From d31cab5ebb88f927df97effa37201ff0aab7720e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicol=C3=B2=20Ribaudo?= <nicolo.ribaudo@gmail.com>
Date: Tue, 5 Nov 2019 01:51:34 +0100
Subject: [PATCH] Add support for TS declare types to types and generator
 (#10544)

---
 .../babel-generator/src/generators/classes.js | 39 +------------------
 .../src/generators/typescript.js              | 23 +++++++++++
 .../typescript/class-field-declare/input.js   |  5 +++
 .../class-field-declare/options.json          |  4 ++
 .../typescript/class-field-declare/output.js  |  5 +++
 .../src/definitions/experimental.js           |  4 ++
 6 files changed, 43 insertions(+), 37 deletions(-)
 create mode 100644 packages/babel-generator/test/fixtures/typescript/class-field-declare/input.js
 create mode 100644 packages/babel-generator/test/fixtures/typescript/class-field-declare/options.json
 create mode 100644 packages/babel-generator/test/fixtures/typescript/class-field-declare/output.js

diff --git a/packages/babel-generator/src/generators/classes.js b/packages/babel-generator/src/generators/classes.js
index e8c62339a6d2..1713293369d4 100644
--- a/packages/babel-generator/src/generators/classes.js
+++ b/packages/babel-generator/src/generators/classes.js
@@ -71,26 +71,8 @@ export function ClassBody(node: Object) {
 
 export function ClassProperty(node: Object) {
   this.printJoin(node.decorators, node);
+  this.tsPrintClassMemberModifiers(node, /* isField */ true);
 
-  if (node.accessibility) {
-    // TS
-    this.word(node.accessibility);
-    this.space();
-  }
-  if (node.static) {
-    this.word("static");
-    this.space();
-  }
-  if (node.abstract) {
-    // TS
-    this.word("abstract");
-    this.space();
-  }
-  if (node.readonly) {
-    // TS
-    this.word("readonly");
-    this.space();
-  }
   if (node.computed) {
     this.token("[");
     this.print(node.key, node);
@@ -148,23 +130,6 @@ export function ClassPrivateMethod(node: Object) {
 
 export function _classMethodHead(node) {
   this.printJoin(node.decorators, node);
-
-  if (node.accessibility) {
-    // TS
-    this.word(node.accessibility);
-    this.space();
-  }
-
-  if (node.abstract) {
-    // TS
-    this.word("abstract");
-    this.space();
-  }
-
-  if (node.static) {
-    this.word("static");
-    this.space();
-  }
-
+  this.tsPrintClassMemberModifiers(node, /* isField */ false);
   this._methodHead(node);
 }
diff --git a/packages/babel-generator/src/generators/typescript.js b/packages/babel-generator/src/generators/typescript.js
index 4ff2fe1ad188..4cc770a48228 100644
--- a/packages/babel-generator/src/generators/typescript.js
+++ b/packages/babel-generator/src/generators/typescript.js
@@ -550,3 +550,26 @@ export function tsPrintSignatureDeclarationBase(node) {
   this.token(")");
   this.print(node.typeAnnotation, node);
 }
+
+export function tsPrintClassMemberModifiers(node, isField) {
+  if (isField && node.declare) {
+    this.word("declare");
+    this.space();
+  }
+  if (node.accessibility) {
+    this.word(node.accessibility);
+    this.space();
+  }
+  if (node.static) {
+    this.word("static");
+    this.space();
+  }
+  if (node.abstract) {
+    this.word("abstract");
+    this.space();
+  }
+  if (isField && node.readonly) {
+    this.word("readonly");
+    this.space();
+  }
+}
diff --git a/packages/babel-generator/test/fixtures/typescript/class-field-declare/input.js b/packages/babel-generator/test/fixtures/typescript/class-field-declare/input.js
new file mode 100644
index 000000000000..0e524a92bb8a
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/typescript/class-field-declare/input.js
@@ -0,0 +1,5 @@
+class A {
+  declare foo;
+  declare bar: string;
+  declare readonly bax: number;
+}
diff --git a/packages/babel-generator/test/fixtures/typescript/class-field-declare/options.json b/packages/babel-generator/test/fixtures/typescript/class-field-declare/options.json
new file mode 100644
index 000000000000..9f3a0c2c0ff1
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/typescript/class-field-declare/options.json
@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "plugins": ["typescript", "classProperties"]
+}
diff --git a/packages/babel-generator/test/fixtures/typescript/class-field-declare/output.js b/packages/babel-generator/test/fixtures/typescript/class-field-declare/output.js
new file mode 100644
index 000000000000..d1d7b1be56aa
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/typescript/class-field-declare/output.js
@@ -0,0 +1,5 @@
+class A {
+  declare foo;
+  declare bar: string;
+  declare readonly bax: number;
+}
\ No newline at end of file
diff --git a/packages/babel-types/src/definitions/experimental.js b/packages/babel-types/src/definitions/experimental.js
index d344630dcc75..f4e110e1002f 100644
--- a/packages/babel-types/src/definitions/experimental.js
+++ b/packages/babel-types/src/definitions/experimental.js
@@ -67,6 +67,10 @@ defineType("ClassProperty", {
       validate: assertValueType("boolean"),
       optional: true,
     },
+    declare: {
+      validate: assertValueType("boolean"),
+      optional: true,
+    },
   },
 });