chore(3p/nix): unvendor tvix 0.1 r/4098

Nothing is using this now, and we'll likely never pick this up again,
but we learned a lot in the process.

Every now and then this breaks in some bizarre way on channel bumps
and it's just a waste of time to maintain that.

Change-Id: Idcf2f5acd4ca7070ce18d7149cbfc0d967dc0a44
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5632
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 1012 deletions

diff --git a/third_party/nix/doc/manual/release-notes/rl-2.0.xml b/third_party/nix/doc/manual/release-notes/rl-2.0.xml
deleted file mode 100644
index fc9a77b08b60..000000000000
--- a/third_party/nix/doc/manual/release-notes/rl-2.0.xml
+++ /dev/null
@@ -1,1012 +0,0 @@
-<section xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      version="5.0"
-      xml:id="ssec-relnotes-2.0">
-
-<title>Release 2.0 (2018-02-22)</title>
-
-<para>The following incompatible changes have been made:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>The manifest-based substituter mechanism
-    (<command>download-using-manifests</command>) has been <link
-    xlink:href="https://github.com/NixOS/nix/commit/867967265b80946dfe1db72d40324b4f9af988ed">removed</link>. It
-    has been superseded by the binary cache substituter mechanism
-    since several years. As a result, the following programs have been
-    removed:
-
-    <itemizedlist>
-      <listitem><para><command>nix-pull</command></para></listitem>
-      <listitem><para><command>nix-generate-patches</command></para></listitem>
-      <listitem><para><command>bsdiff</command></para></listitem>
-      <listitem><para><command>bspatch</command></para></listitem>
-    </itemizedlist>
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>The “copy from other stores” substituter mechanism
-    (<command>copy-from-other-stores</command> and the
-    <envar>NIX_OTHER_STORES</envar> environment variable) has been
-    removed. It was primarily used by the NixOS installer to copy
-    available paths from the installation medium. The replacement is
-    to use a chroot store as a substituter
-    (e.g. <literal>--substituters /mnt</literal>), or to build into a
-    chroot store (e.g. <literal>--store /mnt --substituters /</literal>).</para>
-  </listitem>
-
-  <listitem>
-    <para>The command <command>nix-push</command> has been removed as
-    part of the effort to eliminate Nix's dependency on Perl. You can
-    use <command>nix copy</command> instead, e.g. <literal>nix copy
-    --to file:///tmp/my-binary-cache <replaceable>paths…</replaceable></literal></para>
-  </listitem>
-
-  <listitem>
-    <para>The “nested” log output feature (<option>--log-type
-    pretty</option>) has been removed. As a result,
-    <command>nix-log2xml</command> was also removed.</para>
-  </listitem>
-
-  <listitem>
-    <para>OpenSSL-based signing has been <link
-    xlink:href="https://github.com/NixOS/nix/commit/f435f8247553656774dd1b2c88e9de5d59cab203">removed</link>. This
-    feature was never well-supported. A better alternative is provided
-    by the <option>secret-key-files</option> and
-    <option>trusted-public-keys</option> options.</para>
-  </listitem>
-
-  <listitem>
-    <para>Failed build caching has been <link
-    xlink:href="https://github.com/NixOS/nix/commit/8cffec84859cec8b610a2a22ab0c4d462a9351ff">removed</link>. This
-    feature was introduced to support the Hydra continuous build
-    system, but Hydra no longer uses it.</para>
-  </listitem>
-
-  <listitem>
-    <para><filename>nix-mode.el</filename> has been removed from
-    Nix. It is now <link
-    xlink:href="https://github.com/NixOS/nix-mode">a separate
-    repository</link> and can be installed through the MELPA package
-    repository.</para>
-  </listitem>
-
-</itemizedlist>
-
-<para>This release has the following new features:</para>
-
-<itemizedlist>
-
-  <listitem>
-    <para>It introduces a new command named <command>nix</command>,
-    which is intended to eventually replace all
-    <command>nix-*</command> commands with a more consistent and
-    better designed user interface. It currently provides replacements
-    for some (but not all) of the functionality provided by
-    <command>nix-store</command>, <command>nix-build</command>,
-    <command>nix-shell -p</command>, <command>nix-env -qa</command>,
-    <command>nix-instantiate --eval</command>,
-    <command>nix-push</command> and
-    <command>nix-copy-closure</command>. It has the following major
-    features:</para>
-
-    <itemizedlist>
-
-      <listitem>
-        <para>Unlike the legacy commands, it has a consistent way to
-        refer to packages and package-like arguments (like store
-        paths). For example, the following commands all copy the GNU
-        Hello package to a remote machine:
-
-        <screen>nix copy --to ssh://machine nixpkgs.hello</screen>
