prepend instead of alias hacks for deprecations

Library/Homebrew/compat/dependency_collector.rb

@@ -1,8 +1,7 @@
 require "dependency_collector"
 
 class DependencyCollector
-  alias _parse_string_spec parse_string_spec
-
+  module Compat
     # Define the languages that we can handle as external dependencies.
     LANGUAGE_MODULES = Set[
       :lua, :lua51, :perl, :python, :python3, :ruby
@@ -13,12 +12,10 @@ class DependencyCollector
         odeprecated "'depends_on :#{tag}'"
         LanguageModuleRequirement.new(tag, spec, tags[1])
       else
-      _parse_string_spec(spec, tags)
+        super
       end
     end
 
-  alias _parse_symbol_spec parse_symbol_spec
-
     def parse_symbol_spec(spec, tags)
       case spec
       when :clt
@@ -64,10 +61,12 @@ class DependencyCollector
         output_deprecation(spec)
         Dependency.new(spec, tags)
       else
-      _parse_symbol_spec(spec, tags)
+        super
       end
     end
 
+    private
+
     def autotools_dep(spec, tags)
       tags << :build unless tags.include? :run
       Dependency.new(spec.to_s, tags)
@@ -78,3 +77,6 @@ class DependencyCollector
                   "'depends_on \"#{new_dependency}\"'"
     end
   end
+
+  prepend Compat
+end

Library/Homebrew/compat/formula_support.rb

@@ -1,8 +1,7 @@
 require "formula_support"
 
 class KegOnlyReason
-  alias _to_s to_s
-
+  module Compat
     def to_s
       case @reason
       when :provided_by_osx
@@ -13,6 +12,9 @@ class KegOnlyReason
         @reason = :shadowed_by_macos
       end
 
-    _to_s
+      super
     end
   end
+
+  prepend Compat
+end

Library/Homebrew/test/dependency_collector_spec.rb

@@ -128,5 +128,15 @@ describe DependencyCollector do
       resource.download_strategy = Class.new
       expect { subject.add(resource) }.to raise_error(TypeError)
     end
+
+    it "is deprecated when called with a language module", :needs_compat do
+      expect(subject).to receive(:odeprecated)
+      subject.add("lpeg" => :lua)
+    end
+
+    it "is deprecated when called with deprecated requirements", :needs_compat do
+      expect(subject).to receive(:odeprecated)
+      subject.add(:python)
+    end
   end
 end

Library/Homebrew/test/formula_support_spec.rb

@@ -3,7 +3,7 @@ require "formula_support"
 describe KegOnlyReason do
   describe "#to_s" do
     it "returns the reason provided" do
-      r = KegOnlyReason.new :provided_by_osx, "test"
+      r = KegOnlyReason.new :provided_by_macos, "test"
       expect(r.to_s).to eq("test")
     end
 
@@ -11,6 +11,12 @@ describe KegOnlyReason do
       r = KegOnlyReason.new :provided_by_macos, ""
       expect(r.to_s).to match(/^macOS already provides/)
     end
+
+    it "is deprecated when reason mentions 'osx'", :needs_compat do
+      r = KegOnlyReason.new :provided_by_osx, "test"
+      expect(r).to receive(:odeprecated)
+      r.to_s
+    end
   end
 end