* lisp/progmodes/ruby-mode.el (ruby-smie--rule-parent-skip-assign): New

function, replacement for `smie-rule-parent' for when we want to
skip over our direct parent if it's an assignment token..
(ruby-smie-rules): Use it.

lisp/ChangeLog

@@ -1,3 +1,10 @@
+2013-11-02  Dmitry Gutov  <dgutov@yandex.ru>
+
+	* progmodes/ruby-mode.el (ruby-smie--rule-parent-skip-assign): New
+	function, replacement for `smie-rule-parent' for when we want to
+	skip over our direct parent if it's an assignment token..
+	(ruby-smie-rules): Use it.
+
 2013-11-02  Dmitry Gutov  <dgutov@yandex.ru>
 
 	* progmodes/ruby-mode.el Use `syntax-propertize-function'

lisp/progmodes/ruby-mode.el

@@ -467,6 +467,16 @@ explicitly declared in magic comment."
            (t ";")))
          (t tok)))))))
 
+(defun ruby-smie--rule-parent-skip-assign ()
+  (let* ((parent (smie-indent--parent))
+         (tok (caddr parent)))
+    (if (and (stringp tok) (string-match-p "[+-*&|^]?=\\'" tok))
+        (progn
+          (goto-char (cadr parent))
+          (let (smie--parent)
+            (smie-rule-parent)))
+      (smie-rule-parent))))
+
 (defun ruby-smie-rules (kind token)
   (pcase (cons kind token)
     (`(:elem . basic) ruby-indent-level)
@@ -489,7 +499,7 @@ explicitly declared in magic comment."
       ((and (equal token "{")
             (not (smie-rule-prev-p "(" "{" "[" "," "=>" "=" "return" ";")))
        ;; Curly block opener.
-       (smie-rule-parent))
+       (ruby-smie--rule-parent-skip-assign))
       ((smie-rule-hanging-p)
        ;; Treat purely syntactic block-constructs as being part of their parent,
        ;; when the opening statement is hanging.
@@ -498,7 +508,7 @@ explicitly declared in magic comment."
        (cons 'column  (smie-indent-virtual)))))
     (`(:after . ,(or "=" "iuwu-mod")) 2)
     (`(:after . " @ ") (smie-rule-parent))
-    (`(:before . "do") (smie-rule-parent))
+    (`(:before . "do") (ruby-smie--rule-parent-skip-assign))
     (`(,(or :before :after) . ".")
      (unless (smie-rule-parent-p ".")
        (smie-rule-parent ruby-indent-level)))

test/indent/ruby.rb

@@ -225,6 +225,14 @@ def bar
         bar
       end
 
+a = b {
+  c
+}
+
+aa = bb do
+  cc
+end
+
 # Examples below still fail with `ruby-use-smie' on:
 
 foo = [1, 2, 3].map do |i|