Fix #3441: parentheses wrapping expression throw invalid error (#4849)

* fix #3441

* improvements

* refactor

lib/coffeescript/nodes.js

@@ -1267,6 +1267,15 @@
         if (!props && base instanceof Value) {
           return base;
         }
+        if (base instanceof Parens && base.contains(function(n) {
+          return n instanceof StatementLiteral;
+        })) {
+          // When `Parens` block includes a `StatementLiteral` (e.g. `(b; break) for a in arr`),
+          // it won't compile since `Parens` (`(b; break)`) is compiled as `Value` and
+          // pure statement (`break`) can't be used in an expression.
+          // For this reasons, we return `Block` instead of `Parens`.
+          return base.unwrap();
+        }
         this.base = base;
         this.properties = props || [];
         if (tag) {

src/nodes.coffee

@@ -863,6 +863,11 @@ exports.Value = class Value extends Base
   constructor: (base, props, tag, isDefaultValue = no) ->
     super()
     return base if not props and base instanceof Value
+    # When `Parens` block includes a `StatementLiteral` (e.g. `(b; break) for a in arr`),
+    # it won't compile since `Parens` (`(b; break)`) is compiled as `Value` and
+    # pure statement (`break`) can't be used in an expression.
+    # For this reasons, we return `Block` instead of `Parens`.
+    return base.unwrap() if base instanceof Parens and base.contains (n) -> n instanceof StatementLiteral
     @base           = base
     @properties     = props or []
     @[tag]          = yes if tag

test/control_flow.coffee

@@ -484,3 +484,34 @@ test "#4267: lots of for-loops in the same scope", ->
       true
   """
   ok CoffeeScript.eval(code)
+
+# Issue #3441: Parentheses wrapping expression throw invalid error in `then` clause
+test "#3441: `StatementLiteral` in parentheses", ->
+  i = 0
+  r1 = ((i++; break) while i < 10)
+  arrayEq r1, []
+
+  i = 0
+  r2 = ((i++; continue) while i < 10)
+  arrayEq r2, []
+
+  i = 0
+  r4 = while i < 10 then (i++; break)
+  arrayEq r4, []
+
+  i = 0
+  r5 = while i < 10 then (i++; continue)
+  arrayEq r5, []
+
+  arr = [0..9]
+  r6 = ((a; break) for a in arr)
+  arrayEq r6, []
+
+  r7 = ((a; continue) for a in arr)
+  arrayEq r7, []
+
+  r8 = for a in arr then (a; break)
+  arrayEq r8, []
+
+  r9 = for a in arr then (a; continue)
+  arrayEq r9, []