[LLDB] Update DIL to pass current 'frame var' tests. (#145055)

As a preliminary to making DIL the default implementation for
 'frame var', ran check-lldb forcing 'frame var' to always use DIL, 
and discovered a few failing tests. This fixes most of them. The only
remaining failing test is TestDAP_evaluate.py, which now passes
a test case that the test says should fail (still investigating this).

Changes in this PR:
- Sets correct VariableSP, as well as returning ValueObjectSP (needed
for several watchpoint tests).
- Updates error messages, when looking up members, to match what the
rest of LLDB expects. Also update appropriate DIL tests to expect the
updated error messages.
- Updates DIL parser to look for and accept "(anonymous namespace)::" at
the front of a variable name.

lldb/source/Target/StackFrame.cpp

@@ -562,6 +562,7 @@ ValueObjectSP StackFrame::DILGetValueForVariableExpressionPath(
     return ValueObjectConstResult::Create(nullptr, std::move(error));
   }
 
+  var_sp = (*valobj_or_error)->GetVariable();
   return *valobj_or_error;
 }
 

lldb/source/ValueObject/DILEval.cpp

@@ -363,8 +363,8 @@ Interpreter::Visit(const MemberOfNode *node) {
 
     if (!m_use_synthetic || !field_obj) {
       std::string errMsg = llvm::formatv(
-          "no member named '{0}' in {1}", node->GetFieldName(),
-          base->GetCompilerType().GetFullyUnqualifiedType().TypeDescription());
+          "\"{0}\" is not a member of \"({1}) {2}\"", node->GetFieldName(),
+          base->GetTypeName().AsCString("<invalid type>"), base->GetName());
       return llvm::make_error<DILDiagnosticError>(
           m_expr, errMsg, node->GetLocation(), node->GetFieldName().size());
     }
@@ -383,9 +383,9 @@ Interpreter::Visit(const MemberOfNode *node) {
   CompilerType base_type = base->GetCompilerType();
   if (node->GetIsArrow() && base->IsPointerType())
     base_type = base_type.GetPointeeType();
-  std::string errMsg =
-      llvm::formatv("no member named '{0}' in {1}", node->GetFieldName(),
-                    base_type.GetFullyUnqualifiedType().TypeDescription());
+  std::string errMsg = llvm::formatv(
+      "\"{0}\" is not a member of \"({1}) {2}\"", node->GetFieldName(),
+      base->GetTypeName().AsCString("<invalid type>"), base->GetName());
   return llvm::make_error<DILDiagnosticError>(
       m_expr, errMsg, node->GetLocation(), node->GetFieldName().size());
 }

lldb/source/ValueObject/DILParser.cpp

@@ -183,12 +183,14 @@ ASTNodeUP DILParser::ParsePostfixExpression() {
 //    "(" expression ")"
 //
 ASTNodeUP DILParser::ParsePrimaryExpression() {
-  if (CurToken().IsOneOf({Token::coloncolon, Token::identifier})) {
+  if (CurToken().IsOneOf(
+          {Token::coloncolon, Token::identifier, Token::l_paren})) {
     // Save the source location for the diagnostics message.
     uint32_t loc = CurToken().GetLocation();
-    auto identifier = ParseIdExpression();
+    std::string identifier = ParseIdExpression();
 
-    return std::make_unique<IdentifierNode>(loc, identifier);
+    if (!identifier.empty())
+      return std::make_unique<IdentifierNode>(loc, identifier);
   }
 
   if (CurToken().Is(Token::l_paren)) {
@@ -232,16 +234,15 @@ std::string DILParser::ParseNestedNameSpecifier() {
         m_dil_lexer.LookAhead(4).Is(Token::coloncolon)) {
       m_dil_lexer.Advance(4);
 
-      assert(
-          (CurToken().Is(Token::identifier) || CurToken().Is(Token::l_paren)) &&
-          "Expected an identifier or anonymous namespace, but not found.");
+      Expect(Token::coloncolon);
+      m_dil_lexer.Advance();
+      if (!CurToken().Is(Token::identifier) && !CurToken().Is(Token::l_paren)) {
+        BailOut("Expected an identifier or anonymous namespace, but not found.",
+                CurToken().GetLocation(), CurToken().GetSpelling().length());
+      }
       // Continue parsing the nested_namespace_specifier.
       std::string identifier2 = ParseNestedNameSpecifier();
-      if (identifier2.empty()) {
-        Expect(Token::identifier);
-        identifier2 = CurToken().GetSpelling();
-        m_dil_lexer.Advance();
-      }
+
       return "(anonymous namespace)::" + identifier2;
     }
 
@@ -301,6 +302,9 @@ std::string DILParser::ParseIdExpression() {
                          nested_name_specifier, unqualified_id);
   }
 
+  if (!CurToken().Is(Token::identifier))
+    return "";
+
   // No nested_name_specifier, but with global scope -- this is also a
   // qualified_id production. Follow the second production rule.
   if (global_scope) {