Make sure native extensions are loaded correctly in rake builder

1 files changed, 13 insertions, 1 deletions

diff --git a/lib/rubygems/ext/rake_builder.rb b/lib/rubygems/ext/rake_builder.rb
index 282285b970..9a3f8ca65e 100644
--- a/lib/rubygems/ext/rake_builder.rb
+++ b/lib/rubygems/ext/rake_builder.rb
@@ -18,8 +18,20 @@ class Gem::Ext::RakeBuilder < Gem::Ext::Builder
       require "shellwords"
       rake = rake.shellsplit
     else
+      # This is only needed when running rubygems test without a proper installation.
+      # Prepending it in a normal installation can cause problem with order of $LOAD_PATH.
+      # Therefore only add rubygems_load_path if it is not present in the default $LOAD_PATH.
+      rubygems_load_path = File.expand_path("../..", __dir__)
+      load_path =
+        case rubygems_load_path
+        when RbConfig::CONFIG["sitelibdir"], RbConfig::CONFIG["vendorlibdir"], RbConfig::CONFIG["rubylibdir"]
+          []
+        else
+          ["-I#{rubygems_load_path}"]
+        end
+
       begin
-        rake = [Gem.ruby, "-I#{File.expand_path("../..", __dir__)}", "-rrubygems", Gem.bin_path("rake", "rake")]
+        rake = [Gem.ruby, *load_path, "-rrubygems", Gem.bin_path("rake", "rake")]
       rescue Gem::Exception
         rake = [Gem.default_exec_format % "rake"]
       end