class LlvmAT11 < Formula
  desc "Next-gen compiler infrastructure"
  homepage "https://llvm.org/"
  url "https://github.com/llvm/llvm-project/releases/download/llvmorg-11.1.0/llvm-project-11.1.0.src.tar.xz"
  sha256 "74d2529159fd118c3eac6f90107b5611bccc6f647fdea104024183e8d5e25831"
  # The LLVM Project is under the Apache License v2.0 with LLVM Exceptions
  license "Apache-2.0" => { with: "LLVM-exception" }
  revision OS.mac? ? 3 : 5

  # This should be removed when LLVM 13 is released, so we only check the
  # current version (the `llvm` formula) and one major version before it
  # (to catch any patch version that may appear, however uncommon).
  livecheck do
    url "https://releases.llvm.org/"
    regex(/["'](11(?:\.\d+)+)["']/i)
  end

  bottle do
    sha256 cellar: :any,                 arm64_big_sur: "0441f32a33dc14393118ff9d047af44d8fa7b87648b09c1e2ffa5c69d3d0c032"
    sha256 cellar: :any,                 big_sur:       "8b9e7e448f801daad56d3180cccf190486bd785c551aeb37300a5296f1d9e81b"
    sha256 cellar: :any,                 catalina:      "47e26656712ba5efa159d2f42334972bf8c510ffa48f0c6ff35d8e55af1b9d94"
    sha256 cellar: :any,                 mojave:        "c7cd19b7849a499acd3d68648fadf9c8283ce47bd1706931c2f3223e8c97d8ac"
    sha256 cellar: :any_skip_relocation, x86_64_linux:  "56ddd61439a2ce0857e7ca3127f038fa4e6e1b55537aea331c9ef59c74ee0375" # linuxbrew-core
  end

  # Clang cannot find system headers if Xcode CLT is not installed
  pour_bottle? only_if: :clt_installed

  keg_only :versioned_formula

  # https://llvm.org/docs/GettingStarted.html#requirement
  # We intentionally use Make instead of Ninja.
  # See: Homebrew/homebrew-core/issues/35513
  depends_on "cmake" => :build
  depends_on "swig" => :build
  depends_on "python@3.9"

  uses_from_macos "libedit"
  uses_from_macos "libffi", since: :catalina
  uses_from_macos "libxml2"
  uses_from_macos "ncurses"
  uses_from_macos "zlib"

  on_linux do
    depends_on "glibc" if Formula["glibc"].any_version_installed?
    depends_on "pkg-config" => :build
    depends_on "binutils" # needed for gold
    depends_on "elfutils" # openmp requires <gelf.h>
  end

  patch do
    url "https://github.com/llvm/llvm-project/commit/c86f56e32e724c6018e579bb2bc11e667c96fc96.patch?full_index=1"
    sha256 "6e13e01b4f9037bb6f43f96cb752d23b367fe7db4b66d9bf2a4aeab9234b740a"
  end

  patch do
    url "https://github.com/llvm/llvm-project/commit/31e5f7120bdd2f76337686d9d169b1c00e6ee69c.patch?full_index=1"
    sha256 "f025110aa6bf80bd46d64a0e2b1e2064d165353cd7893bef570b6afba7e90b4d"
  end

  patch do
    url "https://github.com/llvm/llvm-project/commit/3c7bfbd6831b2144229734892182d403e46d7baf.patch?full_index=1"
    sha256 "62014ddad6d5c485ecedafe3277fe7978f3f61c940976e3e642536726abaeb68"
  end

  patch do
    url "https://github.com/llvm/llvm-project/commit/c4d7536136b331bada079b2afbb2bd09ad8296bf.patch?full_index=1"
    sha256 "2b894cbaf990510969bf149697882c86a068a1d704e749afa5d7b71b6ee2eb9f"
  end

  patch do
    url "https://github.com/llvm/llvm-project/commit/c997867dc084a1bcf631816f964b3ff49a297ba3.patch?full_index=1"
    sha256 "a215925cb872406fe770369ef3adfef1170c6ffbd65f1de44358a240307faab1"
  end