-        <screen>nix copy --to ssh://machine /nix/store/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9-hello-2.10</screen>
-        <screen>nix copy --to ssh://machine '(with import &lt;nixpkgs> {}; hello)'</screen>
-
-        By contrast, <command>nix-copy-closure</command> only accepted
-        store paths as arguments.</para>
-      </listitem>
-
-      <listitem>
-        <para>It is self-documenting: <option>--help</option> shows
-        all available command-line arguments. If
-        <option>--help</option> is given after a subcommand, it shows
-        examples for that subcommand. <command>nix
-        --help-config</command> shows all configuration
-        options.</para>
-      </listitem>
-
-      <listitem>
-        <para>It is much less verbose. By default, it displays a
-        single-line progress indicator that shows how many packages
-        are left to be built or downloaded, and (if there are running
-        builds) the most recent line of builder output. If a build
-        fails, it shows the last few lines of builder output. The full
-        build log can be retrieved using <command>nix
-        log</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para>It <link
-        xlink:href="https://github.com/NixOS/nix/commit/b8283773bd64d7da6859ed520ee19867742a03ba">provides</link>
-        all <filename>nix.conf</filename> configuration options as
-        command line flags. For example, instead of <literal>--option
-        http-connections 100</literal> you can write
-        <literal>--http-connections 100</literal>. Boolean options can
-        be written as
-        <literal>--<replaceable>foo</replaceable></literal> or
-        <literal>--no-<replaceable>foo</replaceable></literal>
-        (e.g. <option>--no-auto-optimise-store</option>).</para>
-      </listitem>
-
-      <listitem>
-        <para>Many subcommands have a <option>--json</option> flag to
-        write results to stdout in JSON format.</para>
-      </listitem>
-
-    </itemizedlist>
-
-    <warning><para>Please note that the <command>nix</command> command
-    is a work in progress and the interface is subject to
-    change.</para></warning>
-
-    <para>It provides the following high-level (“porcelain”)
-    subcommands:</para>
-
-    <itemizedlist>
-
-      <listitem>
-        <para><command>nix build</command> is a replacement for
-        <command>nix-build</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix run</command> executes a command in an
-        environment in which the specified packages are available. It
-        is (roughly) a replacement for <command>nix-shell
-        -p</command>. Unlike that command, it does not execute the
-        command in a shell, and has a flag (<command>-c</command>)
-        that specifies the unquoted command line to be
-        executed.</para>
-
-        <para>It is particularly useful in conjunction with chroot
-        stores, allowing Linux users who do not have permission to
-        install Nix in <command>/nix/store</command> to still use
-        binary substitutes that assume
-        <command>/nix/store</command>. For example,
-
-        <screen>nix run --store ~/my-nix nixpkgs.hello -c hello --greeting 'Hi everybody!'</screen>
-
-        downloads (or if not substitutes are available, builds) the
-        GNU Hello package into
-        <filename>~/my-nix/nix/store</filename>, then runs
-        <command>hello</command> in a mount namespace where
-        <filename>~/my-nix/nix/store</filename> is mounted onto
-        <command>/nix/store</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix search</command> replaces <command>nix-env
-        -qa</command>. It searches the available packages for
-        occurrences of a search string in the attribute name, package
-        name or description. Unlike <command>nix-env -qa</command>, it
-        has a cache to speed up subsequent searches.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix copy</command> copies paths between
-        arbitrary Nix stores, generalising
-        <command>nix-copy-closure</command> and
-        <command>nix-push</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix repl</command> replaces the external
-        program <command>nix-repl</command>. It provides an
-        interactive environment for evaluating and building Nix
-        expressions. Note that it uses <literal>linenoise-ng</literal>
-        instead of GNU Readline.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix upgrade-nix</command> upgrades Nix to the
-        latest stable version. This requires that Nix is installed in
-        a profile. (Thus it won’t work on NixOS, or if it’s installed
-        outside of the Nix store.)</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix verify</command> checks whether store paths
-        are unmodified and/or “trusted” (see below). It replaces
