consider es6 module syntax to be plain JS [fixes #3162]

src/lexer.coffee

@@ -56,6 +56,7 @@ exports.Lexer = class Lexer
     i = 0
     while @chunk = code[i..]
       consumed = \
+           @moduleToken()     or
            @identifierToken() or
            @commentToken()    or
            @whitespaceToken() or
@@ -255,6 +256,12 @@ exports.Lexer = class Lexer
     @token 'JS', (script = match[0])[1...-1], 0, script.length
     script.length
 
+  # Matches JavaScript interpolated directly into the source via module syntax.
+  moduleToken: ->
+    return 0 unless match = MODULETOKEN.exec @chunk
+    @token 'JS', (script = match[0]), 0, script.length
+    script.length
+
   # Matches regular expression literals, as well as multiline extended ones.
   # Lexing regular expressions is difficult to distinguish from division, so we
   # borrow some basic heuristics from JavaScript and Ruby.
@@ -824,6 +831,8 @@ MULTI_DENT = /^(?:\n[^\n\S]*)+/
 
 JSTOKEN    = /^`[^\\`]*(?:\\.[^\\`]*)*`/
 
+MODULETOKEN   = /^(import|export)\s+[^#\\\n]*/
+
 # String-matching-regexes.
 STRING_START   = /^(?:'''|"""|'|")/
 

test/javascript_literals.coffee

@@ -8,3 +8,52 @@ eq '\\`', `
   // Inline JS
   "\\\`"
 `
+
+toJS = (str)->
+  CoffeeScript.compile str, bare: true
+  .replace /^\s+|\s+$/g, ""
+
+test "regular JS literal import statement", ->
+  input = '`import { member as alias } from "module-name"`'
+  output = 'import { member as alias } from "module-name";'
+  eq toJS(input), output
+
+test "module import test, syntax #1", ->
+  input = "import foo from 'lib'"
+  output = "import foo from 'lib';"
+  eq toJS(input), output
+
+test "module import test, syntax #2", ->
+  input = "import { foo } from 'lib'"
+  output = "import { foo } from 'lib';"
+  eq toJS(input), output
+
+test "module import test, syntax #3", ->
+  input = "import { default as foo } from 'lib'"
+  output = "import { default as foo } from 'lib';"
+  eq toJS(input), output
+
+test "module import test, syntax #4", ->
+  input = "import { square, diag } from 'lib'"
+  output = "import { square, diag } from 'lib';"
+  eq toJS(input), output
+
+test "module import test, syntax #5", ->
+  input = "import { foo } from 'lib' # with a comment"
+  output = "import { foo } from 'lib' ;"
+  eq toJS(input), output
+
+test "module export test, syntax #1", ->
+  input = "export default mixin"
+  output = "export default mixin;"
+  eq toJS(input), output
+
+test "module export test, syntax #2", ->
+  input = "export { D as default }"
+  output = "export { D as default };"
+  eq toJS(input), output
+
+test "module export test, syntax #3", ->
+  input = "export const sqrt = Math.sqrt"
+  output = "export const sqrt = Math.sqrt;"
+  eq toJS(input), output