  # Upstream ARM patch for OpenMP runtime, remove in next version
  # https://reviews.llvm.org/D91002
  # https://bugs.llvm.org/show_bug.cgi?id=47609
  patch do
    url "https://raw.githubusercontent.com/Homebrew/formula-patches/6166a68c/llvm/openmp_arm.patch"
    sha256 "70fe3836b423e593688cd1cc7a3d76ee6406e64b9909f1a2f780c6f018f89b1e"
  end

  # Support for macOS 11.3+ SDKs
  patch do
    url "https://github.com/llvm/llvm-project/commit/a3a24316087d0e1b4db0b8fee19cdee8b7968032.patch?full_index=1"
    sha256 "744aaebcc8da875892a00cbe2ebc6bb16db97431808b49f134adf70e64cf0e91"
  end

  def install
    projects = %w[
      clang
      clang-tools-extra
      lld
      lldb
      openmp
      polly
      mlir
    ]
    runtimes = %w[
      compiler-rt
      libcxx
      libcxxabi
      libunwind
    ]

    py_ver = Language::Python.major_minor_version("python3")
    site_packages = Language::Python.site_packages("python3").delete_prefix("lib/")

    # Apple's libstdc++ is too old to build LLVM
    ENV.libcxx if ENV.compiler == :clang

    # compiler-rt has some iOS simulator features that require i386 symbols
    # I'm assuming the rest of clang needs support too for 32-bit compilation
    # to work correctly, but if not, perhaps universal binaries could be
    # limited to compiler-rt. llvm makes this somewhat easier because compiler-rt
    # can almost be treated as an entirely different build from llvm.
    ENV.permit_arch_flags

    # we install the lldb Python module into libexec to prevent users from
    # accidentally importing it with a non-Homebrew Python or a Homebrew Python
    # in a non-default prefix. See https://lldb.llvm.org/resources/caveats.html
    args = %W[
      -DLLVM_ENABLE_PROJECTS=#{projects.join(";")}
      -DLLVM_ENABLE_RUNTIMES=#{runtimes.join(";")}
      -DLLVM_POLLY_LINK_INTO_TOOLS=ON
      -DLLVM_BUILD_EXTERNAL_COMPILER_RT=ON
      -DLLVM_LINK_LLVM_DYLIB=ON
      -DLLVM_ENABLE_EH=ON
      -DLLVM_ENABLE_FFI=ON
      -DLLVM_ENABLE_RTTI=ON
      -DLLVM_INCLUDE_DOCS=OFF
      -DLLVM_INCLUDE_TESTS=OFF
      -DLLVM_INSTALL_UTILS=ON
      -DLLVM_ENABLE_Z3_SOLVER=OFF
      -DLLVM_OPTIMIZED_TABLEGEN=ON
      -DLLVM_TARGETS_TO_BUILD=all
      -DLLDB_USE_SYSTEM_DEBUGSERVER=ON
      -DLLDB_ENABLE_PYTHON=ON
      -DLLDB_ENABLE_LUA=OFF
      -DLLDB_ENABLE_LZMA=ON
      -DLLDB_PYTHON_RELATIVE_PATH=libexec/#{site_packages}
      -DLIBOMP_INSTALL_ALIASES=OFF
      -DCLANG_PYTHON_BINDINGS_VERSIONS=#{py_ver}
      -DPACKAGE_VENDOR=#{tap.user}
      -DPACKAGE_BUGREPORT=#{tap.issues_url}
      -DCLANG_VENDOR_UTI=org.#{tap.user.downcase}.clang
    ]

    if MacOS.version >= :catalina
      args << "-DFFI_INCLUDE_DIR=#{MacOS.sdk_path}/usr/include/ffi"
      args << "-DFFI_LIBRARY_DIR=#{MacOS.sdk_path}/usr/lib"
    else
      args << "-DFFI_INCLUDE_DIR=#{Formula["libffi"].opt_include}"
      args << "-DFFI_LIBRARY_DIR=#{Formula["libffi"].opt_lib}"
    end