-        <command>nix-store --verify</command> and <command>nix-store
-        --verify-path</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix log</command> shows the build log of a
-        package or path. If the build log is not available locally, it
-        will try to obtain it from the configured substituters (such
-        as <uri>cache.nixos.org</uri>, which now provides build
-        logs).</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix edit</command> opens the source code of a
-        package in your editor.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix eval</command> replaces
-        <command>nix-instantiate --eval</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command
-        xlink:href="https://github.com/NixOS/nix/commit/d41c5eb13f4f3a37d80dbc6d3888644170c3b44a">nix
-        why-depends</command> shows why one store path has another in
-        its closure. This is primarily useful to finding the causes of
-        closure bloat. For example,
-
-        <screen>nix why-depends nixpkgs.vlc nixpkgs.libdrm.dev</screen>
-
-        shows a chain of files and fragments of file contents that
-        cause the VLC package to have the “dev” output of
-        <literal>libdrm</literal> in its closure — an undesirable
-        situation.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix path-info</command> shows information about
-        store paths, replacing <command>nix-store -q</command>. A
-        useful feature is the option <option>--closure-size</option>
-        (<option>-S</option>). For example, the following command show
-        the closure sizes of every path in the current NixOS system
-        closure, sorted by size:
-
-        <screen>nix path-info -rS /run/current-system | sort -nk2</screen>
-
-        </para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix optimise-store</command> replaces
-        <command>nix-store --optimise</command>. The main difference
-        is that it has a progress indicator.</para>
-      </listitem>
-
-    </itemizedlist>
-
-    <para>A number of low-level (“plumbing”) commands are also
-    available:</para>
-
-    <itemizedlist>
-
-      <listitem>
-        <para><command>nix ls-store</command> and <command>nix
-        ls-nar</command> list the contents of a store path or NAR
-        file. The former is primarily useful in conjunction with
-        remote stores, e.g.
-
-        <screen>nix ls-store --store https://cache.nixos.org/ -lR /nix/store/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9-hello-2.10</screen>
-
-        lists the contents of path in a binary cache.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix cat-store</command> and <command>nix
-        cat-nar</command> allow extracting a file from a store path or
-        NAR file.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix dump-path</command> writes the contents of
-        a store path to stdout in NAR format. This replaces
-        <command>nix-store --dump</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command
-        xlink:href="https://github.com/NixOS/nix/commit/e8d6ee7c1b90a2fe6d824f1a875acc56799ae6e2">nix
-        show-derivation</command> displays a store derivation in JSON
-        format. This is an alternative to
-        <command>pp-aterm</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command
-        xlink:href="https://github.com/NixOS/nix/commit/970366266b8df712f5f9cedb45af183ef5a8357f">nix
-        add-to-store</command> replaces <command>nix-store
-        --add</command>.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix sign-paths</command> signs store
-        paths.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix copy-sigs</command> copies signatures from
-        one store to another.</para>
-      </listitem>
-
-      <listitem>
-        <para><command>nix show-config</command> shows all
-        configuration options and their current values.</para>
-      </listitem>
-
-    </itemizedlist>
-
-  </listitem>
-
-  <listitem>
-    <para>The store abstraction that Nix has had for a long time to
-    support store access via the Nix daemon has been extended
-    significantly. In particular, substituters (which used to be
-    external programs such as
-    <command>download-from-binary-cache</command>) are now subclasses
-    of the abstract <classname>Store</classname> class. This allows
-    many Nix commands to operate on such store types. For example,
-    <command>nix path-info</command> shows information about paths in
-    your local Nix store, while <command>nix path-info --store
-    https://cache.nixos.org/</command> shows information about paths
-    in the specified binary cache. Similarly,
-    <command>nix-copy-closure</command>, <command>nix-push</command>
-    and substitution are all instances of the general notion of
