Report which locked gems have no variant for the current platform

Author: Mousa96

lib/bundler/definition.rb

@@ -743,7 +743,9 @@ def materialize(dependencies)
       loop do
         break if incomplete_specs.empty?
 
-        Bundler.ui.debug("The lockfile does not have all gems needed for the current platform though, Bundler will still re-resolve dependencies")
+        Bundler.ui.debug("The lockfile does not have all gems needed for the current platform (#{Bundler.local_platform}) though, " \
+                         "Bundler will still re-resolve dependencies. The following locked gems have no variant for it: " \
+                         "#{incomplete_specs.map(&:full_name).join(", ")}")
         sources.remote!
         reresolve_without(incomplete_specs)
         specs = resolve.materialize(dependencies)

spec/runtime/platform_spec.rb

@@ -433,7 +433,8 @@
         gem "requires_platform_specific"
       G
 
-      expect(out).to include("lockfile does not have all gems needed for the current platform")
+      expect(out).to include("lockfile does not have all gems needed for the current platform (x64-mingw-ucrt)")
+      expect(out).to include("no variant for it: platform_specific-1.0-x86-mingw32")
       expect(the_bundle).to include_gem "platform_specific 1.0 x64-mingw-ucrt"
     end
   end