GCCDevFlake

A pinned Nix development environment for building, testing and debugging GCC from an editable source checkout.

The flake provides GCC build dependencies, testsuite tools, debugging tools and standalone reproducer tooling. GCC itself remains a normal Git checkout and is built out of tree.

Supported environment

This repository currently provides and validates an x86_64-linux development shell.

It is a development environment, not a container or security sandbox. The development tools are pinned by flake.lock; the GCC source revision is pinned separately through Git.

Enter the environment

git clone git@github.com:V4LKdev/GCCDevFlake.git
cd GCCDevFlake
nix develop

Clone GCC

git clone \
  --single-branch \
  --branch master \
  --no-tags \
  https://github.com/gcc-mirror/gcc.git gcc

git -C gcc remote rename origin mirror
git -C gcc remote add upstream https://gcc.gnu.org/git/gcc.git
git -C gcc -c http.version=HTTP/1.1 fetch upstream master

Create a development branch and prepare generated-file timestamps:

git -C gcc switch -c my-gcc-change upstream/master

(
  cd gcc
  ./contrib/gcc_update --touch
)

Configure a development build

The validated Linux workflow uses the host system's native Binutils for the GCC being built. This prevents host system files from being linked with runtime paths injected by Nix's wrapped linker.

mkdir -p build-debug install-debug
cd build-debug

../gcc/configure \
  --prefix="$(realpath ../install-debug)" \
  --enable-languages=c,c++ \
  --disable-bootstrap \
  --disable-multilib \
  --disable-nls \
  --disable-werror \
  --enable-checking=yes,extra \
  --with-build-time-tools=/usr/bin \
  --with-as=/usr/bin/as \
  --with-ld=/usr/bin/ld

Build

make -j"$(nproc)" \
  all-gcc \
  all-target-libgcc \
  all-target-libstdc++-v3 \
  all-target-libatomic

Install locally

make \
  install-gcc \
  install-target-libgcc \
  install-target-libstdc++-v3 \
  install-target-libatomic

Smoke test

cat >/tmp/gcc-dev-smoke.cpp <<'CPP'
#include <iostream>

int main()
{
    std::cout << "GCC dev compiler works\n";
}
CPP

../install-debug/bin/g++ \
  -std=c++23 \
  /tmp/gcc-dev-smoke.cpp \
  -o /tmp/gcc-dev-smoke

/tmp/gcc-dev-smoke

Validate the flake

nix fmt
nix flake check

License

The files in this repository are available under the MIT License.

GCC is a separate project distributed under its own licensing terms.