[rubygems/rubygems] Pull `Gem.win_platform?` out of a hot path

`normalize_path` is a pretty hot path, it's called many times per file
in each gem. Since the platform isn't going to change from call to call,
we can conditionally define `normalize_path` based on the value of
`Gem.win_platform?`.

https://github.com/rubygems/rubygems/commit/d5e61411f2

3 files changed, 38 insertions, 29 deletions

diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index f8f1451ee6..8bb8cdfc04 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -16,6 +16,7 @@ require_relative "rubygems/defaults"
 require_relative "rubygems/deprecate"
 require_relative "rubygems/errors"
 require_relative "rubygems/target_rbconfig"
+require_relative "rubygems/win_platform"
 
 ##
 # RubyGems is the Ruby standard for publishing and managing third party
@@ -113,18 +114,6 @@ require_relative "rubygems/target_rbconfig"
 module Gem
   RUBYGEMS_DIR = __dir__
 
-  ##
-  # An Array of Regexps that match windows Ruby platforms.
-
-  WIN_PATTERNS = [
-    /bccwin/i,
-    /cygwin/i,
-    /djgpp/i,
-    /mingw/i,
-    /mswin/i,
-    /wince/i,
-  ].freeze
-
   GEM_DEP_FILES = %w[
     gem.deps.rb
     gems.rb
@@ -160,8 +149,6 @@ module Gem
 
   DEFAULT_SOURCE_DATE_EPOCH = 315_619_200
 
-  @@win_platform = nil
-
   @configuration = nil
   @gemdeps = nil
   @loaded_specs = {}
@@ -1092,18 +1079,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   end
 
   ##
-  # Is this a windows platform?
-
-  def self.win_platform?
-    if @@win_platform.nil?
-      ruby_platform = RbConfig::CONFIG["host_os"]
-      @@win_platform = !WIN_PATTERNS.find {|r| ruby_platform =~ r }.nil?
-    end
-
-    @@win_platform
-  end
-
-  ##
   # Is this a java platform?
 
   def self.java_platform?
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index cd8dfdf37d..b56d68cc45 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -7,6 +7,7 @@
 
 # rubocop:enable Style/AsciiComments
 
+require_relative "win_platform"
 require_relative "security"
 require_relative "user_interaction"
 
@@ -518,10 +519,12 @@ EOM
     destination
   end
 
-  def normalize_path(pathname)
-    if Gem.win_platform?
+  if Gem.win_platform?
+    def normalize_path(pathname) # :nodoc:
       pathname.downcase
-    else
+    end
+  else
+    def normalize_path(pathname) # :nodoc:
       pathname
     end
   end
diff --git a/lib/rubygems/win_platform.rb b/lib/rubygems/win_platform.rb
new file mode 100644
index 0000000000..78e968fe49
--- /dev/null
+++ b/lib/rubygems/win_platform.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+
+module Gem
+  ##
+  # An Array of Regexps that match windows Ruby platforms.
+
+  WIN_PATTERNS = [
+    /bccwin/i,
+    /cygwin/i,
+    /djgpp/i,
+    /mingw/i,
+    /mswin/i,
+    /wince/i,
+  ].freeze
+
+  @@win_platform = nil
+
+  ##
+  # Is this a windows platform?
+
+  def self.win_platform?
+    if @@win_platform.nil?
+      ruby_platform = RbConfig::CONFIG["host_os"]
+      @@win_platform = !WIN_PATTERNS.find {|r| ruby_platform =~ r }.nil?
+    end
+
+    @@win_platform
+  end
+end