brew extract from all taps

Library/Homebrew/dev-cmd/extract.rb

@@ -97,47 +97,64 @@ module Homebrew
     # Expect exactly two named arguments: formula and tap
     raise UsageError if ARGV.named.length != 2
 
+    if ARGV.named.first !~ HOMEBREW_TAP_FORMULA_REGEX
+      name = ARGV.named.first.downcase
+      source_tap = CoreTap.instance
+    else
+      name = Regexp.last_match(3).downcase
+      source_tap = Tap.fetch(Regexp.last_match(1), Regexp.last_match(2))
+      raise TapFormulaUnavailableError.new(source_tap, name) unless source_tap.installed?
+    end
+
     destination_tap = Tap.fetch(ARGV.named.second)
     odie "Cannot extract formula to homebrew/core!" if destination_tap.core_tap?
+    odie "Cannot extract formula to the same tap!" if destination_tap == source_tap
     destination_tap.install unless destination_tap.installed?
 
-    name = ARGV.named.first.downcase
-    repo = CoreTap.instance.path
-    # Formulae can technically live in "<repo>/<formula>.rb" or
-    # "<repo>/Formula/<formula>.rb", but explicitly use the latter for now
-    # since that is how the core tap is structured.
-    file = repo/"Formula/#{name}.rb"
+    repo = source_tap.path
+    pattern = source_tap.core_tap? ? repo/"Formula/#{name}.rb" : repo/"{,**/}#{name}.rb"
 
     if args.version
       ohai "Searching repository history"
       version = args.version
       rev = "HEAD"
       test_formula = nil
+      result = ""
       loop do
-        loop do
-          rev = Git.last_revision_commit_of_file(repo, file, before_commit: "#{rev}~1")
-          break if rev.empty?
-          break unless Git.last_revision_of_file(repo, file, before_commit: rev).empty?
+        rev, (path,) = Git.last_revision_commit_of_files(repo, pattern, before_commit: "#{rev}~1")
+        odie "Could not find #{name}! The formula or version may not have existed." if rev.nil?
 
+        file = repo/path
+        result = Git.last_revision_of_file(repo, file, before_commit: rev)
+        if result.empty?
           ohai "Skipping revision #{rev} - file is empty at this revision" if ARGV.debug?
+          next
         end
+
         test_formula = formula_at_revision(repo, name, file, rev)
         break if test_formula.nil? || test_formula.version == version
 
         ohai "Trying #{test_formula.version} from revision #{rev} against desired #{version}" if ARGV.debug?
       end
       odie "Could not find #{name}! The formula or version may not have existed." if test_formula.nil?
-      result = Git.last_revision_of_file(repo, file, before_commit: rev)
-    elsif File.exist?(file)
-      rev = "HEAD"
-      version = Formulary.factory(file).version
-      result = File.read(file)
     else
-      ohai "Searching repository history"
-      rev = Git.last_revision_commit_of_file(repo, file)
-      version = formula_at_revision(repo, name, file, rev).version
-      odie "Could not find #{name}! The formula or version may not have existed." if rev.empty?
-      result = Git.last_revision_of_file(repo, file)
+      files = Dir[repo/"{,**/}"].map do |dir|
+        Pathname.glob(["#{dir}/#{name}.rb"]).find(&:file?)
+      end.compact
+
+      if files.empty?
+        ohai "Searching repository history"
+        rev, (path,) = Git.last_revision_commit_of_files(repo, pattern)
+        odie "Could not find #{name}! The formula or version may not have existed." if rev.nil?
+        file = repo/path
+        version = formula_at_revision(repo, name, file, rev).version
+        result = Git.last_revision_of_file(repo, file)
+      else
+        file = files.first.realpath
+        rev = "HEAD"
+        version = Formulary.factory(file).version
+        result = File.read(file)
+      end
     end
 