-    copying paths between different kinds of Nix stores.</para>
-
-    <para>Stores are specified using an URI-like syntax,
-    e.g. <uri>https://cache.nixos.org/</uri> or
-    <uri>ssh://machine</uri>. The following store types are supported:
-
-    <itemizedlist>
-
-      <listitem>
-
-        <para><classname>LocalStore</classname> (stori URI
-        <literal>local</literal> or an absolute path) and the misnamed
-        <classname>RemoteStore</classname> (<literal>daemon</literal>)
-        provide access to a local Nix store, the latter via the Nix
-        daemon. You can use <literal>auto</literal> or the empty
-        string to auto-select a local or daemon store depending on
-        whether you have write permission to the Nix store. It is no
-        longer necessary to set the <envar>NIX_REMOTE</envar>
-        environment variable to use the Nix daemon.</para>
-
-        <para>As noted above, <classname>LocalStore</classname> now
-        supports chroot builds, allowing the “physical” location of
-        the Nix store
-        (e.g. <filename>/home/alice/nix/store</filename>) to differ
-        from its “logical” location (typically
-        <filename>/nix/store</filename>). This allows non-root users
-        to use Nix while still getting the benefits from prebuilt
-        binaries from <uri>cache.nixos.org</uri>.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>BinaryCacheStore</classname> is the abstract
-        superclass of all binary cache stores. It supports writing
-        build logs and NAR content listings in JSON format.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>HttpBinaryCacheStore</classname>
-        (<literal>http://</literal>, <literal>https://</literal>)
-        supports binary caches via HTTP or HTTPS. If the server
-        supports <literal>PUT</literal> requests, it supports
-        uploading store paths via commands such as <command>nix
-        copy</command>.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>LocalBinaryCacheStore</classname>
-        (<literal>file://</literal>) supports binary caches in the
-        local filesystem.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>S3BinaryCacheStore</classname>
-        (<literal>s3://</literal>) supports binary caches stored in
-        Amazon S3, if enabled at compile time.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>LegacySSHStore</classname> (<literal>ssh://</literal>)
-        is used to implement remote builds and
-        <command>nix-copy-closure</command>.</para>
-
-      </listitem>
-
-      <listitem>
-
-        <para><classname>SSHStore</classname>
-        (<literal>ssh-ng://</literal>) supports arbitrary Nix
-        operations on a remote machine via the same protocol used by
-        <command>nix-daemon</command>.</para>
-
-      </listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem>
-
-    <para>Security has been improved in various ways:
-
-    <itemizedlist>
-
-      <listitem>
-        <para>Nix now stores signatures for local store
-        paths. When paths are copied between stores (e.g., copied from
-        a binary cache to a local store), signatures are
-        propagated.</para>
-
-        <para>Locally-built paths are signed automatically using the
-        secret keys specified by the <option>secret-key-files</option>
-        store option. Secret/public key pairs can be generated using
-        <command>nix-store
-        --generate-binary-cache-key</command>.</para>
-
-        <para>In addition, locally-built store paths are marked as
-        “ultimately trusted”, but this bit is not propagated when
-        paths are copied between stores.</para>
-      </listitem>
-
-      <listitem>
-        <para>Content-addressable store paths no longer require
-        signatures — they can be imported into a store by unprivileged
-        users even if they lack signatures.</para>
-      </listitem>
-
-      <listitem>
-        <para>The command <command>nix verify</command> checks whether
-        the specified paths are trusted, i.e., have a certain number
-        of trusted signatures, are ultimately trusted, or are
-        content-addressed.</para>
-      </listitem>
-
-      <listitem>
-        <para>Substitutions from binary caches <link
-        xlink:href="https://github.com/NixOS/nix/commit/ecbc3fedd3d5bdc5a0e1a0a51b29062f2874ac8b">now</link>
-        require signatures by default. This was already the case on
-        NixOS.</para>
-      </listitem>
-
-      <listitem>
-        <para>In Linux sandbox builds, we <link
-        xlink:href="https://github.com/NixOS/nix/commit/eba840c8a13b465ace90172ff76a0db2899ab11b">now</link>
-        use <filename>/build</filename> instead of
-        <filename>/tmp</filename> as the temporary build
-        directory. This fixes potential security problems when a build
-        accidentally stores its <envar>TMPDIR</envar> in some
