pointee_type = symbol_file->ResolveTypeUID(
         pointer_type->getPointeeType()->getSymIndexId());
     if (!pointee_type)
       return nullptr;
@@ -719,8 +740,7 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
     if (pointer_type->isPointerToDataMember() ||
         pointer_type->isPointerToMemberFunction()) {
       auto class_parent_uid = pointer_type->getRawSymbol().getClassParentId();
-      auto class_parent_type =
-          m_ast.GetSymbolFile()->ResolveTypeUID(class_parent_uid);
+      auto class_parent_type = symbol_file->ResolveTypeUID(class_parent_uid);
       assert(class_parent_type);
 
       CompilerType pointer_ast_type;

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -9306,11 +9306,11 @@ CompilerType TypeSystemClang::DeclGetFunctionArgumentType(void *opaque_decl,
 std::vector<CompilerDecl> TypeSystemClang::DeclContextFindDeclByName(
     void *opaque_decl_ctx, ConstString name, const bool ignore_using_decls) {
   std::vector<CompilerDecl> found_decls;
-  if (opaque_decl_ctx) {
+  SymbolFile *symbol_file = GetSymbolFile();
+  if (opaque_decl_ctx && symbol_file) {
     DeclContext *root_decl_ctx = (DeclContext *)opaque_decl_ctx;
     std::set<DeclContext *> searched;
     std::multimap<DeclContext *, DeclContext *> search_queue;
-    SymbolFile *symbol_file = GetSymbolFile();
 
     for (clang::DeclContext *decl_context = root_decl_ctx;
          decl_context != nullptr && found_decls.empty();
@@ -9404,10 +9404,10 @@ uint32_t TypeSystemClang::CountDeclLevels(clang::DeclContext *frame_decl_ctx,
                                           clang::DeclContext *child_decl_ctx,
                                           ConstString *child_name,
                                           CompilerType *child_type) {
-  if (frame_decl_ctx) {
+  SymbolFile *symbol_file = GetSymbolFile();
+  if (frame_decl_ctx && symbol_file) {
     std::set<DeclContext *> searched;
     std::multimap<DeclContext *, DeclContext *> search_queue;
-    SymbolFile *symbol_file = GetSymbolFile();
 
     // Get the lookup scope for the decl we're trying to find.
     clang::DeclContext *parent_decl_ctx = child_decl_ctx->getParent();

lldb/source/Symbol/Type.cpp

@@ -730,7 +730,8 @@ ModuleSP Type::GetModule() {
 ModuleSP Type::GetExeModule() {
   if (m_compiler_type) {
     SymbolFile *symbol_file = m_compiler_type.GetTypeSystem()->GetSymbolFile();
-    return symbol_file->GetObjectFile()->GetModule();
+    if (symbol_file)
+      return symbol_file->GetObjectFile()->GetModule();
   }
   return ModuleSP();
 }

lldb/unittests/Symbol/TestTypeSystemClang.cpp

@@ -741,3 +741,15 @@ TEST(TestScratchTypeSystemClang, InferSubASTFromLangOpts) {
       ScratchTypeSystemClang::IsolatedASTKind::CppModules,
       ScratchTypeSystemClang::InferIsolatedASTKindFromLangOpts(lang_opts));
 }
+
+TEST_F(TestTypeSystemClang, GetExeModuleWhenMissingSymbolFile) {
+  CompilerType compiler_type = m_ast->GetBasicTypeFromAST(lldb::eBasicTypeInt);
+  lldb_private::Type t(0, nullptr, ConstString("MyType"), llvm::None, nullptr,
+                       0, {}, {}, compiler_type,
+                       lldb_private::Type::ResolveState::Full);
+  // Test that getting the execution module when no type system is present
+  // is handled gracefully.
+  ModuleSP module = t.GetExeModule();
+  EXPECT_EQ(module.get(), nullptr);
+}
+