# The C++ driver for the musl target: musl-clang++, the counterpart of
# Fedora's musl-clang (which covers C only).
#
# Unlike musl-clang, this wrapper does not use ld.musl-clang: that ld
# wrapper keeps only the -L/-l arguments between its -l-user-start/-end
# markers, and clang++'s implicitly appended C++ runtime libraries land
# outside them and are silently dropped.  The wrapper instead relies on
# --sysroot/-B/-L and the merged libc++.a from musl-libcxx, so the stock
# link path works and user flags appended after the wrapper's own win.

%global musl_prefix /usr/x86_64-linux-musl

# Only a shell script is shipped: debuginfo extraction would produce an
# empty debugsource and fail the build.
%global debug_package %{nil}

Name:           musl-llvm
Version:        1
Release:        2%{?dist}
Summary:        Clang C++ driver for the musl target

License:        MIT
URL:            https://musl.libc.org/
ExclusiveArch:  x86_64

Source0:        musl-clang++.in

Requires:       clang
Requires:       musl-devel
Requires:       musl-libcxx
# A -static link needs libc.a; the crt begin/end objects and libgcc.a
# come from the host GCC installation.
Requires:       musl-libc-static
Requires:       gcc

# For the %%check link-and-run probe.
BuildRequires:  clang
BuildRequires:  gcc
BuildRequires:  musl-devel
BuildRequires:  musl-libc-static
BuildRequires:  musl-libcxx
BuildRequires:  file


%description
musl-clang++ drives the distribution clang++ at the x86_64-linux-musl
target against the musl-libcxx runtimes, the way musl-clang does for C.

With musl-libc-static installed, musl-clang++ -static links
self-contained static C++ binaries.


%prep
%setup -q -c -T


%build
sed -e 's|@MUSL_PREFIX@|%{musl_prefix}|g' \
    -e 's|@MUSL_INCLUDEDIR@|%{_musl_includedir}|g' \
    -e 's|@MUSL_LIBDIR@|%{_musl_libdir}|g' \
    %{SOURCE0} > musl-clang++
# Assert every sed: an @-marker surviving means a substitution went dead.
grep -q -- '-B%{_musl_libdir}' musl-clang++
if grep -q '@MUSL' musl-clang++ ; then
    echo "unsubstituted marker in musl-clang++"
    exit 1
fi


%install
mkdir -p %{buildroot}%{_bindir}
install -m 755 musl-clang++ %{buildroot}%{_bindir}/musl-clang++


%check
# The point of the package: the installed wrapper links a static C++
# program -- std::format, a thrown exception, a std::thread -- and it
# runs.
cat > _probe.cpp <<'EOF'
#include <cstdio>
#include <format>
#include <stdexcept>
#include <string>
#include <thread>

int main()
{
    std::string out;
    std::thread t([&] { out = std::format("std::{} on {}", "format", "musl"); });
    t.join();

    try {
        throw std::runtime_error("unwound");
    } catch (const std::exception &e) {
        std::printf("%s, exception: %s\n", out.c_str(), e.what());
    }
    return 0;
}
EOF

%{buildroot}%{_bindir}/musl-clang++ -std=c++23 -static -o _probe _probe.cpp
file _probe
file _probe | grep -q 'statically linked'
out=$(./_probe)
echo "$out"
test "$out" = "std::format on musl, exception: unwound"

# meson runs its compiler probes with -Werror=unused-command-line-
# argument; the wrapper's link-only flags must not trip it.
%{buildroot}%{_bindir}/musl-clang++ -std=c++23 \
    -Werror=unused-command-line-argument -c -o _probe.o _probe.cpp

# A non-static link must also work (libc++.a into a musl-dynamic
# binary); it cannot run in this chroot without ld-musl, so link only.
%{buildroot}%{_bindir}/musl-clang++ -std=c++23 -o _probe_dyn _probe.cpp
interp=$(readelf -l _probe_dyn | grep 'interpreter')
echo "$interp"
echo "$interp" | grep -q 'ld-musl-x86_64'


%files
%{_bindir}/musl-clang++


%changelog
* Thu Aug 20 2026 Erik Berg <fedora@slipsprogrammor.no> - 1-2
- Add -Qunused-arguments: the wrapper's link-only flags warn on every
  compile-only invocation, and meson runs its compiler probes with
  -Werror=unused-command-line-argument, failing them all (the mingw
  clang drivers hit the same trap)

* Thu Aug 20 2026 Erik Berg <fedora@slipsprogrammor.no> - 1-1
- Initial package: musl-clang++, the C++ counterpart of musl-clang,
  driving the distribution clang++ against the musl-libcxx runtimes
- Deliberately not built on ld.musl-clang, which silently drops the
  driver's implicitly appended C++ runtime libraries (they land outside
  its -l-user-start/-end markers)