-        security-sensitive place, such as an RPATH.</para>
-      </listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem>
-    <para><emphasis>Pure evaluation mode</emphasis>. This is a variant
-    of the existing restricted evaluation mode. In pure mode, the Nix
-    evaluator forbids access to anything that could cause different
-    evaluations of the same command line arguments to produce a
-    different result. This includes builtin functions such as
-    <function>builtins.getEnv</function>, but more importantly,
-    <emphasis>all</emphasis> filesystem or network access unless a
-    content hash or commit hash is specified. For example, calls to
-    <function>builtins.fetchGit</function> are only allowed if a
-    <varname>rev</varname> attribute is specified.</para>
-
-    <para>The goal of this feature is to enable true reproducibility
-    and traceability of builds (including NixOS system configurations)
-    at the evaluation level. For example, in the future,
-    <command>nixos-rebuild</command> might build configurations from a
-    Nix expression in a Git repository in pure mode. That expression
-    might fetch other repositories such as Nixpkgs via
-    <function>builtins.fetchGit</function>. The commit hash of the
-    top-level repository then uniquely identifies a running system,
-    and, in conjunction with that repository, allows it to be
-    reproduced or modified.</para>
-
-  </listitem>
-
-  <listitem>
-    <para>There are several new features to support binary
-    reproducibility (i.e. to help ensure that multiple builds of the
-    same derivation produce exactly the same output). When
-    <option>enforce-determinism</option> is set to
-    <literal>false</literal>, it’s <link
-    xlink:href="https://github.com/NixOS/nix/commit/8bdf83f936adae6f2c907a6d2541e80d4120f051">no
-    longer</link> a fatal error if build rounds produce different
-    output. Also, a hook named <option>diff-hook</option> is <link
-    xlink:href="https://github.com/NixOS/nix/commit/9a313469a4bdea2d1e8df24d16289dc2a172a169">provided</link>
-    to allow you to run tools such as <command>diffoscope</command>
-    when build rounds produce different output.</para>
-  </listitem>
-
-  <listitem>
-    <para>Configuring remote builds is a lot easier now. Provided you
-    are not using the Nix daemon, you can now just specify a remote
-    build machine on the command line, e.g. <literal>--option builders
-    'ssh://my-mac x86_64-darwin'</literal>. The environment variable
-    <envar>NIX_BUILD_HOOK</envar> has been removed and is no longer
-    needed. The environment variable <envar>NIX_REMOTE_SYSTEMS</envar>
-    is still supported for compatibility, but it is also possible to
-    specify builders in <command>nix.conf</command> by setting the
-    option <literal>builders =
-    @<replaceable>path</replaceable></literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>If a fixed-output derivation produces a result with an
-    incorrect hash, the output path is moved to the location
-    corresponding to the actual hash and registered as valid. Thus, a
-    subsequent build of the fixed-output derivation with the correct
-    hash is unnecessary.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> <link
-    xlink:href="https://github.com/NixOS/nix/commit/ea59f39326c8e9dc42dfed4bcbf597fbce58797c">now</link>
-    sets the <varname>IN_NIX_SHELL</varname> environment variable
-    during evaluation and in the shell itself. This can be used to
-    perform different actions depending on whether you’re in a Nix
-    shell or in a regular build. Nixpkgs provides
-    <varname>lib.inNixShell</varname> to check this variable during
-    evaluation.</para>
-  </listitem>
-
-  <listitem>
-    <para><envar>NIX_PATH</envar> is now lazy, so URIs in the path are
-    only downloaded if they are needed for evaluation.</para>
-  </listitem>
-
-  <listitem>
-    <para>You can now use
-    <uri>channel:<replaceable>channel-name</replaceable></uri> as a
-    short-hand for
-    <uri>https://nixos.org/channels/<replaceable>channel-name</replaceable>/nixexprs.tar.xz</uri>. For
-    example, <literal>nix-build channel:nixos-15.09 -A hello</literal>
-    will build the GNU Hello package from the
-    <literal>nixos-15.09</literal> channel. In the future, this may
-    use Git to fetch updates more efficiently.</para>
-  </listitem>
-
-  <listitem>
-    <para>When <option>--no-build-output</option> is given, the last
-    10 lines of the build log will be shown if a build
-    fails.</para>
-  </listitem>
-
-  <listitem>
-    <para>Networking has been improved:
-
-    <itemizedlist>
-
-      <listitem>
-        <para>HTTP/2 is now supported. This makes binary cache lookups
-        <link
-        xlink:href="https://github.com/NixOS/nix/commit/90ad02bf626b885a5dd8967894e2eafc953bdf92">much