    if OS.mac?
      args << "-DLLVM_BUILD_LLVM_C_DYLIB=ON"
      args << "-DLLVM_ENABLE_LIBCXX=ON"
      args << "-DLLVM_CREATE_XCODE_TOOLCHAIN=#{MacOS::Xcode.installed? ? "ON" : "OFF"}"

      sdk = MacOS.sdk_path_if_needed
      args << "-DDEFAULT_SYSROOT=#{sdk}" if sdk
    else
      args << "-DLLVM_ENABLE_LIBCXX=OFF"
      args << "-DLLVM_CREATE_XCODE_TOOLCHAIN=OFF"
      args << "-DCLANG_DEFAULT_CXX_STDLIB=libstdc++"
      # Enable llvm gold plugin for LTO
      args << "-DLLVM_BINUTILS_INCDIR=#{Formula["binutils"].opt_include}"
      runtime_args = %w[
        -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF
        -DCMAKE_POSITION_INDEPENDENT_CODE=ON

        -DLIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON
        -DLIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY=OFF
        -DLIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY=ON
        -DLIBCXX_USE_COMPILER_RT=ON
        -DLIBCXX_HAS_ATOMIC_LIB=OFF

        -DLIBCXXABI_ENABLE_STATIC_UNWINDER=ON
        -DLIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY=OFF
        -DLIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY=ON
        -DLIBCXXABI_USE_COMPILER_RT=ON
        -DLIBCXXABI_USE_LLVM_UNWINDER=ON

        -DLIBUNWIND_USE_COMPILER_RT=ON
      ]
      args << "-DRUNTIMES_CMAKE_ARGS=#{runtime_args.join(";")}"
    end

    llvmpath = buildpath/"llvm"
    mkdir llvmpath/"build" do
      system "cmake", "-G", "Unix Makefiles", "..", *(std_cmake_args + args)
      system "cmake", "--build", "."
      system "cmake", "--build", ".", "--target", "install"
      system "cmake", "--build", ".", "--target", "install-xcode-toolchain" if MacOS::Xcode.installed?
    end

    # Install LLVM Python bindings
    # Clang Python bindings are installed by CMake
    (lib/site_packages).install llvmpath/"bindings/python/llvm"

    # Install Emacs modes
    elisp.install Dir[llvmpath/"utils/emacs/*.el"] + Dir[share/"clang/*.el"]
  end

  def caveats
    <<~EOS
      To use the bundled libc++ please add the following LDFLAGS:
        LDFLAGS="-L#{opt_lib} -Wl,-rpath,#{opt_lib}"
    EOS
  end

  test do
    assert_equal prefix.to_s, shell_output("#{bin}/llvm-config --prefix").chomp

    (testpath/"omptest.c").write <<~EOS
      #include <stdlib.h>
      #include <stdio.h>
      #include <omp.h>
      int main() {
          #pragma omp parallel num_threads(4)
          {
            printf("Hello from thread %d, nthreads %d\\n", omp_get_thread_num(), omp_get_num_threads());
          }
          return EXIT_SUCCESS;
      }
    EOS

    clean_version = version.to_s[/(\d+\.?)+/]

    system "#{bin}/clang", "-L#{lib}", "-fopenmp", "-nobuiltininc",
                           "-I#{lib}/clang/#{clean_version}/include",
                           "omptest.c", "-o", "omptest"
    testresult = shell_output("./omptest")

    sorted_testresult = testresult.split("\n").sort.join("\n")
    expected_result = <<~EOS
      Hello from thread 0, nthreads 4
      Hello from thread 1, nthreads 4
      Hello from thread 2, nthreads 4
      Hello from thread 3, nthreads 4
    EOS
    assert_equal expected_result.strip, sorted_testresult.strip

