Usually this just writes to stdout, but for ProgressBar, we need to
clear the current line, write the line to stdout, and then redraw the
progress bar.
Previously the memory would occasionally be collected during eval since
the GC doesn't consider the member variable as alive / doesn't scan the
region of memory where the pointer lives.
By using the traceable_allocator<T> allocator provided by Boehm GC we
can ensure the memory isn't collected. It should be properly freed when
SourceExprCommand goes out of scope.
Future editions of flakes or the Nix language can be supported by
renaming flake.nix (e.g. flake-v2.nix). This avoids a bootstrap
problem where we don't know which grammar to use to parse
flake*.nix. It also allows a project to support multiple flake
editions, in theory.
This provides a pluggable mechanism for defining new fetchers. It adds
a builtin function 'fetchTree' that generalizes existing fetchers like
'fetchGit', 'fetchMercurial' and 'fetchTarball'. 'fetchTree' takes a
set of attributes, e.g.
fetchTree {
type = "git";
url = "https://example.org/repo.git";
ref = "some-branch";
rev = "abcdef...";
}
The existing fetchers are just wrappers around this. Note that the
input attributes to fetchTree are the same as flake input
specifications and flake lock file entries.
All fetchers share a common cache stored in
~/.cache/nix/fetcher-cache-v1.sqlite. This replaces the ad hoc caching
mechanisms in fetchGit and download.cc (e.g. ~/.cache/nix/{tarballs,git-revs*}).
This also adds support for Git worktrees (c169ea5904).
This is useful for finding out what a registry lookup resolves to, e.g
$ nix flake info patchelf
Resolved URL: github:NixOS/patchelf
Locked URL: github:NixOS/patchelf/cd7955af31698c571c30b7a0f78e59fd624d0229
One application for this is pinning the 'nixpkgs' flake to the exact
revision used to build the NixOS system, e.g.
{
"flakes": [
{
"from": {
"id": "nixpkgs",
"type": "indirect"
},
"to": {
"owner": "NixOS",
"repo": "nixpkgs",
"type": "github",
"rev": "b0c285807d6a9f1b7562ec417c24fa1a30ecc31a"
}
}
],
"version": 2
}
Note: like 'nix run', and unlike 'nix-shell', this takes an argv
vector rather than a shell command. So
nix dev-shell -c 'echo $PATH'
doesn't work. Instead you need to do
nix dev-shell -c bash -c 'echo $PATH'
This copies a flake and all its inputs recursively to a store (e.g. a
binary cache). This is intended to enable long-term reproducibility
for flakes. However this will also require #3253.
Example:
$ nix flake archive --json --to file:///tmp/my-cache nixops
{"path":"/nix/store/272igzkgl1gdzmabsjvb2kb2zqbphb3p-source","inputs":{"nixops-aws":{"path":"/nix/store/ybcykw13gr7iq1pzg18iyibbcv8k9q1v-source","inputs":{}},"nixops-hetzner":{"path":"/nix/store/6yn0205x3nz55w8ms3335p2841javz2d-source","inputs":{}},"nixpkgs":{"path":"/nix/store/li3lkr2ajrzphqqz3jj2avndnyd3i5lc-source","inputs":{}}}}
$ ll /tmp/my-cache
total 16
-rw-r--r-- 1 eelco users 403 Jan 30 01:01 272igzkgl1gdzmabsjvb2kb2zqbphb3p.narinfo
-rw-r--r-- 1 eelco users 403 Jan 30 01:01 6yn0205x3nz55w8ms3335p2841javz2d.narinfo
-rw-r--r-- 1 eelco users 408 Jan 30 01:01 li3lkr2ajrzphqqz3jj2avndnyd3i5lc.narinfo
drwxr-xr-x 2 eelco users 6 Jan 30 01:01 nar
-rw-r--r-- 1 eelco users 21 Jan 30 01:01 nix-cache-info
-rw-r--r-- 1 eelco users 404 Jan 30 01:01 ybcykw13gr7iq1pzg18iyibbcv8k9q1v.narinfo
Fixes#3336.
Typical usage:
$ nix flake update ~/Misc/eelco-configurations/hagbard --update-input nixpkgs
to update the 'nixpkgs' input of a flake while leaving every other
input unchanged.
The argument is an input path, so you can do e.g. '--update-input
dwarffs/nixpkgs' to update an input of an input.
Fixes#2928.
Added a flag --no-update-lock-file to barf if the lock file needs any
changes. This is useful for CI systems if you're building a
checkout. Fixes#2947.
Renamed --no-save-lock-file to --no-write-lock-file. It is now a fatal
error if the lock file needs changes but --no-write-lock-file is not
given.
E.g.
$ nix flake update ~/Misc/eelco-configurations/hagbard \
--override-input 'dwarffs/nixpkgs' ../my-nixpkgs
overrides the 'nixpkgs' input of the 'dwarffs' input of the top-level
flake.
Fixes#2837.
Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.
Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.
Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
