Try doing this instead in the parser

Author: jakebailey

src/compiler/checker.ts

@@ -28912,14 +28912,7 @@ namespace ts {
             return nonNullType;
         }
 
-        function checkGrammarPropertyAccessExpression(node: PropertyAccessExpression) {
-            if (node.expression.kind === SyntaxKind.ExpressionWithTypeArguments) {
-                grammarErrorOnNode(node.name, Diagnostics.Instantiation_expression_cannot_be_followed_by_property_access);
-            }
-        }
-
         function checkPropertyAccessExpression(node: PropertyAccessExpression, checkMode: CheckMode | undefined) {
-            checkGrammarPropertyAccessExpression(node);
             return node.flags & NodeFlags.OptionalChain ? checkPropertyAccessChain(node as PropertyAccessChain, checkMode) :
                 checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullExpression(node.expression), node.name, checkMode);
         }

src/compiler/parser.ts

@@ -5646,6 +5646,9 @@ namespace ts {
             if (isOptionalChain && isPrivateIdentifier(propertyAccess.name)) {
                 parseErrorAtRange(propertyAccess.name, Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
             }
+            else if (isExpressionWithTypeArguments(expression)) {
+                parseErrorAtRange(propertyAccess.name, Diagnostics.Instantiation_expression_cannot_be_followed_by_property_access);
+            }
             return finishNode(propertyAccess, pos);
         }
 

tests/baselines/reference/instantiationExpressionErrors.errors.txt

@@ -1,3 +1,5 @@
+tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(7,22): error TS1477: Instantiation expression cannot be followed by property access.
+tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(8,22): error TS1477: Instantiation expression cannot be followed by property access.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(13,12): error TS2365: Operator '>' cannot be applied to types 'boolean' and 'string[]'.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(13,14): error TS2693: 'number' only refers to a type, but is being used as a value here.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(18,12): error TS2365: Operator '>' cannot be applied to types 'boolean' and 'number'.
@@ -14,15 +16,19 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpr
 tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts(45,12): error TS2365: Operator '>' cannot be applied to types 'boolean' and 'number'.
 
 
-==== tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts (14 errors) ====
+==== tests/cases/conformance/types/typeParameters/typeArgumentLists/instantiationExpressionErrors.ts (16 errors) ====
     declare let f: { <T>(): T, g<U>(): U };
 
     // Type arguments in member expressions
 
     const a1 = f<number>;  // { (): number; g<U>(): U; }
     const a2 = f.g<number>;  // () => number
     const a3 = f<number>.g;  // <U>() => U
+                         ~
+!!! error TS1477: Instantiation expression cannot be followed by property access.
     const a4 = f<number>.g<number>;  // () => number
+                         ~
+!!! error TS1477: Instantiation expression cannot be followed by property access.
     const a5 = f['g']<number>;  // () => number
 
     // `[` is an expression starter and cannot immediately follow a type argument list