From 78a4f51662acb236f1a5f327b3429d5cd9cff931 Mon Sep 17 00:00:00 2001
From: Jed Fox <git@twopointzero.us>
Date: Wed, 14 Feb 2018 11:19:39 +0000
Subject: [PATCH] Wrap ternaries in Flow typecasts in parens (#3940)

* Wrap TypeCastExpression in parens

* Tests
---
 src/common/fast-path.js                       |  1 +
 .../__snapshots__/jsfmt.spec.js.snap          | 25 +++++++++++++++++++
 tests/flow_type_cast/expression.js            |  4 +++
 tests/flow_type_cast/jsfmt.spec.js            |  1 +
 tests/flow_type_cast/statement.js             |  3 +++
 5 files changed, 34 insertions(+)
 create mode 100644 tests/flow_type_cast/__snapshots__/jsfmt.spec.js.snap
 create mode 100644 tests/flow_type_cast/expression.js
 create mode 100644 tests/flow_type_cast/jsfmt.spec.js
 create mode 100644 tests/flow_type_cast/statement.js

diff --git a/src/common/fast-path.js b/src/common/fast-path.js
index 97e10252..eae670e9 100644
--- a/src/common/fast-path.js
+++ b/src/common/fast-path.js
@@ -560,6 +560,7 @@ FastPath.prototype.needsParens = function(options) {
         case "AwaitExpression":
         case "JSXSpreadAttribute":
         case "TSTypeAssertionExpression":
+        case "TypeCastExpression":
         case "TSAsExpression":
         case "TSNonNullExpression":
           return true;
diff --git a/tests/flow_type_cast/__snapshots__/jsfmt.spec.js.snap b/tests/flow_type_cast/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 00000000..a413b447
--- /dev/null
+++ b/tests/flow_type_cast/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,25 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`expression.js 1`] = `
+let x: string = (foo: string);
+
+// https://github.com/prettier/prettier/issues/3936
+const foo = ((1?2:3): number);
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+let x: string = (foo: string);
+
+// https://github.com/prettier/prettier/issues/3936
+const foo = ((1 ? 2 : 3): number);
+
+`;
+
+exports[`statement.js 1`] = `
+foo: string;
+bar: number;
+(foo.bar: SomeType);
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+foo: string;
+bar: number;
+(foo.bar: SomeType);
+
+`;
diff --git a/tests/flow_type_cast/expression.js b/tests/flow_type_cast/expression.js
new file mode 100644
index 00000000..50ecacd5
--- /dev/null
+++ b/tests/flow_type_cast/expression.js
@@ -0,0 +1,4 @@
+let x: string = (foo: string);
+
+// https://github.com/prettier/prettier/issues/3936
+const foo = ((1?2:3): number);
diff --git a/tests/flow_type_cast/jsfmt.spec.js b/tests/flow_type_cast/jsfmt.spec.js
new file mode 100644
index 00000000..c1ba82f4
--- /dev/null
+++ b/tests/flow_type_cast/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, ["flow", "babylon"]);
diff --git a/tests/flow_type_cast/statement.js b/tests/flow_type_cast/statement.js
new file mode 100644
index 00000000..0dc735b4
--- /dev/null
+++ b/tests/flow_type_cast/statement.js
@@ -0,0 +1,3 @@
+foo: string;
+bar: number;
+(foo.bar: SomeType);