#!/bin/sh -e

#===============================================================
# Filename : bootstrap
# Purpose  : Builds a GCC toolchain and robust development tools
# Authors  : Zach van Rijn <me@zv.io>
# License  : MIT
# Revision : 20260205
#===============================================================

##
# This software is currently considered experimental, pre-alpha,
# and may not work in new or ill-configured environments. Please
# report any issues you encounter (email is fine) and attach the
# build log (or relevant portions) and files referenced therein.
#
# Log files are located adjacent to the build directories, named
# <PACKAGE>-<VERSION><EXTENSION>.log.{err,out}. Please compress
# before submitting logs.

#===============================================================
# README
#===============================================================
#
# overview
# --------
#
# This script builds a GCC toolchain and other utilities for any
# supported unix-like platform (Solaris, AIX, Linux, BSD, macOS)
# where the resulting tooling provides a consistent environment
# in which "musl-cross-make" can be built. Windows platforms are
# currently under testing (Cygwin, MSYS2, WSL). Your particular
# system may call for adjustments to certain build parameters.
#
# No arguments are passed to this script. Edit the parameters in
# the subsequent sections. Reasonable defaults are listed.
#
# The user's system is assumed to have limited functionality, in
# that it lacks tooling which obeys any reasonable standards, so
# all necessary tools are built from source prior to GCC.
#
# Output of this script is a "system" directory containing built
# tools, a "host toolchain" directory containing a native albeit
# modern GNU Compiler Collection (GCC) toolchain and binutils,
# and "musl toolchain" directory containing a cross-compilation
# toolchain targeting musl libc (https://musl.libc.org) if it is
# supported by your system's architecture.
#
# When operating in "bootstrap" mode, all utilities are rebuilt
# statically using the musl toolchain from the first step. This
# provides a reliable set of static, but not relocatable, tools.
#
# All user-facing options are found in the "Build Configuration"
# section, though it is trivial to customize other sections.
#
#
# source code
# -----------
#
# The latest version of this script and corresponding notes may
# be found at the following location (which may be git-cloned):
#
#     https://git.zv.io/toolchains/bootstrap
#
#
# features
# --------
#
#   * Platform compatibility (Solaris, AIX, Linux, BSD, macOS);
#
#   * Caching of source and build artifacts reduces time wasted
#     waiting for builds and rebuilds if the script is modified
#     or in the event of a component failing to build;
#
#   * Build artifacts are cached even if the whole bootstrapping
#     tree is destroyed (stored in '$HOME/.ccache' by default);
#
#   * Wide array of tools available and a framework conducive to
#     the brick-simple addition of new tools, and unwanted tools
#     can be disabled trivially with "if-false" barriers;
#
#   * Modern GCC includes the best freely-available optimization
#     support for your applications;
#
#   * Once installed, the necessary 'PATH' variable is shown and
#     may be used immediately;
#
#
# requirements
# ------------
#
# You'll need a working internet connection and all of the tools
# listed in the "Baseline System" section below. If the build is
# unsuccessful, you may consider verifying these tools are up to
# date and reporting the issue to me for documentation updates.
#
# Either 'curl' (preferred) or 'wget' will be used; they must be
# configured to support TLS connections and to use any necessary
# proxy settings for your company firewall, if applicable. You
# do not need to specify which to use; this script auto-detects.
#
# If a file fails to download, you may need to remove a sentinel
# indicating (erroneously) that the download was completed. At a
# future point, a retry mechanim may be implemented.
#
# You will need the 'which' command before proceeding. The early
# stages (environment sanity checking and preparation) may not
# print the friendliest error messages. Use 'set -x' to debug.
#
# Broadly speaking, you'll also need (and be told if missing):
#
#   * bash
#   * coreutils
#   * diffutils
#   * flex
#   * gcc, g++
#   * m4
#   * make
#   * perl
#   * xz, bzip2, gzip
#
# Few minimum utility versions are needed during bootstrap only:
#
#   * GNU m4 1.4.6 or greater, necessary to build autotools and
#     bootstrap a newer 'gnulib' and 'm4' on platforms that the
#     current 'm4' doesn't support. This will be simplified upon
#     the next 'm4' release.
#
#   * curl newer than ~7.40.0, unless you host all of the source
#     tarballs yourself and use a single mirror supported by the
#     available encryption protocols. The OpenCSW version is OK
#     if you're a Solaris user without a support contract.
#
#
# usage
# -----
#
# The following example demonstrates building a musl-cross-make
# toolchain from scratch using the bootstrapped compiler and one
# directory as its pristine PATH:
#
#   $ /path/to/bootstrap # (this script)
#   $ export PATH="<value_printed_after_this_script_runs>"
#   $ bash
#   $ git clone https://git.zv.io/toolchains/musl-cross-make.git
#   $ cd musl-cross-make
#   $ curl -so config.mak https://conf.musl.cc/...
#   $ make ...
#
# where 'make ...' refers to the standard musl-cross-make build
# command. See https://git.zv.io/toolchains/musl-cross-make for
# more information. Don't forget to specify TARGET and OUTPUT.
#
#
# supported platforms
# -------------------
#
# The following list is not exhaustive. These are platforms on
# which this script is known to work without errors or kludges,
# though this list may be out of date and may use settings that
# are not currently presented in this version. Adjust as needed.
#
#   * AIX         (POWER7)  -- very difficult to get working!
#   * Linux glibc (x86[_64], powerpc64[le], SPARC64)
#   * Linux musl  (x86[_64], powerpc64[le])
#   * macOS       (x86_64)  -- still a work-in-progress
#   * Solaris 10  (SPARC64) -- use OpenCSW tools when possible!
#   * Solaris 11  (SPARC64) -- use OpenCSW tools when possible!
#
#
# multilib support
# ----------------
#
# Many systems are configured with "multilib" support, in that a
# handful of libraries are built several times, each with slight
# differences in their configuration. There is no "portable" way
# to ensure this script runs correctly on every system, and you
# will likely need to modify the build flags under the "Platform
# Adjustments" section. Non-Linux platforms are less-friendly.
#
# This "multilib" support primarily applies to GNU binutils and
# GCC; it has little or no relation to the other dependencies. A
# system configured to explicitly disable "multilib" support is
# detected by this script and the same convention is followed.
#
# If your system is configured with explicit "multilib" support,
# your distribution vendor may have omitted necessary libraries,
# which will cause this build (also auto-detected) to fail.
#
# As a quick example, on x86_64 Debian, you may need to do:
#
#   $ sudo apt-get install libc6-dev{,-i386,-x32}
#
# which implies additional packages may be required depending on
# how your distribution configured its GCC. This script detects
# most of the relevant multilib-related configuration flags. The
# key here is: we'll try to model your system's GCC as closely
# as possible, and this varies widely by distribution.
#
# On SPARC64 Debian, you may need to do:
#
#   $ sudo apt-get install libc6-dev{,-sparc}
#
# In some cases, you may wish to change compiler, assembler, and
# linker flags. You should delete and rebuild the entire output
# directory unless you absolutely know what you are doing. Why?
# Because this script uses the same flags for all packages/libs,
# and changes to these flags can cause difficult-to-debug bugs.
#
# You are responsible for ensuring you have a working setup and
# flags appropriate for your system. Do not contact me for this
# unless you are willing to help and for documentation purposes.
#
#
# design
# ------
#
# At startup, this script symlinks a number of "essential" tools
# from your system into a single directory, which replaces PATH.
#
# Each tool is built and installed into a common directory which
# is already prepended to the PATH environment variable. Thus, a
# tool is built using any available tools built prior to it, and
# only falls back to the system-provided tools if they cannot be
# found. The minimum list of build-time dependencies is defined
# in the "Baseline System" section. Many of these utilities are
# built from source (newer versions or differing configuration).
#
# Built tools are only guaranteed to run on the machine on which
# they are built. Portability in terms of machine and directory
# location (i.e., the output directory is moved) and the ability
# to cross-compile these tools is possible, but not guaranteed.
#
# Some programs are built differently on each platform and their
# usage may not be compatible with other system utilities.
#
# Once this script finishes executing, "musl-cross-make" tooling
# can be reproduced using only the output directories as PATH.
#
# The PATH variable is comprised of "utilities" and "toolchain"
# directories, as there may be several toolchains (host-libc and
# musl-libc). PATH is therefore ("glue" is not strictly needed):
#
#     PATH=<mcmtools>/{host,sys,glue}/bin
#
#   * "host" is a (modern) host-libc-to-host-libc toolchain
#
#   * "musl" only exists if your system supports musl (optional)
#
#   * "sys"  is a directory containing all the fresh tooling
#
#   * "glue" is a directory containing symlinks to old tooling
#            and should not be needed for "musl-cross-make"
#
#
# planned items
# -------------
#
#   * Verify end-to-end production of "musl-cross-make" tooling
#     on all existing "supported" platforms, fix any issues, and
#     continue adding more;
#
#   * Investigate whether 'rbash' (restricted bash) can be used
#     as a bulletproof command whitelisting mechanism, otherwise
#     consider writing one in C -- the goal is to eliminate all
#     possible sources of contamination during build -- include
#     also the verification of functionality and/or versions;
#
#   * Support hash/checksum verification for all source packages
#     and allow user-override in cases where the user explicitly
#     requests to use a custom version. Downloads which fail to
#     verify will be retried N times before we give up;
#
#
# script execution
# ----------------
#
# Package installation order is important. This configuration is
# routinely tested on a number of diverse platforms. You may run
# into silent breakage if you reorder the dependencies.
#
# Some dependencies are only necessary for building others, and
# may become obsolete as new packages are released. Do not rely
# on the availability of any tool except those that are required
# for building "musl-cross-make". That list is subject to change
# as well, so interpret this as "use these at your own risk".
#
# Each platform may have additional build-time dependencies; for
# example, macOS requires the 'lipo' utility. It's not necessary
# to build this for all platforms, so we "whitelist" access to
# the host system's copy and allow it to be used only during the
# bootstrap process. It is not included in the final output.
#
# This script relies heavily on the fact that 'configure' script
# or other tools which accept command-line arguments, allow the
# override of previously-specified arguments. Care must be taken
# modifying the order or values of any such parameter sequence.
#
#
# troubleshooting
# ---------------
#
# (1) In the event of a failed source tarball download, you will
#     see errors relating to "invalid file format". To remedy, a
#     (broken) source tarball file must be deleted, e.g.:
#
#         $HOME/mcmtools/sys/._curl-7.69.1.tar.xz.bin
#
# (2) In the event of changing a package's configuration after a
#     package has been installed (i.e., to trigger a rebuild),
#     a sentinel file must be deleted (this is an empty file):
#
#         $HOME/mcmtools/sys/._curl-7.69.1.tar.xz
#
#
# other remarks
# -------------
#
# Platform-specific notes (and some of my debugging madness) can
# be found in the 'README.<platform>' file(s). No guarantees on
# the accuracy or helpfulness of these files, but it's possible.


