Compare RuboCop version against strings

As of Rubygems 3.5.6 (included in Ruby 3.2 onwards, and often available
in environments with older Ruby versions where Rubygems has been
updated), `Gem::Version#<=>` supports passing in a `String`, instead of
needing to create a `Gem::Version` to pass in.

If we temporarily add a backport, we can use this approach, which makes
the version checks in the YAML+ERB config files more straightforward.

The backport is done in a separate file so we can leverage the
deduplication `require` provides out of the box, so as not to trigger a
method redefinition warning. It also means we'll be able to import it in
our upcoming plugin config files, rather than duplicating it.

lib/rubocop/shopify/gem_version_string_comparable_backport.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# This is true for Ruby 3.2+, so once support for 3.1 is dropped, we can remove this.
+# Until then, some installations may have a recent enough version of RubyGems, but it is not guaranteed.
+return if Gem::Version.new(Gem::VERSION) >= Gem::Version.new("3.5.6")
+
+module RuboCop
+  module Shopify
+    # Backport rubygems/rubygems#5275, so we can compare `Gem::Version`s directly against `String`s.
+    #
+    #     Gem::Version.new("1.2.3") > "1.2"
+    #
+    # Without this, to support Ruby < 3.2, we would have to create a new `Gem::Version` instance ourselves.
+    #
+    #     Gem::Version.new("1.2.3") > Gem::Version.new("1.2")
+    #
+    # This would get very verbose in our RuboCop config files.
+    module GemVersionStringComparableBackport
+      def <=>(other)
+        return self <=> self.class.new(other) if (String === other) && self.class.correct?(other)
+
+        super
+      end
+
+      Gem::Version.prepend(self)
+    end
+  end
+end

rubocop.yml

@@ -1,8 +1,7 @@
 <%
+  require "rubocop/shopify/gem_version_string_comparable_backport"
+
   rubocop_version = Gem.loaded_specs.fetch("rubocop").version
-  v1_57 = Gem::Version.new("1.57")
-  v1_58 = Gem::Version.new("1.58")
-  v1_59 = Gem::Version.new("1.59")
 %>
 
 inherit_mode:
@@ -190,15 +189,15 @@ Lint/IncompatibleIoSelectWithFiberScheduler:
 Lint/InterpolationCheck:
   Enabled: false
 
-<% if rubocop_version >= v1_59 %>
+<% if rubocop_version >= "1.59" %>
 Lint/ItWithoutArgumentsInBlock:
   Enabled: true
 <% end %>
 
 Lint/LambdaWithoutLiteralBlock:
   Enabled: false
 
-<% if rubocop_version >= v1_58 %>
+<% if rubocop_version >= "1.58" %>
 Lint/LiteralAssignmentInCondition:
   Enabled: true
 <% end %>
@@ -811,7 +810,7 @@ Style/SelectByRegexp:
 Style/SingleArgumentDig:
   Enabled: false
 
-<% if rubocop_version >= v1_57 %>
+<% if rubocop_version >= "1.57" %>
 Style/SingleLineDoEndBlock:
   Enabled: true
 <% end %>
@@ -840,7 +839,7 @@ Style/StringLiteralsInInterpolation:
 Style/StructInheritance:
   Enabled: false
 
-<% if rubocop_version >= v1_58 %>
+<% if rubocop_version >= "1.58" %>
 Style/SuperWithArgsParentheses:
   Enabled: true
 <% end %>