-        more efficient</link>.</para>
-      </listitem>
-
-      <listitem>
-        <para>We now retry downloads on many HTTP errors, making
-        binary caches substituters more resilient to temporary
-        failures.</para>
-      </listitem>
-
-      <listitem>
-        <para>HTTP credentials can now be configured via the standard
-        <filename>netrc</filename> mechanism.</para>
-      </listitem>
-
-      <listitem>
-        <para>If S3 support is enabled at compile time,
-        <uri>s3://</uri> URIs are <link
-        xlink:href="https://github.com/NixOS/nix/commit/9ff9c3f2f80ba4108e9c945bbfda2c64735f987b">supported</link>
-        in all places where Nix allows URIs.</para>
-      </listitem>
-
-      <listitem>
-        <para>Brotli compression is now supported. In particular,
-        <uri>cache.nixos.org</uri> build logs are now compressed using
-        Brotli.</para>
-      </listitem>
-
-    </itemizedlist>
-
-    </para>
-
-  </listitem>
-
-  <listitem>
-    <para><command>nix-env</command> <link
-    xlink:href="https://github.com/NixOS/nix/commit/b0cb11722626e906a73f10dd9a0c9eea29faf43a">now</link>
-    ignores packages with bad derivation names (in particular those
-    starting with a digit or containing a dot).</para>
-  </listitem>
-
-  <listitem>
-    <para>Many configuration options have been renamed, either because
-    they were unnecessarily verbose
-    (e.g. <option>build-use-sandbox</option> is now just
-    <option>sandbox</option>) or to reflect generalised behaviour
-    (e.g. <option>binary-caches</option> is now
-    <option>substituters</option> because it allows arbitrary store
-    URIs). The old names are still supported for compatibility.</para>
-  </listitem>
-
-  <listitem>
-    <para>The <option>max-jobs</option> option can <link
-    xlink:href="https://github.com/NixOS/nix/commit/7251d048fa812d2551b7003bc9f13a8f5d4c95a5">now</link>
-    be set to <literal>auto</literal> to use the number of CPUs in the
-    system.</para>
-  </listitem>
-
-  <listitem>
-    <para>Hashes can <link
-    xlink:href="https://github.com/NixOS/nix/commit/c0015e87af70f539f24d2aa2bc224a9d8b84276b">now</link>
-    be specified in base-64 format, in addition to base-16 and the
-    non-standard base-32.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-shell</command> now uses
-    <varname>bashInteractive</varname> from Nixpkgs, rather than the
-    <command>bash</command> command that happens to be in the caller’s
-    <envar>PATH</envar>. This is especially important on macOS where
-    the <command>bash</command> provided by the system is seriously
-    outdated and cannot execute <literal>stdenv</literal>’s setup
-    script.</para>
-  </listitem>
-
-  <listitem>
-    <para>Nix can now automatically trigger a garbage collection if
-    free disk space drops below a certain level during a build. This
-    is configured using the <option>min-free</option> and
-    <option>max-free</option> options.</para>
-  </listitem>
-
-  <listitem>
-    <para><command>nix-store -q --roots</command> and
-    <command>nix-store --gc --print-roots</command> now show temporary
-    and in-memory roots.</para>
-  </listitem>
-
-  <listitem>
-    <para>
-      Nix can now be extended with plugins. See the documentation of
-      the <option>plugin-files</option> option for more details.
-    </para>
-  </listitem>
-
-</itemizedlist>
-
-<para>The Nix language has the following new features:
-
-<itemizedlist>
-
-  <listitem>
-    <para>It supports floating point numbers. They are based on the
-    C++ <literal>float</literal> type and are supported by the
-    existing numerical operators. Export and import to and from JSON
-    and XML works, too.</para>
-  </listitem>
-
-  <listitem>
-    <para>Derivation attributes can now reference the outputs of the
-    derivation using the <function>placeholder</function> builtin
-    function. For example, the attribute
-
-<programlisting>
-configureFlags = "--prefix=${placeholder "out"} --includedir=${placeholder "dev"}";
-</programlisting>
-
-    will cause the <envar>configureFlags</envar> environment variable
-    to contain the actual store paths corresponding to the
-    <literal>out</literal> and <literal>dev</literal> outputs.</para>
-  </listitem>
-
-</itemizedlist>
-
-</para>
-
-<para>The following builtin functions are new or extended:
-
-<itemizedlist>
-
-  <listitem>
-    <para><function
-    xlink:href="https://github.com/NixOS/nix/commit/38539b943a060d9cdfc24d6e5d997c0885b8aa2f">builtins.fetchGit</function>
-    allows Git repositories to be fetched at evaluation time. Thus it
-    differs from the <function>fetchgit</function> function in
-    Nixpkgs, which fetches at build time and cannot be used to fetch
-    Nix expressions during evaluation. A typical use case is to import
-    external NixOS modules from your configuration, e.g.