#===============================================================
# Dependency Versions
#===============================================================

##
# Ordering is consistent with installation. Please maintain it.
#
# Not all software here may be pulled from canonical mirrors; it
# is important to verify mirror availability before changing the
# version of any component below. Some versions may refer to git
# tags or commit hashes and may not be official releases. Check
# the mirroring section ("Dependency Mirrors") for information.
#
# Items commented with an asterisk ('*') in the rightmost column
# anticipate major changes in the next-released version.
# See the comments below ("Special Cases").
#
# Items commented with the letter ('X') in the rightmost column
# cannot be upgraded without investigation into incompatibility.
# See the comments below ("Special Cases").
#
# Items commented with a plus sign ('+') in the rightmost column
# may require some additional setup or may not be portable.
# See the comments below ("Special Cases").


##
# Phase 0
#
V_CAB=2023-05-30;               # curl CA bundle


##
# Phase 1  (dependencies for reliable build).
#
V_CFG=a2287c3;                  # config
V_MAK=4.3    ;                  # make
V_GLB=475eac6;                  # gnulib                       X
V_CCA=3.7.12 ;                  # ccache                       X
V_PAT=2.7.6  ;                  # patch
V_GBS=5.3    ;                  # bash
V_SED=4.8    ;                  # sed
V_CNF=1.7.3  ;                  # pkgconf
V_GAC=2.69   ;                  # autoconf                     X
V_GAA=2021.02.19;               # autoconf-archive
V_GAM=1.16.5 ;                  # automake
V_TEX=7.2    ;                  # texinfo
V_GPF=3.1    ;                  # gperf
V_GM4=1.4.18 ;                  # m4                           *
V_AWK=5.1.1  ;                  # gawk
V_GLT=2.4.6  ;                  # libtool
V_GET=0.21   ;                  # gettext
V_H2M=1.48.5 ;                  # help2man
V_ML2=ec6e3ef;                  # libxml2
V_SLT=b0074ee;                  # libxslt
V_GIN=2.2.12 ;                  # indent
V_CUT=9.0    ;                  # coreutils
V_BIS=3.8.2  ;                  # bison
V_FLX=04c5b7c;                  # flex
V_PR2=10.39  ;                  # pcre2
V_GRP=3.7    ;                  # grep


##
# Phase 2a (preparation for combined GCC build).
#
V_GMP=6.2.1  ;                  # GMP
V_MPF=4.1.0  ;                  # MPFR
V_MPC=1.2.1  ;                  # MPC
V_ISL=0.24   ;                  # ISL


##
# Phase 2b (host-native toolchain).
#
V_BUT=2.43   ;                  # binutils
V_GCC=13.3.0 ;                  # GCC


##
# Phase 3a (dependencies for upstream "musl-cross-make").
#
V_FUT=4.8.0  ;                  # findutils
V_RSY=3.2.3  ;                  # rsync
V_TAR=1.34   ;                  # tar
V_BZ2=1.0.8  ;                  # bzip2
V_XZU=5.2.5  ;                  # xz
V_GZP=1.11   ;                  # gzip
V_DUT=3.8    ;                  # diffutils
V_ZIP=30     ;                  # zip (infozip)
V_WHC=2.21   ;                  # which


##
# Phase 3b (dependencies for my fork of "musl-cross-make").
#
V_ZLB=1.3.2  ;                  # zlib
V_SSL=b2ec203;                  # bearssl
V_CRL=7.80.0 ;                  # curl
V_GDB=11.1   ;                  # gdb (optional, but useful)   +
V_XPT=ee695c7;                  # libexpat
V_GIT=2.33.0 ;                  # git


##
# Phase 4  (optional miscellaneous utilities).
#
V_HBC=7f6a907d;                 # bc (for kernel builds)
V_PAR=20211022;                 # parallel
V_PRL=5.36.0  ;                 # perl
V_PCR=1.4     ;                 # perl-cross


##
# Phase 5  (host-libc-linked proper "musl-cross-make" toolchain)
#
V_MLC=v1.2.5 ;                  # musl
V_MCM=musl.cc;                  # musl-cross-make
V_KRN=6.1.36 ;                  # kernel headers


#===============================================================
# Special Cases
#===============================================================
#
#   * m4 1.4.18 does not build on at least SPARC64 and requires
#     manually upgrading its internal 'gnulib'. This kludge will
#     hopefully become obsolete in the next release. A similar
#     issue occurs with the previous version of 'coreutils'. The
#     upgrade is performed on all platforms indiscriminately.
#
#   * m4 1.4.19 fails to build from source.
#
#   * autoconf 2.69 /exactly/ is required for GCC 10.3.0
#
#   * gdb (any version) likely requires Linux kernel headers to
#     be made available in the toolchain's preprocessor search
#     path; this is not done by default so it is left disabled.


#===============================================================
# Dependency Mirrors
#===============================================================

##
# This section of mirrors consolidates common download locations
# across multiple packages by the same vendor, or choosing exact
# mirrors best suited for your geographic location or firewall.
#
# Order is approximately "as used" but this is not enforced, and
# no distinction is made between "sections" because mirrors may
# be reused across sections. The question becomes where to put?
#
M_CAB=https://curl.haxx.se/ca;
M_GNU=https://ftp.gnu.org/gnu;
M_SVG=https://gitweb.git.savannah.gnu.org/gitweb;
M_CCA=https://github.com/ccache/ccache/releases/download;
M_DRF=https://distfiles.dereferenced.org;
M_FLX=https://github.com/westes/flex/archive;
M_PR2=https://github.com/PhilipHazel/pcre2/releases/download;
M_GNO=https://gitlab.gnome.org/GNOME;
M_ISL=https://downloads.sourceforge.net/project/libisl/;
M_RSY=https://download.samba.org/pub/rsync/src;
M_SRW=https://sourceware.org/pub;
M_TUK=https://tukaani.org;
M_SFN=https://downloads.sourceforge.net;
M_ZLB=https://www.zlib.net;
M_SSL="https://bearssl.org/gitweb/?p=BearSSL;a=snapshot;sf=tgz"
M_CRL=https://curl.haxx.se/download;
M_XPT=https://github.com/libexpat/libexpat/archive;
M_GIT=https://mirrors.edge.kernel.org/pub/software/scm/git;
M_HBC=https://github.com/gavinhoward/bc/archive;
M_PRL=https://www.cpan.org/src;
M_MLC=https://git.musl-libc.org/cgit/musl/snapshot;
M_MCM=https://git.zv.io/toolchains/musl-cross-make/-/archive;


#===============================================================
# Platform Adjustments
#===============================================================

##
# The following global variables are declared empty by default.
# Unless adjusted below, they are prepended to the corresponding
# environment variable(s) during dependency builds. For example,
# a variable '_KALE' here becomes 'export KALE="${_KALE} ...";'
# where additional build- but not platform- specific changes may
# be made. An example of that is 'CFLAGS= ... -I/custom/path;'.
#
_SYSTEM="$(uname -s)";          # abort on failure; we need this
#
_PATH=/dev/null;                # if modified, don't prepend ':'
_CPPFLAGS=;
#
_CFLAGS=;
_CXXFLAGS=;
_FFLAGS=;
#
_AR=;
_ARFLAGS=;
#
_LD=;
_LDFLAGS=;
#
_M4=;
_MAKEINFO=;
_ACLOCAL_PATH=;


##
# These must be nonempty by default (i.e. they must be populated
# by the logic either directly or further below).
#
_NPROC=;
_SHELL=;
_BUILD=;
_TOOLS=;


##
#
# Some features (packages) may be skipped if not supported by the
# build platform. This is a global flag and may be used anywhere.
#
_CHECK=;

