class GccAT7 < Formula
  desc "GNU compiler collection"
  homepage "https://gcc.gnu.org/"
  url "https://ftp.gnu.org/gnu/gcc/gcc-7.5.0/gcc-7.5.0.tar.xz"
  mirror "https://ftpmirror.gnu.org/gcc/gcc-7.5.0/gcc-7.5.0.tar.xz"
  sha256 "b81946e7f01f90528a1f7352ab08cc602b9ccc05d4e44da4bd501c5a189ee661"
  revision 2

  livecheck do
    url :stable
    regex(%r{href=.*?gcc[._-]v?(7(?:\.\d+)+)(?:/?["' >]|\.t)}i)
  end

  bottle do
    sha256 "4dca3b07173bffba262e003b345970119626a4d60a25c167d6bc216c46f1d83e" => :catalina
    sha256 "5d4086421866078dc4d9bfe623a38160dbcf04ff88b4d0284dee9da66ff50f4c" => :mojave
    sha256 "3c2135fc0b1c7f0ce048c1f610d2131a237911bdbd66d8bff731bbf9c6d84bcc" => :high_sierra
  end

  # 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

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

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

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

    version_suffix = version.major.to_s

    # Even when suffixes are appended, the info pages conflict when
    # install-info is run so pretend we have an outdated makeinfo
    # to prevent their build.
    ENV["gcc_cv_prog_makeinfo_modern"] = "no"

    # 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]

    args = [
      "--build=x86_64-apple-darwin#{OS.kernel_version}",
      "--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",
      "--disable-nls",
    ]

    # Xcode 10 dropped 32-bit support
    args << "--disable-multilib" if DevelopmentTools.clang_build_version >= 1000

    # System headers may not be in /usr/include
    sdk = MacOS.sdk_path_if_needed
    if sdk
      args << "--with-native-system-header-dir=/usr/include"
      args << "--with-sysroot=#{sdk}"
    end

    # Avoid reference to sed shim
    args << "SED=/usr/bin/sed"

    # 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
      system "../configure", *args

      system "make"
      system "make", "install"
    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.major}", "-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.major}", "-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-#{version.major}", "-o", "test", "test.f90"
    assert_equal "Done\n", `./test`
  end
end