From e51bc1ab23bb2551370f16f6806989b1ecae8e2f Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@midstall.com>
Date: Thu, 29 May 2025 19:58:36 -0700
Subject: [PATCH 1/2] gccNGPackages: init

---
 ...ram-First-search-with-machine-prefix.patch | 137 ++++++++
 ...pass-Pass-to-callback-whether-dir-is.patch | 103 ++++++
 ...nly-search-for-prefixed-paths-in-und.patch |  75 +++++
 .../ng/15/gcc/custom-threading-model.patch    | 180 ++++++++++
 .../gcc/ng/15/gcc/fix-collect2-paths.diff     | 315 ++++++++++++++++++
 pkgs/development/compilers/gcc/ng/README.md   |   3 +
 .../compilers/gcc/ng/common/common-let.nix    |  47 +++
 .../compilers/gcc/ng/common/default.nix       | 221 ++++++++++++
 .../compilers/gcc/ng/common/gcc/default.nix   | 249 ++++++++++++++
 .../gcc/ng/common/libatomic/default.nix       |  48 +++
 .../gcc/ng/common/libbacktrace/default.nix    |  74 ++++
 .../gcc/ng/common/libgcc/default.nix          | 205 ++++++++++++
 .../gcc/ng/common/libgfortran/default.nix     | 190 +++++++++++
 .../gcc/ng/common/libiberty/default.nix       |  67 ++++
 .../gcc/ng/common/libquadmath/default.nix     |  51 +++
 .../gcc/ng/common/libsanitizer/default.nix    |  57 ++++
 .../gcc/ng/common/libssp/default.nix          |  68 ++++
 .../gcc/ng/common/libstdcxx/default.nix       |  87 +++++
 .../compilers/gcc/ng/common/patches.nix       |  32 ++
 pkgs/development/compilers/gcc/ng/default.nix |  69 ++++
 pkgs/top-level/all-packages.nix               |  11 +
 21 files changed, 2289 insertions(+)
 create mode 100644 pkgs/development/compilers/gcc/ng/15/gcc/0001-find_a_program-First-search-with-machine-prefix.patch
 create mode 100644 pkgs/development/compilers/gcc/ng/15/gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch
 create mode 100644 pkgs/development/compilers/gcc/ng/15/gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch
 create mode 100644 pkgs/development/compilers/gcc/ng/15/gcc/custom-threading-model.patch
 create mode 100644 pkgs/development/compilers/gcc/ng/15/gcc/fix-collect2-paths.diff
 create mode 100644 pkgs/development/compilers/gcc/ng/README.md
 create mode 100644 pkgs/development/compilers/gcc/ng/common/common-let.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/gcc/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libatomic/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libbacktrace/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libgcc/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libgfortran/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libiberty/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libquadmath/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libsanitizer/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libssp/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/libstdcxx/default.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/common/patches.nix
 create mode 100644 pkgs/development/compilers/gcc/ng/default.nix

diff --git a/pkgs/development/compilers/gcc/ng/15/gcc/0001-find_a_program-First-search-with-machine-prefix.patch b/pkgs/development/compilers/gcc/ng/15/gcc/0001-find_a_program-First-search-with-machine-prefix.patch
new file mode 100644
index 0000000000000..46eb8d03b89a7
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/15/gcc/0001-find_a_program-First-search-with-machine-prefix.patch
@@ -0,0 +1,137 @@
+From 3af17de3a5f6acd5a2f9340d84b8667459f43eea Mon Sep 17 00:00:00 2001
+From: John Ericson <git@JohnEricson.me>
+Date: Wed, 18 Aug 2021 01:55:31 -0400
+Subject: [PATCH 1/3] find_a_program: First search with machine prefix
+
+This matches the behavior of Clang, and makes it easier to work with
+cross compilers without heeding to hard-code paths at build time.
+---
+ gcc/gcc.cc | 78 +++++++++++++++++++++++++++++++++++++++++++++++-------
+ 1 file changed, 68 insertions(+), 10 deletions(-)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index 4fd87f2c4a1..55738d258b3 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -1600,6 +1600,11 @@ static const char *machine_suffix = 0;
+ 
+ static const char *just_machine_suffix = 0;
+ 
++/* Prefix to attach to *basename* of commands being searched.
++   This is just `MACHINE-'.  */
++
++static const char *just_machine_prefix = 0;
++
+ /* Adjusted value of GCC_EXEC_PREFIX envvar.  */
+ 
+ static const char *gcc_exec_prefix;
+@@ -3043,15 +3048,6 @@ file_at_path (char *path, void *data)
+   memcpy (path + len, info->name, info->name_len);
+   len += info->name_len;
+ 
+-  /* Some systems have a suffix for executable files.
+-     So try appending that first.  */
+-  if (info->suffix_len)
+-    {
+-      memcpy (path + len, info->suffix, info->suffix_len + 1);
+-      if (access_check (path, info->mode) == 0)
+-	return path;
+-    }
+-
+   path[len] = '\0';
+   if (access_check (path, info->mode) == 0)
+     return path;
+@@ -3091,12 +3087,52 @@ find_a_file (const struct path_prefix *pprefix, const char *name, int mode,
+ 				file_at_path, &info);
+ }
+ 
++/* Callback for find_a_program.  Appends the file name to the directory
++   path. Like file_at_path but tries machine prefix and exe suffix too. */
++
++static void *
++program_at_path (char *path, void *data)
++{
++  /* try first with machine-prefixed name */
++  struct file_at_path_info *info = (struct file_at_path_info *) data;
++  size_t path_len = strlen (path);
++
++  for (auto prefix : { just_machine_prefix, "" })
++    {
++      auto len = path_len;
++
++      auto prefix_len = strlen(prefix);
++      memcpy (path + len, prefix, prefix_len);
++      len += prefix_len;
++
++      memcpy (path + len, info->name, info->name_len);
++      len += info->name_len;
++
++      /* Some systems have a suffix for executable files.
++	 So try appending that first.  */
++      if (info->suffix_len)
++	{
++	  memcpy (path + len, info->suffix, info->suffix_len + 1);
++	  if (access_check (path, info->mode) == 0)
++	    return path;
++	}
++
++      path[len] = '\0';
++      if (access_check (path, info->mode) == 0)
++	return path;
++    }
++
++  return NULL;
++}
++
+ /* Specialization of find_a_file for programs that also takes into account
+    configure-specified default programs. */
+ 
+ static char*
+ find_a_program (const char *name)
+ {
++  const int mode = X_OK;
++
+   /* Do not search if default matches query. */
+ 
+ #ifdef DEFAULT_ASSEMBLER
+@@ -3114,7 +3150,28 @@ find_a_program (const char *name)
+     return xstrdup (DEFAULT_DSYMUTIL);
+ #endif
+ 
+-  return find_a_file (&exec_prefixes, name, X_OK, false);
++  /* Find the filename in question (special case for absolute paths).  */
++
++  if (IS_ABSOLUTE_PATH (name))
++    {
++      if (access (name, mode) == 0)
++	return xstrdup (name);
++
++      return NULL;
++    }
++
++  struct file_at_path_info info;
++
++  info.name = name;
++  info.suffix = HOST_EXECUTABLE_SUFFIX;
++  info.name_len = strlen (info.name);
++  info.suffix_len = strlen (info.suffix);
++  info.mode = mode;
++
++  return (char*) for_each_path (
++    &exec_prefixes, false,
++    info.name_len + info.suffix_len + strlen(just_machine_prefix),
++    program_at_path, &info);
+ }
+ 
+ /* Ranking of prefixes in the sort list. -B prefixes are put before
+@@ -8492,6 +8549,7 @@ driver::set_up_specs () const
+   machine_suffix = concat (spec_host_machine, dir_separator_str, spec_version,
+ 			   accel_dir_suffix, dir_separator_str, NULL);
+   just_machine_suffix = concat (spec_machine, dir_separator_str, NULL);
++  just_machine_prefix = concat (spec_machine, "-", NULL);
+ 
+   specs_file = find_a_file (&startfile_prefixes, "specs", R_OK, true);
+   /* Read the specs file unless it is a default one.  */
+-- 
+2.47.2
+
diff --git a/pkgs/development/compilers/gcc/ng/15/gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch b/pkgs/development/compilers/gcc/ng/15/gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch
new file mode 100644
index 0000000000000..e0f295f8b88cb
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/15/gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch
@@ -0,0 +1,103 @@
+From 8e1b7a128a69393c6d3f53b8f66bd52c6bbce908 Mon Sep 17 00:00:00 2001
+From: John Ericson <git@JohnEricson.me>
+Date: Wed, 18 Aug 2021 01:55:45 -0400
+Subject: [PATCH 2/3] driver: for_each_pass: Pass to callback whether dir is
+ machine-disambiguated
+
+We will use this in the subsequent diff to control what basenames we
+search for. In machine-specific subdirectories, we should just look for
+the original basename, but in machine-agnostic subdirectories, we might
+additionally look for prefixed disambiguated names, as an alternate
+method of keeping targets apart.