##
# Each supported platform is split into a 'case' below. Certain
# adjustments are made based on my own testing, and shouldn't be
# considered a requirement or best practice.
#
# Variables prefixed by a double-underscore ('__') are not to be
# used elsewhere in this script; they are used for intermediate
# local computations. Please unset them immediately!
#
# Commented values are left in-place as "potentially useful" for
# folks experiencing build-time issues. Please report successful
# flags and system information to me (failures, too).
#
case "${_SYSTEM}" in
    AIX)
#        _CPPFLAGS="-maix64";
#        _CFLAGS="-maix64";
#        _CXXFLAGS="-maix64";
#        _LDFLAGS="-maix64 -lpthread";
        _LDFLAGS="-lpthread";
        _AR="ar rcs";
        # TODO: https://github.com/openssl/openssl/pull/5386
#        _ARFLAGS="-X64";
        __core=$(lparstat -i | grep Online.\*CPUs              \
            | awk '{print $5}');
        __nsmt=$(lparstat -i | grep SMT                        \
            | awk -F'[-:]' '{print $4}');
        _NPROC=$((${__core} * ${__nsmt}));
        _SHELL=$(command -v bash);
        unset __core __nsmt;
        ;;
    Darwin)                     # FIXME: may require fiddling
#        _CFLAGS="-arch x86_64 -m64";
#        _CXXFLAGS="-arch x86_64 -m64";
        # TODO: https://github.com/rust-lang/rust/pull/10013
#        _LDFLAGS="-Wl,-no_compact_unwind";
#        _LDFLAGS="-m64";
        _NPROC=$(sysctl hw.logicalcpu                          \
            | awk '{print $2}');
        _SHELL=$(command -v bash);
        _TOOLS="lipo ranlib cpio";
        ;;
    FreeBSD|OpenBSD)
        _NPROC=$(sysctl hw.ncpu | awk '{print $2}');
        _SHELL=$(command -v bash);
        ;;
    Linux)
        _NPROC=$(nproc);
        _SHELL=$(command -v bash);
        ;;
    SunOS)                      # FIXME: only 64-bit supported
        _CPPFLAGS="-D_XPG6 -D_STDC_C99=";
#        _CPPFLAGS="-D_XPG6 -D_STDC_C99= -mcpu=v9 -m64";
#        _CPPFLAGS="-D_XPG6 -mcpu=v9 -m64";
#        _CFLAGS="-mcpu=v9 -m64";
#        _CXXFLAGS="-mcpu=v9 -m64";
#        _LDFLAGS="-m64";
        _NPROC=$(2>/dev/null nproc || psrinfo | wc -l          \
            | awk '{print $1}');
        _SHELL=$(command -v bash);
        ;;
    CYGWIN_NT*)                 # FIXME: close to working
        __gccd=$(gcc -print-search-dirs | grep install         \
            | cut -d' ' -f2);
        __gccl=$(find "${__gccd}" -type f -name "*.dll");
        _PATH="/usr/bin:${__gccd}";
        _NPROC=$(nproc);
        _SHELL=$(command -v bash);
        _TOOLS="${__gccl}";
        unset __gccd __gccl;
        ;;
    MSYS_NT*|MINGW*_NT*)        # FIXME: probably very difficult
        __gccd=$(gcc -print-search-dirs | grep install         \
            | cut -d' ' -f2);
        __gccl=$(find "${__gccd}" -type f -name "*.dll");
        _PATH="/c/Windows/system32:/usr/bin:${__gccd}";
        _NPROC=$(nproc);
        _SHELL=$(command -v bash);
        _TOOLS="${__gccl}";
        unset __gccd __gccl;
        ;;
    *)                          # FIXME: please consider helping
        printf "Unsupported platform: '%s'\n" "${_SYSTEM}";
        exit 1;
        ;;
esac


#===============================================================
# Baseline System
#===============================================================

##
# The baseline list of system-provided tools that are necessary
# to ensure a correct bootstrap process. Lexicographic order.
#
# Consider this a "whitelist" of utilities to allow (they are to
# be symlinked to a directory in the PATH environment variable),
# and the existing value of PATH is replaced exclusively by this
# list in addition to a "system root" (--prefix=) constructed as
# this script proceeds to build and install each component.
#
# Items prefixed by a hyphen ('-') indicate shell builtins that
# may require additional processing to locate a full path to the
# equivalent utility. For now, the 'which' command is called, as
# 'command -v' does not appear to locate these correctly.
#
# This list is a superset of the utilities required in order to
# build "musl-cross-make"; some of these are only needed for the
# bootstrap process.
#
tool=$(grep -v ^# <<EOF
${_TOOLS}
-[
ar
as
awk
basename
bzip2
cat
chmod
cmp
cp
cut
date
diff
dirname
-echo
egrep
env
expr
-false
find
flex
g++
gcc
grep
gzip
head
hostname
join
ld
ln
ls
m4
make
mkdir
mv
nm
perl
-printf
ranlib
rm
rmdir
sed
sleep
sort
tar
tee
-test
touch
tr
-true
uname
uniq
wc
which
xargs
xz
EOF
);


#===============================================================
# Build Configuration
#===============================================================

##
# This can be done in /tmp but should be persistent if you plan
# on reusing the infrastructure.
#
DEST=${DEST:-"$HOME/mcmtools"}; # system tooling build prefix
case "$(uname -m)" in
#   uname         gcc
#   -----         ---
    aarch64)    m=aarch64:      ; ;;
    armv7l)     m=armv7l:eabihf ; ;;
    ppc)        m=powerpc:      ; ;;
    ppc64)      m=powerpc64:    ; ;;
    x86_64)     m=x86_64:       ; ;;
    i386)       m=i386:         ; ;;
    i586)       m=i586:         ; ;;
    i686)       m=i686:         ; ;;
    m68k)       m=m68k:         ; ;;
    mips64)     m=mips64:       ; ;;
    riscv64)    m=riscv64:      ; ;;
    s390x)      m=s390x:        ; ;;

    *) usage ;;
esac
ARCH=${ARCH:-"${m%:*}-linux-musl${m#*:}"};


##
# This directory will contain dependency build trees. It can be
# deleted after the bootstrap process is completed. Persistent
# storage is recommended if you intend to reboot between builds.
#
bdir="${DEST}/tmp";             # scratch directory location


##
# Within each dependency build tree, we want to perform an out-
# of-tree build. This is the (arbitrary) name of that directory,
# and the user should /not/ modify this unless there is a naming
# conflict with any custom packages added to this framework.
#
tdir=x;                         # out-of-tree directory name


##
# This directory will contain the dependency libraries and tools
# and can also be deleted after the toolchains are built, but it
# may be useful to maintain this directory for future builds of
# "musl-cross-make" or to be repurposed for other uses.
#
sdir="${DEST}/sys";             # system installation directory


##
# This directory will be populated with symbolic links to system
# provided tools suitable for the bootstrap process. This is the
# effective environment (via PATH) for the bootstrap process.
#
gen1="${DEST}/glue";            # unstable system tool symlinks
bin1="${gen1}/bin";


##
# Gen2: local  universal toolchain
# Gen3: local musl-based toolchain (optional)
#
gen2="${DEST}/host";            # can build any musl-based chain
bin2="${gen2}/bin";

gen3="${DEST}/musl";            # can only run on Linux systems
bin3="${gen3}/bin";


##
# This directory will contain the contents 'sdir' and 'gen2',
# in addition to the (detected) shared libraries needed by the
# 'sdir/bin' directory. 'gen3' (static) is optionally added.
#
root="${DEST}/rootfs";          # merged system, host, [musl]


##
# Common flags (CFLAGS, CXXFLAGS, FFLAGS) to be appended to the
# command-line arguments that the compiler(s) used during this
# bootstrap process. These will override package defaults unless
# they conflict with existing options. Do not modify unless you
# know what you are doing or are willing to test the full build.
#
flag="-O3";                     # injected into CFLAGS etc.


#===============================================================
# Program Aliasing
#===============================================================

##
# In most cases, it would be sufficient to wrap functions in the
# sense of mapping 'make' to 'gmake' and so forth. Here, we rely
# on subshells to build toolchains with exported environment and
# other variables. As we have PATH, we can create symbolic links
# from e.g. '/custom/path/bin/make' --> '/host/native/gmake'.
#
# It's possible that some platforms require shared libraries to
# be present adjacent to the system tools, since we destroy PATH
# (e.g., Cygwin DLLs are no longer accessible). In this case the
# '_TOOLS' variable is populated with a list of required DLLs
# specified by absolute path. When we create a symlink for these
# we need to take the effective basename.

g=g;                            # few systems have g-pref. tools
h=-;                            # character designating builtins

mkdir -p "${sdir}/bin";

mkdir -p "${bin1}";
mkdir -p "${bin2}";
mkdir -p "${bin3}";

for k in ${tool}; do

    case "${k}" in
        /*)                     # absolute paths handled first
            ln -s "${k}" "${bin1}/${k##*/}" || true;
            continue;
            ;;
    esac

    k=${k##*/};                 # effective basename

    case "${k}" in
        "${h}"*) k=${k#*${h}};  # remove the builtin designation
            skip=1;             # skip normal link; search fails
            ;;
        *)                      # otherwise proceed as normal
            skip=0;             # the 'command' utility works
            ;;
    esac

    test ! -f "${bin1}/${k}" || continue;

    p=$(command -v "${g}${k}" 2> /dev/null || true);
    if test "x${p}" = "x"; then # prefixed version not found
        p=$(command -v "${k}" 2> /dev/null || true);
        if test "x${p}" = "x"; then
            printf 1>&2 "ERROR: '%s' not found!\n" "${k}";
            exit 1;             # fatal: neither version found
        else                    # found normal
            r="${p}";           # name is unmodified
        fi
    else                        # found prefixed
        r="${p#${g}*}";         # name is stripped of prefix
    fi

    case "${r##*/}" in
        gperl) r=${r%/*}/perl;  # SPECIAL: unrelated to perl
    esac

    if test ${skip} -eq 0; then # we have a non-builtin utility
        ln -s "${r}" "${bin1}/${k}" 2>/dev/null || true;
    else                        # we need to search for builtin
        ln -s "$(which ${r})" "${bin1}/${k}" 2>/dev/null || true;
    fi
done


##
# Download mechanism. Adjust names or add conditions if using
# custom software or passing additional flags.
#
__curl=curl;                    # name in case of non-standard
__wget=wget;                    # name in case of non-standard
#
if   test "x$(command -v ${__curl} 2>/dev/null)" != "x"; then
    test -f "${bin1}/curl"                                     \
        || ln -s "$(command -v ${__curl})" "${bin1}/curl";
    DRSO="curl -sL";
elif test "x$(command -v ${__wget} 2>/dev/null)" != "x"; then
    test -f "${bin1}/wget"                                     \
        || ln -s "$(command -v ${__wget})" "${bin1}/wget";
    DRSO="wget -qO-";
else
    printf 1>&2 "ERROR: Could not find 'curl' or 'wget'\n";
    exit 1;
fi
unset __curl __wget;


#===============================================================
# PATH-related
#===============================================================

export PATH="${bin1}:${_PATH}"; # here forward, whitelist only


##
# Locates and prints the correct value for '--sysroot=' on POSIX
# systems having GCC. Tested on Linux, macOS, Solaris, and AIX.
#
gsys ()
{
    d=usr/include;              # directory pattern for search
    f=stdio.h;                  # name of one file expected here

    ${CC-gcc} -E -Wp,-v -</dev/null 2>&1                       \
        | awk '{if($1~/^\//)print $1;}' | while read k; do
              if test -f "${k%${d}*}${d}/${f}"; then
                  printf "%s\n" "${k%${d}*}";
              fi
          done 2>/dev/null | head -n 1;
}
_SYSROOT=$(gsys);               # for GCC and binutils only


