Disallow old style octal literal types

src/compiler/checker.ts

@@ -21845,8 +21845,13 @@ namespace ts {
 
         function checkGrammarNumericLiteral(node: NumericLiteral): boolean {
             // Grammar checking
-            if (node.isOctalLiteral && languageVersion >= ScriptTarget.ES5) {
-                return grammarErrorOnNode(node, Diagnostics.Octal_literals_are_not_available_when_targeting_ECMAScript_5_and_higher);
+            if (node.isOctalLiteral) {
+                if (languageVersion >= ScriptTarget.ES5) {
+                    return grammarErrorOnNode(node, Diagnostics.Octal_literals_are_not_available_when_targeting_ECMAScript_5_and_higher_Use_the_syntax_0o_0, node.text);
+                }
+                if (isChildOfLiteralType(node)) {
+                    return grammarErrorOnNode(node, Diagnostics.Octal_literal_types_must_use_ES2015_syntax_Use_the_syntax_0o_0, node.text);
+                }
             }
         }
 

src/compiler/diagnosticMessages.json

@@ -227,7 +227,7 @@
         "category": "Error",
         "code": 1084
     },
-    "Octal literals are not available when targeting ECMAScript 5 and higher.": {
+    "Octal literals are not available when targeting ECMAScript 5 and higher. Use the syntax '0o{0}'.": {
         "category": "Error",
         "code": 1085
     },
@@ -3234,5 +3234,9 @@
     "Add {0} to existing import declaration from {1}": {
         "category": "Message",
         "code": 90015
+    },
+    "Octal literal types must use ES2015 syntax. Use the syntax '0o{0}'.": {
+        "category": "Error",
+        "code": 8017
     }
 }

src/compiler/utilities.ts

@@ -732,6 +732,16 @@ namespace ts {
         return false;
     }
 
+    export function isChildOfLiteralType(node: Node): boolean {
+        while (node) {
+            if (node.kind === SyntaxKind.LiteralType) {
+                return true;
+            }
+            node = node.parent;
+        }
+        return false;
+    }
+
     // Warning: This has the same semantics as the forEach family of functions,
     //          in that traversal terminates in the event that 'visitor' supplies a truthy value.
     export function forEachReturnStatement<T>(body: Block, visitor: (stmt: ReturnStatement) => T): T {