Fix issue where negative integers were being treated incorrectly in s…

…printf. This was causing a bug in ActiveSupport.

kernel/common/sprintf.rb

@@ -283,23 +283,31 @@ def pad(val, width, precision, pad_override = nil)
       ret = val.to_s
       modded_width = width.to_i + (flags[:plus] ? 1 : 0)
       width = nil if modded_width <= val.to_s.size
+      sign = plus_char
+
       if precision || flags[:zero]
         ret.gsub!("..", "")
       end
       if precision
         if precision > PrecisionMax
           raise ArgumentError, "precision too big"
         end
-        ret = plus_char + ret.send(direction, precision, pad_override || "0")
+        ret = sign + ret.send(direction, precision, pad_override || "0")
         flags[:zero] = flags[:plus] = flags[:space] = nil
       end
       if width
-        ret = ret.send(direction, width, pad_char)
-        ret[0] = plus_char unless plus_char.empty?
-      else
-        ret = plus_char + ret
+        if pad_char != " " && ret[0] == ?-
+          ret.slice!(0)
+          sign = "-"
+          width -= 1
+          ret = ret.rjust(width, pad_char)
+        else
+          ret = ret.send(direction, width, pad_char)
+          ret[0] = sign unless sign.empty?
+          return ret
+        end
       end
-      ret
+      sign + ret
     end
 
     def pad_char

spec/frozen/core/string/modulo_spec.rb

@@ -336,6 +336,16 @@ def universal.to_f() 0.0 end
       ("%04#{f}" % 10).should == "0010"
       ("%*#{f}" % [10, 4]).should == "         4"
     end
+
+    it "supports negative integers using #{format}" do
+      ("%#{f}" % -5).should == "-5"
+      ("%3#{f}" % -5).should == " -5"
+      ("%03#{f}" % -5).should == "-05"
+      ("%+03#{f}" % -5).should == "-05"
+      ("%-3#{f}" % -5).should == "-5 "
+      ("%-03#{f}" % -5).should == "-05"
+      ("%+-03#{f}" % -5).should == "-05"
+    end
   end
 
   it "supports float formats using %e" do
@@ -417,7 +427,7 @@ def universal.to_f() 0.0 end
         ("%E" % (-0e0/0)).should == "NAN"
       end
     end
-    
+
     # TODO: If http://redmine.ruby-lang.org/issues/show/1566 is confirmed, we
     # can guard the behaviour of capitalising Inf and NaN as a bug, and
     # removed the compliance guards.
@@ -438,7 +448,7 @@ def universal.to_f() 0.0 end
         end
       end
     end
-    
+
     ruby_version_is "1.9" do
       it "pads with spaces for %E with Inf, -Inf, and NaN" do
         ("%010E" % -1e1020).should == "      -Inf"
@@ -655,7 +665,7 @@ def obj.to_s() "obj" end
       ("%d" % -(2 ** 64 + 5)).should == "-18446744073709551621"
     end
   end
-  
+
   it "supports hex formats using %x for positive numbers" do
     ("%x" % 10).should == "a"
     ("% x" % 10).should == " a"
@@ -788,7 +798,7 @@ def obj.to_s() "obj" end
       obj.should_receive(:to_int).and_return(6)
       (format % obj).should == (format % 6)
     end
-    
+
     # 1.9 raises a TypeError for Kernel.Integer(nil), so we version guard this
     # case
     ruby_version_is ""..."1.9" do
@@ -797,7 +807,7 @@ def obj.to_s() "obj" end
           format = "%" + f
           (format % nil).should == (format % Kernel.Integer(nil))
         end
-      end   
+      end
     end
 
     it "doesn't taint the result for #{format} when argument is tainted" do