+---
+ gcc/gcc.cc | 18 +++++++++---------
+ 1 file changed, 9 insertions(+), 9 deletions(-)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index 55738d258b3..f9f83d1a804 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -2783,7 +2783,7 @@ static void *
+ for_each_path (const struct path_prefix *paths,
+ 	       bool do_multi,
+ 	       size_t extra_space,
+-	       void *(*callback) (char *, void *),
++	       void *(*callback) (char *, bool, void *),
+ 	       void *callback_info)
+ {
+   struct prefix_list *pl;
+@@ -2844,7 +2844,7 @@ for_each_path (const struct path_prefix *paths,
+ 	  if (!skip_multi_dir)
+ 	    {
+ 	      memcpy (path + len, multi_suffix, suffix_len + 1);
+-	      ret = callback (path, callback_info);
++	      ret = callback (path, true, callback_info);
+ 	      if (ret)
+ 		break;
+ 	    }
+@@ -2855,7 +2855,7 @@ for_each_path (const struct path_prefix *paths,
+ 	      && pl->require_machine_suffix == 2)
+ 	    {
+ 	      memcpy (path + len, just_multi_suffix, just_suffix_len + 1);
+-	      ret = callback (path, callback_info);
++	      ret = callback (path, true, callback_info);
+ 	      if (ret)
+ 		break;
+ 	    }
+@@ -2865,7 +2865,7 @@ for_each_path (const struct path_prefix *paths,
+ 	      && !pl->require_machine_suffix && multiarch_dir)
+ 	    {
+ 	      memcpy (path + len, multiarch_suffix, multiarch_len + 1);
+-	      ret = callback (path, callback_info);
++	      ret = callback (path, true, callback_info);
+ 	      if (ret)
+ 		break;
+ 	    }
+@@ -2893,7 +2893,7 @@ for_each_path (const struct path_prefix *paths,
+ 	      else
+ 		path[len] = '\0';
+ 
+-	      ret = callback (path, callback_info);
++	      ret = callback (path, false, callback_info);
+ 	      if (ret)
+ 		break;
+ 	    }
+@@ -2948,7 +2948,7 @@ struct add_to_obstack_info {
+ };
+ 
+ static void *
+-add_to_obstack (char *path, void *data)
++add_to_obstack (char *path, bool, void *data)
+ {
+   struct add_to_obstack_info *info = (struct add_to_obstack_info *) data;
+ 
+@@ -3040,7 +3040,7 @@ struct file_at_path_info {
+ };
+ 
+ static void *
+-file_at_path (char *path, void *data)
++file_at_path (char *path, bool, void *data)
+ {
+   struct file_at_path_info *info = (struct file_at_path_info *) data;
+   size_t len = strlen (path);
+@@ -3091,7 +3091,7 @@ find_a_file (const struct path_prefix *pprefix, const char *name, int mode,
+    path. Like file_at_path but tries machine prefix and exe suffix too. */
+ 
+ static void *
+-program_at_path (char *path, void *data)
++program_at_path (char *path, bool machine_specific, void *data)
+ {
+   /* try first with machine-prefixed name */
+   struct file_at_path_info *info = (struct file_at_path_info *) data;
+@@ -6074,7 +6074,7 @@ struct spec_path_info {
+ };
+ 
+ static void *
+-spec_path (char *path, void *data)
++spec_path (char *path, bool, void *data)
+ {
+   struct spec_path_info *info = (struct spec_path_info *) data;
+   size_t len = 0;
+-- 
+2.47.2
+
diff --git a/pkgs/development/compilers/gcc/ng/15/gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch b/pkgs/development/compilers/gcc/ng/15/gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch
new file mode 100644
index 0000000000000..8fd83506b4d42
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/15/gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch
@@ -0,0 +1,75 @@
+From e1ee1a2df1ad32de24e8fdaeac0a533681710578 Mon Sep 17 00:00:00 2001
+From: John Ericson <git@JohnEricson.me>
+Date: Wed, 18 Aug 2021 01:55:52 -0400
+Subject: [PATCH 3/3] find_a_program: Only search for prefixed paths in
+ undisambiguated dirs
+
+This means, we might search for:
+
+- path/$machine/$version/prog
+- path/$machine/prog
+- path/$machine-prog
+
+But not
+
+- path/$machine/$version/$machine-prog
+
+because disambiguating $machine twice is unnecessary.
+
+This does mean we less liberal in what we accept than LLVM, but that's
+OK. The down side of always Postel's law is everyone converges on
+accepting all sorts of garbage, which makes debugging end-to-end hard
+when mistakes are not caught early.
+---
+ gcc/gcc.cc | 25 ++++++++++++++++---------
+ 1 file changed, 16 insertions(+), 9 deletions(-)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index f9f83d1a804..d837b6ea779 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -3097,15 +3097,9 @@ program_at_path (char *path, bool machine_specific, void *data)
+   struct file_at_path_info *info = (struct file_at_path_info *) data;
+   size_t path_len = strlen (path);
+ 
+-  for (auto prefix : { just_machine_prefix, "" })
++  auto search = [=](size_t len) -> void *
+     {
+-      auto len = path_len;
+-
+-      auto prefix_len = strlen(prefix);
+-      memcpy (path + len, prefix, prefix_len);
+-      len += prefix_len;
+-
+-      memcpy (path + len, info->name, info->name_len);
++      memcpy (path + len, info->name, info->name_len + 1);
+       len += info->name_len;
+ 
+       /* Some systems have a suffix for executable files.
+@@ -3120,9 +3114,22 @@ program_at_path (char *path, bool machine_specific, void *data)
+       path[len] = '\0';
+       if (access_check (path, info->mode) == 0)
+ 	return path;
++
++      return NULL;
++    };
++
++  /* Additionally search for $target-prog in machine-agnostic dirs, as an
++     additional way to disambiguate targets. Do not do this in machine-specific
++     dirs because so further disambiguation is needed. */
++  if (!machine_specific)
++    {
++      auto prefix_len = strlen(just_machine_prefix);
++      memcpy (path + path_len, just_machine_prefix, prefix_len);
++      auto res = search(path_len + prefix_len);
++      if (res) return res;
+     }
+ 
+-  return NULL;
++  return search(path_len);
+ }
+ 
+ /* Specialization of find_a_file for programs that also takes into account
+-- 
+2.47.2
+
diff --git a/pkgs/development/compilers/gcc/ng/15/gcc/custom-threading-model.patch b/pkgs/development/compilers/gcc/ng/15/gcc/custom-threading-model.patch
new file mode 100644
index 0000000000000..1a61dbbd7446f
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/15/gcc/custom-threading-model.patch
@@ -0,0 +1,180 @@
+From 1eaf7ce77bb4eb73e5565ede220557c2ef0290b0 Mon Sep 17 00:00:00 2001
+From: John Ericson <git@JohnEricson.me>
+Date: Sun, 22 Aug 2021 01:14:22 -0400
+Subject: [PATCH] Allow explicitly specifying the thread model for runtime libs
+
+Previously, they always scraped the thread mode from `$CC -v', now, that
+is the default but one may pass `--with-threads=MODEL` to be explicit
+instead.
+
+One use-case is bootstraping with a shorter critical path. The
+traditionally route was to build an entire "static stage" GCC, build
+libc, and then build GCC again supporting dynamic linking,
+multithreading, etc. But this is wasteful in that GCC itself is built
+twice.
+
+With this change, rather than having to mess with spec files we can just
+configure the runtime libraries the way we want directly. In turn, that
+opens to just building libgcc twice rather than all of GCC.
+
+Frankly, specs were always a rather indirect approach to coordinate this
+during GCC's bootstrap, since GCC itself really doesn't care what the
+threading model is, just that the runtime libraries agree among
+themselves. Relying on a hard-coded spec for this also keeps us one step
+further from the long-term goal of multi-target GCC, for what it's
+worth.
+
+For the record, "single stage" builds of GCC have some precedent in
+downstream packaging, for example with [1]. That one, as far as I can
+tell, builds libgcc once, but with the headers of the libc
+implementation provided and then cyclic linking down later. They are
+both fine approaches, but I don't think one should have to be forced
+into cyclic dependencies if they don't want to. That opens the door to
+non-terminating programs due to, e.g., atomics used in a threads
+implementation being lowered to threads absent hardware support.
+
+Finally, I understand that such custom bootstrapping is not officially
+supported. I don't mean to imply it should be --- a lot more cleanup
+work to the build system would be necessary before supporting it
+wouldn't be a huge additional maintainer burden --- I just hope to add a
+reasonable knob for those comfortable with doing unsupported things
+already.
+
+[1]: https://github.com/richfelker/musl-cross-make
+---
+ config/gthr.m4              | 32 ++++++++++++++++++++++++++++++++
+ libatomic/configure.ac      |  4 +---
+ libgcc/configure.ac         |  4 +---
+ libphobos/m4/druntime/os.m4 |  2 +-
+ libstdc++-v3/acinclude.m4   |  8 +++-----
+ 5 files changed, 38 insertions(+), 12 deletions(-)
+
+diff --git a/config/gthr.m4 b/config/gthr.m4
+index 11996247f15..7aed5d3df0d 100644
+--- a/config/gthr.m4
++++ b/config/gthr.m4
+@@ -5,6 +5,35 @@ dnl Public License, this file may be distributed as part of a program
+ dnl that contains a configuration script generated by Autoconf, under
+ dnl the same distribution terms as the rest of that program.
+ 
++dnl Define thread model
++
++dnl usage: GCC_AC_THREAD_MODEL
++AC_DEFUN([GCC_AC_THREAD_MODEL],
++[
++# With threads
++# Pass with no value to take from compiler's metadata
++# Pass with a value to specify a thread package
++# 'single' means single threaded -- without threads.
++AC_ARG_WITH(threads,
++[AS_HELP_STRING([[--with-threads=MODEL]],
++		[specify thread model for this GCC
++		 runtime library])],,
++[with_threads=''])
++
++if test x"$with_threads" = x'yes'; then
++    AC_MSG_ERROR([Cannot pass bare --with-threads, must pass explicit --with-threads=MODEL])
++elif test x"$with_threads" = x'no'; then
++    target_thread_file=single
++elif test x"$with_threads" = x''; then
++    AC_MSG_CHECKING([for thread model used by GCC])
++    target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
++    AC_MSG_RESULT([$target_thread_file])
++else
++    target_thread_file=$with_threads
++fi
++])
++
++
+ dnl Define header location by thread model
+ 
+ dnl usage: GCC_AC_THREAD_HEADER([thread_model])
+@@ -23,6 +52,9 @@ case $1 in
+     vxworks)	thread_header=config/gthr-vxworks.h ;;
+     win32)	thread_header=config/i386/gthr-win32.h ;;
+     mcf)	thread_header=config/i386/gthr-mcf.h ;;
++    *)
++        AC_MSG_ERROR([No known header for threading model '$1'.])
++        ;;
+ esac
+ AC_SUBST(thread_header)
+ ])
+diff --git a/libatomic/configure.ac b/libatomic/configure.ac
+index 85824fa7614..691f4948f6c 100644
+--- a/libatomic/configure.ac
++++ b/libatomic/configure.ac
+@@ -162,9 +162,7 @@ libtool_VERSION=3:0:2
+ AC_SUBST(libtool_VERSION)
+ 
+ # Check for used threading-model
+-AC_MSG_CHECKING([for thread model used by GCC])
+-target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
+-AC_MSG_RESULT([$target_thread_file])
++GCC_AC_THREAD_MODEL
+ 
+ case "$target" in
+  *aarch64*)
+diff --git a/libgcc/configure.ac b/libgcc/configure.ac
+index 4e8c036990f..acf54e24c79 100644
+--- a/libgcc/configure.ac
++++ b/libgcc/configure.ac
+@@ -305,9 +305,7 @@ AC_SUBST([use_tm_clone_registry])
+ 
+ AC_LIB_PROG_LD_GNU
+ 
+-AC_MSG_CHECKING([for thread model used by GCC])
+-target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
+-AC_MSG_RESULT([$target_thread_file]) 
++GCC_AC_THREAD_MODEL
+ 
+ # Check for assembler CFI support.
