fix splat error with soak properties or expressions

Author: Zdenko Vujasinovic

lib/coffee-script/nodes.js

@@ -1812,7 +1812,21 @@ exports.Splat = class Splat extends Base
   assigns: (name) ->
     @name.assigns name
 
+  propHasSoak: ->
+    return no unless @name.properties
+    isSoak = yes for prop in @name.properties when prop.soak
+    isSoak ? no
+
   compileToFragments: (o) ->
+    # Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
+    # and ensure correct compilation by wrapping the @name in `Parens`.
+    # Examples:
+    # [a?.b...]    => [(a?.b)...]
+    # f(a.b?.c...) => f((a.b?.c)...)
+    # [a if b...]  => [(a if b)...]
+    if not (@name instanceof Value) or
+        (not (@name.base instanceof Parens) and @propHasSoak())
+      @name = new Value new Parens @name
     @name.compileToFragments o
 
   unwrap: -> @name