Support case insensitive filename

On Windows and some other file systems, they support case insensitve
filenames.  This patch almost supports case insensitve file name
on break command. Maybe we need more features to support case insensitve
file names, so reports are welcome.

fix #554

Author: ko1

lib/debug/breakpoint.rb

@@ -220,7 +220,7 @@ def try_activate
       nearest = nil # NearestISeq
 
       ObjectSpace.each_iseq{|iseq|
-        if (iseq.absolute_path || iseq.path) == self.path &&
+        if DEBUGGER__.compare_path((iseq.absolute_path || iseq.path), self.path) &&
             iseq.first_lineno <= self.line &&
             iseq.type != :ensure # ensure iseq is copied (duplicated)
 

lib/debug/session.rb

@@ -1582,7 +1582,7 @@ def on_load iseq, src
       end
 
       pending_line_breakpoints.each do |_key, bp|
-        if bp.path == (iseq.absolute_path || iseq.path)
+        if DEBUGGER__.compare_path(bp.path, (iseq.absolute_path || iseq.path))
           bp.try_activate
         end
       end
@@ -2107,6 +2107,20 @@ def self.step_in &b
     yield
   end
 
+  if File.identical?(__FILE__.upcase, __FILE__.downcase)
+    # For case insensitive file system (like Windows)
+    # Note that this check is not enough because case sensitive/insensitive is
+    # depend on the file system. So this check is only roughly estimation.
+
+    def self.compare_path(a, b)
+      a.downcase == b.downcase
+    end
+  else
+    def self.compare_path(a, b)
+      a == b
+    end
+  end
+
   module ForkInterceptor
     def fork(&given_block)
       return super unless defined?(SESSION) && SESSION.active?