lightgbm 2.2.3 (new formula)

Closes #43244.

Signed-off-by: FX Coudert <fxcoudert@gmail.com>

Formula/lightgbm.rb

@@ -0,0 +1,34 @@
+class Lightgbm < Formula
+  desc "Fast, distributed, high performance gradient boosting framework"
+  homepage "https://github.com/microsoft/LightGBM"
+  url "https://github.com/microsoft/LightGBM/archive/v2.2.3.tar.gz"
+  sha256 "4a6414e808b343a784f0ee805ac723c094488f9e9a951dd3f709dc31ffb4ea4c"
+
+  depends_on "cmake" => :build
+  depends_on "libomp"
+
+  def install
+    mkdir "build" do
+      libomp = Formula["libomp"]
+      args = std_cmake_args
+      args << "-DOpenMP_C_FLAGS=\"-Xpreprocessor -fopenmp -I#{libomp.opt_include}\""
+      args << "-DOpenMP_C_LIB_NAMES=omp"
+      args << "-DOpenMP_CXX_FLAGS=\"-Xpreprocessor -fopenmp -I#{libomp.opt_include}\""
+      args << "-DOpenMP_CXX_LIB_NAMES=omp"
+      args << "-DOpenMP_omp_LIBRARY=#{libomp.opt_lib}/libomp.dylib"
+      args << "-DAPPLE_OUTPUT_DYLIB=ON"
+
+      system "cmake", *args, ".."
+      system "make"
+      system "make", "install"
+    end
+    pkgshare.install "examples"
+  end
+
+  test do
+    cp_r (pkgshare/"examples/regression"), testpath
+    cd "regression" do
+      system "#{bin}/lightgbm", "config=train.conf"
+    end
+  end
+end