class Gcc < Formula
  desc "GNU compiler collection"
  homepage "https://gcc.gnu.org/"
  head "svn://gcc.gnu.org/svn/gcc/trunk"

  stable do
    url "https://ftp.gnu.org/gnu/gcc/gcc-7.3.0/gcc-7.3.0.tar.xz"
    mirror "https://ftpmirror.gnu.org/gcc/gcc-7.3.0/gcc-7.3.0.tar.xz"
    sha256 "832ca6ae04636adbb430e865a1451adf6979ab44ca1c8374f61fba65645ce15c"
  end

  bottle do
    sha256 "276420d0b1f1355189ee6701408dfbf351477b7d7166c1ffca313a4368bfb5d8" => :high_sierra
    sha256 "a1f43d52abe183d270997256f32463281ae3d3c5d2a40f7348d6170a55555246" => :sierra
    sha256 "f582beda3d37ceaa591bdf3070e357adb31967d8edee2f8075c15732740c7fe8" => :el_capitan
  end

  option "with-jit", "Build just-in-time compiler"
  option "with-nls", "Build with native language support (localization)"

  depends_on "gmp"
  depends_on "libmpc"
  depends_on "mpfr"
  depends_on "isl"

  # GCC bootstraps itself, so it is OK to have an incompatible C++ stdlib
  cxxstdlib_check :skip

  # The bottles are built on systems with the CLT installed, and do not work
  # out of the box on Xcode-only systems due to an incorrect sysroot.
  pour_bottle? do
    reason "The bottle needs the Xcode CLT to be installed."
    satisfy { MacOS::CLT.installed? }
  end

  def version_suffix
    if build.head?
      "HEAD"
    else
      version.to_s.slice(/\d/)
    end
  end

  # Fix for libgccjit.so linkage on Darwin
  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64089
  # https://github.com/Homebrew/homebrew-core/issues/1872#issuecomment-225625332
  # https://github.com/Homebrew/homebrew-core/issues/1872#issuecomment-225626490
  patch do
    url "https://raw.githubusercontent.com/Homebrew/formula-patches/e9e0ee09389a54cc4c8fe1c24ebca3cd765ed0ba/gcc/6.1.0-jit.patch"
    sha256 "863957f90a934ee8f89707980473769cff47ca0663c3906992da6afb242fb220"
  end

  # Use -headerpad_max_install_names in the build,
  # otherwise lto1 load commands cannot be edited on El Capitan
  if MacOS.version == :el_capitan
    patch do
      url "https://raw.githubusercontent.com/Homebrew/formula-patches/32cf103/gcc/7.1.0-headerpad.patch"
      sha256 "dd884134e49ae552b51085116e437eafa63460b57ce84252bfe7a69df8401640"
    end
  end

  # Fix parallel build on APFS filesystem
  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
  if MacOS.version >= :high_sierra
    patch do
      url "https://raw.githubusercontent.com/Homebrew/formula-patches/df0465c02a/gcc/apfs.patch"
      sha256 "f7772a6ba73f44a6b378e4fe3548e0284f48ae2d02c701df1be93780c1607074"
    end
  end

  def install
    # GCC will suffer build errors if forced to use a particular linker.
    ENV.delete "LD"

    # We avoiding building:
    #  - Ada, which requires a pre-existing GCC Ada compiler to bootstrap
    #  - Go, currently not supported on macOS
    #  - BRIG
    languages = %w[c c++ objc obj-c++ fortran]

    # JIT compiler is off by default, enabling it has performance cost
    languages << "jit" if build.with? "jit"

    osmajor = `uname -r`.chomp

    args = [
      "--build=x86_64-apple-darwin#{osmajor}",
      "--prefix=#{prefix}",
      "--libdir=#{lib}/gcc/#{version_suffix}",
      "--enable-languages=#{languages.join(",")}",
      # Make most executables versioned to avoid conflicts.
      "--program-suffix=-#{version_suffix}",
      "--with-gmp=#{Formula["gmp"].opt_prefix}",
      "--with-mpfr=#{Formula["mpfr"].opt_prefix}",
      "--with-mpc=#{Formula["libmpc"].opt_prefix}",
      "--with-isl=#{Formula["isl"].opt_prefix}",
      "--with-system-zlib",
      "--enable-checking=release",
      "--with-pkgversion=Homebrew GCC #{pkg_version} #{build.used_options*" "}".strip,
      "--with-bugurl=https://github.com/Homebrew/homebrew-core/issues",
    ]

    args << "--disable-nls" if build.without? "nls"
    args << "--enable-host-shared" if build.with?("jit")

    # Ensure correct install names when linking against libgcc_s;
    # see discussion in https://github.com/Homebrew/homebrew/pull/34303
    inreplace "libgcc/config/t-slibgcc-darwin", "@shlib_slibdir@", "#{HOMEBREW_PREFIX}/lib/gcc/#{version_suffix}"

    mkdir "build" do
      unless MacOS::CLT.installed?
        # For Xcode-only systems, we need to tell the sysroot path.
        # "native-system-headers" will be appended
        args << "--with-native-system-header-dir=/usr/include"
        args << "--with-sysroot=#{MacOS.sdk_path}"
      end

      system "../configure", *args
      system "make"
      system "make", "install"

      bin.install_symlink bin/"gfortran-#{version_suffix}" => "gfortran"
    end

    # Handle conflicts between GCC formulae and avoid interfering
    # with system compilers.
    # Rename man7.
    Dir.glob(man7/"*.7") { |file| add_suffix file, version_suffix }
    # Even when we disable building info pages some are still installed.
    info.rmtree
  end

  def add_suffix(file, suffix)
    dir = File.dirname(file)
    ext = File.extname(file)
    base = File.basename(file, ext)
    File.rename file, "#{dir}/#{base}-#{suffix}#{ext}"
  end

  test do
    (testpath/"hello-c.c").write <<~EOS
      #include <stdio.h>
      int main()
      {
        puts("Hello, world!");
        return 0;
      }
    EOS
    system "#{bin}/gcc-#{version_suffix}", "-o", "hello-c", "hello-c.c"
    assert_equal "Hello, world!\n", `./hello-c`

    (testpath/"hello-cc.cc").write <<~EOS
      #include <iostream>
      int main()
      {
        std::cout << "Hello, world!" << std::endl;
        return 0;
      }
    EOS
    system "#{bin}/g++-#{version_suffix}", "-o", "hello-cc", "hello-cc.cc"
    assert_equal "Hello, world!\n", `./hello-cc`

    (testpath/"test.f90").write <<~EOS
      integer,parameter::m=10000
      real::a(m), b(m)
      real::fact=0.5

      do concurrent (i=1:m)
        a(i) = a(i) + fact*b(i)
      end do
      write(*,"(A)") "Done"
      end
    EOS
    system "#{bin}/gfortran", "-o", "test", "test.f90"
    assert_equal "Done\n", `./test`
  end
end