Disallow multiple assignment for constants. Fixes #3466

sdogruyol · Ary Borenszweig · commit df2890ab9919 · 2016-12-20T13:27:03.000+02:00
diff --git a/spec/compiler/normalize/multi_assign_spec.cr b/spec/compiler/normalize/multi_assign_spec.cr
@@ -5,10 +5,6 @@ describe "Normalize: multi assign" do
     assert_expand "a, b, c = 1, 2, 3", "__temp_1 = 1\n__temp_2 = 2\n__temp_3 = 3\na = __temp_1\nb = __temp_2\nc = __temp_3"
   end
 
-  it "normalizes n to n with constants" do
-    assert_expand "a, B, C = 1, 2, 3", "__temp_1 = 1\na = __temp_1\nB = 2\nC = 3"
-  end
-
   it "normalizes 1 to n" do
     assert_expand_second "d = 1\na, b, c = d", "__temp_1 = d\na = __temp_1[0]\nb = __temp_1[1]\nc = __temp_1[2]"
   end
diff --git a/spec/compiler/parser/parser_spec.cr b/spec/compiler/parser/parser_spec.cr
@@ -134,7 +134,6 @@ describe "Parser" do
 
   it_parses "@a, b = 1, 2", MultiAssign.new(["@a".instance_var, "b".var] of ASTNode, [1.int32, 2.int32] of ASTNode)
   it_parses "@@a, b = 1, 2", MultiAssign.new(["@@a".class_var, "b".var] of ASTNode, [1.int32, 2.int32] of ASTNode)
-  it_parses "A, b = 1, 2", MultiAssign.new(["A".path, "b".var] of ASTNode, [1.int32, 2.int32] of ASTNode)
 
   assert_syntax_error "1 == 2, a = 4"
   assert_syntax_error "x : String, a = 4"
@@ -1324,6 +1323,8 @@ describe "Parser" do
     "can't change the value of self"
   assert_syntax_error "self += 1",
     "can't change the value of self"
+  assert_syntax_error "FOO, BAR = 1, 2",
+    "Multiple assignment is not allowed for constants"
   assert_syntax_error "self, x = 1, 2",
     "can't change the value of self"
   assert_syntax_error "x, self = 1, 2",
diff --git a/src/compiler/crystal/syntax/parser.cr b/src/compiler/crystal/syntax/parser.cr
@@ -116,8 +116,10 @@ module Crystal
 
       case @token.type
       when :","
-        # Continue
-        unexpected_token unless last_is_target
+        unless last_is_target
+          raise "Multiple assignment is not allowed for constants" if last.is_a?(Path)
+          unexpected_token
+        end
       when :NEWLINE, :";"
         return last
       else
@@ -173,7 +175,7 @@ module Crystal
         targets << assign
         values << assign.args.pop
       else
-        raise "Bug: mutliassign index expression can only be Assign or Call"
+        raise "Bug: multiassign index expression can only be Assign or Call"
       end
 
       values.concat exps[assign_index + 1..-1]
@@ -187,7 +189,7 @@ module Crystal
 
     def multi_assign_target?(exp)
       case exp
-      when Underscore, Var, InstanceVar, ClassVar, Global, Path, Assign
+      when Underscore, Var, InstanceVar, ClassVar, Global, Assign
         true
       when Call
         !exp.has_parentheses? && (
