Ensure we associate an error with all missing identifiers in the parser. (#44389)

* Ensure we associate an error with all missing identifiers in the parser.

* Fix test

* REstore original error

src/Compilers/CSharp/Portable/Parser/LanguageParser.cs

@@ -6867,13 +6867,9 @@ private TypeSyntax ParseUnderlyingType(ParseTypeMode mode, NameOptions options =
                 return ParseFunctionPointerTypeSyntax();
             }
 
-            var name = this.CreateMissingIdentifierName();
-            if (mode != ParseTypeMode.NewExpression)
-            {
-                return this.AddError(name, ErrorCode.ERR_TypeExpected);
-            }
-
-            return name;
+            return this.AddError(
+                this.CreateMissingIdentifierName(),
+                mode == ParseTypeMode.NewExpression ? ErrorCode.ERR_BadNewExpr : ErrorCode.ERR_TypeExpected);
         }
 
 #nullable enable
@@ -11505,11 +11501,11 @@ private ExpressionSyntax ParseArrayOrObjectCreationExpression()
                 initializer = this.ParseObjectOrCollectionInitializer();
             }
 
-            // we need one or the other
+            // we need one or the other.  also, don't bother reporting this if we already complained about the new type.
             if (argumentList == null && initializer == null)
             {
                 argumentList = _syntaxFactory.ArgumentList(
-                    this.EatToken(SyntaxKind.OpenParenToken, ErrorCode.ERR_BadNewExpr),
+                    this.EatToken(SyntaxKind.OpenParenToken, ErrorCode.ERR_BadNewExpr, reportError: type?.ContainsDiagnostics == false),
                     default(SeparatedSyntaxList<ArgumentSyntax>),
                     SyntaxFactory.MissingToken(SyntaxKind.CloseParenToken));
             }

src/Compilers/CSharp/Test/IOperation/IOperation/IOperationTests_IConversionExpression.cs

@@ -947,7 +947,7 @@ static void Main(string[] args)
             Children(0)
 ";
             var expectedDiagnostics = new DiagnosticDescription[] {
-                // CS1526: A new expression requires (), [], or {} after type
+                // file.cs(8,41): error CS1526: A new expression requires an argument list or (), [], or {} after type
                 //         C1 /*<bind>*/c1 = new/*</bind>*/;
                 Diagnostic(ErrorCode.ERR_BadNewExpr, ";").WithLocation(8, 41)
             };

src/Compilers/CSharp/Test/Syntax/Parsing/RefReadonlyTests.cs

@@ -500,11 +500,8 @@ public void TestNewRefArray()
             UsingStatement("new ref[];",
                 // (1,8): error CS1031: Type expected
                 // new ref[];
-                Diagnostic(ErrorCode.ERR_TypeExpected, "[").WithLocation(1, 8),
-                // (1,10): error CS1526: A new expression requires an argument list or (), [], or {} after type
-                // new ref[];
-                Diagnostic(ErrorCode.ERR_BadNewExpr, ";").WithLocation(1, 10)
-                );
+                Diagnostic(ErrorCode.ERR_TypeExpected, "[").WithLocation(1, 8));
+
             N(SyntaxKind.ExpressionStatement);
             {
                 N(SyntaxKind.ObjectCreationExpression);

src/Compilers/CSharp/Test/Syntax/Parsing/TargetTypedObjectCreationParsingTests.cs

@@ -19,10 +19,9 @@ public class TargetTypedObjectCreationParsingTests : ParsingTests
         public void TestNoRegressionOnNew()
         {
             UsingExpression("new", DefaultParseOptions,
-                // (1,4): error CS1526: A new expression requires (), [], or {} after type
+                // (1,4): error CS1526: A new expression requires an argument list or (), [], or {} after type
                 // new
-                Diagnostic(ErrorCode.ERR_BadNewExpr, "").WithLocation(1, 4)
-                );
+                Diagnostic(ErrorCode.ERR_BadNewExpr, "").WithLocation(1, 4));
 
             N(SyntaxKind.ObjectCreationExpression);
             {