    (testpath/"test.c").write <<~EOS
      #include <stdio.h>
      int main()
      {
        printf("Hello World!\\n");
        return 0;
      }
    EOS

    (testpath/"test.cpp").write <<~EOS
      #include <iostream>
      int main()
      {
        std::cout << "Hello World!" << std::endl;
        return 0;
      }
    EOS

    # Testing default toolchain and SDK location.
    system "#{bin}/clang++", "-v",
           "-std=c++11", "test.cpp", "-o", "test++"
    assert_includes MachO::Tools.dylibs("test++"), "/usr/lib/libc++.1.dylib" if OS.mac?
    assert_equal "Hello World!", shell_output("./test++").chomp
    system "#{bin}/clang", "-v", "test.c", "-o", "test"
    assert_equal "Hello World!", shell_output("./test").chomp

    # Testing Command Line Tools
    if MacOS::CLT.installed?
      toolchain_path = "/Library/Developer/CommandLineTools"
      system "#{bin}/clang++", "-v",
             "-isysroot", MacOS::CLT.sdk_path,
             "-isystem", "#{toolchain_path}/usr/include/c++/v1",
             "-isystem", "#{toolchain_path}/usr/include",
             "-isystem", "#{MacOS::CLT.sdk_path}/usr/include",
             "-std=c++11", "test.cpp", "-o", "testCLT++"
      assert_includes MachO::Tools.dylibs("testCLT++"), "/usr/lib/libc++.1.dylib"
      assert_equal "Hello World!", shell_output("./testCLT++").chomp
      system "#{bin}/clang", "-v", "test.c", "-o", "testCLT"
      assert_equal "Hello World!", shell_output("./testCLT").chomp
    end

    # Testing Xcode
    if MacOS::Xcode.installed?
      system "#{bin}/clang++", "-v",
             "-isysroot", MacOS::Xcode.sdk_path,
             "-isystem", "#{MacOS::Xcode.toolchain_path}/usr/include/c++/v1",
             "-isystem", "#{MacOS::Xcode.toolchain_path}/usr/include",
             "-isystem", "#{MacOS::Xcode.sdk_path}/usr/include",
             "-std=c++11", "test.cpp", "-o", "testXC++"
      assert_includes MachO::Tools.dylibs("testXC++"), "/usr/lib/libc++.1.dylib"
      assert_equal "Hello World!", shell_output("./testXC++").chomp
      system "#{bin}/clang", "-v",
             "-isysroot", MacOS.sdk_path,
             "test.c", "-o", "testXC"
      assert_equal "Hello World!", shell_output("./testXC").chomp
    end

    # link against installed libc++
    # related to https://github.com/Homebrew/legacy-homebrew/issues/47149
    system "#{bin}/clang++", "-v",
           "-isystem", "#{opt_include}/c++/v1",
           "-std=c++11", "-stdlib=libc++", "test.cpp", "-o", "testlibc++",
           "-rtlib=compiler-rt", "-L#{opt_lib}", "-Wl,-rpath,#{opt_lib}"
    assert_includes (testpath/"testlibc++").dynamically_linked_libraries,
      (opt_lib/shared_library("libc++", "1")).to_s
    (testpath/"testlibc++").dynamically_linked_libraries.each do |lib|
      refute_match(/libstdc\+\+/, lib)
      refute_match(/libgcc/, lib)
      refute_match(/libatomic/, lib)
    end
    assert_equal "Hello World!", shell_output("./testlibc++").chomp

    on_linux do
      # Link installed libc++, libc++abi, and libunwind archives both into
      # a position independent executable (PIE), as well as into a fully
      # position independent (PIC) DSO for things like plugins that export
      # a C-only API but internally use C++.
      #
      # FIXME: It'd be nice to be able to use flags like `-static-libstdc++`
      # together with `-stdlib=libc++` (the latter one we need anyways for
      # headers) to achieve this but those flags don't set up the correct
      # search paths or handle all of the libraries needed by `libc++` when
      # linking statically.

