From 17f6f77de5dc6629b487d4a9d060b48811e46882 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Wed, 26 Jun 2019 11:49:45 -0700
Subject: [PATCH] Fix declaration emit for negative number property
 declarations

---
 src/compiler/checker.ts                                      | 3 +++
 .../computedPropertyNamesDeclarationEmit6_ES5.ts             | 5 +++++
 .../computedPropertyNamesDeclarationEmit6_ES6.ts             | 5 +++++
 3 files changed, 13 insertions(+)
 create mode 100644 tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES5.ts
 create mode 100644 tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES6.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 64bf09d8b37..61bdee79e39 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4652,6 +4652,9 @@ namespace ts {
                     if (!isIdentifierText(name, compilerOptions.target) && !isNumericLiteralName(name)) {
                         return `"${escapeString(name, CharacterCodes.doubleQuote)}"`;
                     }
+                    if (isNumericLiteralName(name) && startsWith(name, "-")) {
+                        return `[${name}]`;
+                    }
                     return name;
                 }
                 if (nameType.flags & TypeFlags.UniqueESSymbol) {
diff --git a/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES5.ts b/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES5.ts
new file mode 100644
index 00000000000..cb120d70822
--- /dev/null
+++ b/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES5.ts
@@ -0,0 +1,5 @@
+// @target: es5
+// @declaration: true
+var v = {
+  [-1]: {}
+}
diff --git a/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES6.ts b/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES6.ts
new file mode 100644
index 00000000000..8d904244f3f
--- /dev/null
+++ b/tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit6_ES6.ts
@@ -0,0 +1,5 @@
+// @target: es6
+// @declaration: true
+var v = {
+  [-1]: {}
+}
\ No newline at end of file