+ AC_CACHE_CHECK([whether assembler supports CFI directives], [libgcc_cv_cfi],
+diff --git a/libphobos/m4/druntime/os.m4 b/libphobos/m4/druntime/os.m4
+index 15cde3b04b8..28bd4d3d2bd 100644
+--- a/libphobos/m4/druntime/os.m4
++++ b/libphobos/m4/druntime/os.m4
+@@ -32,7 +32,7 @@ case $1 in
+     # TODO: These targets need porting.
+     dce|mipssde|rtems|tpf|vxworks)
+ 	    DCFG_THREAD_MODEL="Single" ;;
+-    *)	    as_fn_error "Thread implementation '$1' not recognised" "$LINENO" 5 ;;
++    *)	    AC_MSG_ERROR([Thread implementation '$1' not recognised]) ;;
+ esac
+ AC_SUBST(DCFG_THREAD_MODEL)
+ ])
+diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
+index 51a08bcc8b1..71697f59d6d 100644
+--- a/libstdc++-v3/acinclude.m4
++++ b/libstdc++-v3/acinclude.m4
+@@ -4342,9 +4342,7 @@ dnl Substs:
+ dnl  thread_header
+ dnl
+ AC_DEFUN([GLIBCXX_ENABLE_THREADS], [
+-  AC_MSG_CHECKING([for thread model used by GCC])
+-  target_thread_file=`$CXX -v 2>&1 | sed -n 's/^Thread model: //p'`
+-  AC_MSG_RESULT([$target_thread_file])
++  GCC_AC_THREAD_MODEL
+   GCC_AC_THREAD_HEADER([$target_thread_file])
+ ])
+ 
+@@ -4354,7 +4352,8 @@ dnl Check if gthread implementation defines the types and functions
+ dnl required by the c++0x thread library.  Conforming gthread
+ dnl implementations can define __GTHREADS_CXX0X to enable use with c++0x.
+ dnl
+-dnl GLIBCXX_ENABLE_SYMVERS must be done before this.
++dnl GLIBCXX_ENABLE_SYMVERS and GLIBCXX_ENABLE_THREADS must be done
++dnl before this.
+ dnl
+ AC_DEFUN([GLIBCXX_CHECK_GTHREADS], [
+   GLIBCXX_ENABLE(libstdcxx-threads,auto,,[enable C++11 threads support])
+@@ -4369,7 +4368,6 @@ AC_DEFUN([GLIBCXX_CHECK_GTHREADS], [
+   CXXFLAGS="$CXXFLAGS -fno-exceptions \
+ 	-I${toplevel_srcdir}/libgcc -I${toplevel_builddir}/libgcc"
+ 
+-  target_thread_file=`$CXX -v 2>&1 | sed -n 's/^Thread model: //p'`
+   case $target_thread_file in
+     posix)
+       CXXFLAGS="$CXXFLAGS -DSUPPORTS_WEAK -DGTHREAD_USE_WEAK -D_PTHREADS"
+-- 
+2.44.1
+
diff --git a/pkgs/development/compilers/gcc/ng/15/gcc/fix-collect2-paths.diff b/pkgs/development/compilers/gcc/ng/15/gcc/fix-collect2-paths.diff
new file mode 100644
index 0000000000000..1fac497660442
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/15/gcc/fix-collect2-paths.diff
@@ -0,0 +1,315 @@
+diff --git a/gcc/collect2.cc b/gcc/collect2.cc
+index 268ac378b9c..8a5c606075a 100644
+--- a/gcc/collect2.cc
++++ b/gcc/collect2.cc
+@@ -327,7 +327,7 @@ static void write_aix_file (FILE *, struct id *);
+ static char *resolve_lib_name (const char *);
+ #endif
+ static char *extract_string (const char **);
+-static void post_ld_pass (bool);
++static void post_ld_pass (bool, bool);
+ static void process_args (int *argcp, char **argv);
+ 
+ /* Enumerations describing which pass this is for scanning the
+@@ -513,12 +513,10 @@ is_ctor_dtor (const char *s)
+ 
+ static struct path_prefix cpath, path;
+ 
+-#ifdef CROSS_DIRECTORY_STRUCTURE
+ /* This is the name of the target machine.  We use it to form the name
+    of the files to execute.  */
+ 
+ static const char *const target_machine = TARGET_MACHINE;
+-#endif
+ 
+ /* Search for NAME using prefix list PPREFIX.  We only look for executable
+    files.
+@@ -577,7 +575,7 @@ add_lto_object (struct lto_object_list *list, const char *name)
+ 
+ static void
+ maybe_run_lto_and_relink (char **lto_ld_argv, char **object_lst,
+-			  const char **object, bool force)
++			  const char **object, bool force, bool is_cross_compiler)
+ {
+   const char **object_file = CONST_CAST2 (const char **, char **, object_lst);
+ 
+@@ -722,7 +720,7 @@ maybe_run_lto_and_relink (char **lto_ld_argv, char **object_lst,
+ 		    "ld_args");
+       /* We assume that temp files were created, and therefore we need to take
+          that into account (maybe run dsymutil).  */
+-      post_ld_pass (/*temp_file*/true);
++      post_ld_pass (/*temp_file*/true, is_cross_compiler);
+       free (lto_ld_argv);
+ 
+       maybe_unlink_list (lto_o_files);
+@@ -734,10 +732,10 @@ maybe_run_lto_and_relink (char **lto_ld_argv, char **object_lst,
+       fork_execute ("ld", lto_ld_argv, HAVE_GNU_LD && at_file_supplied,
+ 		    "ld_args");
+       /* No LTO objects were found, so no new temp file.  */
+-      post_ld_pass (/*temp_file*/false);
++      post_ld_pass (/*temp_file*/false, is_cross_compiler);
+     }
+   else
+-    post_ld_pass (false); /* No LTO objects were found, no temp file.  */
++    post_ld_pass (false, is_cross_compiler); /* No LTO objects were found, no temp file.  */
+ }
+ /* Entry point for linker invoation.  Called from main in collect2.cc.
+    LD_ARGV is an array of arguments for the linker.  */
+@@ -799,33 +797,14 @@ main (int argc, char **argv)
+   static const char *const gstrip_suffix = "gstrip";
+ 
+   const char *full_ld_suffixes[USE_LD_MAX];
+-#ifdef CROSS_DIRECTORY_STRUCTURE
+-  /* If we look for a program in the compiler directories, we just use
+-     the short name, since these directories are already system-specific.
+-     But it we look for a program in the system directories, we need to
+-     qualify the program name with the target machine.  */
+-
+-  const char *const full_nm_suffix =
+-    concat (target_machine, "-", nm_suffix, NULL);
+-  const char *const full_gnm_suffix =
+-    concat (target_machine, "-", gnm_suffix, NULL);
+-#ifdef LDD_SUFFIX
+-  const char *const full_ldd_suffix =
+-    concat (target_machine, "-", ldd_suffix, NULL);
+-#endif
+-  const char *const full_strip_suffix =
+-    concat (target_machine, "-", strip_suffix, NULL);
+-  const char *const full_gstrip_suffix =
+-    concat (target_machine, "-", gstrip_suffix, NULL);
+-#else
++  const char *full_nm_suffix;
++  const char *full_gnm_suffix;
++  const char *full_strip_suffix;
++  const char *full_gstrip_suffix;
++
+ #ifdef LDD_SUFFIX
+-  const char *const full_ldd_suffix	= ldd_suffix;
++  const char *full_ldd_suffix;
+ #endif
+-  const char *const full_nm_suffix	= nm_suffix;
+-  const char *const full_gnm_suffix	= gnm_suffix;
+-  const char *const full_strip_suffix	= strip_suffix;
+-  const char *const full_gstrip_suffix	= gstrip_suffix;
+-#endif /* CROSS_DIRECTORY_STRUCTURE */
+ 
+   const char *arg;
+   FILE *outf;
+@@ -840,6 +819,7 @@ main (int argc, char **argv)
+   const char **ld1;
+   bool use_plugin = false;
+   bool use_collect_ld = false;
++  bool is_cross_compiler = false;
+ 
+   /* The kinds of symbols we will have to consider when scanning the
+      outcome of a first pass link.  This is ALL to start with, then might
+@@ -864,17 +844,6 @@ main (int argc, char **argv)
+ #endif
+   int i;
+ 
+-  for (i = 0; i < USE_LD_MAX; i++)
+-#ifdef CROSS_DIRECTORY_STRUCTURE
+-    /* lld and mold are platform-agnostic and not prefixed with target
+-       triple.  */
+-    if (!(i == USE_LLD_LD || i == USE_MOLD_LD))
+-      full_ld_suffixes[i] = concat (target_machine, "-", ld_suffixes[i],
+-				    NULL);
+-    else
+-#endif
+-      full_ld_suffixes[i] = ld_suffixes[i];
+-
+   p = argv[0] + strlen (argv[0]);
+   while (p != argv[0] && !IS_DIR_SEPARATOR (p[-1]))
+     --p;
+@@ -1050,6 +1019,65 @@ main (int argc, char **argv)
+   prefix_from_env ("COMPILER_PATH", &cpath);
+   prefix_from_env ("PATH", &path);
+ 
++  /* Determine the full path name of the C compiler to use.  */
++  c_file_name = getenv ("COLLECT_GCC");
++  if (c_file_name == 0)
++    {
++      c_file_name = concat (target_machine, "-gcc", NULL);
++      p = find_a_file (&cpath, c_file_name, X_OK);
++      if (p == 0)
++        p = find_a_file (&path, c_file_name, X_OK);
++
++      if (p == 0) {
++        c_file_name = "gcc";
++        p = find_a_file (&cpath, c_file_name, X_OK);
++        if (p == 0)
++          p = find_a_file (&path, c_file_name, X_OK);
++      }
++    }
++  else
++    {
++      p = find_a_file (&cpath, c_file_name, X_OK);
++
++      /* Here it should be safe to use the system search path since we should have
++        already qualified the name of the compiler when it is needed.  */
++      if (p == 0)
++        p = find_a_file (&path, c_file_name, X_OK);
++    }
++
++  if (p)
++    c_file_name = p;
++
++  if (c_file_name) {
++    is_cross_compiler = strncmp(basename(c_file_name), target_machine, strlen(target_machine)) == 0;
++  }
++
++  for (i = 0; i < USE_LD_MAX; i++)
++    /* lld and mold are platform-agnostic and not prefixed with target
++       triple.  */
++    if (!(i == USE_LLD_LD || i == USE_MOLD_LD) && is_cross_compiler)
++      full_ld_suffixes[i] = concat (target_machine, "-", ld_suffixes[i],
++				    NULL);
++    else
++      full_ld_suffixes[i] = ld_suffixes[i];
++
++  full_nm_suffix =
