Auto merge of #5933 - NickLaMuro:bundle-pristine-respect-bundler-config, r=segiddins

Use Bundler::Installer for bundle pristine

Fixes bundler pristine to respect the `bundle config` options for particular gems.  In my particular case, on OSX I have a keg version of `pg` and a bundle config with the following entry:

```console
$ bundle config
...

build.pg
Set for the current user (/Users/nicklamuro/.bundle/config): "--with-pg-config=/usr/local/Cellar/postgresql@9.5/9.5.6/bin/pg_config"

```

This would not be respected

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

See above, but steps to reproduce (requires `bundler` >= 1.15):

1. Install postgres on your machine if it is not already there (OS dependent)

2. Add the following bundler build arg for `pg`:

  ```console
  $ bundle config build.pg -- --with-pg-config=$(which pg_config)
  ```

2. Make sure `pg_config` is not in your `$PATH`:

  ```console
  $ export PATH=$(echo "$PATH" | sed "s|:$(dirname $(which pg_conf)))||")
  ```

* Create a simple project with `pg` as a single gem in your Gemfile:

  ```
  # Gemfile
  gem "pg"
  ```

* Bundle:

  ```console
  $ bundle install
  ```

* Attempt to `bundle pristine` (you should get an error):

  ```console
  $ bundle pristine
  ```

What was your diagnosis of the problem?
---------------------------------------

The newly added `bundle pristine` did no use the same code that was used by `bundle install` to execute the re-installation of the gem.

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

By making use of the `Bundler::Installer` and `Bundler::Installer::GemInstaller` code that is already used with `bundle install`, we can reuse the code that injects the `bundle config` options into each gem that is being installed.

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

Didn't want to repeat code that was already being used elsewhere.  Caused a few lines of code to be added that weren't there previously, but nothing obscene.

(cherry picked from commit da6a52a9b255147b389d29e2b22ce397bbb8377b)

# Conflicts:
#	lib/bundler/cli/pristine.rb
#	spec/commands/pristine_spec.rb

3 files changed, 37 insertions, 8 deletions

diff --git a/lib/bundler/cli/pristine.rb b/lib/bundler/cli/pristine.rb
index 30542b583e..10d03b4b41 100644
--- a/lib/bundler/cli/pristine.rb
+++ b/lib/bundler/cli/pristine.rb
@@ -4,29 +4,32 @@ require "bundler/cli/common"
 module Bundler
   class CLI::Pristine
     def run
+      definition = Bundler.definition
+      definition.validate_runtime!
+      installer = Bundler::Installer.new(Bundler.root, definition)
+
       Bundler.load.specs.each do |spec|
         next if spec.name == "bundler" # Source::Rubygems doesn't install bundler
 
         gem_name = "#{spec.name} (#{spec.version}#{spec.git_version})"
         gem_name += " (#{spec.platform})" if !spec.platform.nil? && spec.platform != Gem::Platform::RUBY
 
-        case spec.source
+        case source = spec.source
         when Source::Rubygems
           cached_gem = spec.cache_file
           unless File.exist?(cached_gem)
             Bundler.ui.error("Failed to pristine #{gem_name}. Cached gem #{cached_gem} does not exist.")
             next
           end
-
-          FileUtils.rm_rf spec.full_gem_path
-          spec.source.install(spec, :force => true)
         when Source::Git
-          git_source = spec.source
-          git_source.remote!
-          git_source.install(spec, :force => true)
+          source.remote!
         else
           Bundler.ui.warn("Cannot pristine #{gem_name}. Gem is sourced from local path.")
+          next
         end
+        FileUtils.rm_rf spec.full_gem_path
+
+        Bundler::GemInstaller.new(spec, installer, false, 0, true).install_from_spec
       end
     end
   end
diff --git a/spec/commands/pristine_spec.rb b/spec/commands/pristine_spec.rb
index a6f991bb4a..5f5e694bc3 100644
--- a/spec/commands/pristine_spec.rb
+++ b/spec/commands/pristine_spec.rb
@@ -12,6 +12,7 @@ RSpec.describe "bundle pristine" do
     build_repo2 do
       build_gem "weakling"
       build_gem "baz-dev", "1.0.0"
+      build_gem "very_simple_binary", &:add_c_extension
       build_git "foo", :path => lib_path("foo")
       build_lib "bar", :path => lib_path("bar")
     end
@@ -19,6 +20,7 @@ RSpec.describe "bundle pristine" do
     install_gemfile! <<-G
       source "file://#{gem_repo2}"
       gem "weakling"
+      gem "very_simple_binary"
       gem "foo", :git => "#{lib_path("foo")}"
       gem "bar", :path => "#{lib_path("bar")}"
 
@@ -99,4 +101,21 @@ RSpec.describe "bundle pristine" do
       expect(changes_txt).to be_file
     end
   end
+
+  context "when a build config exists for one of the gems" do
+    let(:very_simple_binary) { Bundler.definition.specs["very_simple_binary"].first }
+    let(:c_ext_dir)          { Pathname.new(very_simple_binary.full_gem_path).join("ext") }
+    let(:build_opt)          { "--with-ext-lib=#{c_ext_dir}" }
+    before { bundle "config build.very_simple_binary -- #{build_opt}" }
+
+    # This just verifies that the generated Makefile from the c_ext gem makes
+    # use of the build_args from the bundle config
+    it "applies the config when installing the gem" do
+      bundle! "pristine"
+
+      makefile_contents = File.read(c_ext_dir.join("Makefile").to_s)
+      expect(makefile_contents).to match(/libpath =.*#{c_ext_dir}/)
+      expect(makefile_contents).to match(/LIBPATH =.*-L#{c_ext_dir}/)
+    end
+  end
 end
diff --git a/spec/support/builders.rb b/spec/support/builders.rb
index 28a271998e..db128d497b 100644
--- a/spec/support/builders.rb
+++ b/spec/support/builders.rb
@@ -562,10 +562,17 @@ module Spec
         write "ext/extconf.rb", <<-RUBY
           require "mkmf"
 
+
           # exit 1 unless with_config("simple")
 
           extension_name = "very_simple_binary_c"
-          dir_config extension_name
+          if extra_lib_dir = with_config("ext-lib")
+            # add extra libpath if --with-ext-lib is
+            # passed in as a build_arg
+            dir_config extension_name, nil, extra_lib_dir
+          else
+            dir_config extension_name
+          end
           create_makefile extension_name
         RUBY
         write "ext/very_simple_binary.c", <<-C