[Bug #19919] Warn class variable assignment and constant declaration in condition

parse.y

@@ -1835,6 +1835,10 @@ get_nd_value(struct parser_params *p, NODE *node)
         return RNODE_DASGN(node)->nd_value;
       case NODE_MASGN:
         return RNODE_MASGN(node)->nd_value;
+      case NODE_CVASGN:
+        return RNODE_CVASGN(node)->nd_value;
+      case NODE_CDECL:
+        return RNODE_CDECL(node)->nd_value;
       default:
         compile_error(p, "unexpected node: %s", parser_node_name(nd_type(node)));
         return 0;
@@ -14044,6 +14048,8 @@ assign_in_cond(struct parser_params *p, NODE *node)
       case NODE_DASGN:
       case NODE_GASGN:
       case NODE_IASGN:
+      case NODE_CVASGN:
+      case NODE_CDECL:
         break;
 
       default:

test/ruby/test_parse.rb

@@ -895,12 +895,14 @@ x = __ENCODING__
   end
 
   def test_assign_in_conditional
+    # multiple assignment
     assert_warning(/`= literal' in conditional/) do
       eval <<-END, nil, __FILE__, __LINE__+1
         (x, y = 1, 2) ? 1 : 2
       END
     end
 
+    # instance variable assignment
     assert_warning(/`= literal' in conditional/) do
       eval <<-END, nil, __FILE__, __LINE__+1
         if @x = true
@@ -910,6 +912,71 @@ x = __ENCODING__
         end
       END
     end
+
+    # local variable assignment
+    assert_warning(/`= literal' in conditional/) do
+      eval <<-END, nil, __FILE__, __LINE__+1
+        def m
+          if x = true
+            1
+          else
+            2
+          end
+        end
+      END
+    end
+
+    # global variable assignment
+    assert_separately([], <<-RUBY)
+      assert_warning(/`= literal' in conditional/) do
+        eval <<-END, nil, __FILE__, __LINE__+1
+          if $x = true
+            1
+          else
+            2
+          end
+        END
+      end
+    RUBY
+
+    # dynamic variable assignment
+    assert_warning(/`= literal' in conditional/) do
+      eval <<-END, nil, __FILE__, __LINE__+1
+        y = 1
+
+        1.times do
+          if y = true
+            1
+          else
+            2
+          end
+        end
+      END
+    end
+
+    # class variable assignment
+    assert_warning(/`= literal' in conditional/) do
+      eval <<-END, nil, __FILE__, __LINE__+1
+        c = Class.new
+        class << c
+          if @@a = 1
+          end
+        end
+      END
+    end
+
+    # constant declaration
+    assert_separately([], <<-RUBY)
+      assert_warning(/`= literal' in conditional/) do
+        eval <<-END, nil, __FILE__, __LINE__+1
+          if Const = true
+            1
+          else
+            2
+          end
+        END
+      end
+    RUBY
   end
 
   def test_literal_in_conditional