Fixing #934 (at least partially).

lib/lexer.js

@@ -604,7 +604,7 @@
   HEREDOC = /^("""|''')([\s\S]*?)(?:\n[^\n\S]*)?\1/;
   OPERATOR = /^(?:[-=]>|[-+*\/%<>&|^!?=]=|>>>=?|([-+:])\1|([&|<>])\2=?|\?\.|\.{2,3})/;
   WHITESPACE = /^[^\n\S]+/;
-  COMMENT = /^###([^#][\s\S]*?)(?:###[^\n\S]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/;
+  COMMENT = /^###([^#][\s\S]*?)(?:###[^\n\S]*|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/;
   CODE = /^[-=]>/;
   MULTI_DENT = /^(?:\n[^\n\S]*)+/;
   SIMPLESTR = /^'[^\\']*(?:\\.[^\\']*)*'/;

lib/nodes.js

@@ -91,7 +91,7 @@
     };
     Base.prototype.containsPureStatement = function() {
       return this.isPureStatement() || this.contains(function(node) {
-        return node.isPureStatement();
+        return node.isPureStatement() && !(node instanceof Comment);
       });
     };
     Base.prototype.toString = function(idt, name) {

src/lexer.coffee

@@ -550,7 +550,7 @@ OPERATOR   = /// ^ (
 
 WHITESPACE = /^[^\n\S]+/
 
-COMMENT    = /^###([^#][\s\S]*?)(?:###[^\n\S]*\n|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/
+COMMENT    = /^###([^#][\s\S]*?)(?:###[^\n\S]*|(?:###)?$)|^(?:\s*#(?!##[^#]).*)+/
 
 CODE       = /^[-=]>/
 

src/nodes.coffee

@@ -97,7 +97,8 @@ exports.Base = class Base
   # Convenience for the most common use of contains. Does the node contain
   # a pure statement?
   containsPureStatement: ->
-    @isPureStatement() or @contains (node) -> node.isPureStatement()
+    @isPureStatement() or @contains (node) ->
+      node.isPureStatement() and node not instanceof Comment
 
   # `toString` representation of the node, for inspecting the parse tree.
   # This is what `coffee --nodes` prints out.

test/comments.coffee

@@ -199,3 +199,13 @@ test "block comments inside class bodies", ->
     b: ->
 
   ok B.prototype.a instanceof Function
+
+test "#934, block comments inside conditional bodies", ->
+
+  eq undefined, (if true
+    ###
+    block comment
+    ###
+  else
+    # comment
+  )