Audit use of :run dependencies.

These are a no-op so let's remove them.

Library/Homebrew/compat.rb

@@ -29,3 +29,4 @@ require "compat/ENV/super"
 require "compat/utils/shell"
 require "compat/extend/string"
 require "compat/gpg"
+require "compat/dependable"

Library/Homebrew/compat/dependable.rb

@@ -0,0 +1,5 @@
+module Dependable
+  def run?
+    tags.include? :run
+  end
+end

Library/Homebrew/compat/dependency_collector.rb

@@ -33,7 +33,6 @@ class DependencyCollector
         output_deprecation(spec)
         Dependency.new(spec.to_s, tags)
       when :libltdl
-        tags << :run
         output_deprecation("libtool")
         Dependency.new("libtool", tags)
       when :apr
@@ -68,7 +67,7 @@ class DependencyCollector
     private
 
     def autotools_dep(spec, tags)
-      tags << :build unless tags.include? :run
+      tags << :build
       Dependency.new(spec.to_s, tags)
     end
 

Library/Homebrew/dependable.rb

@@ -1,6 +1,8 @@
 require "options"
 
 module Dependable
+  # :run and :linked are no longer used but keep them here to avoid them being
+  # misused in future.
   RESERVED_TAGS = [:build, :optional, :recommended, :run, :test, :linked].freeze
 
   def build?
@@ -15,10 +17,6 @@ module Dependable
     tags.include? :recommended
   end
 
-  def run?
-    tags.include? :run
-  end
-
   def test?
     tags.include? :test
   end

Library/Homebrew/dependency.rb

@@ -163,13 +163,9 @@ class Dependency
     end
 
     def merge_temporality(deps)
-      if deps.all?(&:build?)
-        [:build]
-      elsif deps.all?(&:run?)
-        [:run]
-      else
-        [] # Means both build and runtime dependency.
-      end
+      # Means both build and runtime dependency.
+      return [] unless deps.all?(&:build?)
+      [:build]
     end
   end
 end

Library/Homebrew/dev-cmd/audit.rb

@@ -172,23 +172,6 @@ class FormulaAuditor
 
   attr_reader :formula, :text, :problems
 
-  BUILD_TIME_DEPS = %w[
-    autoconf
-    automake
-    boost-build
-    bsdmake
-    cmake
-    godep
-    imake
-    intltool
-    libtool
-    pkg-config
-    scons
-    smake
-    sphinx-doc
-    swig
-  ].freeze
-
   def initialize(formula, options = {})
     @formula = formula
     @new_formula = options[:new_formula]
@@ -377,17 +360,12 @@ class FormulaAuditor
           problem "Dependency #{dep} does not define option #{opt.name.inspect}"
         end
 
-        case dep.name
-        when "git"
+        if dep.name == "git"
           problem "Don't use git as a dependency (it's always available)"
-        when *BUILD_TIME_DEPS
-          next if dep.build? || dep.run?
-          problem <<~EOS
-            #{dep} dependency should be
-              depends_on "#{dep}" => :build
-            Or if it is indeed a runtime dependency
-              depends_on "#{dep}" => :run
-          EOS
+        end
+
+        if dep.tags.include?(:run)
+          problem "Dependency '#{dep.name}' is marked as :run. Remove :run; it is a no-op."
         end
       end
     end

Library/Homebrew/rubocops/dependency_order_cop.rb

@@ -48,7 +48,7 @@ module RuboCop
         def sort_dependencies_by_type(dependency_nodes)
           ordered = []
           ordered.concat(dependency_nodes.select { |dep| buildtime_dependency? dep }.to_a)
-          ordered.concat(dependency_nodes.select { |dep| runtime_dependency? dep }.to_a)
+          ordered.concat(dependency_nodes.select { |dep| test_dependency? dep }.to_a)
           ordered.concat(dependency_nodes.reject { |dep| negate_normal_dependency? dep }.to_a)
           ordered.concat(dependency_nodes.select { |dep| recommended_dependency? dep }.to_a)
           ordered.concat(dependency_nodes.select { |dep| optional_dependency? dep }.to_a)
@@ -106,11 +106,11 @@ module RuboCop
 
         def_node_search :recommended_dependency?, "(sym :recommended)"
 
