fix corner case in `collapse_vars` (#3597)

fixes #3596

1 files changed, 17 insertions, 10 deletions

diff --git a/lib/output.js b/lib/output.js
index d59176c3..0f8ef1cd 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -711,16 +711,23 @@ function OutputStream(options) {
 
     PARENS(AST_Sequence, function(output) {
         var p = output.parent();
-        return p instanceof AST_Call             // (foo, bar)() or foo(1, (2, 3), 4)
-            || p instanceof AST_Unary            // !(foo, bar, baz)
-            || p instanceof AST_Binary           // 1 + (2, 3) + 4 ==> 8
-            || p instanceof AST_VarDef           // var a = (1, 2), b = a + a; ==> b == 4
-            || p instanceof AST_PropAccess       // (1, {foo:2}).foo or (1, {foo:2})["foo"] ==> 2
-            || p instanceof AST_Array            // [ 1, (2, 3), 4 ] ==> [ 1, 3, 4 ]
-            || 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) */
-        ;
+            // (foo, bar)() or foo(1, (2, 3), 4)
+        return p instanceof AST_Call
+            // !(foo, bar, baz)
+            || p instanceof AST_Unary
+            // 1 + (2, 3) + 4 ==> 8
+            || p instanceof AST_Binary
+            // var a = (1, 2), b = a + a; ==> b == 4
+            || p instanceof AST_VarDef
+            // (1, {foo:2}).foo or (1, {foo:2})["foo"] ==> 2
+            || p instanceof AST_PropAccess && p.expression === this
+            // [ 1, (2, 3), 4 ] ==> [ 1, 3, 4 ]
+            || p instanceof AST_Array
+            // { foo: (1, 2) }.foo ==> 2
+            || p instanceof AST_ObjectProperty
+            // (false, true) ? (a = 10, b = 20) : (c = 30)
+            // ==> 20 (side effect, set a := 10 and b := 20)
+            || p instanceof AST_Conditional;
     });
 
     PARENS(AST_Binary, function(output) {