From 8ae5a8cfcedaa840f8764ad1d3e58522115837a5 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Tue, 12 Nov 2019 10:15:30 -0800
Subject: [PATCH] useDefineForClassFields skips emit of ambient properties

Previously:

```ts
class C {
  declare p
}
```

would incorrectly emit

```js
class C {
    constructor() {
        Object.defineProperty(this, "p", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
    }
}
```

when useDefineForClassFields was turned on (for targets <ESNext).
---
 src/compiler/transformers/utilities.ts                         | 2 +-
 tests/baselines/reference/definePropertyES5.js                 | 1 +
 tests/baselines/reference/definePropertyES5.symbols            | 3 +++
 tests/baselines/reference/definePropertyES5.types              | 3 +++
 .../classes/propertyMemberDeclarations/definePropertyES5.ts    | 1 +
 5 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/compiler/transformers/utilities.ts b/src/compiler/transformers/utilities.ts
index e2029ff7b60..3cd246c9094 100644
--- a/src/compiler/transformers/utilities.ts
+++ b/src/compiler/transformers/utilities.ts
@@ -314,7 +314,7 @@ namespace ts {
      */
     function isInitializedOrStaticProperty(member: ClassElement, requireInitializer: boolean, isStatic: boolean) {
         return isPropertyDeclaration(member)
-            && (!!member.initializer || !requireInitializer)
+            && (!!member.initializer || !requireInitializer && !(getOriginalNode(member).flags & NodeFlags.Ambient))
             && hasStaticModifier(member) === isStatic;
     }
 
diff --git a/tests/baselines/reference/definePropertyES5.js b/tests/baselines/reference/definePropertyES5.js
index a0bc4a64db4..b61e8c11465 100644
--- a/tests/baselines/reference/definePropertyES5.js
+++ b/tests/baselines/reference/definePropertyES5.js
@@ -6,6 +6,7 @@ class A {
     ["computed"] = 13
     ;[x] = 14
     m() { }
+    declare notEmitted: boolean;
 }
 
 
diff --git a/tests/baselines/reference/definePropertyES5.symbols b/tests/baselines/reference/definePropertyES5.symbols
index f9afa028687..48ec310926f 100644
--- a/tests/baselines/reference/definePropertyES5.symbols
+++ b/tests/baselines/reference/definePropertyES5.symbols
@@ -21,5 +21,8 @@ class A {
 
     m() { }
 >m : Symbol(A.m, Decl(definePropertyES5.ts, 5, 13))
+
+    declare notEmitted: boolean;
+>notEmitted : Symbol(A.notEmitted, Decl(definePropertyES5.ts, 6, 11))
 }
 
diff --git a/tests/baselines/reference/definePropertyES5.types b/tests/baselines/reference/definePropertyES5.types
index 3f82787c13a..7fffb77b74c 100644
--- a/tests/baselines/reference/definePropertyES5.types
+++ b/tests/baselines/reference/definePropertyES5.types
@@ -25,5 +25,8 @@ class A {
 
     m() { }
 >m : () => void
+
+    declare notEmitted: boolean;
+>notEmitted : boolean
 }
 
diff --git a/tests/cases/conformance/classes/propertyMemberDeclarations/definePropertyES5.ts b/tests/cases/conformance/classes/propertyMemberDeclarations/definePropertyES5.ts
index 73e1ee515d1..a2338889134 100644
--- a/tests/cases/conformance/classes/propertyMemberDeclarations/definePropertyES5.ts
+++ b/tests/cases/conformance/classes/propertyMemberDeclarations/definePropertyES5.ts
@@ -7,4 +7,5 @@ class A {
     ["computed"] = 13
     ;[x] = 14
     m() { }
+    declare notEmitted: boolean;
 }