[Nix-dev] Nix 1.11 released

[Shea Levy]

Another new feature of potential interest: attribute sets with a 
'__toString' attribute are coerced to string (i.e. when doing 
${}-interpolation or using builtins.toString) by calling the function at 
__toString with the set itself as an argument and coercing the result to 
a string. Among other things, this may enable simpler overriding: rather 
than trying to extract out the original arguments to a function (e.g. 
mkDerivation) and passing new ones to it, we merely delay the call of 
the function to the toString call and use normal attribute set update to 
override any values.

~Shea

On 2016-01-19 08:19, Eelco Dolstra wrote:
> Hi,
>
> I'm pleased to announce the availability of a new stable release of 
> the
> Nix package manager.  Release 1.11 can be found at
>
>   http://hydra.nixos.org/release/nix/nix-1.11
>
> and
>
>   http://nixos.org/releases/nix/nix-1.11
>
> This is primarily a bug fix release. It also has a number of new 
> features:
>
>   • nix-prefetch-url can now download URLs specified in a Nix 
> expression. For
>     example,
>
>     $ nix-prefetch-url -A hello.src
>
>     will prefetch the file specified by the fetchurl call in the 
> attribute
>     hello.src from the Nix expression in the current directory, and 
> print the
>     cryptographic hash of the resulting file on stdout. This differs 
> from
>     nix-build -A hello.src in that it doesn't verify the hash, and is 
> thus
>     useful when you’re updating a Nix expression.
>
>     You can also prefetch the result of functions that unpack a 
> tarball, such
>     as fetchFromGitHub. For example:
>
>     $ nix-prefetch-url --unpack
> https://github.com/NixOS/patchelf/archive/0.8.tar.gz
>
>     or from a Nix expression:
>
>     $ nix-prefetch-url -A nix-repl.src
>
>   • The builtin function <nix/fetchurl.nix> now supports downloading 
> and
>     unpacking NARs. This removes the need to have multiple downloads 
> in the
>     Nixpkgs stdenv bootstrap process (like a separate busybox binary 
> for Linux,
>     or curl/mkdir/sh/bzip2 for Darwin). Now all those files can be 
> combined
>     into a single NAR, optionally compressed using xz.
>
>   • Nix now supports SHA-512 hashes for verifying fixed-output 
> derivations, and
>     in builtins.hashString.
>
>   • The new flag --option build-repeat N will cause every build to be 
> executed
>     N+1 times. If the build output differs between any round, the 
> build is
>     rejected, and the output paths are not registered as valid. This 
> is
>     primarily useful to verify build determinism. (We already had a 
> --check
>     option to repeat a previously succeeded build. However, with 
> --check,
>     non-deterministic builds are registered in the DB. Preventing 
> that is
>     useful for Hydra to ensure that non-deterministic builds don't 
> end up
>     getting published to the binary cache.)
>
>   • The options --check and --option build-repeat N, if they detect a
>     difference between two runs of the same derivation and -K is 
> given, will
>     make the output of the other run available under 
> store-path-check. This
>     makes it easier to investigate the non-determinism using tools 
> like
>     diffoscope, e.g.,
>
>     $ nix-build pkgs/stdenv/linux -A stage1.pkgs.zlib --check -K
>     error: derivation ‘/nix/store/l54i8wlw2265…-zlib-1.2.8.drv’ may 
> not
>     be deterministic: output ‘/nix/store/11a27shh6n2i…-zlib-1.2.8’
>     differs from ‘/nix/store/11a27shh6n2i…-zlib-1.2.8-check’
>
>     $ diffoscope /nix/store/11a27shh6n2i…-zlib-1.2.8
> /nix/store/11a27shh6n2i…-zlib-1.2.8-check
>     …
>     ├── lib/libz.a
>     │   ├── metadata
>     │   │ @@ -1,15 +1,15 @@
>     │   │ -rw-r--r-- 30001/30000   3096 Jan 12 15:20 2016 adler32.o
>     …
>     │   │ +rw-r--r-- 30001/30000   3096 Jan 12 15:28 2016 adler32.o
>     …
>
>   • Improved FreeBSD support.
>
>   • nix-env -qa --xml --meta now prints license information.
>
>   • The maximum number of parallel TCP connections that the binary 
> cache
>     substituter will use has been decreased from 150 to 25. This 
> should prevent
>     upsetting some broken NAT routers, and also improves performance.
>
>   • All "chroot"-containing strings got renamed to "sandbox". In 
> particular,
>     some Nix options got renamed, but the old names are still 
> accepted as
>     lower-priority aliases.
>
> This release has contributions from Anders Claesson, Anthony Cowley, 
> Bjørn
> Forsman, Brian McKenna, Danny Wilson, davidak, Eelco Dolstra, Fabian
> Schmitthenner, FrankHB, Ilya Novoselov, janus, Jim Garrison, John 
> Ericson, Jude
> Taylor, Ludovic Courtès, Manuel Jacob, Mathnerd314, Pascal Wittmann, 
> Peter
> Simons, Philip Potter, Preston Bennes, Rommel M. Martinez, Sander van 
> der Burg,
> Shea Levy, Tim Cuthbertson, Tuomas Tynkkynen, Utku Demir and Vladimír 
> Čunát.