#===============================================================
# Supporting Routines
#===============================================================

_BASE=;
_NAME=;
_CONF=;


##
# Skips a recipe step, permitting e.g. '_PREPARE=skip;'
#
skip ()
{
    :;                          # no-op
}


##
# Marks a package as installed. Internal use only, please, which
# means do not use this outside of 'prep' or 'bake'.
#
mark ()
{
    touch "${sdir}/._${_BASE}";
}


##
# State variables with global scope.
#
_SPECIAL=;
_MACHINE=;
_PATCHES=;
_AUTOFOO=;
_PREPARE=;
_COMPILE=;
_INSTALL=;


##
# Extract a file specified by the first parameter into whichever
# directory from which this routine is called. Internal only.
#
# Note: due to '-e' some 'tar' implementations (e.g. libarchive
# bsdtar) can return nonzero for "warnings" like failing to set
# permissions on symlinks. Any real errors will cause failures
# during build, so this is an acceptable workaround.
#
tarx ()
{
    tar --strip-components="${_str}" -xv"${_tar}"f "${1}" || true;
}


##
# Downloads, extracts, and prepares for build a given software
# package of this syntax, caching or overwriting as needed:
#
# Usage:
#
#     prep <URL> <TARFLAG> <STRIP> [<CONFIG> ...]
#
# It is typically expected that URLs are direct links to source
# tarballs of the form: "https://source.to/mypkg-1.0.0.tar.xz".
#
# This is easily parsed into "mypkg" (name of package) and the
# file is downloaded as expected. Text after the hyphen ('-') is
# assumed to be unique to that package's version, but version is
# not taken into account when packages are built -- we cache the
# extracted source files and build trees by this identifier.
#
# NOTE: URL can be provided as a string with two words; e.g., an
# unusual tarball URL "foo https://source.to/?what_is&this=tgz".
# This will be parsed as "foo" (name of package) and the file is
# downloaded as expected (otherwise '?what...tgz' is the name).
#
# Recommended, but not required, is to use "foo-${V_FOO} <URL>",
# which re-enables the versioning functionality.
#
prep ()
{
    _tar="${1}"; shift;
    _str="${1}"; shift;
    _url="${1}"; shift;
    conf=${@};

    mkdir -p "${bdir}";         # user may delete to clear space


    ##
    # This implements the two-word URL format for overriding the
    # package name. It does not account for package versioning!
    #
    if test  "${_url}" != "${_url%\ *}"; then
        _pkg="${_url%\ *}";     # word 1 (package name)
        _url="${_url#*\ }";     # word 2 (download URL)
        base="${_pkg}";         # BUG? does not assign otherwise
    else                        # default case: one-word URL
        base=${_url##*/};       # effective basename
    fi

    printf "  * %s\n" "${base%.tar.*}";

    name=${base%-*};            # name of project w/o version


    ##
    # Populate globals (postcondition: these are nonempty).
    #
    _BASE=${base};              # package base w/ version info.
    _NAME=${name};              # package name
    _CONF=${conf};              # set user-provided conf. flags


    ##
    # Reset globals (postcondition: these are empty).
    #
    _SPECIAL=;
    _MACHINE=;
    _PATCHES=;
    _AUTOFOO=;
    _PREPARE=;
    _COMPILE=;
    _INSTALL=;

    _IGNB=;
    _IGNI=;


    ##
    # Create the system installation directory if not exist.
    #
    mkdir -p "${sdir}";


    ##
    # The package has already been built and installed; done.
    #
    test ! -f "${sdir}/._${base}" || return 0;


    ##
    # Unpack a fresh tree (and download tarball if needed).
    #
    rm    -f  "${bdir}/${name}.log.*";
    rm    -fr "${bdir}/${name}/${tdir}";
    mkdir -p  "${bdir}/${name}/${tdir}";

    (                           # subshell for capturing logs
    cd "${bdir}/${name}";       # enter source tree

    if test ! -f "${sdir}/._${base}.bin"; then
        ${DRSO} "${_url}"                                      \
            | tee   "${sdir}/._${base}.bin" | tarx -;
    else
        tarx "${sdir}/._${base}.bin";
    fi
    )                                                          \
    1>> "${bdir}/${name}.log.out"                              \
    2>> "${bdir}/${name}.log.err"                              \
    ;
}


##
# Execute a series of pre-populated command sequences (e.g., for
# manual configuration, build, and/or installation of packages),
# defaulting to a standardized recipe if none is provided. This
# routine executes in a subshell with a custom environment, so a
# call to 'return' is insufficient; you must use 'exit'.
#
# The following global variables are recognized, all optional:
#
#   * _SPECIAL
#
#     Given the syntax 'PLAT:OPTS', applies extra (overriding)
#     configure-time options, appending to arguments to 'prep'.
#
#     The 'PLAT' (PLATFORM) is e.g. { Darwin, Linux, ... }.
#
#     Setting 'PLAT' to an asterisk ('*') indicates the options
#     are appended unconditionally to all platforms.
#
#
#   * _MACHINE
#
#     Given the syntax 'MACH:OPTS', applies extra (overriding)
#     configure-time options, appending to arguments to 'prep'.
#
#     The 'MACH' (MACHINE) is e.g. { powerpc64, riscv32, ... }
#     and comes from the first part of the target tuple.
#
#     Setting 'MACH' to an asterisk ('*') indicates the options
#     are appended unconditionally to all platforms.
#
#
#   * _PATCHES
#
#     If you intend to "patch" unmodified source files, please
#     specify these commands here. Syntax is: one entry per line
#     where each line is 'PLAT:URL'; the URL is fetched and sent
#     to the 'patch' command only if the architecture matches.
#
#     The 'PLAT' (PLATFORM) is e.g. { Darwin, Linux, ... }.
#
#     Setting 'PLAT' to an asterisk ('*') indicates the patches
#     are applied unconditionally to all platforms.
#
#     The linked file should contain a trailing newline. This is
#     NOT aware of package versions; verify patches before bump.
#     Patches are filtered by platform and applied in order.
#
#     TODO: Accept platform list 'SunOS,AIX:https://foo.com...'.
#
#
#   * _AUTOFOO
#
#     If the source package *DOES NOT* have a 'configure' script
#     and you wish to either skip or override this step, you are
#     required to specify this variable appropriately.
#
#
#   * _PREPARE
#
#     This variable is to manually override a default invocation
#     of 'configure' and can, for example, simply change current
#     working directories.
#
#
#   * _COMPILE
#
#     This variable overrides the default 'make' command. Use it
#     to override 'make' if the source package does not need to
#     be compiled, or if you need to compile it differently.
#
#
#   * _INSTALL
#
#     Some source packages are not installed via 'make install'
#     and require some additional (or less) processing. This is
#     an easy way to override the default. Use this if you must
#     specify a prefix, copy or delete certain files, or in any
#     other way deviate from standard behavior.
#
bake ()
{
    (                           # subshell for capturing logs

    ##
    # The package has already been built and installed; done. If
    # you wish to rebuild the package, delete the file manually.
    #
    test ! -f "${sdir}/._${base}" || exit 0;


    ##
    # Set environment variables within this subshell only. They
    # must be exported; please do not remove that!
    #
    export PATH="${sdir}/bin:$PATH";
    #
    export SHELL="${_SHELL}";
    export CONFIG_SHELL="${_SHELL}";
    #
    export CPPFLAGS="${CPPFLAGS-${_CPPFLAGS}}";
    export CPATH="${sdir}/include";
    #
    export CFLAGS="${CFLAGS-${_CFLAGS}} ${flag}"; # OVERRIDE
    export CXXFLAGS="${CXXFLAGS-${_CXXFLAGS}} ${flag}"; # OVERRIDE
    export FFLAGS="${FFLAGS-${_FFLAGS}} ${flag}"; # OVERRIDE
    #
    export AR="${AR-${_AR}}";
    export ARFLAGS="${ARFLAGS-${_ARFLAGS}}";
    #
    export LD="${LD-${_LD}}";
    export LDFLAGS="${LDFLAGS-${_LDFLAGS}}";
    export LIBRARY_PATH="${sdir}/lib";
    #
    export M4="${M4-${_M4}}";
    export MAKEINFO="${MAKEINFO-${_MAKEINFO}}";
    export ACLOCAL_PATH="${ACLOCAL_PATH-${_ACLOCAL_PATH}}";


    ##
    # Enter source tree. This may or may not be the build tree.
    #
    cd "${bdir}/${name}";


    ##
    # (0) _SPECIAL or default recipe (no-op) is at top-level.
    #
    if  test ! -z "${_SPECIAL}"; then
        printf "%s\n" "${_SPECIAL}" | while read k; do
            __plat=${k%%:*};
            __opts=${k#*:};
            if test "x${__plat}" = "x${_SYSTEM}"               \
            || test "x${__plat}" = "x*"; then
                _CONF="${_CONF} ${__opts}";
            fi
            unset __plat __opts;
        done
    fi


    ##
    # (1) _MACHINE or default recipe (no-op) is at top-level.
    #
    if  test ! -z "${_MACHINE}"; then
        printf "%s\n" "${_MACHINE}" | while read k; do
            __mach=${k%%:*};
            __opts=${k#*:};
            if test "x${__mach}" = "x${ARCH%%-*}"              \
            || test "x${__mach}" = "x*"; then
                _CONF="${_CONF} ${__opts}";
            fi
            unset __mach __opts;
        done
    fi


    ##
    # (2) _PATCHES or default recipe (no-op) is at top-level.
    #
    if  test ! -z "${_PATCHES}"; then
        printf "%s\n" "${_PATCHES}" | while read k; do
            __plat=${k%%:*};
            __file=${k#*:};
            if test "x${__plat}" = "x${_SYSTEM}"               \
            || test "x${__plat}" = "x*"; then
                ${DRSO} "${__file}" | patch -p1;
            fi
            unset __plat __file;
        done
    fi

    ##
    # If we have a new 'config.sub' and 'config.guess', use it.
    #
    for ext in guess sub; do
        case "${_NAME}" in
            musl-cross-make)
                continue;
                ;;
        esac
        if test -f "${sdir}/bin/config.${ext}"; then
            find . -name config.${ext} | while read k; do
                cp "${sdir}/bin/config.${ext}" "${k}";
            done
        fi
    done


