From 4d52753942e9affdc64e6ce884db9bde9653b5fe Mon Sep 17 00:00:00 2001
From: Wesley Wigham <wewigham@microsoft.com>
Date: Thu, 24 Aug 2017 13:36:16 -0700
Subject: [PATCH] Escape \0 followed by a number as a hex escape to avoid
 printing an octal literal

---
 src/compiler/utilities.ts                     |  7 ++++++-
 ...uldNotPrintNullEscapesIntoOctalLiterals.js | 15 +++++++++++++++
 ...tPrintNullEscapesIntoOctalLiterals.symbols |  8 ++++++++
 ...NotPrintNullEscapesIntoOctalLiterals.types | 19 +++++++++++++++++++
 ...uldNotPrintNullEscapesIntoOctalLiterals.ts |  6 ++++++
 5 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.js
 create mode 100644 tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.symbols
 create mode 100644 tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.types
 create mode 100644 tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index d906ab4f6b1e7..6d53f9e8e996c 100644
--- a/src/compiler/utilities.ts
+++ b/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) {
diff --git a/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.js b/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.js
new file mode 100644
index 0000000000000..4654558135c94
--- /dev/null
+++ b/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";
diff --git a/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.symbols b/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.symbols
new file mode 100644
index 0000000000000..3ffb259aed0c9
--- /dev/null
+++ b/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.
\ No newline at end of file
diff --git a/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.types b/tests/baselines/reference/shouldNotPrintNullEscapesIntoOctalLiterals.types
new file mode 100644
index 0000000000000..8f76e66255853
--- /dev/null
+++ b/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"
+
diff --git a/tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts b/tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts
new file mode 100644
index 0000000000000..fbbab43319a8b
--- /dev/null
+++ b/tests/cases/compiler/shouldNotPrintNullEscapesIntoOctalLiterals.ts
@@ -0,0 +1,6 @@
+"use strict";
+`\x001`;
+`\u00001`;
+`\u{00000000}1`;
+`\u{000000}1`;
+`\u{0}1`;
\ No newline at end of file