Escape \0 followed by a number as a hex escape to avoid printing an octal literal (#18026)

Author: weswigham

src/compiler/utilities.ts

@@ -2380,6 +2380,7 @@ namespace ts {
         "\u2029": "\\u2029", // paragraphSeparator
         "\u0085": "\\u0085"  // nextLine
     });
+    const escapedNullRegExp = /\\0[0-9]/g;
 
     /**
      * Based heavily on the abstract 'Quote'/'QuoteJSONString' operation from ECMA-262 (24.3.2.2),
@@ -2391,7 +2392,11 @@ namespace ts {
             quoteChar === CharacterCodes.backtick ? backtickQuoteEscapedCharsRegExp :
             quoteChar === CharacterCodes.singleQuote ? singleQuoteEscapedCharsRegExp :
             doubleQuoteEscapedCharsRegExp;
-        return s.replace(escapedCharsRegExp, getReplacement);
+        return s.replace(escapedCharsRegExp, getReplacement).replace(escapedNullRegExp, nullReplacement);
+    }
+
+    function nullReplacement(c: string) {
+        return "\\x00" + c.charAt(c.length - 1);
     }
 
     function getReplacement(c: string) {

tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.js

@@ -0,0 +1,15 @@
+//// [shouldNotPrintNullEscapesIntoOctalLiterals.ts]
+"use strict";
+`\x001`;
+`\u00001`;
+`\u{00000000}1`;
+`\u{000000}1`;
+`\u{0}1`;
+
+//// [shouldNotPrintNullEscapesIntoOctalLiterals.js]
+"use strict";
+"\x001";
+"\x001";
+"\x001";
+"\x001";
+"\x001";

tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.symbols

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts ===
+"use strict";
+No type information for this code.`\x001`;
+No type information for this code.`\u00001`;
+No type information for this code.`\u{00000000}1`;
+No type information for this code.`\u{000000}1`;
+No type information for this code.`\u{0}1`;
+No type information for this code.

tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.types

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts ===
+"use strict";
+>"use strict" : "use strict"
+
+`\x001`;
+>`\x001` : "\x001"
+
+`\u00001`;
+>`\u00001` : "\x001"
+
+`\u{00000000}1`;
+>`\u{00000000}1` : "\x001"
+
+`\u{000000}1`;
+>`\u{000000}1` : "\x001"
+
+`\u{0}1`;
+>`\u{0}1` : "\x001"
+

tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts

@@ -0,0 +1,6 @@
+"use strict";
+`\x001`;
+`\u00001`;
+`\u{00000000}1`;
+`\u{000000}1`;
+`\u{0}1`;