    ##
    # (3) _AUTOFOO or default recipe.
    #
    if  test -z "${_AUTOFOO}"; then
        if test ! -f ./configure; then
            autoreconf --install --force || true;
        fi
    else
        eval    "${_AUTOFOO}";
    fi


    ##
    # Some packages may not support out-of-tree builds. In those
    # cases, remain in the top-level source directory and not an
    # ephemeral build directory. The '__dotty' variable must be
    # empty for non-standard packages and will otherwise contain
    # a single period ('.'). This is prepended to another period
    # producing either '.' or '..' for this or parent directory.
    #
    __dotty=;
    case "${_NAME}" in
        git)                    # what a special cookie
            ;;
        bearssl)                # bears don't like cookies
            ;;
        zip)                    # zip it with the terrible puns?
            ;;
        bzip2)                  # can't think of one
            ;;
        musl-cross-make)        # TODO: involves 'cowpatch'
            ;;
        perl)                   # rotten oyster of software
            ;;
        *)
            __dotty=.;
            cd "${tdir}";
            ;;
    esac


    ##
    # (4) _PREPARE or default recipe.
    #
    if  test -z "${_PREPARE}"; then
        ac_cv_func_statx=no                                    \
        ${__dotty}./configure                                  \
            --cache-file="${bdir}/${name}.cache"               \
            --prefix="${sdir}"                                 \
            --build="${_BUILD}"                                \
            --host="${_BUILD}"                                 \
            --target="${_BUILD}"                               \
            ${_CONF}                                           \
            ;
    else
        eval    "${_PREPARE}";
    fi
    unset __dotty;


    ##
    # (5) _COMPILE or default recipe.
    #
    if  test -z "${_COMPILE}"; then
        make ${_OUTSYNC} ${_IGNB} -j"${_NPROC}";
    else
        eval    "${_COMPILE}";
    fi


    ##
    # (6) _INSTALL or default recipe.
    #
    if  test -z "${_INSTALL}"; then
        make ${_OUTSYNC} ${_IGNI} install;
    else
        eval    "${_INSTALL}";
    fi


    ##
    # Installation completed successfully; mark completed.
    #
    mark;

    )                                                          \
    1>> "${bdir}/${name}.log.out"                              \
    2>> "${bdir}/${name}.log.err"                              \
    ;
}


#===============================================================
# Stage 0: Prerequisites
#===============================================================

if ! test -f "${sdir}/cacert.pem"; then
    ${DRSO} ${M_CAB}/cacert-${V_CAB}.pem > "${sdir}/cacert.pem";
fi
export CURL_CA_BUNDLE="${sdir}/cacert.pem";


#===============================================================
# Stage 1: Bootstrap Environment
#===============================================================

#---------------------------------------------------------------
# (GLOBAL)

cat <<EOF

================================================================
NOTE: The 'mcmtools' build is starting. If it is interrupted, it
      will resume from the last successfully-built component.

      To completely remove the temporary/cache data (save disk):
        $ rm -fr "${bdir}" "$HOME/.ccache"

      To completely remove the installed utilities:
        $ rm -fr "${sdir}"

      To completely remove everything (glue directory, etc.):
        $ rm -fr "${DEST}"
================================================================

EOF


#---------------------------------------------------------------
# (GLOBAL)

_OUTSYNC=;                      # using yet-known 'make' version


#---------------------------------------------------------------
# config

## NOTES
#
# These are not installed into the 'glue' directory because user
# may blast that at any time. It is OK, but messy, to leave it
# in the utility output directory (which is already in PATH).
#
prep z 1 "${M_SVG}/?p=config.git;a=snapshot;h=${V_CFG};sf=tgz" \
    ;
_AUTOFOO=skip;
_PREPARE=skip;
_COMPILE=skip;
_INSTALL=$(cat <<'EOF'
cp "$(pwd)/../config.guess" "${sdir}/bin/config.guess";
cp "$(pwd)/../config.sub"   "${sdir}/bin/config.sub";
EOF
);
bake;


#---------------------------------------------------------------
# (GLOBAL)

##
# Canonicalize the tuple to be used for build, host, and target.
# If 'config.guess' and your compiler disagree, a warning prints
# and we assume your compiler is configured correctly.
#
# The output ('_BUILD') variable is always a four-part tuple. It
# always contains the string '-local-' as its second part, which
# is used to indicate that the toolchain is not portable across
# other systems. It also prevents packages from misinterpreting.
#
__tget1=$("${sdir}/bin/config.guess" 2>/dev/null);
__tget2=$("${sdir}/bin/config.sub" $(gcc -dumpmachine));
if test "${__tget1}" != "${__tget2}"; then
    __build="${__tget2}";       # assume the compiler is right
    printf "WARN: config.guess ('%s') != compiler ('%s')\n"    \
        "${__tget1}" "${__tget2}";
else
    __build="${__tget1}";       # config.guess & compiler agree
fi
unset __tget1 __tget2;
__parts=$(printf "%s\n" "${__build}"                           \
    | sed -e 's/-/ /g' | wc -w | awk '{print $1}');
case "${__parts}" in
    3) _BUILD=$(printf "${__build}"                            \
        | awk -F'[-]' '{print $1"-local-"$2"-"$3}');
        ;;
    4) _BUILD=$(printf "${__build}"                            \
        | awk -F'[-]' '{print $1"-local-"$3"-"$4}');
        ;;
    *)
        printf 1>&2 "ERROR: '%s' not supported!\n" "${__build}";
        exit 1;
        ;;
esac
unset __parts __build;


#---------------------------------------------------------------
# make

prep z 1 ${M_GNU}/make/make-${V_MAK}.tar.gz                    \
    --disable-nls                                              \
    --disable-dependency-tracking                              \
    ;
bake;


#---------------------------------------------------------------
# (GLOBAL)

# FIXME: This is disabled until 'make' is patched (4.1 works but
# fails to build on musl; 4.2 introduces the bug, so it will be
# best to patch in 4.3 and beyond).
#_OUTSYNC="-O";                  # build output is easier to read


#---------------------------------------------------------------
# gnulib

prep z 1 "${M_SVG}/?p=gnulib.git;a=snapshot;h=${V_GLB};sf=tgz" \
    --disable-nls                                              \
    ;
_AUTOFOO=skip;
_PREPARE=skip;
_COMPILE=skip;
_INSTALL=$(cat <<'EOF'
ln -sf "$(pwd)/../gnulib-tool" "${bin1}/gnulib-tool";
EOF
);
bake;


#---------------------------------------------------------------
# ccache

prep J 1 ${M_CCA}/v${V_CCA}/ccache-${V_CCA}.tar.xz             \
    ;
bake;
(
    cd "${sdir}/bin";           # ccache will find correct GCC
    for k in g++ gcc; do
        test -f ${k} || ln -s ccache ${k};
    done
)


#---------------------------------------------------------------
# patch

prep J 1 ${M_GNU}/patch/patch-${V_PAT}.tar.xz                  \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# bash

prep z 1 ${M_GNU}/bash/bash-${V_GBS}.tar.gz                    \
    --disable-nls                                              \
    --without-bash-malloc                                      \
    --without-curses                                           \
    ;
_PATCHES=$(grep -v ^# <<'EOF'
#5.1*:https://gitweb.gentoo.org/repo/gentoo.git/plain/app-shells/bash/files/bash-5.1-parallel_make.patch?id=4c2ebbf4b8bc660beb98cc2d845c73375d6e4f50
Darwin:https://raw.githubusercontent.com/Homebrew/formula-patches/cda4fced/bash/bash.patch
EOF
);
bake;
(
    cd "${sdir}/bin";
    test -f sh || ln -s bash sh;
)


#---------------------------------------------------------------
# (GLOBAL)

_SHELL="${sdir}/bin/sh";


#---------------------------------------------------------------
# sed

prep J 1 ${M_GNU}/sed/sed-${V_SED}.tar.xz                      \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# pkgconf

prep J 1 ${M_DRF}/pkgconf/pkgconf-${V_CNF}.tar.xz              \
    --disable-shared                                           \
    --enable-static                                            \
    ;
bake;


#---------------------------------------------------------------
# autoconf

prep J 1 ${M_GNU}/autoconf/autoconf-${V_GAC}.tar.xz            \
    M4="${bin1}/m4"                                            \
    ;
bake;


#---------------------------------------------------------------
# autoconf-archive

prep J 1                                                       \
    ${M_GNU}/autoconf-archive/autoconf-archive-${V_GAA}.tar.xz \
    ;
bake;


#---------------------------------------------------------------
# automake

prep J 1 ${M_GNU}/automake/automake-${V_GAM}.tar.xz            \
    ;
bake;


#---------------------------------------------------------------
# texinfo

prep J 1 ${M_GNU}/texinfo/texinfo-${V_TEX}.tar.xz              \
    --disable-nls                                              \
    ; # required for 'bison' to build in some cases
bake;


#---------------------------------------------------------------
# gperf

prep z 1 ${M_GNU}/gperf/gperf-${V_GPF}.tar.gz                  \
    ; # required for 'm4' to build in some cases
bake;


#---------------------------------------------------------------
# m4

## NOTES
#
# This patch is required only because we update 'gnulib':
# https://www.mail-archive.com/bug-m4@gnu.org/msg03225.html
# https://lists.gnu.org/archive/html/bug-m4/2020-07/msg00000.html
# https://lists.gnu.org/archive/html/bug-m4/2020-07/msg00001.html
#
prep J 1 ${M_GNU}/m4/m4-${V_GM4}.tar.xz                        \
    --without-libiconv-prefix                                  \
    --without-libintl-prefix                                   \
    MAKEINFO=true                                              \
    ;
_AUTOFOO=$(cat <<'EOF'
__old='1\.15';
__new=$(printf "%s\n" "${V_GAM}" | cut -d'.' -f1,2);
sed -i configure.ac                                            \
    -e "/AC_PREREQ/c\\AC_PREREQ\(\[${V_GAC}\]\)"               \
    ;
gnulib-tool --add-import;
grep -rl ${__old} . | while read k; do
    sed -i "${k}"                                              \
        -e "s/${__old}/${__new}/g"                             \
        ;
done
unset __old __new;
EOF
);
_PATCHES=$(grep -v ^# <<'EOF'
*:https://git.zv.io/snippets/49/raw
EOF
);
bake;


