Auto merge of #6628 - bundler:segiddins/bundler-2-global-path-ruby-scope, r=colby-swandale

[Settings] Append the ruby scope on Bundler 2 with a global path setting

### What was the end-user problem that led to this PR?

The problem was `bundle config path` behaving differently depending on whether the config is local or global was... confusing.

Closes https://github.com/bundler/bundler/issues/6619#issuecomment-405460114.

### What was your diagnosis of the problem?

My diagnosis was setting the `path` setting should be consistent, regardless of the level of configuration it is set at.

### What is your fix for the problem, implemented in this PR?

My fix appends the "ruby scope" to the path when set globally on Bundler 2.

### Why did you choose this fix out of the possible options?

I chose this fix because it means users won't have to re-install gems when switching rubies with a global `BUNDLE_PATH` set.

(cherry picked from commit 0fc64a60b9dfe2f5275f6001a34ea2bf078fd12c)

6 files changed, 79 insertions, 31 deletions

diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index 6a1809cd40..23e581e65e 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -38,6 +38,7 @@ module Bundler
     settings_flag(:disable_multisource) { bundler_2_mode? }
     settings_flag(:error_on_stderr) { bundler_2_mode? }
     settings_flag(:forget_cli_options) { bundler_2_mode? }
+    settings_flag(:global_path_appends_ruby_scope) { bundler_2_mode? }
     settings_flag(:global_gem_cache) { bundler_2_mode? }
     settings_flag(:init_gems_rb) { bundler_2_mode? }
     settings_flag(:list_command) { bundler_2_mode? }
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index aec25c3e5e..6ba739623f 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -34,6 +34,7 @@ module Bundler
       frozen
       gem.coc
       gem.mit
+      global_path_appends_ruby_scope
       global_gem_cache
       ignore_messages
       init_gems_rb
@@ -214,13 +215,13 @@ module Bundler
       locations
     end
 
-    # for legacy reasons, the ruby scope isnt appended when the setting comes from ENV or the global config,
+    # for legacy reasons, in Bundler 1, the ruby scope isnt appended when the setting comes from ENV or the global config,
     # nor do we respect :disable_shared_gems
     def path
       key  = key_for(:path)
       path = ENV[key] || @global_config[key]
       if path && !@temporary.key?(key) && !@local_config.key?(key)
-        return Path.new(path, false, false, false)
+        return Path.new(path, Bundler.feature_flag.global_path_appends_ruby_scope?, false, false)
       end
 
       system_path = self["path.system"] || (self[:disable_shared_gems] == false)
diff --git a/man/bundle-config.ronn b/man/bundle-config.ronn
index a3930c6ce8..3eda468688 100644
--- a/man/bundle-config.ronn
+++ b/man/bundle-config.ronn
@@ -198,6 +198,9 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
 * `global_gem_cache` (`BUNDLE_GLOBAL_GEM_CACHE`):
    Whether Bundler should cache all gems globally, rather than locally to the
    installing Ruby installation.
+* `global_path_appends_ruby_scope` (`BUNDLE_GLOBAL_PATH_APPENDS_RUBY_SCOPE`):
+   Whether Bundler should append the Ruby scope (e.g. engine and ABI version)
+   to a globally-configured path.
 * `ignore_messages` (`BUNDLE_IGNORE_MESSAGES`): When set, no post install
    messages will be printed. To silence a single gem, use dot notation like
    `ignore_messages.httparty true`.
diff --git a/spec/install/bundler_spec.rb b/spec/install/bundler_spec.rb
index 08b7e2b673..42863ed89b 100644
--- a/spec/install/bundler_spec.rb
+++ b/spec/install/bundler_spec.rb
@@ -140,6 +140,7 @@ RSpec.describe "bundle install" do
 
     it "can install dependencies with newer bundler version with a local path", :ruby => "> 2" do
       bundle! "config path .bundle"
+      bundle! "config global_path_appends_ruby_scope true"
       install_gemfile! <<-G
         source "file://#{gem_repo2}"
         gem "rails", "3.0"
diff --git a/spec/install/gems/sudo_spec.rb b/spec/install/gems/sudo_spec.rb
index ae94eee9c6..1781451c98 100644
--- a/spec/install/gems/sudo_spec.rb
+++ b/spec/install/gems/sudo_spec.rb
@@ -52,6 +52,8 @@ RSpec.describe "when using sudo", :sudo => true do
     end
 
     it "installs when BUNDLE_PATH is owned by root" do
+      bundle! "config global_path_appends_ruby_scope false" # consistency in tests between 1.x and 2.x modes
+
       bundle_path = tmp("owned_by_root")
       FileUtils.mkdir_p bundle_path
       sudo "chown -R root #{bundle_path}"
@@ -68,6 +70,8 @@ RSpec.describe "when using sudo", :sudo => true do
     end
 
     it "installs when BUNDLE_PATH does not exist" do
+      bundle! "config global_path_appends_ruby_scope false" # consistency in tests between 1.x and 2.x modes
+
       root_path = tmp("owned_by_root")
       FileUtils.mkdir_p root_path
       sudo "chown -R root #{root_path}"
diff --git a/spec/install/path_spec.rb b/spec/install/path_spec.rb
index 3fce72b78e..59d151e5bf 100644
--- a/spec/install/path_spec.rb
+++ b/spec/install/path_spec.rb
@@ -72,44 +72,82 @@ RSpec.describe "bundle install" do
     end
 
