Merge pull request #6305 from dearblue/method_missing

Protect keyword arguments in `prepare_missing()`

mrbgems/mruby-method/test/method.rb

@@ -138,6 +138,36 @@ assert 'Method#call with undefined method' do
   assert_raise(NoMethodError) { m.call(:arg1, :arg2) }
 end
 
+assert 'Method#call with undefined method -- only kwargs' do
+  c = Class.new {
+    attr_accessor :m, :argv, :kwargs
+    def respond_to_missing?(m, b)
+      m == :foo
+    end
+
+    def method_missing(m, *argv, **kwargs)
+      @m = m
+      @argv = argv
+      @kwargs = kwargs
+      super
+    end
+  }
+  cc = c.new
+  assert_kind_of Method, cc.method(:foo)
+
+  # Calling cc.method(:foo) works
+  assert_raise(NoMethodError) { cc.method(:foo).call(kwarg1: :val1, kwarg2: :val2) }
+  assert_equal :foo, cc.m
+  assert_equal [], cc.argv
+  assert_equal({ kwarg1: :val1, kwarg2: :val2 }, cc.kwargs)
+
+  # calling cc.foo fails
+  assert_raise(NoMethodError) { cc.foo(kwarg1: :val1, kwarg2: :val2) }
+  assert_equal :foo, cc.m
+  assert_equal [], cc.argv
+  assert_equal({ kwarg1: :val1, kwarg2: :val2 }, cc.kwargs)
+end
+
 assert 'Method#source_location' do
   skip if proc{}.source_location.nil?
 

src/vm.c

@@ -629,7 +629,6 @@ prepare_missing(mrb_state *mrb, mrb_callinfo *ci, mrb_value recv, mrb_sym mid, m
   stack_extend(mrb, 4);
 
   argv = &ci->stack[1];         /* maybe reallocated */
-  argv[0] = args;
   if (ci->nk == 0) {
     argv[1] = blk;
   }
@@ -638,6 +637,7 @@ prepare_missing(mrb_state *mrb, mrb_callinfo *ci, mrb_value recv, mrb_sym mid, m
     argv[1] = argv[ci->n];
     argv[2] = blk;
   }
+  argv[0] = args;               /* must be replaced after saving argv[0] as it may be a keyword argument */
   ci->n = CALL_MAXARGS;
   /* ci->nk is already set to zero or CALL_MAXARGS */
   mrb_ary_unshift(mrb, args, mrb_symbol_value(mid));