Move expand action constants to Dependable module

PRUNE, SKIP, and KEEP_BUT_PRUNE_RECURSIVE_DEPS were defined
separately on Dependency and Requirement with identical values.
This coupling was fragile — if either constant changed, the
polymorphic code in dependencies_helpers.rb would silently break.

Move the constants to the shared Dependable module (included by
both classes) so there is a single source of truth, and update
all callers to reference Dependable:: directly.

Author: dduugg

Library/Homebrew/build.rb

@@ -62,7 +62,7 @@ def expand_reqs
       dependent = T.cast(dependent, Formula)
       build = effective_build_options_for(dependent)
       if req.prune_from_option?(build) || req.prune_if_build_and_not_dependent?(dependent, formula) || req.test?
-        next Requirement::PRUNE
+        next Dependable::PRUNE
       end
     end
   end
@@ -74,9 +74,9 @@ def expand_deps
       if dep.prune_from_option?(build) ||
          dep.prune_if_build_and_not_dependent?(T.cast(dependent, Formula), formula) ||
          (dep.test? && !dep.build?) || dep.implicit?
-        next Dependency::PRUNE
+        next Dependable::PRUNE
       elsif dep.build?
-        next Dependency::KEEP_BUT_PRUNE_RECURSIVE_DEPS
+        next Dependable::KEEP_BUT_PRUNE_RECURSIVE_DEPS
       end
     end
   end

Library/Homebrew/dependable.rb

@@ -7,6 +7,16 @@
 module Dependable
   extend T::Helpers
 
+  # Return from an {Dependency.expand} or {Requirement.expand} block to remove
+  # a dependency/requirement and all of its recursive dependencies from the result list.
+  PRUNE = :prune
+  # Return from a {Dependency.expand} block to omit a dependency from the result
+  # list but continue expanding its children.
+  SKIP = :skip
+  # Return from a {Dependency.expand} block to keep a dependency in the result
+  # list but stop recursing into its own dependencies.
+  KEEP_BUT_PRUNE_RECURSIVE_DEPS = :keep_but_prune_recursive_deps
+
   # `:run` and `:linked` are no longer used but keep them here to avoid their
   # misuse in future.
   RESERVED_TAGS = T.let(

Library/Homebrew/dependencies_helpers.rb

@@ -50,11 +50,9 @@ def recursive_req_includes(root_dependent, includes, ignores)
   def recursive_includes(klass, root_dependent, includes, ignores)
     cache_key = "recursive_includes_#{includes}_#{ignores}"
 
-    # Dependency::PRUNE and Requirement::PRUNE are both :prune, so these
-    # constants work regardless of which klass is passed.
     klass.expand(root_dependent, cache_key:) do |dependent, dep|
-      next Dependency::PRUNE if ignores.any? { |ignore| dep.public_send(ignore) }
-      next Dependency::PRUNE if includes.none? do |include|
+      next Dependable::PRUNE if ignores.any? { |ignore| dep.public_send(ignore) }
+      next Dependable::PRUNE if includes.none? do |include|
         # Ignore indirect test dependencies
         next if include == :test? && dependent != root_dependent
 
@@ -63,7 +61,7 @@ def recursive_includes(klass, root_dependent, includes, ignores)
 
       # If a tap isn't installed, we can't find the dependencies of one of
       # its formulae and an exception will be thrown if we try.
-      next Dependency::KEEP_BUT_PRUNE_RECURSIVE_DEPS if klass == Dependency && (tap = dep.tap) && !tap.installed?
+      next Dependable::KEEP_BUT_PRUNE_RECURSIVE_DEPS if klass == Dependency && (tap = dep.tap) && !tap.installed?
     end
   end
 

Library/Homebrew/dependency.rb

@@ -10,16 +10,6 @@
 class Dependency
   include Dependable
 
-  # Return from an {expand} block to keep a dependency in the result list
-  # but stop recursing into its own dependencies.
-  KEEP_BUT_PRUNE_RECURSIVE_DEPS = :keep_but_prune_recursive_deps
-  # Return from an {expand} block to remove a dependency and all of its
-  # recursive dependencies from the result list.
-  PRUNE = :prune
-  # Return from an {expand} block to omit a dependency from the result list
-  # but continue expanding its children.
-  SKIP = :skip
-
   sig { returns(String) }
   attr_reader :name
 
@@ -211,13 +201,13 @@ def expand(dependent, deps = dependent.deps, cache_key: nil, cache_timestamp: ni
           next if dependent.name == dep.name
 
           case action(dependent, dep, &block)
-          when PRUNE
+          when Dependable::PRUNE
             next
-          when SKIP
+          when Dependable::SKIP
             next if @expand_stack.include? dep.name
 
             expanded_deps.concat(expand(dep.to_formula, cache_key:, &block))
-          when KEEP_BUT_PRUNE_RECURSIVE_DEPS
+          when Dependable::KEEP_BUT_PRUNE_RECURSIVE_DEPS
             expanded_deps << dep
           else
             next if @expand_stack.include? dep.name
@@ -252,7 +242,7 @@ def action(dependent, dep, &block)
       if block
         yield dependent, dep
       elsif dep.optional? || dep.recommended?
-        PRUNE unless T.cast(dependent, Formula).build.with?(dep)
+        Dependable::PRUNE unless T.cast(dependent, Formula).build.with?(dep)
       end
     end
 

