Support exporting non-default identifiers and classes; limit the default expressions that we allow to be exported to the types of expressions that make sense; more tests and error-checking

Author: GeoffreyBooth

src/grammar.coffee

@@ -370,8 +370,12 @@ grammar =
   Export: [
     o 'EXPORT ExportClause',                    -> new Module 'export', $2
     o 'EXPORT ExportClause FROM SimpleString',  -> new Module 'export', $2, $4
-    o 'EXPORT DEFAULT Expression',              -> new Module 'export', $3, null, yes
+    o 'EXPORT Identifier',                      -> new Module 'export', $2
     o 'EXPORT Class',                           -> new Module 'export', $2
+    o 'EXPORT DEFAULT Value',                   -> new Module 'export', $3, null, yes
+    o 'EXPORT DEFAULT Code',                    -> new Module 'export', $3, null, yes
+    o 'EXPORT DEFAULT Assign',                  -> new Module 'export', $3, null, yes
+    o 'EXPORT DEFAULT Class',                   -> new Module 'export', $3, null, yes
   ]
 
   ExportClause: [

src/nodes.coffee

@@ -1230,6 +1230,10 @@ exports.Module = class Module extends Base
     if @type isnt 'import' and @type isnt 'export'
       @error 'module type must be import or export'
 
+    if @type is 'export' and @default is no and @clause instanceof Class and not @clause.variable?
+      @error 'anonymous classes cannot be exported'
+
+
   children: ['clause', 'moduleName']
 
   isStatement: YES

test/error_messages.coffee

@@ -994,3 +994,20 @@ test "`&&=` and `||=` with a space in-between", ->
     a or = 1
          ^
   '''
+
+test "anonymous functions cannot be exported", ->
+  assertErrorFormat '''
+    export ->
+      console.log 'hello, world!'
+  ''', '''
+    [stdin]:1:8: error: unexpected ->
+    export ->
+           ^^
+  '''
+
+test "anonymous classes cannot be exported", ->
+  assertErrorFormat '''
+    export class
+      @constructor: ->
+        console.log 'hello, world!'
+  ''', 'SyntaxError: anonymous classes cannot be exported'

test/modules.coffee

@@ -248,6 +248,21 @@ test "export default multiline function", ->
     };"""
   eq toJS(input), output
 
+test "export predefined function", ->
+  input = """
+    foo = (bar) ->
+      console.log bar
+    export foo"""
+  output = """
+    var foo;
+
+    foo = function(bar) {
+      return console.log(bar);
+    };
+
+    export foo;"""
+  eq toJS(input), output
+
 # Uncomment this test once ES2015+ `class` support is added
 
 # test "export default class", ->