Auto merge of #5790 - bundler:seg-suppress-using-messages, r=indirect

[2.0] Suppress `Using …` messages during installation when a version has not changed

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

The problem was that `bundle install` output can get very verbose, even when Bundler is not doing anything.

See https://github.com/bundler/bundler-features/issues/33.

### Was was your diagnosis of the problem?

My diagnosis was that bundler was printing a bunch of `Using name (version)` messages, even when we were already using that gem at the same version.

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

My fix is to introduce a feature flag (enabled by default on 2.0), that will only print those extra `Using` messages when `--verbose` is passed, and will continue to print them when there was an old version we can tell users about. Note that we still print a message when installing a gem for the first time.

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

I chose this fix because it was essentially what had been done in https://github.com/bundler/bundler/pull/3872, and allows for easy feature-flagging.

7 files changed, 14 insertions, 4 deletions

diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index 318ad5dee7..bca2c615b3 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -38,6 +38,7 @@ module Bundler
     settings_flag(:plugins) { @bundler_version >= Gem::Version.new("1.14") }
     settings_flag(:prefer_gems_rb) { bundler_2_mode? }
     settings_flag(:skip_default_git_sources) { bundler_2_mode? }
+    settings_flag(:suppress_install_using_messages) { bundler_2_mode? }
     settings_flag(:unlock_source_unlocks_spec) { !bundler_2_mode? }
     settings_flag(:update_requires_all_flag) { bundler_2_mode? }
 
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 8521f8658d..092cd26c22 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -36,6 +36,7 @@ module Bundler
       prefer_gems_rb
       silence_root_warning
       skip_default_git_sources
+      suppress_install_using_messages
       unlock_source_unlocks_spec
       update_requires_all_flag
     ].freeze
diff --git a/lib/bundler/source.rb b/lib/bundler/source.rb
index cb5f2da83e..f3d50adecf 100644
--- a/lib/bundler/source.rb
+++ b/lib/bundler/source.rb
@@ -60,5 +60,13 @@ module Bundler
     def earlier_version?(spec_version, locked_spec_version)
       Gem::Version.new(spec_version) < Gem::Version.new(locked_spec_version)
     end
+
+    def print_using_message(message)
+      if !message.include?("(was ") && Bundler.feature_flag.suppress_install_using_messages?
+        Bundler.ui.debug message
+      else
+        Bundler.ui.info message
+      end
+    end
   end
 end
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index c331af967e..d1e32946eb 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -169,7 +169,7 @@ module Bundler
       def install(spec, options = {})
         force = options[:force]
 
-        Bundler.ui.info "Using #{version_message(spec)} from #{self}"
+        print_using_message "Using #{version_message(spec)} from #{self}"
 
         if requires_checkout? && !@copied && !force
           Bundler.ui.debug "  * Checking out revision: #{ref}"
diff --git a/lib/bundler/source/metadata.rb b/lib/bundler/source/metadata.rb
index f6d2f0729d..1d62a1f76a 100644
--- a/lib/bundler/source/metadata.rb
+++ b/lib/bundler/source/metadata.rb
@@ -36,7 +36,7 @@ module Bundler
       end
 
       def install(spec, _opts = {})
-        Bundler.ui.info "Using #{version_message(spec)}"
+        print_using_message "Using #{version_message(spec)}"
         nil
       end
 
diff --git a/lib/bundler/source/path.rb b/lib/bundler/source/path.rb
index 99808d2ef2..84a98420a9 100644
--- a/lib/bundler/source/path.rb
+++ b/lib/bundler/source/path.rb
@@ -76,7 +76,7 @@ module Bundler
       end
 
       def install(spec, options = {})
-        Bundler.ui.info "Using #{version_message(spec)} from #{self}"
+        print_using_message "Using #{version_message(spec)} from #{self}"
         generate_bin(spec, :disable_extensions => true)
         nil # no post-install message
       end
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 70f7819f3a..e76a00361a 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -106,7 +106,7 @@ module Bundler
         end
 
         if installed?(spec) && !force
-          Bundler.ui.info "Using #{version_message(spec)}"
+          print_using_message "Using #{version_message(spec)}"
           return nil # no post-install message
         end