Somewhat amusingly given its name, "clang.patch" applies to both 5 and 6
but is the cause of ncurses6 breakage on 6 but is required on 5...
gcc is happy in all four configurations:
5 5p 6 6p
gcc ✓ ✓ ✓ ✓
clang ✗ ✓ ✓ ✗
Which is why this commit enables the patch for 5 but not 6;
this matches behavior in Gentoo, for example.
For further simplification, we also use gcc-5 patch regardless.
This pushes check-meta evaluation to derivation evaluation step, leaving all other
attributes accessible.
Before this commit:
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
as expected
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.name --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.meta.description --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
which is unfortunate since its impossible to use packages in autogenerated
documentation on all platforms.
After this commit:
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen --argstr system aarch64-linux
still fails
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.name --argstr system aarch64-linux
> "xen-4.5.5"
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.meta.description --argstr system aarch64-linux
> "Xen hypervisor and related components (vanilla)"
before:
- /var/run/memcached is a bad default for a socket path, since its
parent directory must be writeable by memcached.
- Socket directory was not created by the module itself -> this was
left as a burden to the user?
- Having a static uid with a dynamic user name is not very useful.
after:
- Replace services.memcached.socket by a boolean flag. This simplifies
our code, since we do not have to check if the user specifies a
path with a parent directory that should be owned by memcached
(/run/memcached/memcached.sock -> /run/memcached).
- Remove fixed uid/gid allocation. The only file ever owned by the
daemon is the socket that will be recreated on every start.
Therefore user and group ids do not need to be static.
- only create the memcached user, if the user has not specified a
different one. The major use case for changing option is to allow
existing services (such as php-fpm) opening the local unix socket.
If we would unconditionally create a user that option would be
useless.
The reason is that if cross compiling (or for other reasons) python
bindings as a whole are turned off. Those two lines then trigger
assertion errors unless manually overridden for cross compilation.
This way:
1. The `enableNumpy` default respects the `enablePython deafult.
2. Cross works by default
3. Absurd manual overrides still break as they should
4. The `>= 1.65` logic is direct and not a maintaince gotcha.