++    is_cross_compiler ? concat (target_machine, "-", nm_suffix, NULL) : nm_suffix;
++
++  full_gnm_suffix =
++    is_cross_compiler ? concat (target_machine, "-", gnm_suffix, NULL) : gnm_suffix;
++
++  full_strip_suffix =
++    is_cross_compiler ? concat (target_machine, "-", strip_suffix, NULL) : strip_suffix;
++
++  full_gstrip_suffix =
++    is_cross_compiler ? concat (target_machine, "-", gstrip_suffix, NULL) : gstrip_suffix;
++
++#ifdef LDD_SUFFIX
++  full_ldd_suffix =
++    is_cross_compiler ? concat (target_machine, "-", ldd_suffix, NULL) : ldd_suffix;
++#endif
++
+   /* Try to discover a valid linker/nm/strip to use.  */
+ 
+   /* Maybe we know the right file to use (if not cross).  */
+@@ -1139,27 +1167,6 @@ main (int argc, char **argv)
+   if (strip_file_name == 0)
+     strip_file_name = find_a_file (&path, full_strip_suffix, X_OK);
+ 
+-  /* Determine the full path name of the C compiler to use.  */
+-  c_file_name = getenv ("COLLECT_GCC");
+-  if (c_file_name == 0)
+-    {
+-#ifdef CROSS_DIRECTORY_STRUCTURE
+-      c_file_name = concat (target_machine, "-gcc", NULL);
+-#else
+-      c_file_name = "gcc";
+-#endif
+-    }
+-
+-  p = find_a_file (&cpath, c_file_name, X_OK);
+-
+-  /* Here it should be safe to use the system search path since we should have
+-     already qualified the name of the compiler when it is needed.  */
+-  if (p == 0)
+-    p = find_a_file (&path, c_file_name, X_OK);
+-
+-  if (p)
+-    c_file_name = p;
+-
+   *ld1++ = *ld2++ = ld_file_name;
+ 
+   /* Make temp file names.  */
+@@ -1595,6 +1602,8 @@ main (int argc, char **argv)
+ 	       (c_file ? c_file : "not found"));
+       fprintf (stderr, "o_file              = %s\n",
+ 	       (o_file ? o_file : "not found"));
++      fprintf (stderr, "is_cross_compiler   = %s\n",
++          (is_cross_compiler ? "yes" : "no"));
+ 
+       ptr = getenv ("COLLECT_GCC_OPTIONS");
+       if (ptr)
+@@ -1644,9 +1653,9 @@ main (int argc, char **argv)
+ 	  maybe_unlink (export_file);
+ #endif
+ 	if (lto_mode != LTO_MODE_NONE)
+-	  maybe_run_lto_and_relink (ld1_argv, object_lst, object, false);
++	  maybe_run_lto_and_relink (ld1_argv, object_lst, object, false, is_cross_compiler);
+ 	else
+-	  post_ld_pass (/*temp_file*/false);
++	  post_ld_pass (/*temp_file*/false, is_cross_compiler);
+ 
+ 	return 0;
+       }
+@@ -1698,7 +1707,7 @@ main (int argc, char **argv)
+ 	do_link (ld1_argv, "ld1_args");
+ 
+       if (lto_mode)
+-        maybe_run_lto_and_relink (ld1_argv, object_lst, object, false);
++        maybe_run_lto_and_relink (ld1_argv, object_lst, object, false, is_cross_compiler);
+ 
+       /* Strip now if it was requested on the command line.  */
+       if (strip_flag)
+@@ -1716,7 +1725,7 @@ main (int argc, char **argv)
+ #ifdef COLLECT_EXPORT_LIST
+       maybe_unlink (export_file);
+ #endif
+-      post_ld_pass (/*temp_file*/false);
++      post_ld_pass (/*temp_file*/false, is_cross_compiler);
+       return 0;
+     }
+ 
+@@ -1799,15 +1808,15 @@ main (int argc, char **argv)
+   do_link (ld2_argv, "ld2_args");
+ 
+   if (lto_mode)
+-    maybe_run_lto_and_relink (ld2_argv, object_lst, object, false);
++    maybe_run_lto_and_relink (ld2_argv, object_lst, object, false, is_cross_compiler);
+ #else
+   /* Otherwise, simply call ld because link is already done.  */
+   if (lto_mode)
+-    maybe_run_lto_and_relink (ld2_argv, object_lst, object, true);
++    maybe_run_lto_and_relink (ld2_argv, object_lst, object, true, is_cross_compiler);
+   else
+     {
+       fork_execute ("ld", ld2_argv, HAVE_GNU_LD && at_file_supplied, "ld_args");
+-      post_ld_pass (/*temp_file*/false);
++      post_ld_pass (/*temp_file*/false, is_cross_compiler);
+     }
+ 
+   /* Let scan_prog_file do any final mods (OSF/rose needs this for
+@@ -3020,7 +3029,7 @@ process_args (int *argcp, char **argv) {
+ }
+ 
+ static void
+-do_dsymutil (const char *output_file) {
++do_dsymutil (const char *output_file, bool is_cross_compiler) {
+   const char *dsymutil = 0;
+   struct pex_obj *pex;
+   char **real_argv = XCNEWVEC (char *, verbose ? 4 : 3);
+@@ -3032,11 +3041,7 @@ do_dsymutil (const char *output_file) {
+    here is consistent with the way other installations work (and one can
+    always symlink a multitarget dsymutil with a target-specific name).  */
+   const char *dsname = "dsymutil";
+-#ifdef CROSS_DIRECTORY_STRUCTURE
+-  const char *qname = concat (target_machine, "-", dsname, NULL);
+-#else
+-  const char *qname = dsname;
+-#endif
++  const char *qname = is_cross_compiler ? concat (target_machine, "-", dsname, NULL) : dsname;
+ #ifdef DEFAULT_DSYMUTIL
+   /* Configured default takes priority.  */
+   if (dsymutil == 0 && access (DEFAULT_DSYMUTIL, X_OK) == 0)
+@@ -3071,14 +3076,14 @@ do_dsymutil (const char *output_file) {
+ }
+ 
+ static void
+-post_ld_pass (bool temp_file) {
++post_ld_pass (bool temp_file, bool is_cross_compiler) {
+   if (!(temp_file && flag_idsym) && !flag_dsym)
+     return;
+ 
+-  do_dsymutil (output_file);
++  do_dsymutil (output_file, is_cross_compiler);
+ }
+ #else
+ static void
+ process_args (int *argcp ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED) { }
+-static void post_ld_pass (bool temp_file ATTRIBUTE_UNUSED) { }
++static void post_ld_pass (bool temp_file ATTRIBUTE_UNUSED, bool is_cross_compiler ATTRIBUTE_UNUSED) { }
+ #endif
diff --git a/pkgs/development/compilers/gcc/ng/README.md b/pkgs/development/compilers/gcc/ng/README.md
new file mode 100644
index 0000000000000..b40070caebc6d
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/README.md
@@ -0,0 +1,3 @@
+# GCC Next-Generation
+
+Experimental split GCC package set based on the LLVM package set design.
diff --git a/pkgs/development/compilers/gcc/ng/common/common-let.nix b/pkgs/development/compilers/gcc/ng/common/common-let.nix
new file mode 100644
index 0000000000000..95f14abd76792
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/common-let.nix
@@ -0,0 +1,47 @@
+{
+  lib,
+  fetchurl ? null,
+  fetchgit ? null,
+  release_version ? null,
+  gitRelease ? null,
+  officialRelease ? null,
+  monorepoSrc' ? null,
+  version ? null,
+}@args:
+
+rec {
+  gcc_meta = {
+    license = with lib.licenses; [ gpl3Plus ];
+    teams = [ lib.teams.gcc ];
+  };
+
+  releaseInfo =
+    if gitRelease != null then
+      rec {
+        original = gitRelease;
+        release_version = args.version or original.version;
+        version = gitRelease.rev-version;
+      }
+    else
+      rec {
+        original = officialRelease;
+        release_version = args.version or original.version;
+        version =
+          if original ? candidate then "${release_version}-${original.candidate}" else release_version;
+      };
+
+  monorepoSrc =
+    if monorepoSrc' != null then
+      monorepoSrc'
+    else if gitRelease != null then
+      fetchgit {
+        url = "https://gcc.gnu.org/git/gcc.git";
+        inherit (gitRelease) rev;
+        hash = releaseInfo.original.sha256;
+      }
+    else
+      fetchurl {
+        url = "mirror://gcc/releases/gcc-${releaseInfo.version}/gcc-${releaseInfo.version}.tar.xz";
+        hash = releaseInfo.original.sha256;
+      };
+}
diff --git a/pkgs/development/compilers/gcc/ng/common/default.nix b/pkgs/development/compilers/gcc/ng/common/default.nix
new file mode 100644
index 0000000000000..1b83e75015f91
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/default.nix
@@ -0,0 +1,221 @@
+{
+  lib,
+  newScope,
+  stdenv,
+  overrideCC,
+  fetchgit,
+  fetchurl,
+  gitRelease ? null,
+  officialRelease ? null,
+  monorepoSrc ? null,
+  version ? null,
+  patchesFn ? lib.id,
+  wrapCCWith,
+  binutilsNoLibc,
+  binutils,
+  buildGccPackages,
+  targetGccPackages,
+  makeScopeWithSplicing',
+  otherSplices,
+  ...
+}@args:
+
+assert lib.assertMsg (lib.xor (gitRelease != null) (officialRelease != null)) (
+  "must specify `gitRelease` or `officialRelease`"
+  + (lib.optionalString (gitRelease != null) " — not both")
+);
+
+let
+  monorepoSrc' = monorepoSrc;
+
+  metadata = rec {
+    inherit
+      (import ./common-let.nix {
+        inherit (args)
+          lib
+          gitRelease
+          officialRelease
+          version
+          ;
+      })
+      releaseInfo
+      ;
+    inherit (releaseInfo) release_version version;
+    inherit
+      (import ./common-let.nix {
+        inherit
+          lib
+          fetchgit
+          fetchurl
+          release_version
+          gitRelease
+          officialRelease
+          monorepoSrc'
+          version
+          ;
+      })
+      gcc_meta
+      monorepoSrc
+      ;
+    src = monorepoSrc;
+    versionDir =
+      (builtins.toString ../.)
