use `caller_locations` instead of `caller`

We have `caller_locations`, so we don't need to parse the strings in the
callstack.

activesupport/lib/active_support/deprecation/proxy_wrappers.rb

@@ -20,7 +20,7 @@ def inspect
 
       private
         def method_missing(called, *args, &block)
-          warn caller, called, args
+          warn caller_locations, called, args
           target.__send__(called, *args, &block)
         end
     end

activesupport/lib/active_support/deprecation/reporting.rb

@@ -14,7 +14,7 @@ module Reporting
       def warn(message = nil, callstack = nil)
         return if silenced
 
-        callstack ||= caller(2)
+        callstack ||= caller_locations(2)
         deprecation_message(callstack, message).tap do |m|
           behavior.each { |b| b.call(m, callstack) }
         end
@@ -37,7 +37,7 @@ def silence
       end
 
       def deprecation_warning(deprecated_method_name, message = nil, caller_backtrace = nil)
-        caller_backtrace ||= caller(2)
+        caller_backtrace ||= caller_locations(2)
         deprecated_method_warning(deprecated_method_name, message).tap do |msg|
           warn(msg, caller_backtrace)
         end
@@ -79,6 +79,17 @@ def deprecation_caller_message(callstack)
         end
 
         def extract_callstack(callstack)
+          return _extract_callstack(callstack) if callstack.first.is_a? String
+
+          rails_gem_root = File.expand_path("../../../../..", __FILE__) + "/"
+          offending_line = callstack.find { |frame|
+            !frame.absolute_path.start_with?(rails_gem_root)
+          } || callstack.first
+          [offending_line.path, offending_line.lineno, offending_line.label]
+        end
+
+        def _extract_callstack(callstack)
+          warn "Please pass `caller_locations` to the deprecation API" if $VERBOSE
           rails_gem_root = File.expand_path("../../../../..", __FILE__) + "/"
           offending_line = callstack.find { |line| !line.start_with?(rails_gem_root) } || callstack.first
           if offending_line