#---------------------------------------------------------------
# gawk

prep J 1 ${M_GNU}/gawk/gawk-${V_AWK}.tar.xz                    \
    --disable-mpfr                                             \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# libtool

prep J 1 ${M_GNU}/libtool/libtool-${V_GLT}.tar.xz              \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# gettext

# FIXME: Can examples be disabled? This slows down the build.
prep J 1 ${M_GNU}/gettext/gettext-${V_GET}.tar.xz              \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    ; # required for 'texinfo' on Darwin
_IGNB="-ik";                     # shared libraries are disabled
_IGNI="-ik";                     # so they fail to install :(
bake;


#---------------------------------------------------------------
# help2man

prep J 1 ${M_GNU}/help2man/help2man-${V_H2M}.tar.xz            \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# libxml2

prep j 1 ${M_GNO}/libxml2/-\
/archive/${V_ML2}/libxml2-${V_ML2}.tar.bz2                     \
    --disable-shared                                           \
    --enable-static                                            \
    --without-python                                           \
    --without-zlib                                             \
    ;
_AUTOFOO=$(cat <<'EOF'
autoreconf -i;
EOF
);
bake;


#---------------------------------------------------------------
# libxslt

prep j 1 ${M_GNO}/libxslt/-\
/archive/${V_SLT}/libxslt-${V_SLT}.tar.bz2                     \
    --disable-shared                                           \
    --enable-static                                            \
    --with-python=no                                           \
    ;
bake;


#---------------------------------------------------------------
# indent

## NOTES
#
# This patch removes a broken conditional header in/exclusion. A
# second issue is that out-of-tree builds are not supported by a
# directory called 'regression' (needs symlink to build dir, the
# removal of 'regression' from any Makefile, or ignore errors).
#
prep J 1 ${M_GNU}/indent/indent-${V_GIN}.tar.xz                \
    --disable-nls                                              \
    CFLAGS="-Wno-error=unused-value"                           \
    MAKEINFO=true                                              \
    ;
_PATCHES=$(grep -v ^# <<'EOF'
*:https://git.zv.io/snippets/46/raw
EOF
);
_IGNB="-i";                     # ignore missing 'regression/'
_IGNI="-i";                     # ignore missing 'regression/'
bake;


#---------------------------------------------------------------
# coreutils

prep J 1 ${M_GNU}/coreutils/coreutils-${V_CUT}.tar.xz          \
    --disable-nls                                              \
    --without-selinux                                          \
    FORCE_UNSAFE_CONFIGURE=1                                   \
    TIME_T_32_BIT_OK=yes                                       \
    ; # 32-bit time only needed on some AIX systems
bake;


#---------------------------------------------------------------
# bison

prep J 1 ${M_GNU}/bison/bison-${V_BIS}.tar.xz                  \
    --disable-nls                                              \
    M4="${sdir}/bin/m4"                                        \
    ;
bake;


#---------------------------------------------------------------
# flex

## NOTES
#
# The state of the master branch of 'flex' is quite poor. There
# are many issues, including broken parallel build support and a
# nasty bug I don't have time to fix involving stage1 and normal
# '*-scan.o' either containing or missing some symbols.
#
# Current observations:
#
#   * new dependency on glue 'ranlib'
#   * custom autofoo step below
#   * disable parallel build
#
#V_FLX=bb9f458;                  # flex good with current kludge
#V_FLX=30d0e5f;                  # flex good (last w/o patching)
#
# FIXME: Clean up this package.
#
prep z 1 "flex-${V_FLX} ${M_FLX}/${V_FLX}.tar.gz"              \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    MAKEINFO=true                                              \
    M4=m4                                                      \
    ac_cv_func_malloc_0_nonnull=yes                            \
    ac_cv_func_realloc_0_nonnull=yes                           \
    ;
_AUTOFOO=$(cat <<'EOF'
./autogen.sh;
sed -e '/nodist_flex_OBJECTS/s/flex-stage1//' -i src/Makefile.in;
EOF
);
_COMPILE=$(cat <<'EOF'
make ${_OUTSYNC} -j1;
EOF
);
bake;


#---------------------------------------------------------------
# pcre2

prep z 1 ${M_PR2}/pcre2-${V_PR2}/pcre2-${V_PR2}.tar.gz         \
    --disable-shared                                           \
    --enable-static                                            \
    ;
bake;


#---------------------------------------------------------------
# grep

prep J 1 ${M_GNU}/grep/grep-${V_GRP}.tar.xz                    \
    --disable-perl-regexp                                      \
    ;
_PATCHES=$(grep -v ^# <<'EOF'
*:https://git.zv.io/-/snippets/68/raw/main/ppc.patch
EOF
);
bake;


#===============================================================
# Stage 2a: Libraries Required by Compiler
#===============================================================

#---------------------------------------------------------------
# gmp

prep J 1 ${M_GNU}/gmp/gmp-${V_GMP}.tar.xz                      \
    --disable-shared                                           \
    --enable-static                                            \
    --enable-cxx                                               \
    --disable-assembly                                         \
    ;
bake;


#---------------------------------------------------------------
# mpfr

prep J 1 ${M_GNU}/mpfr/mpfr-${V_MPF}.tar.xz                    \
    --disable-shared                                           \
    --enable-static                                            \
    --with-gmp="${sdir}"                                       \
    ;
bake;


#---------------------------------------------------------------
# mpc

prep z 1 ${M_GNU}/mpc/mpc-${V_MPC}.tar.gz                      \
    --disable-shared                                           \
    --enable-static                                            \
    --with-gmp="${sdir}"                                       \
    ;
bake;


#---------------------------------------------------------------
# isl

prep z 1 ${M_ISL}/isl-${V_ISL}.tar.gz                          \
    --disable-shared                                           \
    --enable-static                                            \
    --with-gmp-prefix="${sdir}"                                \
    ;
bake;


#===============================================================
# Stage 2b: Compiler and Required Utilities
#===============================================================

export PATH="${bin2}:${PATH}";  # for local new toolchain only


#---------------------------------------------------------------
# binutils

## NOTES
#
# The "multilib" option does not behave the same way as for GCC;
# it is explicitly enabled for consistency.
#
#     --enable-64-bit-bfd       : be consistent on all platforms
#     --enable-targets=all      : be consistent on all platforms
#
prep J 1 ${M_GNU}/binutils/binutils-${V_BUT}.tar.xz            \
    --prefix="${gen2}"                                         \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    --disable-gprofng                                          \
    --enable-multilib                                          \
    --with-sysroot="${_SYSROOT}"                               \
    --enable-64-bit-bfd                                        \
    --enable-targets=all                                       \
    ;
_PATCHES=$(grep -v ^# <<'EOF'
SunOS:https://buildfarm.opencsw.org/source/raw/opencsw/csw/mgar/pkg/binutils/trunk/files/0001-Remove-existing-definition-of-SHARED-from-Solaris.patch
EOF
);
case "${_SYSTEM}" in
    Darwin)                     # use system utilities
        mark;
        ;;
esac
bake;


#---------------------------------------------------------------
# gcc

## NOTES
#
# It is not yet known whether the '--with-{as,ld}=...' flags are
# beneficial or not; only appears to be needed on Solaris but it
# may reduce portability of the toolchain.
#
#     --disable-multilib        : non-default; __conf2 overrides
#     --disable-libsanitizer    : may fail to build; not needed
#     --enable-obsolete         : required for old Solaris etc.
#     --disable-comdat          : required for any Solaris (?)
#     --{build,host,target}=    : Solaris override (see README)
#
__conf1=$(gcc -v 2>&1 | grep Configure                         \
    | "${sdir}/bin/pcre2grep" -io                              \
        -e '--with-[a-z0-9_-]*=[a-z0-9_,-]*(\s|$)' || true);
__conf2=$(gcc -v 2>&1 | grep Configure                         \
    | "${sdir}/bin/pcre2grep" -io                              \
        -e '--(en|dis)able-multi(arch|lib)' || true);
__conf3=;
case ${_BUILD} in
    p*pc64*-*linux-*)
        __conf3="--without-long-double-128";
        ;;
esac
prep J 1 ${M_GNU}/gcc/gcc-${V_GCC}/gcc-${V_GCC}.tar.xz         \
    ${__conf1}                                                 \
    --disable-multiarch                                        \
    --disable-multilib                                         \
    ${__conf2}                                                 \
    --prefix="${gen2}"                                         \
    --disable-nls                                              \
    --with-gmp="${sdir}"                                       \
    --with-mpfr="${sdir}"                                      \
    --with-mpc="${sdir}"                                       \
    --with-isl="${sdir}"                                       \
    --enable-languages=c,c++,fortran                           \
    --disable-bootstrap                                        \
    --disable-libsanitizer                                     \
    --with-sysroot="${_SYSROOT}"                               \
    --with-as="${bin2}/as"                                     \
    --with-ld="${bin2}/ld"                                     \
    ${__conf3}                                                 \
    ;
_SPECIAL=$(grep -v ^# <<'EOF'
SunOS:--disable-comdat --enable-obsolete --build= --host= --target=
EOF
);
_MACHINE=$(grep -v ^# <<'EOF'
powerpc64:--with-abi=elfv2
EOF
);
_PATCHES=$(grep -v ^# <<'EOF'
SunOS:https://git.zv.io/snippets/42/raw
#SunOS:https://git.zv.io/snippets/43/raw
#SunOS:https://gcc.gnu.org/bugzilla/attachment.cgi?id=44083
EOF
);
_AUTOFOO=$(cat <<'EOF'
autoreconf -i;
EOF
);
_IGNB="-ik";                    # texinfo-related?
case "${_SYSTEM}" in
    Darwin)                     # use system utilities
        (
            cd "${bin2}";
            test -f "${bin2}/cc"  || ln -s "${bin1}/gcc" cc ;
            test -f "${bin2}/c++" || ln -s "${bin1}/gcc" c++;
        )
        mark;
        ;;
esac
bake;
unset __conf1 __conf2;
(
    cd "${bin2}";               # create missing aliases
    test -f cc  || ln -s gcc cc ;
    test -f c++ || ln -s g++ c++;
)