+      + "/${if (gitRelease != null) then "git" else lib.versions.major release_version}";
+    getVersionFile =
+      p:
+      builtins.path {
+        name = builtins.baseNameOf p;
+        path =
+          let
+            patches = args.patchesFn (import ./patches.nix);
+
+            constraints = patches."${p}" or null;
+            matchConstraint =
+              {
+                before ? null,
+                after ? null,
+                path,
+              }:
+              let
+                check = fn: value: if value == null then true else fn release_version value;
+                matchBefore = check lib.versionOlder before;
+                matchAfter = check lib.versionAtLeast after;
+              in
+              matchBefore && matchAfter;
+
+            patchDir =
+              toString
+                (
+                  if constraints == null then
+                    { path = metadata.versionDir; }
+                  else
+                    (lib.findFirst matchConstraint { path = metadata.versionDir; } constraints)
+                ).path;
+          in
+          "${patchDir}/${p}";
+      };
+  };
+in
+makeScopeWithSplicing' {
+  inherit otherSplices;
+  f =
+    gccPackages:
+    let
+      callPackage = gccPackages.newScope (args // metadata);
+    in
+    {
+      stdenv = overrideCC stdenv gccPackages.gcc;
+
+      gcc-unwrapped = callPackage ./gcc {
+        bintools = binutils;
+      };
+
+      libbacktrace = callPackage ./libbacktrace { };
+      libiberty = callPackage ./libiberty { };
+      libsanitizer = callPackage ./libsanitizer { };
+      libquadmath = callPackage ./libquadmath { };
+
+      gfortran-unwrapped = gccPackages.gcc-unwrapped.override {
+        stdenv = overrideCC stdenv buildGccPackages.gcc;
+        langFortran = true;
+      };
+
+      gfortran = wrapCCWith rec {
+        cc = gccPackages.gfortran-unwrapped;
+        libcxx = targetGccPackages.libstdcxx;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+          "-B${targetGccPackages.libssp}/lib"
+          "-B${targetGccPackages.libatomic}/lib"
+        ];
+      };
+
+      gcc = wrapCCWith rec {
+        cc = gccPackages.gcc-unwrapped;
+        libcxx = targetGccPackages.libstdcxx;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+          "-B${targetGccPackages.libssp}/lib"
+          "-B${targetGccPackages.libatomic}/lib"
+        ];
+      };
+
+      gccNoLibgcc = wrapCCWith rec {
+        cc = gccPackages.gcc-unwrapped;
+        libcxx = null;
+        bintools = binutilsNoLibc;
+        extraPackages = [ ];
+        nixSupport.cc-cflags = [
+          "-nostartfiles"
+        ];
+      };
+
+      libgcc = callPackage ./libgcc {
+        stdenv = overrideCC stdenv buildGccPackages.gccNoLibgcc;
+      };
+
+      gccWithLibc = wrapCCWith rec {
+        cc = gccPackages.gcc-unwrapped;
+        libcxx = null;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+        ];
+      };
+
+      libssp = callPackage ./libssp {
+        stdenv = overrideCC stdenv buildGccPackages.gccWithLibc;
+      };
+
+      gccWithLibssp = wrapCCWith rec {
+        cc = gccPackages.gcc-unwrapped;
+        libcxx = null;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+          "-B${targetGccPackages.libssp}/lib"
+        ];
+      };
+
+      libatomic = callPackage ./libatomic {
+        stdenv = overrideCC stdenv buildGccPackages.gccWithLibssp;
+      };
+
+      gccWithLibatomic = wrapCCWith rec {
+        cc = gccPackages.gcc-unwrapped;
+        libcxx = null;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+          "-B${targetGccPackages.libssp}/lib"
+          "-B${targetGccPackages.libatomic}/lib"
+        ];
+      };
+
+      libgfortran = callPackage ./libgfortran {
+        stdenv = overrideCC stdenv buildGccPackages.gcc;
+        inherit (buildGccPackages) gfortran;
+      };
+
+      libstdcxx = callPackage ./libstdcxx {
+        stdenv = overrideCC stdenv buildGccPackages.gccWithLibatomic;
+      };
+    };
+}
diff --git a/pkgs/development/compilers/gcc/ng/common/gcc/default.nix b/pkgs/development/compilers/gcc/ng/common/gcc/default.nix
new file mode 100644
index 0000000000000..1be2f007df5df
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/gcc/default.nix
@@ -0,0 +1,249 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  langAda ? false,
+  langC ? true,
+  langCC ? true,
+  langD ? false,
+  langFortran ? false,
+  langGo ? false,
+  langJava ? false,
+  langObjC ? stdenv.targetPlatform.isDarwin,
+  langObjCpp ? stdenv.targetPlatform.isDarwin,
+  langJit ? false,
+  enablePlugin ? lib.systems.equals stdenv.hostPlatform stdenv.buildPlatform,
+  runCommand,
+  buildPackages,
+  isl,
+  zlib,
+  gmp,
+  libmpc,
+  mpfr,
+  libelf,
+  perl,
+  texinfo,
+  which,
+  gettext,
+  getVersionFile,
+  buildGccPackages,
+  targetPackages,
+  libc,
+  bintools,
+}:
+let
+  inherit (stdenv) targetPlatform hostPlatform;
+  targetPrefix = lib.optionalString (targetPlatform != hostPlatform) "${targetPlatform.config}-";
+in
+stdenv.mkDerivation (finalAttrs: {
+  pname = "${targetPrefix}${if langFortran then "gfortran" else "gcc"}";
+  inherit version;
+
+  src = monorepoSrc;
+
+  outputs = [
+    "out"
+    "man"
+    "info"
+  ];
+
+  patches = [
+    # Submitted:
+    #  - https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577639.html
+    #  - https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577640.html
+    #  - https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577638.html
+    #
+    # In Git: https://github.com/Ericson2314/gcc/tree/prog-target-15
+    (getVersionFile "gcc/0001-find_a_program-First-search-with-machine-prefix.patch")
+    (getVersionFile "gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch")
+    (getVersionFile "gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch")
+
+    # Submitted: https://inbox.sourceware.org/gcc-patches/20210818203840.1550133-1-John.Ericson@Obsidian.Systems/T/#t
+    # In Git: https://github.com/Ericson2314/gcc/tree/libgcc-custom-threading-model-15
+    (getVersionFile "gcc/custom-threading-model.patch")
+
+    # TODO: fix up and send to upstream
+    (getVersionFile "gcc/fix-collect2-paths.diff")
+  ];
+
+  enableParallelBuilding = true;
+
+  hardeningDisable = [
+    "format" # Some macro-indirect formatting in e.g. libcpp
+  ];
+
+  strictDeps = true;
+
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+  nativeBuildInputs = [
+    texinfo
+    which
+    gettext
+  ] ++ lib.optional (perl != null) perl;
+
+  buildInputs =
+    [
+      gmp
+      libmpc
+      mpfr
+      libelf
+    ]
+    ++ lib.optional (isl != null) isl
+    ++ lib.optional (zlib != null) zlib;
+
+  postUnpack = ''
+    mkdir -p ./build
+    buildRoot=$(readlink -e "./build")
+  '';
+
+  postPatch =
+    ''
+      configureScripts=$(find . -name configure)
+      for configureScript in $configureScripts; do
+        patchShebangs $configureScript
+      done
+
+      patchShebangs libbacktrace/install-debuginfo-for-buildid.sh
+      patchShebangs runtest
+    ''
+    # This should kill all the stdinc frameworks that gcc and friends like to
+    # insert into default search paths.
+    + lib.optionalString hostPlatform.isDarwin ''
+      substituteInPlace gcc/config/darwin-c.c \
+        --replace 'if (stdinc)' 'if (0)'
+    '';
+
+  preConfigure =
+    # Don't built target libraries, because we want to build separately
+    ''
+      substituteInPlace configure \
+        --replace 'noconfigdirs=""' 'noconfigdirs="$noconfigdirs $target_libraries"'
+    ''
+    # HACK: if host and target config are the same, but the platforms are
+    # actually different we need to convince the configure script that it
+    # is in fact building a cross compiler although it doesn't believe it.
+    +
+      lib.optionalString (targetPlatform.config == hostPlatform.config && targetPlatform != hostPlatform)
+        ''
+          substituteInPlace configure --replace is_cross_compiler=no is_cross_compiler=yes
+        ''
+    # Cannot configure from src dir
+    + ''
+      cd "$buildRoot"
+
+      mkdir -p "$buildRoot/libbacktrace/.libs"
+      cp ${buildGccPackages.libbacktrace}/lib/libbacktrace.a "$buildRoot/libbacktrace/.libs/libbacktrace.a"
+      cp -r ${buildGccPackages.libbacktrace}/lib/*.la "$buildRoot/libbacktrace"
+      cp -r ${buildGccPackages.libbacktrace.dev}/include/*.h "$buildRoot/libbacktrace"
+
+      mkdir -p "$buildRoot/libiberty/pic"
+      cp ${buildGccPackages.libiberty}/lib/libiberty.a "$buildRoot/libiberty"
+      cp ${buildGccPackages.libiberty}/lib/libiberty_pic.a "$buildRoot/libiberty/pic/libiberty.a"
+      touch "$buildRoot/libiberty/stamp-noasandir"
+      touch "$buildRoot/libiberty/stamp-h"
+      touch "$buildRoot/libiberty/stamp-picdir"
+
+      mkdir -p "$buildRoot/build-${stdenv.hostPlatform.config}"
+      cp -r "$buildRoot/libiberty" "$buildRoot/build-${stdenv.hostPlatform.config}/libiberty"
+
+      configureScript=../$sourceRoot/configure
+    '';
+
+  # Don't store the configure flags in the resulting executables.
+  postConfigure = ''
+    sed -e '/TOPLEVEL_CONFIGURE_ARGUMENTS=/d' -i Makefile
+  '';
+
+  dontDisableStatic = true;
+
+  configurePlatforms = [
+    "build"
+    "host"
+    "target"
+  ];
+
+  configureFlags =
+    [
+      # Force target prefix. The behavior if `--target` and `--host` are
+      # specified is inconsistent: Sometimes specifying `--target` always causes
+      # a prefix to be generated, sometimes it's only added if the `--host` and
+      # `--target` differ. This means that sometimes there may be a prefix even
+      # though nixpkgs doesn't expect one and sometimes there may be none even
+      # though nixpkgs expects one (since not all information is serialized into
+      # the config attribute). The easiest way out of these problems is to always
+      # set the program prefix, so gcc will conform to our expectations.
