[rubygems/rubygems] Avoid crashing with a corrupted lockfile

I did a bad thing (script that edits the Gemfile.lock directly) and
ended up with a Gemfile.lock that was completely missing some indirect
dependencies. While this is my fault and an error is reasonable, I
noticed that the error got progressively less friendly in recent
versions of bundler.

Something similar came up in https://github.com/rubygems/rubygems/issues/6210,
and this commit would have helped with that case as well
(although we've already handled this a different way with #6219).

Details:
---

Back on Bundler 2.2.23, a corrupt lockfile like this would cause a helpful error:

```
Unable to find a spec satisfying minitest (>= 5.1) in the set. Perhaps the lockfile is corrupted?
```

Bundler 2.3.26 gave a helpful warning:

```
Warning:
Your lockfile was created by an old Bundler that left some things out.
Because of the missing DEPENDENCIES, we can only install gems one at a time,
instead of installing 16 at a time.
You can fix this by adding the missing gems to your Gemfile, running bundle
install, and then removing the gems from your Gemfile.
The missing gems are:
* minitest depended upon by activesupport
```

But then continued on and crashed while trying to report the unmet
dependency:

```
--- ERROR REPORT TEMPLATE -------------------------------------------------------

NoMethodError: undefined method `full_name' for nil:NilClass
lib/bundler/installer/parallel_installer.rb:127:in `block (2 levels) in check_for_unmet_dependencies'

...
```

Bundler 2.4.0 and up crash as above when jobs=1, but crash
even harder when run in parallel:

```
--- ERROR REPORT TEMPLATE -------------------------------------------------------

fatal: No live threads left. Deadlock?
3 threads, 3 sleeps current:0x00007fa6b6704660 main thread:0x00007fa6b6704660
* #<Thread:0x000000010833b130 sleep_forever>
   rb_thread_t:0x00007fa6b6704660 native:0x0000000108985600 int:0

* #<Thread:0x0000000108dea630@Parallel Installer Worker #0 tmp/1/gems/system/gems/bundler-2.5.0.dev/lib/bundler/worker.rb:90 sleep_forever>
   rb_thread_t:0x00007fa6b67f67c0 native:0x0000700009a62000 int:0

* #<Thread:0x0000000108dea4a0@Parallel Installer Worker #1 tmp/1/gems/system/gems/bundler-2.5.0.dev/lib/bundler/worker.rb:90 sleep_forever>
   rb_thread_t:0x00007fa6b67f63c0 native:0x0000700009c65000 int:0

<internal:thread_sync>:18:in `pop'
tmp/1/gems/system/gems/bundler-2.5.0.dev/lib/bundler/worker.rb:42:in `deq'

...
```

Changes
---

This commit fixes the confusing thread deadlock crash by detecting if
dependencies are missing such that we'll never be able to enqueue. When
that happens we treat it as a failure so the install can finish.

That gets us back to the `NoMethodError`, which this commit fixes by
using a different warning in the case where no spec is found.

https://github.com/rubygems/rubygems/commit/d73001a21d

1 files changed, 15 insertions, 1 deletions

diff --git a/lib/bundler/installer/parallel_installer.rb b/lib/bundler/installer/parallel_installer.rb
index c1bc8eff55..851b6c8d41 100644
--- a/lib/bundler/installer/parallel_installer.rb
+++ b/lib/bundler/installer/parallel_installer.rb
@@ -47,6 +47,13 @@ module Bundler
         dependencies.all? {|d| installed_specs.include? d.name }
       end
 
+      # Check whether spec's dependencies are missing, which can indicate a
+      # corrupted lockfile
+      def dependencies_missing?(all_specs)
+        spec_names = all_specs.map(&:name)
+        dependencies.any? {|d| !spec_names.include? d.name }
+      end
+
       # Represents only the non-development dependencies, the ones that are
       # itself and are in the total list.
       def dependencies
@@ -115,7 +122,12 @@ module Bundler
 
       unmet_dependencies.each do |spec, unmet_spec_dependencies|
         unmet_spec_dependencies.each do |unmet_spec_dependency|
-          warning << "* #{unmet_spec_dependency}, dependency of #{spec.full_name}, unsatisfied by #{@specs.find {|s| s.name == unmet_spec_dependency.name && !unmet_spec_dependency.matches_spec?(s.spec) }.full_name}"
+          found = @specs.find {|s| s.name == unmet_spec_dependency.name && !unmet_spec_dependency.matches_spec?(s.spec) }
+          if found
+            warning << "* #{unmet_spec_dependency}, dependency of #{spec.full_name}, unsatisfied by #{found.full_name}"
+          else
+            warning << "* #{unmet_spec_dependency}, dependency of #{spec.full_name} but missing from lockfile"
+          end
         end
       end
 
@@ -212,6 +224,8 @@ module Bundler
         if spec.dependencies_installed? @specs
           spec.state = :enqueued
           worker_pool.enq spec
+        elsif spec.dependencies_missing? @specs
+          spec.state = :failed
         end
       end
     end