From e6092bcf3922477330c6df6f5137c081ac011da2 Mon Sep 17 00:00:00 2001
From: Richard van Velzen <rvanvelzen@experty.com>
Date: Thu, 1 Sep 2016 09:35:31 +0200
Subject: [PATCH 1/2] Don't parenthesize arrow functions in parameter lists

---
 lib/output.js            |  2 +-
 test/compress/harmony.js | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/output.js b/lib/output.js
index d0238da8..6cf031bf 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -944,7 +944,7 @@ function OutputStream(options) {
         var parent = output.parent();
         var needs_parens = parent instanceof AST_Binary ||
             parent instanceof AST_Unary ||
-            parent instanceof AST_Call;
+            (parent instanceof AST_Call && self === parent.expression);
         if (needs_parens) { output.print("(") }
         if (self.argnames.length === 1 && self.argnames[0] instanceof AST_Symbol && !self.argnames[0].default) {
             self.argnames[0].print(output);
diff --git a/test/compress/harmony.js b/test/compress/harmony.js
index 122069dd..77c37b84 100644
--- a/test/compress/harmony.js
+++ b/test/compress/harmony.js
@@ -390,4 +390,12 @@ regression_cannot_use_of: {
         x.of;
         foo();  /* Label statement missing? No prob. */
     }
-}
\ No newline at end of file
+}
+
+fat_arrow_as_param: {
+    input: {
+        foo(x => x);
+        foo(x => x, y => y);
+    }
+    expect_exact: "foo(x=>x);foo(x=>x,y=>y);"
+}

From fd38acae43533f3b0e9747b0da8d4b7a857a685f Mon Sep 17 00:00:00 2001
From: Richard van Velzen <rvanvelzen@experty.com>
Date: Thu, 1 Sep 2016 10:05:59 +0200
Subject: [PATCH 2/2] Add parenthesis around sequences in arrow bodies

---
 lib/output.js            | 1 +
 test/compress/harmony.js | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/output.js b/lib/output.js
index 6cf031bf..81712d21 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -597,6 +597,7 @@ function OutputStream(options) {
             || p instanceof AST_ObjectProperty   // { foo: (1, 2) }.foo ==> 2
             || p instanceof AST_Conditional      /* (false, true) ? (a = 10, b = 20) : (c = 30)
                                                   * ==> 20 (side effect, set a := 10 and b := 20) */
+            || p instanceof AST_Arrow            // x => (x, x)
         ;
     });
 
diff --git a/test/compress/harmony.js b/test/compress/harmony.js
index 77c37b84..e13b27e0 100644
--- a/test/compress/harmony.js
+++ b/test/compress/harmony.js
@@ -396,6 +396,9 @@ fat_arrow_as_param: {
     input: {
         foo(x => x);
         foo(x => x, y => y);
+
+        foo(x => (x, x));
+        foo(x => (x, x), y => (y, y));
     }
-    expect_exact: "foo(x=>x);foo(x=>x,y=>y);"
+    expect_exact: "foo(x=>x);foo(x=>x,y=>y);foo(x=>(x,x));foo(x=>(x,x),y=>(y,y));"
 }