-
-    <programlisting>imports = [ (builtins.fetchGit https://github.com/edolstra/dwarffs + "/module.nix") ];</programlisting>
-
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>Similarly, <function>builtins.fetchMercurial</function>
-    allows you to fetch Mercurial repositories.</para>
-  </listitem>
-
-  <listitem>
-    <para><function>builtins.path</function> generalises
-    <function>builtins.filterSource</function> and path literals
-    (e.g. <literal>./foo</literal>). It allows specifying a store path
-    name that differs from the source path name
-    (e.g. <literal>builtins.path { path = ./foo; name = "bar";
-    }</literal>) and also supports filtering out unwanted
-    files.</para>
-  </listitem>
-
-  <listitem>
-    <para><function>builtins.fetchurl</function> and
-    <function>builtins.fetchTarball</function> now support
-    <varname>sha256</varname> and <varname>name</varname>
-    attributes.</para>
-  </listitem>
-
-  <listitem>
-    <para><function
-    xlink:href="https://github.com/NixOS/nix/commit/b8867a0239b1930a16f9ef3f7f3e864b01416dff">builtins.split</function>
-    splits a string using a POSIX extended regular expression as the
-    separator.</para>
-  </listitem>
-
-  <listitem>
-    <para><function
-    xlink:href="https://github.com/NixOS/nix/commit/26d92017d3b36cff940dcb7d1611c42232edb81a">builtins.partition</function>
-    partitions the elements of a list into two lists, depending on a
-    Boolean predicate.</para>
-  </listitem>
-
-  <listitem>
-    <para><literal>&lt;nix/fetchurl.nix&gt;</literal> now uses the
-    content-addressable tarball cache at
-    <uri>http://tarballs.nixos.org/</uri>, just like
-    <function>fetchurl</function> in
-    Nixpkgs. (f2682e6e18a76ecbfb8a12c17e3a0ca15c084197)</para>
-  </listitem>
-
-  <listitem>
-    <para>In restricted and pure evaluation mode, builtin functions
-    that download from the network (such as
-    <function>fetchGit</function>) are permitted to fetch underneath a
-    list of URI prefixes specified in the option
-    <option>allowed-uris</option>.</para>
-  </listitem>
-
-</itemizedlist>
-
-</para>
-
-<para>The Nix build environment has the following changes:
-
-<itemizedlist>
-
-  <listitem>
-    <para>Values such as Booleans, integers, (nested) lists and
-    attribute sets can <link
-    xlink:href="https://github.com/NixOS/nix/commit/6de33a9c675b187437a2e1abbcb290981a89ecb1">now</link>
-    be passed to builders in a non-lossy way. If the special attribute
-    <varname>__structuredAttrs</varname> is set to
-    <literal>true</literal>, the other derivation attributes are
-    serialised in JSON format and made available to the builder via
-    the file <envar>.attrs.json</envar> in the builder’s temporary
-    directory. This obviates the need for
-    <varname>passAsFile</varname> since JSON files have no size
-    restrictions, unlike process environments.</para>
-
-    <para><link
-    xlink:href="https://github.com/NixOS/nix/commit/2d5b1b24bf70a498e4c0b378704cfdb6471cc699">As
-    a convenience to Bash builders</link>, Nix writes a script named
-    <envar>.attrs.sh</envar> to the builder’s directory that
-    initialises shell variables corresponding to all attributes that
-    are representable in Bash. This includes non-nested (associative)
-    arrays. For example, the attribute <literal>hardening.format =
-    true</literal> ends up as the Bash associative array element
-    <literal>${hardening[format]}</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>Builders can <link
-    xlink:href="https://github.com/NixOS/nix/commit/88e6bb76de5564b3217be9688677d1c89101b2a3">now</link>
-    communicate what build phase they are in by writing messages to
-    the file descriptor specified in <envar>NIX_LOG_FD</envar>. The
-    current phase is shown by the <command>nix</command> progress
-    indicator.
