[lldb] Remove ClangExpressionDeclMap::ResolveUnknownTypes

Summary:
This is some really shady code. It's supposed to kick in after an expression already failed and then try to look
up "unknown types" that for some undocumented reason can't be resolved during/before parsing. Beside the
fact that we never mark any type as `EVUnknownType` in either swift-lldb or lldb (which means this code is unreachable),
this code doesn't even make the expression evaluation succeed if if would ever be executed but instead seems
to try to load more debug info that maybe any following expression evaluations might succeed.

This patch removes ClangExpressionDeclMap::ResolveUnknownTypes and the related data structures/checks/calls.

Reviewers: davide

Reviewed By: davide

Subscribers: aprantl, abidh, JDevlieghere, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D70388

lldb/include/lldb/Expression/ExpressionVariable.h

@@ -98,9 +98,7 @@ class ExpressionVariable
     EVTypeIsReference = 1 << 6, ///< The original type of this variable is a
                                 ///reference, so materialize the value rather
                                 ///than the location
-    EVUnknownType = 1 << 7, ///< This is a symbol of unknown type, and the type
-                            ///must be resolved after parsing is complete
-    EVBareRegister = 1 << 8 ///< This variable is a direct reference to $pc or
+    EVBareRegister = 1 << 7 ///< This variable is a direct reference to $pc or
                             ///some other entity.
   };
 

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp

@@ -1769,80 +1769,6 @@ void ClangExpressionDeclMap::AddOneGenericVariable(NameSearchContext &context,
   }
 }
 
-bool ClangExpressionDeclMap::ResolveUnknownTypes() {
-  Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
-  Target *target = m_parser_vars->m_exe_ctx.GetTargetPtr();
-
-  ClangASTContextForExpressions *scratch_ast_context =
-      static_cast<ClangASTContextForExpressions *>(
-          target->GetScratchClangASTContext());
-
-  for (size_t index = 0, num_entities = m_found_entities.GetSize();
-       index < num_entities; ++index) {
-    ExpressionVariableSP entity = m_found_entities.GetVariableAtIndex(index);
-
-    ClangExpressionVariable::ParserVars *parser_vars =
-        llvm::cast<ClangExpressionVariable>(entity.get())
-            ->GetParserVars(GetParserID());
-
-    if (entity->m_flags & ClangExpressionVariable::EVUnknownType) {
-      const NamedDecl *named_decl = parser_vars->m_named_decl;
-      const VarDecl *var_decl = dyn_cast<VarDecl>(named_decl);
-
-      if (!var_decl) {
-        LLDB_LOGF(log, "Entity of unknown type does not have a VarDecl");
-        return false;
-      }
-
-      if (log) {
-        ASTDumper ast_dumper(const_cast<VarDecl *>(var_decl));
-        LLDB_LOGF(log, "Variable of unknown type now has Decl %s",
-                  ast_dumper.GetCString());
-      }
-
-      QualType var_type = var_decl->getType();
-      TypeFromParser parser_type(
-          var_type.getAsOpaquePtr(),
-          ClangASTContext::GetASTContext(&var_decl->getASTContext()));
-
-      lldb::opaque_compiler_type_t copied_type = nullptr;
-      if (m_ast_importer_sp) {
-        copied_type = m_ast_importer_sp->CopyType(
-            scratch_ast_context->getASTContext(), &var_decl->getASTContext(),
-            var_type.getAsOpaquePtr());
-      } else if (HasMerger()) {
-        copied_type = CopyTypeWithMerger(
-                          var_decl->getASTContext(),
-                          scratch_ast_context->GetMergerUnchecked(), var_type)
-                          .getAsOpaquePtr();
-      } else {
-        lldbassert(0 && "No mechanism to copy a resolved unknown type!");
-        return false;
-      }
-
-      if (!copied_type) {
-        LLDB_LOGF(log, "ClangExpressionDeclMap::ResolveUnknownType - Couldn't "
-                       "import the type for a variable");
-
-        return (bool)lldb::ExpressionVariableSP();
-      }
-
-      TypeFromUser user_type(copied_type, scratch_ast_context);
-
-      //            parser_vars->m_lldb_value.SetContext(Value::eContextTypeClangType,
-      //            user_type.GetOpaqueQualType());
-      parser_vars->m_lldb_value.SetCompilerType(user_type);
-      parser_vars->m_parser_type = parser_type;
-
-      entity->SetCompilerType(user_type);
-
-      entity->m_flags &= ~(ClangExpressionVariable::EVUnknownType);
-    }
-  }
-
-  return true;
-}
-
 void ClangExpressionDeclMap::AddOneRegister(NameSearchContext &context,
                                             const RegisterInfo *reg_info,
                                             unsigned int current_id) {

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.h

@@ -98,13 +98,6 @@ class ClangExpressionDeclMap : public ClangASTSource {
 
   void InstallCodeGenerator(clang::ASTConsumer *code_gen);
 
-  /// [Used by ClangExpressionParser] For each variable that had an unknown
-  ///     type at the beginning of parsing, determine its final type now.
-  ///
-  /// \return
-  ///     True on success; false otherwise.
-  bool ResolveUnknownTypes();
-
   /// Disable the state needed for parsing and IR transformation.
   void DidParse();
 

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -1033,15 +1033,6 @@ ClangExpressionParser::ParseInternal(DiagnosticManager &diagnostic_manager,
         m_pp_callbacks->getErrorString());
   }
 
-  if (!num_errors) {
-    if (type_system_helper->DeclMap() &&
-        !type_system_helper->DeclMap()->ResolveUnknownTypes()) {
-      diagnostic_manager.Printf(eDiagnosticSeverityError,
-                                "Couldn't infer the type of a variable");
-      num_errors++;
-    }
-  }
-
   if (!num_errors) {
     type_system_helper->CommitPersistentDecls();
   }