Merge pull request #18675 from Homebrew/formula_auditor-pkgconf

Library/Homebrew/formula_auditor.rb

@@ -361,8 +361,10 @@ def audit_deps
             EOS
           end
 
-          # we want to allow uses_from_macos for aliases but not bare dependencies
-          if self.class.aliases.include?(dep.name) && !dep.uses_from_macos?
+          # we want to allow uses_from_macos for aliases but not bare dependencies.
+          # we also allow `pkg-config` for backwards compatibility in external taps.
+          # TODO: after migrating all `pkg-config` usage to `pkgconf`, do not allow `pkg-config` in core tap
+          if self.class.aliases.include?(dep.name) && !dep.uses_from_macos? && dep.name != "pkg-config"
             problem "Dependency '#{dep.name}' is an alias; use the canonical name '#{dep.to_formula.full_name}'."
           end