Add parenthesis for single arg types with generics (#1814)

Fixes #1813

src/printer.js

@@ -3229,6 +3229,8 @@ function printFunctionParams(path, print, options, expandArg) {
     fun[paramsField][0].typeAnnotation &&
     flowTypeAnnotations.indexOf(fun[paramsField][0].typeAnnotation.type) !==
       -1 &&
+    !(fun[paramsField][0].typeAnnotation.type === "GenericTypeAnnotation" &&
+      fun[paramsField][0].typeAnnotation.typeParameters) &&
     !fun.rest;
 
   if (isFlowShorthandWithOneArg) {

tests/flow_function_parentheses/__snapshots__/jsfmt.spec.js.snap

@@ -78,6 +78,8 @@ class X {
 interface F {
   ideConnectionFactoryLongLongLong: (child_process$ChildProcess) => FlowIDEConnection
 }
+
+type ExtractType = <A>(B<C>) => D
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 type Banana = {
   eat: string => boolean
@@ -121,6 +123,8 @@ interface F {
   ideConnectionFactoryLongLongLong: child_process$ChildProcess => FlowIDEConnection
 }
 
+type ExtractType = <A>(B<C>) => D;
+
 `;
 
 exports[`test.js 2`] = `
@@ -167,6 +171,8 @@ class X {
 interface F {
   ideConnectionFactoryLongLongLong: (child_process$ChildProcess) => FlowIDEConnection
 }
+
+type ExtractType = <A>(B<C>) => D
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 type Banana = {
   eat: string => boolean,
@@ -210,4 +216,6 @@ interface F {
   ideConnectionFactoryLongLongLong: child_process$ChildProcess => FlowIDEConnection,
 }
 
+type ExtractType = <A>(B<C>) => D;
+
 `;

tests/flow_function_parentheses/test.js

@@ -41,3 +41,5 @@ class X {
 interface F {
   ideConnectionFactoryLongLongLong: (child_process$ChildProcess) => FlowIDEConnection
 }
+
+type ExtractType = <A>(B<C>) => D