Merge #7614

7614: Workaround jruby issue r=deivid-rodriguez a=deivid-rodriguez

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

The problem is that if a Gemfile contains `:path` gem with a relative path, the bundler environment no longer works when the app is packaged as a `jar` with [warbler](https://github.com/jruby/warbler).

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

<!-- Explain the fix being implemented. Include any diagnosis you run to
determine the cause of the issue and your conclusions. If you considered other
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Issue was introduced https://github.com/rubygems/bundler/commit/c7532ced89bbc8ddc7296c56391c1c3cc981c54a, since when `jruby` deals with urls of the form "uri:classloader", it has a weird inconsistency where `Pathname#expand_path` with an argument always returns `uri:classloader://` (double slash) as the canonical version of the path, while `Pathname#expand_path` without an argument always returns `uri:classloader/` (single slash) as the canonical version of it.

```
Pathname.new("uri:classloader://foo/bar").expand_path
#  => <Pathname:uri:classloader:/foo/bar>

Pathname.new("uri:classloader:/foo/bar").expand_path
# => <Pathname:uri:classloader:/foo/bar>

Pathname.new("foo/bar").expand_path("uri:classloader://")
# => <Pathname:uri:classloader://foo/bar>

Pathname.new("foo/bar").expand_path("uri:classloader:/")
# => <Pathname:uri:classloader://foo/bar>
```

That makes `Pathname#relative_path_from` (introduced with the offending commit) explode because we end up passing to different "uri:classloader" kind of paths to it.

I believe this should be fixed in `jruby` be doing either or both of the following things:

* Make `Pathname#expand_path` return consistent versions of "uri:classpath" paths.
* Make `Pathname#relative_path_from` support different versions of "uri:classpath" paths, since they are both absolute paths after all.

But I'm workarounding the issue in `bundler` by adding an extra `expand_path` call at an appropriate place to make sure that the URLs we pass to `Pathname#relative_path_from` have a consistent shape.

Fixes #7598.

NOTE: We currently don't have the ability to run a full test suite for every PR on jruby because it's too slow (#4796 attempted to improve that but it was never completed), and it doesn't even fully pass (#7603). As an alternative, I'm adding some realworld bare tests to be run under jruby, just to make sure common tasks like this one work.

Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

7 files changed, 60 insertions, 1 deletions

diff --git a/.github/workflows/jruby.yml b/.github/workflows/jruby.yml
new file mode 100644
index 0000000000..4974787eed
--- /dev/null
+++ b/.github/workflows/jruby.yml
@@ -0,0 +1,31 @@
+name: jruby
+
+on:
+  pull_request:
+
+  push:
+    branches:
+      - staging
+      - trying
+
+jobs:
+  warbler:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+
+      - name: Setup ruby
+        uses: eregon/use-ruby-action@v1
+        with:
+          ruby-version: jruby-9.2.9.0
+
+      - name: Install local bundler
+        run: bin/rake install:local
+
+      - name: Run a warbler project
+        run: |
+          cd spec/realworld/fixtures/warbler
+          bundle install
+          bundle exec warble
+          java -jar warbler.jar
diff --git a/.rubocop.yml b/.rubocop.yml
index 604300a117..3a4d8cb295 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -408,6 +408,8 @@ Naming/ConstantName:
 
 Naming/FileName:
   Enabled: true
+  Exclude:
+    - 'spec/realworld/fixtures/warbler/bin/warbler-example.rb'
 
 Naming/HeredocDelimiterCase:
   Enabled: true
diff --git a/lib/bundler/source/path.rb b/lib/bundler/source/path.rb
index f98f5155fb..e73e33d922 100644
--- a/lib/bundler/source/path.rb
+++ b/lib/bundler/source/path.rb
@@ -132,7 +132,11 @@ module Bundler
       end
 
       def expand(somepath)
-        somepath.expand_path(root_path)
+        if Bundler.current_ruby.jruby? # TODO: Unify when https://github.com/rubygems/bundler/issues/7598 fixed upstream and all supported jrubies include the fix
+          somepath.expand_path(root_path).expand_path
+        else
+          somepath.expand_path(root_path)
+        end
       rescue ArgumentError => e
         Bundler.ui.debug(e)
         raise PathError, "There was an error while trying to use the path " \
diff --git a/spec/realworld/fixtures/warbler/.gitignore b/spec/realworld/fixtures/warbler/.gitignore
new file mode 100644
index 0000000000..6ac0bb4663
--- /dev/null
+++ b/spec/realworld/fixtures/warbler/.gitignore
@@ -0,0 +1,2 @@
+*.jar
+Gemfile.lock
diff --git a/spec/realworld/fixtures/warbler/Gemfile b/spec/realworld/fixtures/warbler/Gemfile
new file mode 100644
index 0000000000..4fbf2d05a7
--- /dev/null
+++ b/spec/realworld/fixtures/warbler/Gemfile
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "demo", :path => "./demo"
+gem "jruby-jars", "~> 9.2"
+gem "warbler", "~> 2.0"
diff --git a/spec/realworld/fixtures/warbler/bin/warbler-example.rb b/spec/realworld/fixtures/warbler/bin/warbler-example.rb
new file mode 100644
index 0000000000..25f614ecc2
--- /dev/null
+++ b/spec/realworld/fixtures/warbler/bin/warbler-example.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+puts require "bundler/setup"
diff --git a/spec/realworld/fixtures/warbler/demo/demo.gemspec b/spec/realworld/fixtures/warbler/demo/demo.gemspec
new file mode 100644
index 0000000000..ed5a0dc080
--- /dev/null
+++ b/spec/realworld/fixtures/warbler/demo/demo.gemspec
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+Gem::Specification.new do |spec|
+  spec.name = "demo"
+  spec.version = "1.0"
+  spec.author = "Somebody"
+  spec.summary = "A demo gem"
+  spec.license = "MIT"
+  spec.homepage = "https://example.org"
+end