Be more discriminating about arguments when checking AST transforms.

lib/compiler/ast/node.rb

@@ -24,8 +24,14 @@ def self.match_send?(node, receiver, method, name)
       end
 
       def self.match_arguments?(arguments, count)
-        (arguments and arguments.body.size == count) or
-          (arguments.nil? and count == 0)
+        case arguments
+        when ArrayLiteral
+          arguments.body.size == count
+        when nil
+          count == 0
+        else
+          false
+        end
       end
 
       def initialize(line)

lib/compiler/ast/transforms.rb

@@ -123,7 +123,8 @@ class SendFastMath < SendWithArguments
       }
 
       def self.match?(line, receiver, name, arguments, privately)
-        if op = Operators[name] and arguments.body.size == 1
+        return false unless op = Operators[name]
+        if match_arguments? arguments, 1
           node = new line, receiver, name, arguments
           node.operator = op
           node

spec/compiler/plugins/fastmath_spec.rb

@@ -15,6 +15,26 @@
     end
   end
 
+  relates "1.+(*a)" do
+    compile do |g|
+      g.push 1
+      g.push :self
+      g.send :a, 0, true
+      g.cast_array
+      g.push :nil
+      g.send_with_splat :+, 0, false, false
+    end
+
+    compile :fastmath do |g|
+      g.push 1
+      g.push :self
+      g.send :a, 0, true
+      g.cast_array
+      g.push :nil
+      g.send_with_splat :+, 0, false, false
+    end
+  end
+
   relates "1 - 1" do
     compile do |g|
       g.push 1