#===============================================================
# Stage 3a: Dependencies for "musl-cross-make" (upstream)
#===============================================================

#---------------------------------------------------------------
# findutils

prep J 1 ${M_GNU}/findutils/findutils-${V_FUT}.tar.xz          \
    --disable-nls                                              \
    ;
bake;


#---------------------------------------------------------------
# rsync

## NOTES
#
# The xxhash dependency is a recent "enhancement" and conftests
# currently do not catch (un)availability for graceful handling.
#
prep z 1 ${M_RSY}/rsync-${V_RSY}.tar.gz                        \
    --disable-asm                                              \
    --disable-xxhash                                           \
    --disable-zstd                                             \
    --disable-lz4                                              \
    --disable-simd                                             \
    --disable-openssl                                          \
    --disable-acl-support                                      \
    ;
_IGNI="-i";
bake;


#---------------------------------------------------------------
# tar

prep J 1 ${M_GNU}/tar/tar-${V_TAR}.tar.xz                      \
    --disable-nls                                              \
    FORCE_UNSAFE_CONFIGURE=1                                   \
    ; # if someone wishes to build as root (not my problem)
bake;


#---------------------------------------------------------------
# bzip2

prep z 1 ${M_SRW}/bzip2/bzip2-${V_BZ2}.tar.gz                  \
    ;
_AUTOFOO=skip;
_PREPARE=skip;
_INSTALL=$(cat <<'EOF'
make ${_OUTSYNC} ${_IGNI} install PREFIX="${sdir}";
EOF
);
bake;


#---------------------------------------------------------------
# xz

export AR="ar rcs";
prep J 1 ${M_TUK}/xz/xz-${V_XZU}.tar.xz                        \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    ;
bake;
export AR=;


#---------------------------------------------------------------
# gzip

prep J 1 ${M_GNU}/gzip/gzip-${V_GZP}.tar.xz                    \
    ;
bake;


#---------------------------------------------------------------
# diffutils

prep J 1 ${M_GNU}/diffutils/diffutils-${V_DUT}.tar.xz          \
    --disable-nls                                              \
    ;
_PATCHES=$(grep -v ^# <<'EOF'
*:https://git.zv.io/-/snippets/68/raw/main/ppc.patch
EOF
);
bake;


#---------------------------------------------------------------
# zip

prep z 1 "zip-${V_ZIP} ${M_SFN}/infozip/zip${V_ZIP}.tar.gz"    \
    ; # (optional; feel free to comment this one out)
_PATCHES=$(grep -v ^# <<'EOF'
*:https://git.alpinelinux.org/aports/plain/main/zip/format-security.patch?id=c81c40f0291807a76db414fb4d8ccacd4ff33292
*:https://git.alpinelinux.org/aports/plain/main/zip/configure-gcc14.patch?id=14226268fa7d58f8faa74d8971ce1503959b8345
EOF
);
_AUTOFOO=skip;
_PREPARE=skip;
_COMPILE=$(cat <<'EOF'
make ${_OUTSYNC} ${_IGNB} -j"${_NPROC}"                        \
    -f unix/Makefile generic                                   \
    ;
EOF
);
_INSTALL=$(cat <<'EOF'
make ${_OUTSYNC} ${_IGNI} install prefix="${sdir}"             \
    -f unix/Makefile                                           \
    ;
EOF
);
case "${_SYSTEM}" in
    Darwin)                     # FIXME: unsupported (bad port?)
        mark;
        ;;
esac
bake;


#---------------------------------------------------------------
# which

prep z 1 ${M_GNU}/which/which-${V_WHC}.tar.gz                  \
    --disable-nls                                              \
    ;
bake;


#===============================================================
# Stage 3b: Dependencies for "musl-cross-make" (my fork)
#===============================================================

#---------------------------------------------------------------
# zlib

export AR="ar rcs";
prep z 1 ${M_ZLB}/zlib-${V_ZLB}.tar.gz                         \
    ;
_PREPARE=$(cat <<'EOF'
../configure --prefix="${sdir}" --static;
EOF
);
bake;
export AR=;


#---------------------------------------------------------------
# bearssl

prep z 1 "bearssl-${V_SSL} ${M_SSL};h=${V_SSL}"                \
    ;
_AUTOFOO=skip;
_PREPARE=skip;
_INSTALL=$(cat <<'EOF'
mkdir -p ${sdir}/bin;
mkdir -p ${sdir}/include;
mkdir -p ${sdir}/lib;
cp $(find build -mindepth 1 -maxdepth 1                        \
    -type f ! -name "*.*") ${sdir}/bin;
cp $(find build -mindepth 1 -maxdepth 1                        \
    -type f   -name "*.a") ${sdir}/lib;
cp $(find   inc -mindepth 1 -maxdepth 1                        \
    -type f              ) ${sdir}/include;
EOF
);
_IGNB="-ik";                     # client/server not necessary
bake;


#---------------------------------------------------------------
# curl

## NOTES
#
# The forced early failure of 'getifaddrs' is to prevent the
# 'configure' check from running; it hangs in some environments.
# This "feature" is not currently used for anything we need.
#
# See also:
#
#   * https://git.adelielinux.org/adelie/bootstrap/-/issues/11
#   * https://gitlab.com/qemu-project/qemu/-/issues/2485
#
prep J 1 ${M_CRL}/curl-${V_CRL}.tar.xz                         \
    ;
_PREPARE=$(cat <<'EOF'
sed -i ../configure -e 's/return getifaddrs/return NX_FUNCTION/g';
../configure                                                   \
    --prefix="${sdir}"                                         \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    --without-ssl                                              \
    --with-bearssl                                             \
    ;
EOF
);
bake;


#---------------------------------------------------------------
# gdb

## NOTES
#
# Temporarily disabled due to insufficient platform support.
#
if false; then
prep J 1 ${M_GNU}/gdb/gdb-${V_GDB}.tar.xz                      \
    --disable-shared                                           \
    --enable-static                                            \
    --disable-nls                                              \
    ;
bake;
fi


#---------------------------------------------------------------
# libexpat

## NOTES
#
# We strip two (2) levels here instead of changing into 'expat/'
# in the top level for convenience and simplicity. This is also
# a dependency for Git.
#
prep z 2 "libexpat-${V_XPT} ${M_XPT}/${V_XPT}.tar.gz"          \
    --disable-shared                                           \
    --enable-static                                            \
    ;
bake;


#---------------------------------------------------------------
# git

## NOTES
#
# Normally, one might elect to use 'configure' and pass along:
#
#     --with-curl={,yes,/path/to/curl/root}
#
# except the Autotools-related files appear to be defective. Use
# of 'autoreconf -i' and recent Autotools does not resolve this.
#
# The solution is therefore: trust that {CPP,C,LD}FLAGS are used
# correctly and just build. Installation requires 'prefix' to be
# specified as this is not populated without a 'configure'.
#
prep J 1 ${M_GIT}/git-${V_GIT}.tar.xz                          \
    ;
_AUTOFOO=skip;
_PREPARE=skip;
_COMPILE=skip;
_INSTALL=$(cat <<'EOF'
make ${_OUTSYNC} ${_IGNI} -j${_NPROC} prefix="${sdir}" install \
    NO_GETTEXT=1                                               \
    NO_OPENSSL=1                                               \
    NO_REGEX=NeedsStartEnd                                     \
    INSTALL=install                                            \
    TAR=tar                                                    \
    ;
EOF
);
bake;


#===============================================================
# Stage 4: Optional Useful Utilities
#===============================================================

#---------------------------------------------------------------
# bc

## NOTES
#
# For now, this 'bc' does not support out-of-tree builds.
# The C compiler defaults to literal 'c99' and we must override.
# It does not ignore unrecognized options, either.
#
prep z 1 "bc-${V_HBC} ${M_HBC}/${V_HBC}.tar.gz"                \
    ;
_PREPARE=$(cat <<'EOF'
CC=gcc ../configure --prefix="${sdir}";
EOF
);
bake;


#---------------------------------------------------------------
# parallel

prep j 1 ${M_GNU}/parallel/parallel-${V_PAR}.tar.bz2           \
    ;
bake;


#---------------------------------------------------------------
# perl

## NOTES
#
# The reason for 'perl-cross' is to better support an autotools-
# style build environment. Without it, I experienced difficulty
# in building Perl on numerous platforms but can't recall how.
#
prep z 1 ${M_PRL}/${V_PRL%%.*}.0/perl-${V_PRL}.tar.gz          \
    ;
_AUTOFOO=skip;
_PREPARE=$(cat <<'EOF'
${DRSO} https://github.com/arsv/perl-cross/releases/download\
/${V_PCR}/perl-cross-${V_PCR}.tar.gz \
    | tar --strip-components=1 -xzf - \
    ;
# https://www.openwall.com/lists/musl/2012/03/09/18
CFLAGS="-D_GNU_SOURCE" \
./configure --prefix="${sdir}";
EOF
);
bake;


#---------------------------------------------------------------
# hostname

##
# In lieu of the 'net-tools' package, we approximate 'hostname'
# using a very simple C program by Michael Kerrisk.
#
test -f "${sdir}/bin/hostname" || ${DRSO} https://man7.org/tlpi\
/code/online/dist/namespaces/hostname.c                        \
    | gcc -o "${sdir}/bin/hostname" -x c -                     \
    2>/dev/null 1>/dev/null;


#---------------------------------------------------------------
# ldd

##
# Do not depend on this to exist on the build system. Instead, a
# super basic wrapper is made; 'objdump -p' could be used, too.
#
test -f "${sdir}/bin/ldd" || cat > "${sdir}/bin/ldd" <<EOF
#!/bin/sh -e
if "${gen2}/bin/readelf" -l "${sdir}/bin/bash"                 \
    | grep Requesting                                          \
    | cut -d':' -f2                                            \
    | tr -d ' ]'                                               \
    | grep 2>/dev/null -- musl; then
    "${gen2}/lib/libc.so" --list "\${@}";
else
    for k in "\${@}"; do
        LD_TRACE_LOADED_OBJECTS=1 "\${k}";
    done
fi
EOF
chmod +x "${sdir}/bin/ldd";