+      "--program-prefix=${targetPrefix}"
+
+      "--disable-dependency-tracking"
+      "--enable-fast-install"
+      "--disable-serial-configure"
+      "--disable-bootstrap"
+      "--disable-decimal-float"
+      "--disable-install-libiberty"
+      "--disable-multilib"
+      "--disable-nls"
+      "--disable-shared"
+      "--enable-languages=${
+        lib.concatStrings (
+          lib.intersperse "," (
+            lib.optional langC "c"
+            ++ lib.optional langCC "c++"
+            ++ lib.optional langD "d"
+            ++ lib.optional langFortran "fortran"
+            ++ lib.optional langJava "java"
+            ++ lib.optional langAda "ada"
+            ++ lib.optional langGo "go"
+            ++ lib.optional langObjC "objc"
+            ++ lib.optional langObjCpp "obj-c++"
+            ++ lib.optional langJit "jit"
+          )
+        )
+      }"
+      (lib.withFeature (isl != null) "isl")
+      "--without-headers"
+      "--with-gnu-as"
+      "--with-gnu-ld"
+      "--with-as=${lib.getExe' bintools "${bintools.targetPrefix}as"}"
+      "--with-system-zlib"
+      "--without-included-gettext"
+      "--enable-linker-build-id"
+      "--with-sysroot=${lib.getDev (targetPackages.libc or libc)}"
+      "--with-native-system-header-dir=/include"
+    ]
+    ++ lib.optionals enablePlugin [
+      "--enable-plugin"
+      "--enable-plugins"
+    ]
+    ++
+      # Only pass when the arch supports it.
+      # Exclude RISC-V because GCC likes to fail when the string is empty on RISC-V.
+      lib.optionals (targetPlatform.isAarch || targetPlatform.isAvr || targetPlatform.isx86_64) [
+        "--with-multilib-list="
+      ];
+
+  doCheck = false;
+
+  postInstall = ''
+    moveToOutput "lib/gcc/${targetPlatform.config}/${version}/plugin/include" "''${!outputDev}"
+  '';
+
+  passthru = {
+    inherit
+      langC
+      langCC
+      langObjC
+      langObjCpp
+      langAda
+      langFortran
+      langGo
+      ;
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libatomic/default.nix b/pkgs/development/compilers/gcc/ng/common/libatomic/default.nix
new file mode 100644
index 0000000000000..ab5632313b760
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libatomic/default.nix
@@ -0,0 +1,48 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  getVersionFile,
+  autoreconfHook269,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libatomic";
+  inherit version;
+
+  src = monorepoSrc;
+
+  patches = [
+    (getVersionFile "gcc/custom-threading-model.patch")
+  ];
+
+  enableParallelBuilding = true;
+
+  nativeBuildInputs = [
+    autoreconfHook269
+  ];
+
+  postPatch = ''
+    sourceRoot=$(readlink -e "./libatomic")
+  '';
+
+  preConfigure = ''
+    mkdir ../build
+    cd ../build
+    configureScript=$sourceRoot/configure
+    chmod +x "$configureScript"
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libbacktrace/default.nix b/pkgs/development/compilers/gcc/ng/common/libbacktrace/default.nix
new file mode 100644
index 0000000000000..33b8174200352
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libbacktrace/default.nix
@@ -0,0 +1,74 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libbacktrace";
+  inherit version;
+
+  src = runCommand "libbacktrace-src-${version}" { src = monorepoSrc; } ''
+    runPhase unpackPhase
+
+    mkdir -p "$out/gcc"
+    cp gcc/BASE-VER "$out/gcc"
+    cp gcc/DATESTAMP "$out/gcc"
+
+    cp -r include "$out"
+    cp -r libbacktrace "$out"
+
+    cp config.guess "$out"
+    cp config.rpath "$out"
+    cp config.sub "$out"
+    cp config-ml.in "$out"
+    cp ltmain.sh "$out"
+    cp install-sh "$out"
+    cp move-if-change "$out"
+    cp mkinstalldirs "$out"
+    cp test-driver "$out"
+
+    [[ -f MD5SUMS ]]; cp MD5SUMS "$out"
+  '';
+
+  outputs = [
+    "out"
+    "dev"
+  ];
+
+  enableParallelBuilding = true;
+
+  sourceRoot = "${finalAttrs.src.name}/libbacktrace";
+
+  preConfigure = ''
+    mkdir ../../build
+    cd ../../build
+    configureScript=../$sourceRoot/configure
+  '';
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p "$out/lib"
+    cp .libs/*.a "$out/lib"
+    cp libbacktrace*.la "$out/lib"
+
+    mkdir -p "$dev/include"
+    cp backtrace-supported.h "$dev/include"
+
+    runHook postInstall
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libgcc/default.nix b/pkgs/development/compilers/gcc/ng/common/libgcc/default.nix
new file mode 100644
index 0000000000000..375ebc747a2fd
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libgcc/default.nix
@@ -0,0 +1,205 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  getVersionFile,
+  monorepoSrc ? null,
+  autoreconfHook269,
+  buildGccPackages,
+  buildPackages,
+  which,
+  python3,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libgcc";
+  inherit version;
+
+  src = monorepoSrc;
+
+  outputs = [
+    "out"
+    "dev"
+  ];
+
+  strictDeps = true;
+
+  depsBuildBuild = [
+    buildPackages.stdenv.cc
+    buildGccPackages.libiberty
+  ];
+
+  nativeBuildInputs = [
+    autoreconfHook269
+    which
+    python3
+  ];
+
+  patches = [
+    (getVersionFile "gcc/custom-threading-model.patch")
+  ];
+
+  autoreconfFlags = "--install --force --verbose . libgcc";
+
+  postUnpack = ''
+    mkdir -p ./build
+    buildRoot=$(readlink -e "./build")
+  '';
+
+  postPatch = ''
+    sourceRoot=$(readlink -e "./libgcc")
+  '';
+
+  enableParallelBuilding = true;
+
+  preConfigure =
+    ''
+      cd "$buildRoot"
+
+      mkdir -p build-${stdenv.buildPlatform.config}/libiberty/
+      cd build-${stdenv.buildPlatform.config}/libiberty/
+      ln -s ${buildGccPackages.libiberty}/lib/libiberty.a ./
+
+      mkdir -p "$buildRoot/gcc"
+      cd "$buildRoot/gcc"
+
+      (
+      export AS_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $AS_FOR_BUILD)"}
+      export CC_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CC_FOR_BUILD)"}
+      export CPP_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CPP_FOR_BUILD)"}
+      export CXX_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CXX_FOR_BUILD)"}
+      export LD_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc.bintools "$(basename $LD_FOR_BUILD)"}
+
+      export AS=$AS_FOR_BUILD
+      export CC=$CC_FOR_BUILD
+      export CPP=$CPP_FOR_BUILD
+      export CXX=$CXX_FOR_BUILD
+      export LD=$LD_FOR_BUILD
+
+      export AS_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $AS)"}
+      export CC_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $CC)"}
+      export CPP_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $CPP)"}
+      export LD_FOR_TARGET=${lib.getExe' stdenv.cc.bintools "$(basename $LD)"}
+
+      export NIX_CFLAGS_COMPILE_FOR_BUILD+=' -DGENERATOR_FILE=1'
+
+      "$sourceRoot/../gcc/configure" $topLevelConfigureFlags
+
+      sed -e 's,libgcc.mvars:.*$,libgcc.mvars:,' -i Makefile
+
+      make \
+        config.h \
+        libgcc.mvars \
+        tconfig.h \
+        tm.h \
+        options.h \
+        insn-constants.h \
+        insn-modes.h \
+        version.h
+      )
+      mkdir -p "$buildRoot/gcc/include"
+
+      mkdir -p "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgcc"
+      cd "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgcc"
+      configureScript=$sourceRoot/configure
+      chmod +x "$configureScript"
+
+      export AS_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $AS_FOR_BUILD)"}
+      export CC_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CC_FOR_BUILD)"}
+      export CPP_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CPP_FOR_BUILD)"}
+      export CXX_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$(basename $CXX_FOR_BUILD)"}
+      export LD_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc.bintools "$(basename $LD_FOR_BUILD)"}
+
+      export AS=${lib.getExe' stdenv.cc "$(basename $AS)"}
+      export CC=${lib.getExe' stdenv.cc "$(basename $CC)"}
+      export CPP=${lib.getExe' stdenv.cc "$(basename $CPP)"}
+      export CXX=${lib.getExe' stdenv.cc "$(basename $CXX)"}
+      export LD=${lib.getExe' stdenv.cc.bintools "$(basename $LD)"}
+
+      export AS_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $AS_FOR_TARGET)"}
+      export CC_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $CC_FOR_TARGET)"}
+      export CPP_FOR_TARGET=${lib.getExe' stdenv.cc "$(basename $CPP_FOR_TARGET)"}
+      export LD_FOR_TARGET=${lib.getExe' stdenv.cc.bintools "$(basename $LD_FOR_TARGET)"}
+    ''
+    + lib.optionalString stdenv.hostPlatform.isMusl ''
+      NIX_CFLAGS_COMPILE_OLD=$NIX_CFLAGS_COMPILE
+      NIX_CFLAGS_COMPILE+=' -isystem ${stdenv.cc.cc}/lib/gcc/${stdenv.hostPlatform.config}/${version}/include-fixed'
+    '';
+
+  topLevelConfigureFlags =
+    [
+      "--build=${stdenv.buildPlatform.config}"
+      "--host=${stdenv.buildPlatform.config}"
+      "--target=${stdenv.hostPlatform.config}"
+
+      "--disable-bootstrap"
+      "--disable-multilib"
+      "--enable-languages=c"
+
+      "--disable-fixincludes"
+      "--disable-intl"
+      "--disable-lto"
+      "--disable-libatomic"
+      "--disable-libbacktrace"
+      "--disable-libcpp"
+      "--disable-libssp"
+      "--disable-libquadmath"
+      "--disable-libgomp"
+      "--disable-libvtv"
+      "--disable-vtable-verify"
+
+      "--with-system-zlib"
+    ]
+    ++
+      lib.optional (!stdenv.hostPlatform.isRiscV)
+        # RISC-V does not like it being empty
+        "--with-multilib-list="
+    ++
+      lib.optional (stdenv.hostPlatform.libc == "glibc")
+        # Cheat and use previous stage's glibc to avoid infinite recursion. As
+        # of GCC 11, libgcc only cares if the version is greater than 2.19,
+        # which is quite ancient, so this little lie should be fine.
+        "--with-glibc-version=${buildPackages.glibc.version}";
+
+  configurePlatforms = [
+    "build"
+    "host"
+  ];
+
+  configureFlags = [
+    "--disable-dependency-tracking"
+    "--with-threads=single"
+    # $CC cannot link binaries, let alone run then
+    "cross_compiling=true"
+    # Do not have dynamic linker without libc
+    "--enable-static"
+    "--disable-shared"
+  ];
+
+  # Set the variable back the way it was, see corresponding code in
+  # `preConfigure`.
