Literal and Escape Sequence

Author: graphemecluster

src/compiler/binder.ts

@@ -2627,8 +2627,15 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
         }
     }
 
+    function checkStrictModeStringLiteral(node: StringLiteral) {
+        if (languageVersion >= ScriptTarget.ES5 && inStrictMode && node.rangesOfOctalSequences) {
+            file.bindDiagnostics.push(...node.rangesOfOctalSequences.map(
+                range => createFileDiagnostic(file, range.pos, range.end - range.pos, Diagnostics.Octal_escape_sequences_are_not_allowed_in_strict_mode)));
+        }
+    }
+
     function checkStrictModeNumericLiteral(node: NumericLiteral) {
-        if (languageVersion < ScriptTarget.ES5 && inStrictMode && node.numericLiteralFlags & TokenFlags.Octal) {
+        if (languageVersion >= ScriptTarget.ES5 && inStrictMode && node.numericLiteralFlags & TokenFlags.Octal) {
             file.bindDiagnostics.push(createDiagnosticForNode(node, Diagnostics.Octal_literals_are_not_allowed_in_strict_mode));
         }
     }
@@ -2875,6 +2882,8 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
                 return checkStrictModeCatchClause(node as CatchClause);
             case SyntaxKind.DeleteExpression:
                 return checkStrictModeDeleteExpression(node as DeleteExpression);
+            case SyntaxKind.StringLiteral:
+                return checkStrictModeStringLiteral(node as StringLiteral);
             case SyntaxKind.NumericLiteral:
                 return checkStrictModeNumericLiteral(node as NumericLiteral);
             case SyntaxKind.PostfixUnaryExpression:

src/compiler/diagnosticMessages.json

@@ -1549,6 +1549,14 @@
         "category": "Message",
         "code": 1483
     },
+    "Octal escape sequences are not allowed in strict mode.": {
+        "category": "Error",
+        "code": 1484
+    },
+    "Octal escape sequences are not allowed in template strings.": {
+        "category": "Error",
+        "code": 1485
+    },
 
     "The types of '{0}' are incompatible between these types.": {
         "category": "Error",

src/compiler/factory/nodeFactory.ts

@@ -374,6 +374,7 @@ import {
     QuestionDotToken,
     QuestionToken,
     ReadonlyKeyword,
+    ReadonlyTextRange,
     reduceLeft,
     RegularExpressionLiteral,
     RestTypeNode,
@@ -1292,10 +1293,11 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
     }
 
     // @api
-    function createStringLiteral(text: string, isSingleQuote?: boolean, hasExtendedUnicodeEscape?: boolean): StringLiteral {
+    function createStringLiteral(text: string, isSingleQuote?: boolean, hasExtendedUnicodeEscape?: boolean, rangesOfOctalSequences?: ReadonlyTextRange[]): StringLiteral {
         const node = createBaseStringLiteral(text, isSingleQuote);
         node.hasExtendedUnicodeEscape = hasExtendedUnicodeEscape;
         if (hasExtendedUnicodeEscape) node.transformFlags |= TransformFlags.ContainsES2015;
+        node.rangesOfOctalSequences = rangesOfOctalSequences;
         return node;
     }
 

src/compiler/parser.ts

@@ -2153,10 +2153,6 @@ namespace Parser {
         return currentToken = scanner.reScanTemplateToken(isTaggedTemplate);
     }
 
-    function reScanTemplateHeadOrNoSubstitutionTemplate(): SyntaxKind {
-        return currentToken = scanner.reScanTemplateHeadOrNoSubstitutionTemplate();
-    }
-
     function reScanLessThanToken(): SyntaxKind {
         return currentToken = scanner.reScanLessThanToken();
     }
@@ -3606,9 +3602,7 @@ namespace Parser {
     }
 
     function parseTemplateHead(isTaggedTemplate: boolean): TemplateHead {
-        if (isTaggedTemplate) {
-            reScanTemplateHeadOrNoSubstitutionTemplate();
-        }
+        reScanTemplateToken(isTaggedTemplate);
         const fragment = parseLiteralLikeNode(token());
         Debug.assert(fragment.kind === SyntaxKind.TemplateHead, "Template head has wrong token kind");
         return fragment as TemplateHead;
@@ -3630,14 +3624,13 @@ namespace Parser {
         const pos = getNodePos();
         const node =
             isTemplateLiteralKind(kind) ? factory.createTemplateLiteralLikeNode(kind, scanner.getTokenValue(), getTemplateLiteralRawText(kind), scanner.getTokenFlags() & TokenFlags.TemplateLiteralLikeFlags) :
-            // Octal literals are not allowed in strict mode or ES5
             // Note that theoretically the following condition would hold true literals like 009,
             // which is not octal. But because of how the scanner separates the tokens, we would
             // never get a token like this. Instead, we would get 00 and 9 as two separate tokens.
             // We also do not need to check for negatives because any prefix operator would be part of a
             // parent unary expression.
             kind === SyntaxKind.NumericLiteral ? factory.createNumericLiteral(scanner.getTokenValue(), scanner.getNumericLiteralFlags()) :
-            kind === SyntaxKind.StringLiteral ? factory.createStringLiteral(scanner.getTokenValue(), /*isSingleQuote*/ undefined, scanner.hasExtendedUnicodeEscape()) :
+            kind === SyntaxKind.StringLiteral ? factory.createStringLiteral(scanner.getTokenValue(), /*isSingleQuote*/ undefined, scanner.hasExtendedUnicodeEscape(), scanner.getRangesOfOctalSequences()) :
             isLiteralKind(kind) ? factory.createLiteralLikeNode(kind, scanner.getTokenValue()) :
             Debug.fail();
 
@@ -6314,7 +6307,7 @@ namespace Parser {
             tag,
             typeArguments,
             token() === SyntaxKind.NoSubstitutionTemplateLiteral ?
-                (reScanTemplateHeadOrNoSubstitutionTemplate(), parseLiteralNode() as NoSubstitutionTemplateLiteral) :
+                (reScanTemplateToken(/*isTaggedTemplate*/ true), parseLiteralNode() as NoSubstitutionTemplateLiteral) :
                 parseTemplateExpression(/*isTaggedTemplate*/ true)
         );
         if (questionDotToken || tag.flags & NodeFlags.OptionalChain) {
@@ -6414,10 +6407,14 @@ namespace Parser {
 
     function parsePrimaryExpression(): PrimaryExpression {
         switch (token()) {
+            case SyntaxKind.NoSubstitutionTemplateLiteral:
+                if (scanner.getTokenFlags() & TokenFlags.ContainsOctalOrInvalidEscape) {
+                    reScanTemplateToken(/* isTaggedTemplate */ false);
+                }
+            // falls through
             case SyntaxKind.NumericLiteral:
             case SyntaxKind.BigIntLiteral:
             case SyntaxKind.StringLiteral:
-            case SyntaxKind.NoSubstitutionTemplateLiteral:
                 return parseLiteralNode();
             case SyntaxKind.ThisKeyword:
             case SyntaxKind.SuperKeyword: