utils/git: modernize

Library/Homebrew/utils/git.rb

 # frozen_string_literal: true
 
-require "open3"
-
 module Utils
   # Helper functions for querying Git information.
   #
@@ -16,7 +14,7 @@ module Utils
     def version
       return @version if defined?(@version)
 
-      stdout, _, status = system_command(HOMEBREW_SHIMS_PATH/"scm/git", args: ["--version"], print_stderr: false)
+      stdout, _, status = system_command(git, args: ["--version"], print_stderr: false)
       @version = status.success? ? stdout.chomp[/git version (\d+(?:\.\d+)*)/, 1] : nil
     end
 
@@ -24,7 +22,13 @@ module Utils
       return unless available?
       return @path if defined?(@path)
 
-      @path = Utils.popen_read(HOMEBREW_SHIMS_PATH/"scm/git", "--homebrew=print-path").chomp.presence
+      @path = Utils.popen_read(git, "--homebrew=print-path").chomp.presence
+    end
+
+    def git
+      return @git if defined?(@git)
+
+      @git = HOMEBREW_SHIMS_PATH/"scm/git"
     end
 
     def remote_exists?(url)
@@ -36,6 +40,7 @@ module Utils
     def clear_available_cache
       remove_instance_variable(:@version) if defined?(@version)
       remove_instance_variable(:@path) if defined?(@path)
+      remove_instance_variable(:@git) if defined?(@git)
     end
 
     def last_revision_commit_of_file(repo, file, before_commit: nil)
@@ -45,12 +50,7 @@ module Utils
         [before_commit.split("..").first]
       end
 
-      out, = Open3.capture3(
-        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo,
-        "log", "--format=%h", "--abbrev=7", "--max-count=1",
-        *args, "--", file
-      )
-      out.chomp
+      Utils.popen_read(git, "-C", repo, "log", "--format=%h", "--abbrev=7", "--max-count=1", *args, "--", file).chomp
     end
 
     def last_revision_commit_of_files(repo, files, before_commit: nil)
@@ -66,12 +66,11 @@ module Utils
       #   <file_path2>
       #   ...
       # return [<commit_hash>, [file_path1, file_path2, ...]]
-      out, = Open3.capture3(
-        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo, "log",
+      rev, *paths = Utils.popen_read(
+        git, "-C", repo, "log",
         "--pretty=format:%h", "--abbrev=7", "--max-count=1",
         "--diff-filter=d", "--name-only", *args, "--", *files
-      )
-      rev, *paths = out.chomp.split(/\n/).reject(&:empty?)
+      ).lines.map(&:chomp).reject(&:empty?)
       [rev, paths]
     end
 
@@ -79,11 +78,7 @@ module Utils
       relative_file = Pathname(file).relative_path_from(repo)
 
       commit_hash = last_revision_commit_of_file(repo, relative_file, before_commit: before_commit)
-      out, = Open3.capture3(
-        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo,
-        "show", "#{commit_hash}:#{relative_file}"
-      )
-      out
+      Utils.popen_read(git, "-C", repo, "show", "#{commit_hash}:#{relative_file}")
     end
 
     def ensure_installed!
@@ -121,7 +116,7 @@ module Utils
     end
 
     def origin_branch(repo)
-      Utils.popen_read("git", "-C", repo, "symbolic-ref", "-q", "--short",
+      Utils.popen_read(git, "-C", repo, "symbolic-ref", "-q", "--short",
                        "refs/remotes/origin/HEAD").chomp.presence
     end
   end