-        def_node_search :runtime_dependency?, "(sym :run)"
+        def_node_search :test_dependency?, "(sym :test)"
 
         def_node_search :optional_dependency?, "(sym :optional)"
 
-        def_node_search :negate_normal_dependency?, "(sym {:build :recommended :run :optional})"
+        def_node_search :negate_normal_dependency?, "(sym {:build :recommended :test :optional})"
 
         # Node pattern method to extract `name` in `depends_on :name`
         def_node_search :dependency_name_node, <<~EOS

Library/Homebrew/rubocops/extend/formula_cop.rb

@@ -171,7 +171,7 @@ module RuboCop
         when :required
           type_match = required_dependency?(node)
           name_match ||= required_dependency_name?(node, name) if type_match
-        when :build, :optional, :recommended, :run
+        when :build, :test, :optional, :recommended
           type_match = dependency_type_hash_match?(node, type)
           name_match ||= dependency_name_hash_match?(node, name) if type_match
         when :any

Library/Homebrew/test/dependency_spec.rb

@@ -2,7 +2,6 @@ require "dependency"
 
 describe Dependency do
   alias_matcher :be_a_build_dependency, :be_build
-  alias_matcher :be_a_runtime_dependency, :be_run
 
   describe "::new" do
     it "accepts a single tag" do
@@ -73,22 +72,10 @@ describe Dependency do
     it "merges temporality tags" do
       normal_dep = described_class.new("foo")
       build_dep = described_class.new("foo", [:build])
-      run_dep = described_class.new("foo", [:run])
 
       deps = described_class.merge_repeats([normal_dep, build_dep])
       expect(deps.count).to eq(1)
       expect(deps.first).not_to be_a_build_dependency
-      expect(deps.first).not_to be_a_runtime_dependency
-
-      deps = described_class.merge_repeats([normal_dep, run_dep])
-      expect(deps.count).to eq(1)
-      expect(deps.first).not_to be_a_build_dependency
-      expect(deps.first).not_to be_a_runtime_dependency
-
-      deps = described_class.merge_repeats([build_dep, run_dep])
-      expect(deps.count).to eq(1)
-      expect(deps.first).not_to be_a_build_dependency
-      expect(deps.first).not_to be_a_runtime_dependency
     end
   end
 

docs/Formula-Cookbook.md

@@ -130,7 +130,7 @@ to favour finding `keg_only` formulae first.
 
 ```ruby
 class Foo < Formula
-  depends_on "pkg-config" => :run
+  depends_on "pkg-config"
   depends_on "jpeg"
   depends_on "readline" => :recommended
   depends_on "gtk+" => :optional
@@ -144,16 +144,13 @@ A Symbol (e.g. `:x11`) specifies a [`Requirement`](http://www.rubydoc.info/githu
 
 A Hash (e.g. `=>`) specifies a formula dependency with some additional information. Given a single string key, the value can take several forms:
 
-*   a Symbol (currently one of `:build`, `:optional`, `:run` or `:recommended`)
+*   a Symbol (currently one of `:build`, `:test`, `:optional` or `:recommended`)
     - `:build` means that dependency is a build-time only dependency so it can
       be skipped when installing from a bottle or when listing missing
       dependencies using `brew missing`.
+      - `:test` means that dependency is only required when running `brew test`.
     - `:optional` generates an implicit `with-foo` option for the formula.
       This means that, given `depends_on "foo" => :optional`, the user must pass `--with-foo` in order to use the dependency.
-    - `:run` can mean the dependency is only required at runtime, or it can be used
-      to declare build dependencies such as `pkg-config` that are needed at
-      runtime as well, which will silence the audit warning. `:run` dependencies
-      are currently available at build time.
     - `:recommended` generates an implicit `without-foo` option, meaning that
       the dependency is enabled by default and the user must pass
       `--without-foo` to disable this dependency. The default