-    </para>
-  </listitem>
-
-  <listitem>
-    <para>In Linux sandbox builds, we <link
-    xlink:href="https://github.com/NixOS/nix/commit/a2d92bb20e82a0957067ede60e91fab256948b41">now</link>
-    provide a default <filename>/bin/sh</filename> (namely
-    <filename>ash</filename> from BusyBox).</para>
-  </listitem>
-
-  <listitem>
-    <para>In structured attribute mode,
-    <varname>exportReferencesGraph</varname> <link
-    xlink:href="https://github.com/NixOS/nix/commit/c2b0d8749f7e77afc1c4b3e8dd36b7ee9720af4a">exports</link>
-    extended information about closures in JSON format. In particular,
-    it includes the sizes and hashes of paths. This is primarily
-    useful for NixOS image builders.</para>
-  </listitem>
-
-  <listitem>
-    <para>Builds are <link
-    xlink:href="https://github.com/NixOS/nix/commit/21948deed99a3295e4d5666e027a6ca42dc00b40">now</link>
-    killed as soon as Nix receives EOF on the builder’s stdout or
-    stderr. This fixes a bug that allowed builds to hang Nix
-    indefinitely, regardless of
-    timeouts.</para>
-  </listitem>
-
-  <listitem>
-    <para>The <option>sandbox-paths</option> configuration
-    option can now specify optional paths by appending a
-    <literal>?</literal>, e.g. <literal>/dev/nvidiactl?</literal> will
-    bind-mount <varname>/dev/nvidiactl</varname> only if it
-    exists.</para>
-  </listitem>
-
-  <listitem>
-    <para>On Linux, builds are now executed in a user
-    namespace with UID 1000 and GID 100.</para>
-  </listitem>
-
-</itemizedlist>
-
-</para>
-
-<para>A number of significant internal changes were made:
-
-<itemizedlist>
-
-  <listitem>
-    <para>Nix no longer depends on Perl and all Perl components have
-    been rewritten in C++ or removed. The Perl bindings that used to
-    be part of Nix have been moved to a separate package,
-    <literal>nix-perl</literal>.</para>
-  </listitem>
-
-  <listitem>
-    <para>All <classname>Store</classname> classes are now
-    thread-safe. <classname>RemoteStore</classname> supports multiple
-    concurrent connections to the daemon. This is primarily useful in
-    multi-threaded programs such as
-    <command>hydra-queue-runner</command>.</para>
-  </listitem>
-
-</itemizedlist>
-
-</para>
-
-<para>This release has contributions from
-
-Adrien Devresse,
-Alexander Ried,
-Alex Cruice,
-Alexey Shmalko,
-AmineChikhaoui,
-Andy Wingo,
-Aneesh Agrawal,
-Anthony Cowley,
-Armijn Hemel,
-aszlig,
-Ben Gamari,
-Benjamin Hipple,
-Benjamin Staffin,
-Benno Fünfstück,
-Bjørn Forsman,
-Brian McKenna,
-Charles Strahan,
-Chase Adams,
-Chris Martin,
-Christian Theune,
-Chris Warburton,
-Daiderd Jordan,
-Dan Connolly,
-Daniel Peebles,
-Dan Peebles,
-davidak,
-David McFarland,
-Dmitry Kalinkin,
-Domen Kožar,
-Eelco Dolstra,
-Emery Hemingway,
-Eric Litak,
-Eric Wolf,
-Fabian Schmitthenner,
-Frederik Rietdijk,
-Gabriel Gonzalez,
-Giorgio Gallo,
-Graham Christensen,
-Guillaume Maudoux,
-Harmen,
-Iavael,
-James Broadhead,
-James Earl Douglas,
-Janus Troelsen,
-Jeremy Shaw,
-Joachim Schiele,
-Joe Hermaszewski,
-Joel Moberg,
-Johannes 'fish' Ziemke,
-Jörg Thalheim,
-Jude Taylor,
-kballou,
-Keshav Kini,
-Kjetil Orbekk,
-Langston Barrett,
-Linus Heckemann,
-Ludovic Courtès,
-Manav Rathi,
-Marc Scholten,
-Markus Hauck,
-Matt Audesse,
-Matthew Bauer,
-Matthias Beyer,
-Matthieu Coudron,
-N1X,
-Nathan Zadoks,
-Neil Mayhew,
-Nicolas B. Pierron,
-Niklas Hambüchen,
-Nikolay Amiantov,
-Ole Jørgen Brønner,
-Orivej Desh,
-Peter Simons,
-Peter Stuart,
-Pyry Jahkola,
-regnat,
-Renzo Carbonara,
-Rhys,
-Robert Vollmert,
-Scott Olson,
-Scott R. Parish,
-Sergei Trofimovich,
-Shea Levy,
-Sheena Artrip,
-Spencer Baugh,
-Stefan Junker,
-Susan Potter,
-Thomas Tuegel,
-Timothy Allen,
-Tristan Hume,
-Tuomas Tynkkynen,
-tv,
-Tyson Whitehead,
-Vladimír Čunát,
-Will Dietz,
-wmertens,
-Wout Mertens,
-zimbatm and
-Zoran Plesivčak.
-</para>
-
-</section>