Library/Homebrew/dev-cmd/test.rb

@@ -58,10 +58,10 @@ def run
 
           # Don't test formulae missing test dependencies
           missing_test_deps = f.recursive_dependencies do |dependent, dependency|
-            next Dependency::PRUNE if dependency.installed?
+            next Dependable::PRUNE if dependency.installed?
             next if dependency.test? && dependent == f
 
-            next Dependency::PRUNE unless dependency.required?
+            next Dependable::PRUNE unless dependency.required?
           end.map(&:to_s)
           unless missing_test_deps.empty?
             ofail "#{f.full_name} is missing test dependencies: #{missing_test_deps.join(" ")}"

Library/Homebrew/dev-cmd/unbottled.rb

@@ -185,7 +185,7 @@ def deps_uses_from_formulae(all_formulae)
 
         all_formulae.each do |f|
           deps = Dependency.expand(f, cache_key: "unbottled") do |_, dep|
-            next Dependency::PRUNE if dep.optional?
+            next Dependable::PRUNE if dep.optional?
           end.map(&:to_formula)
           deps_hash[f.name] = deps
 

Library/Homebrew/extend/os/linux/cmd/update-report.rb

@@ -20,7 +20,7 @@ def migrate_gcc_dependents_if_needed
         formula,
         cache_key: "update-report",
       ) do |_, dependency|
-        next Dependency::PRUNE if dependency.build? || dependency.test?
+        next Dependable::PRUNE if dependency.build? || dependency.test?
       end
       next unless recursive_runtime_dependencies.map(&:name).include? "gcc"
 

Library/Homebrew/formula.rb

@@ -3264,13 +3264,13 @@ def declared_runtime_dependencies
       cache_timestamp = Time.now
     end
     Dependency.expand(self, cache_key:, cache_timestamp:) do |_, dependency|
-      next Dependency::PRUNE if dependency.build?
+      next Dependable::PRUNE if dependency.build?
       next if dependency.required?
 
       if build.any_args_or_options?
-        next Dependency::PRUNE if build.without?(dependency)
+        next Dependable::PRUNE if build.without?(dependency)
       elsif !dependency.recommended?
-        next Dependency::PRUNE
+        next Dependable::PRUNE
       end
     end
   ensure

Library/Homebrew/formula_installer.rb

@@ -704,7 +704,7 @@ def check_requirements(req_map)
   def runtime_requirements(formula)
     runtime_deps = formula.runtime_formula_dependencies(undeclared: false)
     recursive_requirements = formula.recursive_requirements do |dependent, _|
-      next Requirement::PRUNE unless runtime_deps.include?(dependent)
+      next Dependable::PRUNE unless runtime_deps.include?(dependent)
     end
     (recursive_requirements.to_a + formula.requirements.to_a).reject(&:build?).uniq
   end
@@ -733,7 +733,7 @@ def expand_requirements
            ((req.build? || req.test?) && !keep_build_test) ||
            formula_deps_map[dependent.name]&.build? ||
            (only_deps? && f == dependent)
-          next Requirement::PRUNE
+          next Dependable::PRUNE
         else
           unsatisfied_reqs[dependent] << req
         end
@@ -762,9 +762,9 @@ def expand_dependencies_for_formula(formula)
       bottle_os_version = @bottle_built_os_version
 
       if dep.prune_from_option?(build) || ((dep.build? || dep.test?) && !keep_build_test)
-        next Dependency::PRUNE
+        next Dependable::PRUNE
       elsif dep.satisfied?(minimum_version:, minimum_revision:, bottle_os_version:)
-        next Dependency::SKIP
+        next Dependable::SKIP
       end
     end
   end

Library/Homebrew/language/python.rb

@@ -195,18 +195,18 @@ def virtualenv_create(venv_root, python = "python", formula = T.cast(self, Formu
         # Find any Python bindings provided by recursive dependencies
         pth_contents = []
         formula.recursive_dependencies do |dependent, dep|
-          next Dependency::PRUNE if dep.build? || dep.test?
+          next Dependable::PRUNE if dep.build? || dep.test?
           # Apply default filter
-          next Dependency::PRUNE if (dep.optional? || dep.recommended?) && !T.cast(dependent,
+          next Dependable::PRUNE if (dep.optional? || dep.recommended?) && !T.cast(dependent,
                                                                                    Formula).build.with?(dep)
           # Do not add the main site-package provided by the brewed
           # Python formula, to keep the virtual-env's site-package pristine
-          next Dependency::PRUNE if python_names.include? dep.name
+          next Dependable::PRUNE if python_names.include? dep.name
           # Skip uses_from_macos dependencies as these imply no Python bindings
-          next Dependency::PRUNE if dep.uses_from_macos?
+          next Dependable::PRUNE if dep.uses_from_macos?
 
           dep_site_packages = dep.to_formula.opt_prefix/Language::Python.site_packages(python)
-          next Dependency::PRUNE unless dep_site_packages.exist?
+          next Dependable::PRUNE unless dep_site_packages.exist?
 
           pth_contents << "import site; site.addsitedir('#{dep_site_packages}')\n"
           nil # Return nil to satisfy T.nilable(Symbol) block sig (Array from << would violate it).