GNU Debugger

GDB has not (yet) been ported to MacOS running on the M2 (AArch64) architecture. Even GDB for MacOS on the old x86-64 was not very well tested as far as I know.

I believe lldb might be available for the MacOS/M2 target, but I know nothing about installing this debugger on MacOS.

After hours and hours of searching, I finally found an obscure gist identifying the issue and detailing the solution.

TL;DR The GNU Debugger requires a patch before it can work with MacOS. gdb v8.0.1 is the last known good version of GDB for MacOS.

1. Uninstall the latest version of gdb (i.e. v8.1)

   brew uninstall --force gdb
   

2. Force Homebrew to install a version of gdb with the patch for MacOS.

   brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/c3128a5c335bd2fa75ffba9d721e9910134e4644/Formula/gdb.rb
   

3. Use the existing certificate to codesign the new install of gdb

   codesign -f -s  "<GNU GDB Certificate>" $(which gdb)
   

Now, gdb works as expected!

Special thanks to https://github.com/marcoparente and https://github.com/lokoum for their gist comments!

Just figured it out. I created a modified version of the formula .rb file in my /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/gdbCustom.rb and added the missing build options. I based it on this formula: https://raw.githubusercontent.com/Homebrew/homebrew-core/9ec9fb27a33698fc7636afce5c1c16787e9ce3f3/Formula/gdb.rb

Yes, I'm a newbie to Homebrew, but have a better understanding of how formulas work now. In case it helps others, see below final .rb. After adding the file to the above homebrew-core/Formula directory, run brew install gdbCustom --with-all-targets. The make takes several minutes, so be patient.

class Gdbcustom < Formula
    desc "GNU debugger"
    homepage "https://www.gnu.org/software/gdb/"
    head "https://sourceware.org/git/binutils-gdb.git"

    stable do
      url "https://ftp.gnu.org/gnu/gdb/gdb-8.2.1.tar.xz"
      mirror "https://ftpmirror.gnu.org/gdb/gdb-8.2.1.tar.xz"
      sha256 "0a6a432907a03c5c8eaad3c3cffd50c00a40c3a5e3c4039440624bae703f2202"

      # Fix build with all targets. Remove for 8.3
      # https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=0c0a40e0abb9f1a584330a1911ad06b3686e5361
      patch do
        url "https://raw.githubusercontent.com/Homebrew/formula-patches/d457e55/gdb/all-targets.diff"
        sha256 "1cb8a1b8c4b4833212e16ba8cfbe620843aba0cba0f5111c2728c3314e10d8fd"
      end

      # Fix debugging of executables of Xcode 10 and later
      # created for 10.14 and newer versions of macOS. Remove for 8.3
      # https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fc7b364aba41819a5d74ae0ac69f050af282d057
      patch do
        url "https://raw.githubusercontent.com/Homebrew/formula-patches/d457e55/gdb/mojave.diff"
        sha256 "6264c71b57a0d5d4aed11430d352b03639370b7d36a5b520e189a6a1f105e383"
      end
    end

    bottle do
        sha256 "01b06c2983503c78bc346b5f5e2c2bdccbc41d6f5ca759542eef712bf123ca30" => :mojave
        sha256 "9824d06b8d0d44e725a1d29f6631828b3b43abb1952c883e9fad559b6a816c04" => :high_sierra
        sha256 "cf7371e9f6257d1a7dee80239d05917e424e5bb3e7577bd93f0e139fe5174198" => :sierra
    end

    # Owen: deprecated_option "with-brewed-python" => "with-python"
    # Owen: deprecated_option "with-guile" => "[email protected]"

    option "with-python", "Use the Homebrew version of Python; by default system Python is used"
    option "with-version-suffix", "Add a version suffix to program"
    option "with-all-targets", "Build with support for all targets"

    depends_on "pkg-config" => :build
    # Owen: depends_on "python" => :optional
    # Owen: depends_on "[email protected]" => :optional

    fails_with :clang do
        build 800
        cause <<~EOS
          probe.c:63:28: error: default initialization of an object of const type
          'const any_static_probe_ops' without a user-provided default constructor
        EOS
    end

    fails_with :clang do
      build 600
      cause <<~EOS
        clang: error: unable to execute command: Segmentation fault: 11
        Test done on: Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
      EOS
    end

    def install
      args = %W[
        --prefix=#{prefix}
        --disable-debug
        --disable-dependency-tracking
        --enable-targets=all
        --with-python=/usr
        --disable-binutils
    ]

        # Owen: args << "--with-guile" if build.with? "[email protected]"
        # Owen: args << "--enable-targets=all" if build.with? "all-targets"

      if build.with? "python"
        args << "--with-python=#{HOMEBREW_PREFIX}"
      else
        args << "--with-python=/usr"
      end

      if build.with? "version-suffix"
        args << "--program-suffix=-#{version.to_s.slice(/^\d/)}"
      end

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

      # Don't install bfd or opcodes, as they are provided by binutils
      # Owen: inreplace ["bfd/Makefile", "opcodes/Makefile"], /^install:/, "dontinstall:"

      # Owen: system "make", "install"
      system "make", "install-gdb"
    end

    def caveats; <<~EOS
      gdb requires special privileges to access Mach ports.
      You will need to codesign the binary. For instructions, see:

        https://sourceware.org/gdb/wiki/BuildingOnDarwin

      On 10.12 (Sierra) or later with SIP, you need to run this:

        echo "set startup-with-shell off" >> ~/.gdbinit
      EOS
    end

    test do
      system bin/"gdb", bin/"gdb", "-configuration"
    end
  end

Figured out what the issue was, turns out that clang really doesn't like when you try and use strncmp without first including string.h. Meanwhile gcc is perfectly happy to compile elf-bfd.h without including string.h. As a result, even though GDB will compile on macOS, it simply refuses to load any ELF files because the ELF code isn't compiled correctly. The fix is just to add #include <string.h> to the top of elf-bfd.h and GDB will correctly load ELF binaries.