     # The class name has to be renamed to match the new filename,

Library/Homebrew/test/dev-cmd/extract_spec.rb

@@ -1,5 +1,5 @@
 describe "brew extract", :integration_test do
-  it "retrieves the specified version of formula, defaulting to most recent" do
+  it "retrieves the specified version of formula from core tap, defaulting to most recent" do
     path = Tap::TAP_DIRECTORY/"homebrew/homebrew-foo"
     (path/"Formula").mkpath
     target = Tap.from_path(path)
@@ -29,4 +29,69 @@ describe "brew extract", :integration_test do
 
     expect(Formulary.factory(path/"Formula/testball@0.1.rb").version).to be == "0.1"
   end
+
+  it "retrieves the specified version of formula from a tap other than core, defaulting to most recent" do
+    destination = Tap::TAP_DIRECTORY/"homebrew/homebrew-foo"
+    (destination/"Formula").mkpath
+    destination_tap = Tap.from_path(destination)
+
+    source = Tap::TAP_DIRECTORY/"homebrew/homebrew-bar"
+    source.mkpath
+    source_tap = Tap.from_path(source)
+
+    tarball = if OS.linux?
+      TEST_FIXTURE_DIR/"tarballs/testball-0.1-linux.tbz"
+    else
+      TEST_FIXTURE_DIR/"tarballs/testball-0.1.tbz"
+    end
+
+    content = <<~RUBY
+      desc "Some test"
+      homepage "https://brew.sh/testball"
+      url "file://#{tarball}"
+      sha256 "#{tarball.sha256}"
+
+      option "with-foo", "Build with foo"
+
+      def install
+        (prefix/"foo"/"test").write("test") if build.with? "foo"
+        prefix.install Dir["*"]
+        (buildpath/"test.c").write \
+          "#include <stdio.h>\\nint main(){return printf(\\"test\\");}"
+        bin.mkpath
+        system ENV.cc, "test.c", "-o", bin/"test"
+      end
+    RUBY
+
+    formula_file = source_tap.path/"testball.rb"
+    formula_file.write <<~RUBY
+      class Testball < Formula
+        #{content}
+      end
+    RUBY
+
+    source_tap.path.cd do
+      system "git", "init"
+      system "git", "add", "--all"
+      system "git", "commit", "-m", "testball 0.1"
+      contents = File.read(formula_file)
+      contents.gsub!("testball-0.1", "testball-0.2")
+      File.write(formula_file, contents)
+      system "git", "add", "--all"
+      system "git", "commit", "-m", "testball 0.2"
+    end
+    expect { brew "extract", "homebrew/bar/testball", destination_tap.name }
+      .to be_a_success
+
+    expect(destination/"Formula/testball@0.2.rb").to exist
+
+    expect(Formulary.factory(destination/"Formula/testball@0.2.rb").version).to be == "0.2"
+
+    expect { brew "extract", "homebrew/bar/testball", destination_tap.name, "--version=0.1" }
+      .to be_a_success
+
+    expect(destination/"Formula/testball@0.1.rb").to exist
+
+    expect(Formulary.factory(destination/"Formula/testball@0.1.rb").version).to be == "0.1"
+  end
 end

Library/Homebrew/utils/git.rb

@@ -14,6 +14,19 @@ module Git
     out.chomp
   end
 
+  def last_revision_commit_of_files(repo, file, before_commit: nil)
+    args = [before_commit.nil? ? "--skip=1" : before_commit.split("..").first]
+
+    cmd = [
+      HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo,
+      "log", "--format=%h", "--abbrev=7", "--max-count=1", "--name-only",
+      *args, "--", file
+    ]
+    out, = Open3.capture3(cmd.join(" "))
+    rev, *files = out.chomp.split(/\n/).reject(&:empty?)
+    [rev, files]
+  end
+
   def last_revision_of_file(repo, file, before_commit: nil)
     relative_file = Pathname(file).relative_path_from(repo)