setup new formula from homebrew-freecad tap ie. swig

Formula/swig@4.1.1.rb

@@ -0,0 +1,79 @@
+class SwigAT411 < Formula
+  desc "Generate scripting interfaces to C/C++ code"
+  homepage "https://www.swig.org/"
+  # NOTE: see github issue, https://github.com/swig/swig/issues/2069
+  url "https://downloads.sourceforge.net/project/swig/swig/swig-4.1.1/swig-4.1.1.tar.gz"
+  sha256 "2af08aced8fcd65cdb5cc62426768914bedc735b1c250325203716f78e39ac9b"
+  license "GPL-3.0-only"
+
+  livecheck do
+    url :stable
+  end
+
+  head do
+    url "https://github.com/swig/swig.git", branch: "master"
+
+    depends_on "autoconf" => :build
+    depends_on "automake" => :build
+  end
+
+  keg_only :versioned_formula
+
+  depends_on "ruby" => :test if OS.linux?
+  depends_on "pcre2"
+
+  uses_from_macos "ruby" => :test
+
+  def install
+    system "./autogen.sh" if build.head?
+    system "./configure", "--disable-dependency-tracking",
+                          "--prefix=#{prefix}"
+    system "make"
+    system "make", "install"
+  end
+
+  def caveats
+    <<-EOS
+    this formula is keg only due to upstream
+    counterpart in homebrew-core
+    EOS
+  end
+
+  # NOTE: add upstream python test to this formula
+  test do
+    (testpath/"test.c").write <<~EOS
+      int add(int x, int y)
+      {
+        return x + y;
+      }
+    EOS
+    (testpath/"test.i").write <<~EOS
+      %module test
+      %inline %{
+      extern int add(int x, int y);
+      %}
+    EOS
+    (testpath/"run.rb").write <<~EOS
+      require "./test"
+      puts Test.add(1, 1)
+    EOS
+    system "#{bin}/swig", "-ruby", "test.i"
+    if OS.mac?
+      system ENV.cc, "-c", "test.c"
+      system ENV.cc, "-c", "test_wrap.c", "-I#{MacOS.sdk_path}/System/Library/Frameworks/Ruby.framework/Headers/"
+      system ENV.cc, "-bundle", "-undefined", "dynamic_lookup", "test.o", "test_wrap.o", "-o", "test.bundle"
+    else
+      ruby = Formula["ruby"]
+      args = Utils.safe_popen_read(
+        ruby.opt_bin/"ruby", "-e", "'puts RbConfig::CONFIG[\"LIBRUBYARG\"]'"
+      ).chomp
+      system ENV.cc, "-c", "-fPIC", "test.c"
+      system ENV.cc, "-c", "-fPIC", "test_wrap.c",
+        "-I#{ruby.opt_include}/ruby-#{ruby.version.major_minor}.0",
+        "-I#{ruby.opt_include}/ruby-#{ruby.version.major_minor}.0/x86_64-linux/"
+      system ENV.cc, "-shared", "test.o", "test_wrap.o", "-o", "test.so",
+        *args.delete("'").split
+    end
+    assert_equal "2", shell_output("ruby run.rb").strip
+  end
+end