     [:env, :global].each do |type|
-      it "installs gems to a path if one is specified" do
-        set_bundle_path(type, bundled_app("vendor2").to_s)
-        bundle! :install, forgotten_command_line_options(:path => "vendor/bundle")
+      context "when set via #{type}" do
+        it "installs gems to a path if one is specified" do
+          set_bundle_path(type, bundled_app("vendor2").to_s)
+          bundle! :install, forgotten_command_line_options(:path => "vendor/bundle")
+
+          expect(vendored_gems("gems/rack-1.0.0")).to be_directory
+          expect(bundled_app("vendor2")).not_to be_directory
+          expect(the_bundle).to include_gems "rack 1.0.0"
+        end
 
-        expect(vendored_gems("gems/rack-1.0.0")).to be_directory
-        expect(bundled_app("vendor2")).not_to be_directory
-        expect(the_bundle).to include_gems "rack 1.0.0"
-      end
+        context "with global_path_appends_ruby_scope set", :bundler => "2" do
+          it "installs gems to ." do
+            set_bundle_path(type, ".")
+            bundle! "config --global disable_shared_gems true"
 
-      it "installs gems to ." do
-        set_bundle_path(type, ".")
-        bundle! "config --global disable_shared_gems true"
+            bundle! :install
 
-        bundle! :install
+            paths_to_exist = %w[cache/rack-1.0.0.gem gems/rack-1.0.0 specifications/rack-1.0.0.gemspec].map {|path| bundled_app(Bundler.ruby_scope, path) }
+            expect(paths_to_exist).to all exist
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
 
-        expect([bundled_app("cache/rack-1.0.0.gem"), bundled_app("gems/rack-1.0.0"), bundled_app("specifications/rack-1.0.0.gemspec")]).to all exist
-        expect(the_bundle).to include_gems "rack 1.0.0"
-      end
+          it "installs gems to the path" do
+            set_bundle_path(type, bundled_app("vendor").to_s)
 
-      it "installs gems to BUNDLE_PATH with #{type}" do
-        set_bundle_path(type, bundled_app("vendor").to_s)
+            bundle! :install
 
-        bundle :install
+            expect(bundled_app("vendor", Bundler.ruby_scope, "gems/rack-1.0.0")).to be_directory
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
 
-        expect(bundled_app("vendor/gems/rack-1.0.0")).to be_directory
-        expect(the_bundle).to include_gems "rack 1.0.0"
-      end
+          it "installs gems to the path relative to root when relative" do
+            set_bundle_path(type, "vendor")
 
-      it "installs gems to BUNDLE_PATH relative to root when relative" do
-        set_bundle_path(type, "vendor")
+            FileUtils.mkdir_p bundled_app("lol")
+            Dir.chdir(bundled_app("lol")) do
+              bundle! :install
+            end
 
-        FileUtils.mkdir_p bundled_app("lol")
-        Dir.chdir(bundled_app("lol")) do
-          bundle :install
+            expect(bundled_app("vendor", Bundler.ruby_scope, "gems/rack-1.0.0")).to be_directory
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
         end
 
-        expect(bundled_app("vendor/gems/rack-1.0.0")).to be_directory
-        expect(the_bundle).to include_gems "rack 1.0.0"
+        context "with global_path_appends_ruby_scope unset", :bundler => "< 2" do
+          it "installs gems to ." do
+            set_bundle_path(type, ".")
+            bundle! "config --global disable_shared_gems true"
+
+            bundle! :install
+
+            expect([bundled_app("cache/rack-1.0.0.gem"), bundled_app("gems/rack-1.0.0"), bundled_app("specifications/rack-1.0.0.gemspec")]).to all exist
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
+
+          it "installs gems to BUNDLE_PATH with #{type}" do
+            set_bundle_path(type, bundled_app("vendor").to_s)
+
+            bundle :install
+
+            expect(bundled_app("vendor/gems/rack-1.0.0")).to be_directory
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
+
+          it "installs gems to BUNDLE_PATH relative to root when relative" do
+            set_bundle_path(type, "vendor")
+
+            FileUtils.mkdir_p bundled_app("lol")
+            Dir.chdir(bundled_app("lol")) do
+              bundle :install
+            end
+
+            expect(bundled_app("vendor/gems/rack-1.0.0")).to be_directory
+            expect(the_bundle).to include_gems "rack 1.0.0"
+          end
+        end
       end
     end
 
@@ -170,7 +208,7 @@ RSpec.describe "bundle install" do
   describe "to a file" do
     before do
       in_app_root do
-        `touch /tmp/idontexist bundle`
+        FileUtils.touch "bundle"
       end
     end
 
@@ -181,7 +219,7 @@ RSpec.describe "bundle install" do
       G
 
       bundle :install, forgotten_command_line_options(:path => "bundle")
-      expect(out).to match(/file already exists/)
+      expect(out).to include("file already exists")
     end
   end
 end