@philiptaron's lix workspace
Find a file
Maximilian Bosch 98946e2d9c
nix-shell: restore backwards-compat with old nixpkgs
Basically an attempt to resume fixing #5543 for a breakage introduced
earlier[1]. Basically, when evaluating an older `nixpkgs` with
`nix-shell` the following error occurs:

    λ ma27 [~] → nix-shell -I nixpkgs=channel:nixos-18.03 -p nix
    error: anonymous function at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/default.nix:20:1 called with unexpected argument 'inNixShell'

           at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/impure.nix:82:1:

               81|
               82| import ./. (builtins.removeAttrs args [ "system" "platform" ] // {
                 | ^
               83|   inherit config overlays crossSystem;

This is a problem because one of the main selling points of Nix is that
you can evaluate any old Nix expression and still get the same result
(which also means that it *still evaluates*). In fact we're deprecating,
but not removing a lot of stuff for that reason such as unquoted URLs[2]
or `builtins.toPath`. However this property was essentially thrown away
here.

The change is rather simple: check if `inNixShell` is specified in the
formals of an auto-called function. This means that

    { inNixShell ? false }:
    builtins.trace inNixShell
      (with import <nixpkgs> { }; makeShell { name = "foo"; })

will show `trace: true` while

    args@{ ... }:
    builtins.trace args.inNixShell
      (with import <nixpkgs> { }; makeShell { name = "foo"; })

will throw the following error:

    error: attribute 'inNixShell' missing

This is explicitly needed because the function in
`pkgs/top-level/impure.nix` of e.g. NixOS 18.03 has an ellipsis[3], but
passes the attribute-set on to another lambda with formals that doesn't
have an ellipsis anymore (hence the error from above). This was perhaps
a mistake, but we can't fix it anymore. This also means that there's
AFAICS no proper way to check if the attr-set that's passed to the Nix
code via `EvalState::autoCallFunction` is eventually passed to a lambda
with formals where `inNixShell` is missing.

However, this fix comes with a certain price. Essentially every
`shell.nix` that assumes `inNixShell` to be passed to the formals even
without explicitly specifying it would break with this[4]. However I think
that this is ugly, but preferable:

* Nix 2.3 was declared stable by NixOS up until recently (well, it still
  is as long as 21.11 is alive), so most people might not have even
  noticed that feature.

* We're talking about a way shorter time-span with this change being
  in the wild, so the fallout should be smaller IMHO.

[1] 9d612c393a
[2] https://github.com/NixOS/rfcs/pull/45#issuecomment-488232537
[3] https://github.com/NixOS/nixpkgs/blob/release-18.03/pkgs/top-level/impure.nix#L75
[4] See e.g. the second expression in this commit-message or the changes
    for `tests/ca/nix-shell.sh`.
2022-06-13 23:29:28 +02:00
.github Correctly get the nix version in the docker job 2022-06-10 12:09:09 +02:00
config Run autoupdate 2021-06-01 11:42:38 +02:00
contrib function-trace: always show the trace 2019-09-18 23:23:21 +02:00
doc/manual Merge branch 'master' into lto 2022-06-01 17:55:03 +02:00
m4 autoconf: Fix C++17 detection not working on Ubuntu 16.04. 2019-07-03 04:32:25 +02:00
maintainers Integrate push-docker.sh into the release script 2022-02-18 13:58:01 +01:00
misc nix-daemon.service: sync LimitNOFILE with the nixos service 2022-05-19 21:16:07 +03:00
mk enable LTO in optimized builds 2022-03-03 17:47:49 +01:00
perl Remove std::string alias (for real this time) 2022-02-25 16:13:02 +01:00
scripts darwin-install: work around existing vim swapfiles 2022-06-01 09:41:00 -05:00
src nix-shell: restore backwards-compat with old nixpkgs 2022-06-13 23:29:28 +02:00
tests nix-shell: restore backwards-compat with old nixpkgs 2022-06-13 23:29:28 +02:00
.dir-locals.el .dir-locals.el: Set c-block-comment-prefix 2020-07-10 11:21:06 +02:00
.editorconfig Add .editorconfig 2017-06-05 22:57:28 +01:00
.gitignore Add unit tests for libexpr (#5377) 2022-05-06 18:05:27 +02:00
.version Bump version 2022-05-30 21:11:20 +02:00
boehmgc-coroutine-sp-fallback.diff Fix leaking pthread_attr_t 2021-11-03 22:54:16 +01:00
bootstrap.sh bootstrap: Simplify & make more robust. 2011-09-06 12:11:05 +00:00
configure.ac Merge branch 'master' into lto 2022-05-25 11:55:13 +00:00
COPYING * Change this to LGPL to keep the government happy. 2006-04-25 16:41:06 +00:00
default.nix Remove url literals 2022-01-24 13:28:21 +01:00
docker.nix feat: include openssh in docker image 2022-04-14 13:49:47 +01:00
flake.lock flake: update to 22.05 2022-05-31 11:51:17 -07:00
flake.nix Merge pull request #6630 from edolstra/boost-dylib 2022-06-08 17:55:21 +02:00
local.mk Remove 'dist' target 2020-12-03 16:17:58 +01:00
Makefile Merge branch 'master' into lto 2022-05-25 11:55:13 +00:00
Makefile.config.in enable LTO in optimized builds 2022-03-03 17:47:49 +01:00
precompiled-headers.h Config: Use nlohmann/json 2020-08-20 11:02:16 +02:00
README.md throw freenode down the memory hole 2021-05-27 21:48:39 +02:00
shell.nix Remove url literals 2022-01-24 13:28:21 +01:00

Nix

Open Collective supporters Test

Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. Please refer to the Nix manual for more details.

Installation

On Linux and macOS the easiest way to install Nix is to run the following shell command (as a user other than root):

$ curl -L https://nixos.org/nix/install | sh

Information on additional installation methods is available on the Nix download page.

Building And Developing

See our Hacking guide in our manual for instruction on how to build nix from source with nix-build or how to get a development environment.

Additional Resources

License

Nix is released under the LGPL v2.1.