From fda7bf59f482c83a9db94bdc1111689a3e4ff474 Mon Sep 17 00:00:00 2001
From: Brian Ng <bng412@gmail.com>
Date: Fri, 25 May 2018 17:23:17 -0500
Subject: [PATCH] Add support for Flow's proto modifier syntax (#4551)

Flow commit: https://github.com/facebook/flow/commit/eb815be907eeae9f4851ff154087ebf079510d18

Babel PR: https://github.com/babel/babel/pull/7978
---
 src/language-js/printer-estree.js                    | 10 +++++++++-
 .../__snapshots__/jsfmt.spec.js.snap                 | 12 ++++++++++++
 tests/flow_proto_props/jsfmt.spec.js                 |  1 +
 tests/flow_proto_props/proto_props.js                |  3 +++
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 tests/flow_proto_props/__snapshots__/jsfmt.spec.js.snap
 create mode 100644 tests/flow_proto_props/jsfmt.spec.js
 create mode 100644 tests/flow_proto_props/proto_props.js

diff --git a/src/language-js/printer-estree.js b/src/language-js/printer-estree.js
index e03565597..663126784 100644
--- a/src/language-js/printer-estree.js
+++ b/src/language-js/printer-estree.js
@@ -2675,8 +2675,16 @@ function printPathNoParens(path, options, print, args) {
     case "ObjectTypeProperty": {
       const variance = getFlowVariance(n);
 
+      let modifier = "";
+
+      if (n.proto) {
+        modifier = "proto ";
+      } else if (n.static) {
+        modifier = "static ";
+      }
+
       return concat([
-        n.static ? "static " : "",
+        modifier,
         isGetterOrSetter(n) ? n.kind + " " : "",
         variance || "",
         printPropertyKey(path, options, print),
diff --git a/tests/flow_proto_props/__snapshots__/jsfmt.spec.js.snap b/tests/flow_proto_props/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..52e130ec1
--- /dev/null
+++ b/tests/flow_proto_props/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,12 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`proto_props.js 1`] = `
+declare class A { proto: T; }
+declare class B { proto x: T; }
+declare class C { proto +x: T; }
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+declare class A { proto: T }
+declare class B { proto x: T }
+declare class C { proto +x: T }
+
+`;
diff --git a/tests/flow_proto_props/jsfmt.spec.js b/tests/flow_proto_props/jsfmt.spec.js
new file mode 100644
index 000000000..b9a908981
--- /dev/null
+++ b/tests/flow_proto_props/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, ["flow"]);
diff --git a/tests/flow_proto_props/proto_props.js b/tests/flow_proto_props/proto_props.js
new file mode 100644
index 000000000..94e6ab9f7
--- /dev/null
+++ b/tests/flow_proto_props/proto_props.js
@@ -0,0 +1,3 @@
+declare class A { proto: T; }
+declare class B { proto x: T; }
+declare class C { proto +x: T; }