dd6a291e9f
Package is marked as broken for >2 years and used a fairly old snapshot from the gcc7-branch, so I fairly doubt that this is somewhere used (and is also pretty misleading as you don't expect a random snapshot from gcc7 at `pkgs.gcc-snapshot`).
To build the manual, you need Nix installed on your system (no need
for NixOS). To install Nix, follow the instructions at
https://nixos.org/nix/download.html
When you have Nix on your system, in the root directory of the project
(i.e., `nixpkgs`), run:
nix-build nixos/release.nix -A manual.x86_64-linux
When this command successfully finishes, it will tell you where the
manual got generated.