[ruby/rubygems] Fall back from per-gem lookup to an :all override

Override.find_for now returns the per-gem entry when present and
otherwise the matching :all entry on the same field. This is the
single dispatch point for overrides in Definition and Resolver, so
the fallback is what wires :all into resolution and lockfile change
detection without further plumbing.

https://github.com/ruby/rubygems/commit/ef24b4eef9

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2 files changed, 18 insertions, 1 deletions

diff --git a/lib/bundler/override.rb b/lib/bundler/override.rb
index 9d0db30d6a..ed5b51281f 100644
--- a/lib/bundler/override.rb
+++ b/lib/bundler/override.rb
@@ -5,7 +5,8 @@ module Bundler
     UPPER_BOUND_OPERATORS = ["<", "<="].freeze
 
     def self.find_for(overrides, name, field)
-      overrides.find {|o| o.target == name && o.field == field }
+      overrides.find {|o| o.target == name && o.field == field } ||
+        overrides.find {|o| o.target == :all && o.field == field }
     end
 
     attr_reader :target, :field, :operation
diff --git a/spec/bundler/bundler/override_spec.rb b/spec/bundler/bundler/override_spec.rb
index e0ef4ed54d..78f7a62900 100644
--- a/spec/bundler/bundler/override_spec.rb
+++ b/spec/bundler/bundler/override_spec.rb
@@ -21,6 +21,22 @@ RSpec.describe Bundler::Override do
     it "returns nil for an empty overrides list" do
       expect(described_class.find_for([], "rails", :version)).to be_nil
     end
+
+    it "falls back to an :all override on the same field" do
+      a = described_class.new(:all, :required_ruby_version, :ignore_upper)
+      expect(described_class.find_for([a], "rails", :required_ruby_version)).to be(a)
+    end
+
+    it "prefers a per-gem override over a matching :all override" do
+      per_gem = described_class.new("rails", :required_ruby_version, ">= 3.4")
+      all_target = described_class.new(:all, :required_ruby_version, :ignore_upper)
+      expect(described_class.find_for([all_target, per_gem], "rails", :required_ruby_version)).to be(per_gem)
+    end
+
+    it "does not fall back to :all when the field differs" do
+      a = described_class.new(:all, :required_ruby_version, :ignore_upper)
+      expect(described_class.find_for([a], "rails", :required_rubygems_version)).to be_nil
+    end
   end
 
   describe "#apply_to" do