      system "#{bin}/clang++", "-v", "-o", "test_pie_runtimes",
             "-pie", "-fPIC", "test.cpp", "-L#{opt_lib}",
             "-stdlib=libc++", "-rtlib=compiler-rt",
             "-static-libstdc++", "-lpthread", "-ldl"
      assert_equal "Hello World!", shell_output("./test_pie_runtimes").chomp
      (testpath/"test_pie_runtimes").dynamically_linked_libraries.each do |lib|
        refute_match(/lib(std)?c\+\+/, lib)
        refute_match(/libgcc/, lib)
        refute_match(/libatomic/, lib)
        refute_match(/libunwind/, lib)
      end

      (testpath/"test_plugin.cpp").write <<~EOS
        #include <iostream>
        __attribute__((visibility("default")))
        extern "C" void run_plugin() {
          std::cout << "Hello Plugin World!" << std::endl;
        }
      EOS
      (testpath/"test_plugin_main.c").write <<~EOS
        extern void run_plugin();
        int main() {
          run_plugin();
        }
      EOS
      system "#{bin}/clang++", "-v", "-o", "test_plugin.so",
             "-shared", "-fPIC", "test_plugin.cpp", "-L#{opt_lib}",
             "-stdlib=libc++", "-rtlib=compiler-rt",
             "-static-libstdc++", "-lpthread", "-ldl"
      system "#{bin}/clang", "-v",
             "test_plugin_main.c", "-o", "test_plugin_libc++",
             "test_plugin.so", "-Wl,-rpath=#{testpath}", "-rtlib=compiler-rt"
      assert_equal "Hello Plugin World!", shell_output("./test_plugin_libc++").chomp
      (testpath/"test_plugin.so").dynamically_linked_libraries.each do |lib|
        refute_match(/lib(std)?c\+\+/, lib)
        refute_match(/libgcc/, lib)
        refute_match(/libatomic/, lib)
        refute_match(/libunwind/, lib)
      end
    end

    # Testing mlir
    (testpath/"test.mlir").write <<~EOS
      func @bad_branch() {
        br ^missing  // expected-error {{reference to an undefined block}}
      }
    EOS
    system "#{bin}/mlir-opt", "--verify-diagnostics", "test.mlir"

    (testpath/"scanbuildtest.cpp").write <<~EOS
      #include <iostream>
      int main() {
        int *i = new int;
        *i = 1;
        delete i;
        std::cout << *i << std::endl;
        return 0;
      }
    EOS
    assert_includes shell_output("#{bin}/scan-build #{bin}/clang++ scanbuildtest.cpp 2>&1"),
      "warning: Use of memory after it is freed"

    (testpath/"clangformattest.c").write <<~EOS
      int    main() {
          printf("Hello world!"); }
    EOS
    assert_equal "int main() { printf(\"Hello world!\"); }\n",
      shell_output("#{bin}/clang-format -style=google clangformattest.c")

    # Ensure LLVM did not regress output of `llvm-config --system-libs` which for a time
    # was known to output incorrect linker flags; e.g., `-llibxml2.tbd` instead of `-lxml2`.
    # On the other hand, note that a fully qualified path to `dylib` or `tbd` is OK, e.g.,
    # `/usr/local/lib/libxml2.tbd` or `/usr/local/lib/libxml2.dylib`.
    shell_output("#{bin}/llvm-config --system-libs").chomp.strip.split.each do |lib|
      if lib.start_with?("-l")
        assert !lib.end_with?(".tbd"), "expected abs path when lib reported as .tbd"
        assert !lib.end_with?(".dylib"), "expected abs path when lib reported as .dylib"
      else
        p = Pathname.new(lib)
        if p.extname == ".tbd" || p.extname == ".dylib"
          assert p.absolute?, "expected abs path when lib reported as .tbd or .dylib"
        end
      end
    end
  end
end