+  postConfigure = lib.optionalString stdenv.hostPlatform.isMusl ''
+    NIX_CFLAGS_COMPILE=$NIX_CFLAGS_COMPILE_OLD
+  '';
+
+  makeFlags = [ "MULTIBUILDTOP:=../" ];
+
+  postInstall = ''
+    cp gthr-default.h "$out/lib/gcc/${stdenv.hostPlatform.config}/${version}/include"
+    moveToOutput "lib/gcc/${stdenv.hostPlatform.config}/${version}/include" "$dev"
+    mkdir -p "$out/lib" "$dev/include"
+    ln -s "$out/lib/gcc/${stdenv.hostPlatform.config}/${version}"/* "$out/lib"
+    ln -s "$dev/lib/gcc/${stdenv.hostPlatform.config}/${version}/include"/* "$dev/include/"
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libgfortran/default.nix b/pkgs/development/compilers/gcc/ng/common/libgfortran/default.nix
new file mode 100644
index 0000000000000..4c328fe116323
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libgfortran/default.nix
@@ -0,0 +1,190 @@
+{
+  lib,
+  stdenv,
+  gfortran,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  buildPackages,
+  autoreconfHook269,
+  libiberty,
+  libgcc,
+  libbacktrace,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libgfortran";
+  inherit version;
+
+  src = monorepoSrc;
+
+  outputs = [
+    "out"
+    "dev"
+  ];
+
+  strictDeps = true;
+
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+  nativeBuildInputs = [
+    autoreconfHook269
+    libiberty
+    gfortran
+  ];
+
+  autoreconfFlags = "--install --force --verbose . libgfortran";
+
+  postUnpack = ''
+    mkdir -p ./build
+    buildRoot=$(readlink -e "./build")
+  '';
+
+  postPatch = ''
+    sourceRoot=$(readlink -e "./libgfortran")
+  '';
+
+  enableParallelBuilding = true;
+
+  preConfigure =
+    ''
+      cd "$buildRoot"
+
+      mkdir -p build-${stdenv.buildPlatform.config}/libiberty/
+      cd build-${stdenv.buildPlatform.config}/libiberty/
+      ln -s ${libiberty}/lib/libiberty.a ./
+
+      mkdir -p "$buildRoot/gcc"
+      cd "$buildRoot/gcc"
+
+      (
+      export AS_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$AS_FOR_BUILD"}
+      export CC_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CC_FOR_BUILD"}
+      export CPP_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CPP_FOR_BUILD"}
+      export CXX_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CXX_FOR_BUILD"}
+      export LD_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc.bintools "$LD_FOR_BUILD"}
+
+      export AS=$AS_FOR_BUILD
+      export CC=$CC_FOR_BUILD
+      export CPP=$CPP_FOR_BUILD
+      export CXX=$CXX_FOR_BUILD
+      export LD=$LD_FOR_BUILD
+
+      export AS_FOR_TARGET=${lib.getExe' stdenv.cc "$AS"}
+      export CC_FOR_TARGET=${lib.getExe' stdenv.cc "$CC"}
+      export CPP_FOR_TARGET=${lib.getExe' stdenv.cc "$CPP"}
+      export LD_FOR_TARGET=${lib.getExe' stdenv.cc.bintools "$LD"}
+
+      export NIX_CFLAGS_COMPILE_FOR_BUILD+=' -DGENERATOR_FILE=1'
+
+      "$sourceRoot/../gcc/configure" $topLevelConfigureFlags
+
+      make \
+        config.h
+      )
+      mkdir -p "$buildRoot/gcc/include"
+
+      mkdir -p "$buildRoot/gcc/libbacktrace/.libs"
+      cp ${libbacktrace}/lib/libbacktrace.a "$buildRoot/gcc/libbacktrace/.libs/libbacktrace.a"
+      cp -r ${libbacktrace}/lib/*.la "$buildRoot/gcc/libbacktrace"
+      cp -r ${libbacktrace.dev}/include/*.h "$buildRoot/gcc/libbacktrace"
+
+      mkdir -p "$buildRoot/gcc/libgcc"
+      ln -s "${libgcc.dev}/include/gthr-default.h" "$buildRoot/gcc/libgcc"
+
+      mkdir -p "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgfortran"
+      ln -s "$buildRoot/gcc/libbacktrace" "$buildRoot/gcc/${stdenv.buildPlatform.config}/libbacktrace"
+      ln -s "$buildRoot/gcc/libgcc" "$buildRoot/gcc/${stdenv.buildPlatform.config}/libgcc"
+      cd "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgfortran"
+      configureScript=$sourceRoot/configure
+      chmod +x "$configureScript"
+
+      export AS_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$AS_FOR_BUILD"}
+      export CC_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CC_FOR_BUILD"}
+      export CPP_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CPP_FOR_BUILD"}
+      export CXX_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc "$CXX_FOR_BUILD"}
+      export LD_FOR_BUILD=${lib.getExe' buildPackages.stdenv.cc.bintools "$LD_FOR_BUILD"}
+
+      export AS=${lib.getExe' stdenv.cc "$AS"}
+      export CC=${lib.getExe' stdenv.cc "$CC"}
+      export CPP=${lib.getExe' stdenv.cc "$CPP"}
+      export CXX=${lib.getExe' stdenv.cc "$CXX"}
+      export LD=${lib.getExe' stdenv.cc.bintools "$LD"}
+
+      export AS_FOR_TARGET=${lib.getExe' stdenv.cc "$AS_FOR_TARGET"}
+      export CC_FOR_TARGET=${lib.getExe' stdenv.cc "$CC_FOR_TARGET"}
+      export CPP_FOR_TARGET=${lib.getExe' stdenv.cc "$CPP_FOR_TARGET"}
+      export LD_FOR_TARGET=${lib.getExe' stdenv.cc.bintools "$LD_FOR_TARGET"}
+    ''
+    + lib.optionalString stdenv.hostPlatform.isMusl ''
+      NIX_CFLAGS_COMPILE_OLD=$NIX_CFLAGS_COMPILE
+      NIX_CFLAGS_COMPILE+=' -isystem ${stdenv.cc.cc}/lib/gcc/${stdenv.hostPlatform.config}/${version}/include-fixed'
+    '';
+
+  topLevelConfigureFlags =
+    [
+      "--build=${stdenv.buildPlatform.config}"
+      "--host=${stdenv.buildPlatform.config}"
+      "--target=${stdenv.hostPlatform.config}"
+
+      "--disable-bootstrap"
+      "--disable-multilib"
+      "--with-multilib-list="
+      "--enable-languages=fortran"
+
+      "--disable-fixincludes"
+      "--disable-intl"
+      "--disable-lto"
+      "--disable-libatomic"
+      "--disable-libbacktrace"
+      "--disable-libcpp"
+      "--disable-libssp"
+      "--disable-libquadmath"
+      "--disable-libgomp"
+      "--disable-libvtv"
+      "--disable-vtable-verify"
+
+      "--with-system-zlib"
+    ]
+    ++ lib.optional (stdenv.hostPlatform.libc == "glibc")
+      # Cheat and use previous stage's glibc to avoid infinite recursion. As
+      # of GCC 11, libgcc only cares if the version is greater than 2.19,
+      # which is quite ancient, so this little lie should be fine.
+      "--with-glibc-version=${buildPackages.glibc.version}";
+
+  configurePlatforms = [
+    "build"
+    "host"
+  ];
+
+  configureFlags = [
+    "--disable-dependency-tracking"
+    "--with-threads=single"
+    # $CC cannot link binaries, let alone run then
+    "cross_compiling=true"
+  ];
+
+  # Set the variable back the way it was, see corresponding code in
+  # `preConfigure`.