#---------------------------------------------------------------
# soggy

##
# This makes it possible to 'chroot' into 'sys/' directory, but
# needs to be run each time the 'sys/' directory is updated. We
# install a new "utility" called 'soggy'.
#
# TODO: test this on other platforms.
# FIXME: make this recursive (or find a better solution).
#
test -f "${sdir}/bin/soggy" || cat > "${sdir}/bin/soggy" <<EOF
#!/bin/sh -e
if ! test -d "${sdir}/tc"; then
    mkdir -p "${sdir}/tc";
    "${sdir}/bin/rsync" -a "${gen2}" "${sdir}/tc/";
    if test -d "${gen3}/${ARCH}"; then
        "${sdir}/bin/rsync" -a "${gen3}" "${sdir}/tc/";
    fi
fi
list=;
# immediate dependencies
"${sdir}/bin/ldd" \$(find "${sdir}/bin" -type f) 2>/dev/null   \
    | "${sdir}/bin/grep" -oE '/.*\ '                           \
    | sort                                                     \
    | uniq                                                     \
    | while read k; do
        "${sdir}/bin/cp" -n --parents "\${k}" "${sdir}";
        list="\${list} \${k}";
    done
# level 2
"${sdir}/bin/ldd" \${list} 2>/dev/null                         \
    | "${sdir}/bin/grep" -oE '/.*\ '                           \
    | sort                                                     \
    | uniq                                                     \
    | while read k; do
        "${sdir}/bin/cp" -n --parents "\${k}" "${sdir}";
        list="\${list} \${k}";
    done
# level 3
"${sdir}/bin/ldd" \${list} 2>/dev/null                         \
    | "${sdir}/bin/grep" -oE '/.*\ '                           \
    | sort                                                     \
    | uniq                                                     \
    | while read k; do
        "${sdir}/bin/cp" -n --parents "\${k}" "${sdir}";
        list="\${list} \${k}";
    done
EOF
chmod +x "${sdir}/bin/soggy";


#---------------------------------------------------------------
# (GLOBAL)

##
# Create a '.bashrc' for the 'chroot'. Unused otherwise.
#
if ! test -d "${sdir}/root"; then
    mkdir -p "${sdir}/root";
    test -f "${sdir}/root/.bashrc" || cat > "${sdir}/root/.bashrc" <<EOF
export PATH="/tc/host/bin:/tc/musl/bin:/bin";
EOF
fi


cat <<EOF

================================================================
NOTE: You may now use the new host-libc toolchain by setting the
      PATH environment variable as follows (e.g., launch shell):

PATH="${sdir}/bin:${bin2}" bash;

      This will provide an environment in which to build native
      software for your machine. We now attempt to build musl.

      It is also possible, if you have permission, to 'chroot':

$ sudo chroot "${sdir}" /bin/bash;
bash-${V_GBS%.*}#
================================================================

EOF


#---------------------------------------------------------------
# musl-gcc

_CHECK=1;                       # assume musl is supported

## NOTES
#
# The intent is to check whether musl supports this architecture
# and to build it if so. If not, we install a no-op shell script
# in place of the GCC wrapper. This will be used to test a Hello
# World application only.
#
#     --enable-wrapper          : called 'musl-gcc'; no conflict
#
prep z 1 ${M_MLC}/musl-${V_MLC}.tar.gz                         \
    --prefix="${gen2}"                                         \
    --syslibdir="${gen2}/lib"                                  \
    --enable-shared                                            \
    --enable-static                                            \
    --enable-wrapper=gcc                                       \
    ;
_PATCHES=$(cat <<'EOF'
*:https://git.zv.io/-/snippets/69/raw/main/snippetfile1.txt
EOF
);
_PREPARE=$(cat <<'EOF'
(
    export AR=ar;
    export RANLIB=ranlib;
    ../configure                                               \
        --target=${_BUILD}                                     \
        --prefix="${gen2}"                                     \
        ${_CONF}                                               \
        || _CHECK=0;            # musl is not supported
)
EOF
);
_COMPILE=$(cat <<'EOF'
if test ${_CHECK} -eq 1; then
    make ${_OUTSYNC} ${_IGNB} -j${_NPROC};
else
    skip;
fi
EOF
);
_INSTALL=$(cat <<'EOF'
if test ${_CHECK} -eq 1; then
    make ${_OUTSYNC} ${_IGNI} install;
else
    touch    "${bin2}/musl-gcc";
    chmod +x "${bin2}/musl-gcc";
fi
EOF
);
bake;

_CHECK=;                        # reset to avoid pollution


#===============================================================
# Stage 3: Local "musl-cross-make" (output of which is bin. eq.)
#===============================================================

export PATH="${bin3}:${PATH}";  # (optional) local musl-based tc

#---------------------------------------------------------------
# hello

_CHECK=1;                       # assume musl/hello is supported

## NOTES
#
# Confirm that the current system is capable of executing musl
# binaries. Only Linux and certain architectures are supported,
# and even if musl built successfully, this is a sanity check.
#
musl-gcc    -o "${sdir}/bin/hello" -x c -static - <<'EOF'
#include <stdio.h>
int main (void) { printf("hello\n"); return 0; }
EOF
if   ! test -f "${sdir}/bin/hello"                             \
    || test  "$(${sdir}/bin/hello)" != "hello"; then
    if ! test -n "${ARCH}"; then
        cat <<EOF

================================================================
WARN: Your system does not appear to be able to build or run any
      musl binaries. Either musl has not yet been ported to your
      platform or your platform is unable to execute Hello World
      which has been statically-linked with musl. Sorry.

      You are still able to build musl-cross-make and it will be
      linked with host-libc (whatever you have), but you'll need
      to use the following variable to specify a (cross) target:

      Near the top of this script, edit the 'ARCH' variable.

      We'll take care of the rest. Instructions will be printed
      after this new toolchain is built.
================================================================

EOF
    _CHECK=0;
    fi
fi


#---------------------------------------------------------------
# musl-cross-make

if test ${_CHECK} -eq 1; then

## NOTES
#
# We use a configuration template so that it may be populated by
# the exact same GCC and component version as used in the native
# toolchain build previously. If you modify those versions to be
# different from what this fork of "musl-cross-make" supports, a
# monster will crawl out from your closet and swallow you whole.
#
# At present, out-of-tree builds are not supported. You may need
# to remove the '-static --static' flag if you encounter errors.
#
__conf=$(cat <<'EOF'
STAT = -static --static
FLAG = -O3

ifneq ($(NATIVE),)
COMMON_CONFIG += CC="$(HOST)-gcc ${STAT}" CXX="$(HOST)-g++ ${STAT}" FC="$(HOST)-gfortran ${STAT}"
else
COMMON_CONFIG += CC="gcc ${STAT}" CXX="g++ ${STAT}" FC="gfortran ${STAT}"
endif
COMMON_CONFIG += CFLAGS="${FLAG}" CXXFLAGS="${FLAG}" FFLAGS="${FLAG}" LDFLAGS="-s ${STAT}"
COMMON_CONFIG += --disable-nls --disable-bootstrap --build=__USER__ --host=__HOST__ --target=__TARG__

BINUTILS_CONFIG += --disable-gold --disable-gprofng
GCC_CONFIG      += --enable-default-pie --enable-static-pie

GCC_VER      = __GCC_VER__
BINUTILS_VER = __BINUTILS_VER__
MUSL_VER     = __MUSL_VER__
GMP_VER      = __GMP_VER__
MPC_VER      = __MPC_VER__
MPFR_VER     = __MPFR_VER__
LINUX_VER    = __LINUX_VER__
EOF
);
prep j 1 ${M_MCM}/${V_MCM}/musl-cross-make-${V_MCM}.tar.bz2    \
    ;
_AUTOFOO=skip;
_PREPARE=$(cat <<'EOF'
test -f config.mak || printf > config.mak "%s\n" "${__conf}";
sed -i "config.mak"                                            \
    -e "s@__USER__@${_BUILD}@"                                 \
    -e "s@__HOST__@${_BUILD}@"                                 \
    -e "s@__TARG__@${ARCH}@"                                   \
                                                               \
    -e "s@__GCC_VER__@${V_GCC}@"                               \
    -e "s@__BINUTILS_VER__@${V_BUT}@"                          \
    -e "s@__MUSL_VER__@git-${V_MLC}@"                          \
    -e "s@__GMP_VER__@${V_GMP}@"                               \
    -e "s@__MPC_VER__@${V_MPC}@"                               \
    -e "s@__MPFR_VER__@${V_MPF}@"                              \
    -e "s@__LINUX_VER__@${V_KRN}@"                             \
    ;
EOF
);
_COMPILE=$(cat <<'EOF'
make TARGET=${ARCH} ${_OUTSYNC} -j"${_NPROC}";
EOF
);
_INSTALL=$(cat <<'EOF'
make TARGET=${ARCH} OUTPUT="${gen3}" install;
EOF
);
bake;
unset __conf;
(
    cd "${bin3}";
    for k in $("${sdir}/bin/find" . -type f -printf '%P\n'); do
        __link=${k#${ARCH}-*};
        test -f ${__link} || ln -s ${k} ${__link};
    done
    test -h cc || ln -s ${ARCH}-cc cc;
)


cat <<EOF

================================================================
NOTE: You may now use the new musl-libc toolchain by setting the
      PATH environment variable as follows (e.g., launch shell):

PATH="${sdir}/bin:${bin3}" bash;

      This will provide an environment in which to build either
      cross- or native- software. If your system is already musl
      based, the output of this toolchain should be identical to
      that of the previous one. Otherwise, only static binaries
      are likely to run.

      If you specified the 'ARCH' variable manually because we
      could not confirm that your platform is supported by musl,
      you effectively have a cross-compiler for that target.
================================================================

DONE.
EOF

fi # _CHECK=1


#---------------------------------------------------------------
# (GLOBAL)

##
# Update shared library dependencies and install musl toolchain.
#
"${sdir}/bin/soggy";