Throw an error if an import or export statement isn’t at the top-level scope, with tests

Author: GeoffreyBooth

src/nodes.coffee

@@ -1243,6 +1243,9 @@ exports.Module = class Module extends Base
   makeReturn:  THIS
 
   compileNode: (o) ->
+    if o.indent.length isnt 0
+      @error "#{@type} statements must be at top-level scope"
+
     code = []
 
     code.push @makeCode "#{@tab}#{@type} "

test/error_messages.coffee

@@ -1008,3 +1008,22 @@ test "anonymous classes cannot be exported", ->
       @constructor: ->
         console.log 'hello, world!'
   ''', 'SyntaxError: anonymous classes cannot be exported'
+
+test "imports and exports must be top-level", ->
+  assertErrorFormat '''
+    if foo
+      import { bar } from 'lib'
+  ''', '''
+    [stdin]:2:3: error: import statements must be at top-level scope
+      import { bar } from 'lib'
+      ^^^^^^^^^^^^^^^^^^^^^^^^^
+  '''
+
+  assertErrorFormat '''
+    foo = ->
+      export { bar }
+  ''', '''
+    [stdin]:2:3: error: export statements must be at top-level scope
+      export { bar }
+      ^^^^^^^^^^^^^^
+  '''