+  postConfigure = lib.optionalString stdenv.hostPlatform.isMusl ''
+    NIX_CFLAGS_COMPILE=$NIX_CFLAGS_COMPILE_OLD
+  '';
+
+  makeFlags = [ "MULTIBUILDTOP:=../" ];
+
+  postInstall = ''
+    moveToOutput "lib/gcc/${stdenv.hostPlatform.config}/${version}/include" "$dev"
+    mkdir -p "$out/lib" "$dev/include"
+    ln -s "$out/lib/gcc/${stdenv.hostPlatform.config}/${version}"/* "$out/lib"
+    ln -s "$dev/lib/gcc/${stdenv.hostPlatform.config}/${version}/include"/* "$dev/include/"
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libiberty/default.nix b/pkgs/development/compilers/gcc/ng/common/libiberty/default.nix
new file mode 100644
index 0000000000000..9ffad2a69ea84
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libiberty/default.nix
@@ -0,0 +1,67 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libiberty";
+  inherit version;
+
+  src = runCommand "libiberty-src-${version}" { src = monorepoSrc; } ''
+    runPhase unpackPhase
+
+    mkdir -p "$out/gcc"
+    cp gcc/BASE-VER "$out/gcc"
+    cp gcc/DATESTAMP "$out/gcc"
+
+    cp -r include "$out"
+    cp -r libiberty "$out"
+
+    cp config.guess "$out"
+    cp config.rpath "$out"
+    cp config.sub "$out"
+    cp config-ml.in "$out"
+    cp ltmain.sh "$out"
+    cp install-sh "$out"
+    cp mkinstalldirs "$out"
+
+    [[ -f MD5SUMS ]]; cp MD5SUMS "$out"
+  '';
+
+  outputs = [
+    "out"
+    "dev"
+  ];
+
+  enableParallelBuilding = true;
+
+  sourceRoot = "${finalAttrs.src.name}/libiberty";
+
+  preConfigure = ''
+    mkdir ../../build
+    cd ../../build
+    configureScript=../$sourceRoot/configure
+  '';
+
+  configureFlags = [
+    "--enable-install-libiberty"
+  ] ++ lib.optional (!stdenv.hostPlatform.isStatic) "--enable-shared";
+
+  postInstall = ''
+    cp pic/libiberty.a $out/lib/libiberty_pic.a
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libquadmath/default.nix b/pkgs/development/compilers/gcc/ng/common/libquadmath/default.nix
new file mode 100644
index 0000000000000..982b4177b749e
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libquadmath/default.nix
@@ -0,0 +1,51 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libquadmath";
+  inherit version;
+
+  src = runCommand "libquadmath-src-${version}" { src = monorepoSrc; } ''
+    runPhase unpackPhase
+
+    mkdir -p "$out/gcc"
+    cp gcc/BASE-VER "$out/gcc"
+    cp gcc/DATESTAMP "$out/gcc"
+
+    cp -r libquadmath "$out"
+
+    cp config.guess "$out"
+    cp config.rpath "$out"
+    cp config.sub "$out"
+    cp config-ml.in "$out"
+    cp ltmain.sh "$out"
+    cp install-sh "$out"
+    cp mkinstalldirs "$out"
+
+    [[ -f MD5SUMS ]]; cp MD5SUMS "$out"
+  '';
+
+  sourceRoot = "${finalAttrs.src.name}/libquadmath";
+
+  preConfigure = ''
+    mkdir ../../build
+    cd ../../build
+    configureScript=../$sourceRoot/configure
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libsanitizer/default.nix b/pkgs/development/compilers/gcc/ng/common/libsanitizer/default.nix
new file mode 100644
index 0000000000000..b42736d122bd5
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libsanitizer/default.nix
@@ -0,0 +1,57 @@
+{
+  lib,
+  stdenv,
+  libstdcxx,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libsanitizer";
+  inherit version;
+
+  src = runCommand "libsanitizer-src-${version}" { src = monorepoSrc; } ''
+    runPhase unpackPhase
+
+    mkdir -p "$out/gcc"
+    cp gcc/BASE-VER "$out/gcc"
+    cp gcc/DATESTAMP "$out/gcc"
+
+    cp -r libsanitizer "$out"
+
+    cp config.guess "$out"
+    cp config.rpath "$out"
+    cp config.sub "$out"
+    cp config-ml.in "$out"
+    cp ltmain.sh "$out"
+    cp install-sh "$out"
+    cp mkinstalldirs "$out"
+
+    [[ -f MD5SUMS ]]; cp MD5SUMS "$out"
+  '';
+
+  sourceRoot = "${finalAttrs.src.name}/libsanitizer";
+
+  postUnpack = ''
+    mkdir -p libstdc++-v3/src/
+    ln -s ${libstdcxx}/lib/libstdc++.la libstdc++-v3/src/libstdc++.la
+  '';
+
+  preConfigure = ''
+    mkdir ../../build
+    cd ../../build
+    configureScript=../$sourceRoot/configure
+  '';
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libssp/default.nix b/pkgs/development/compilers/gcc/ng/common/libssp/default.nix
new file mode 100644
index 0000000000000..3c4cc19582c58
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libssp/default.nix
@@ -0,0 +1,68 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  monorepoSrc ? null,
+  runCommand,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libssp";
+  inherit version;
+
+  src = runCommand "libssp-src-${version}" { src = monorepoSrc; } ''
+    runPhase unpackPhase
+
+    mkdir -p "$out/gcc"
+    cp gcc/BASE-VER "$out/gcc"
+    cp gcc/DATESTAMP "$out/gcc"
+
+    cp -r libssp "$out"
+
+    cp config.guess "$out"
+    cp config.rpath "$out"
+    cp config.sub "$out"
+    cp config-ml.in "$out"
+    cp ltmain.sh "$out"
+    cp install-sh "$out"
+    cp mkinstalldirs "$out"
+
+    [[ -f MD5SUMS ]]; cp MD5SUMS "$out"
+  '';
+
+  sourceRoot = "${finalAttrs.src.name}/libssp";
+
+  configurePlatforms = [
+    "build"
+    "host"
+  ];
+  configureFlags = [
+    "--disable-dependency-tracking"
+    "--with-toolexeclibdir=${builtins.placeholder "out" + "/lib"}"
+    "cross_compiling=true"
+    "--disable-multilib"
+  ];
+
+  preConfigure = ''
+    mkdir ../../build
+    cd ../../build
+    configureScript=../$sourceRoot/configure
+  '';
+
+  hardeningDisable = [
+    "fortify"
+    # Because we are building it!
+    "stackprotector"
+  ];
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/libstdcxx/default.nix b/pkgs/development/compilers/gcc/ng/common/libstdcxx/default.nix
new file mode 100644
index 0000000000000..3fed3ada04923
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/libstdcxx/default.nix
@@ -0,0 +1,87 @@
+{
+  lib,
+  stdenv,
+  gcc_meta,
+  release_version,
+  version,
+  getVersionFile,
+  monorepoSrc ? null,
+  runCommand,
+  autoreconfHook269,
+  gettext,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  pname = "libstdcxx";
+  inherit version;
+
+  src = monorepoSrc;
+
+  enableParallelBuilding = true;
+
+  nativeBuildInputs = [
+    autoreconfHook269
+    gettext
+  ];
+
+  patches = [
+    (getVersionFile "gcc/custom-threading-model.patch")
+  ];
+
+  postUnpack = ''
+    mkdir -p ./build
+    buildRoot=$(readlink -e "./build")
+  '';
+
+  preAutoreconf = ''
+    sourceRoot=$(readlink -e "./libstdc++-v3")
+    cd $sourceRoot
+  '';
+
+  postPatch = ''
+    sed -i \
+      -e 's/AM_ENABLE_MULTILIB(/AM_ENABLE_MULTILIB(NOPE/' \
+      -e 's#glibcxx_toolexeclibdir=no#glibcxx_toolexeclibdir=${builtins.placeholder "out"}/libexec#' \
+      configure.ac
+  '';
+
+  preConfigure = ''
+    cd "$buildRoot"
+    configureScript=$sourceRoot/configure
+    chmod +x "$configureScript"
+  '';
+
+  configureFlags = [
+    "--disable-dependency-tracking"
+    "--with-toolexeclibdir=${builtins.placeholder "out"}/lib"
+    "--with-threads=posix"
+    "cross_compiling=true"
+    "--disable-multilib"
+
+    "--enable-clocale=gnu"
+    "--disable-libstdcxx-pch"
+    "--disable-vtable-verify"
+    "--enable-libstdcxx-visibility"
+    "--with-default-libstdcxx-abi=new"
+  ];
+
+  outputs = [
+    "out"
+    "dev"
+  ];
+
+  hardeningDisable = [
+    # PATH_MAX
+    "fortify"
+  ];
+
+  doCheck = true;
+
+  passthru = {
+    isGNU = true;
+  };
+
+  meta = gcc_meta // {
+    homepage = "https://gcc.gnu.org/onlinedocs/libstdc++";
+    description = "GNU C++ Library";
+  };
+})
diff --git a/pkgs/development/compilers/gcc/ng/common/patches.nix b/pkgs/development/compilers/gcc/ng/common/patches.nix
new file mode 100644
index 0000000000000..0db7ec10262be
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/common/patches.nix
@@ -0,0 +1,32 @@
+{
+  "gcc/fix-collect2-paths.diff" = [
+    {
+      after = "15";
+      path = ../15;
+    }
+  ];
+  "gcc/0001-find_a_program-First-search-with-machine-prefix.patch" = [
+    {
+      after = "15";
+      path = ../15;
+    }
+  ];
+  "gcc/0002-driver-for_each_pass-Pass-to-callback-whether-dir-is.patch" = [
+    {
+      after = "15";
+      path = ../15;
+    }
+  ];
+  "gcc/0003-find_a_program-Only-search-for-prefixed-paths-in-und.patch" = [
+    {
+      after = "15";
+      path = ../15;
+    }
+  ];
+  "gcc/custom-threading-model.patch" = [
+    {
+      after = "15";
+      path = ../15;
+    }
+  ];
+}
diff --git a/pkgs/development/compilers/gcc/ng/default.nix b/pkgs/development/compilers/gcc/ng/default.nix
new file mode 100644
index 0000000000000..3fb74d722d062
--- /dev/null
+++ b/pkgs/development/compilers/gcc/ng/default.nix
@@ -0,0 +1,69 @@
+{
+  lib,
+  callPackage,
+  stdenv,
+  stdenvAdapters,
+  recurseIntoAttrs,
+  gccVersions ? { },
+  patchesFn ? lib.id,
+  buildPackages,
+  targetPackages,
+  binutilsNoLibc,
+  binutils,
+  generateSplicesForMkScope,
+  ...
+}@packageSetArgs:
+let
+  versions = {
+    "15.1.0".officialRelease.sha256 = "sha256-4rCewhZg8B/s/7cV4BICZSFpQ/A40OSKmGhxPlTwbOo=";
+  } // gccVersions;
+
+  mkPackage =
+    {
+      name ? null,
+      officialRelease ? null,
+      gitRelease ? null,
+      monorepoSrc ? null,
+      version ? null,
+    }@args:
+    let
+      inherit
+        (import ./common/common-let.nix {
+          inherit
+            lib
+            gitRelease
+            officialRelease
+            version
+            ;
+        })
+        releaseInfo
+        ;
+      inherit (releaseInfo) release_version;
+      attrName =
+        args.name or (if (gitRelease != null) then "git" else lib.versions.major release_version);
+    in
+    lib.nameValuePair attrName (
+      recurseIntoAttrs (
+        callPackage ./common (
+          {
+            inherit (stdenvAdapters) overrideCC;
+            inherit
+              officialRelease
+              gitRelease
+              monorepoSrc
+              version
+              patchesFn
+              ;
+
+            buildGccPackages = buildPackages."gccNGPackages_${attrName}";
+            targetGccPackages = targetPackages."gccNGPackages_${attrName}" or gccPackages."${attrName}";
+            otherSplices = generateSplicesForMkScope "gccNGPackages_${attrName}";
+          }
+          // packageSetArgs # Allow overrides.
+        )
+      )
+    );
+
+  gccPackages = lib.mapAttrs' (version: args: mkPackage (args // { inherit version; })) versions;
+in
+gccPackages // { inherit mkPackage; }
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 09a5540fec3f4..f324b91b7ffa5 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5042,6 +5042,17 @@ with pkgs;
   gccFun = callPackage ../development/compilers/gcc;
   gcc-unwrapped = gcc.cc;
 
+  inherit
+    (rec {
+      # NOTE: keep this with the "NG" label until we're ready to drop the monolithic GCC
+      gccNGPackagesSet = recurseIntoAttrs (callPackages ../development/compilers/gcc/ng { });
+      gccNGPackages_15 = gccNGPackagesSet."15";
+      mkGCCNGPackages = gccNGPackagesSet.mkPackage;
+    })
+    gccNGPackages_15
+    mkGCCNGPackages
+    ;
+
   wrapNonDeterministicGcc =
     stdenv: ccWrapper:
     if ccWrapper.isGNU then

From 101bb13d4804c81b1ec56ada646c437ecff16ff8 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@midstall.com>
Date: Thu, 26 Jun 2025 20:27:25 -0700
Subject: [PATCH 2/2] binutilsNoLibc: fix cross

---
 pkgs/top-level/all-packages.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index f324b91b7ffa5..b19d15bfca4a0 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -6981,7 +6981,7 @@ with pkgs;
   });
   binutilsNoLibc = wrapBintoolsWith {
     bintools = binutils-unwrapped;
-    libc = targetPackages.preLibcHeaders;
+    libc = targetPackages.preLibcHeaders or preLibcHeaders;
   };
 
   libbfd = callPackage ../development/tools/misc/binutils/libbfd.nix { };