1. This makes aggregates of submodules (including the very important
"nixos-option users.users.<username>" case) behave the same way as any
other you-need-to-keep-typing-to-get-to-an-option-leaf (eg:
"nixos-option environment").
Before e0780c5:
$ nixos-option users.users.root
error: At 'root' in path 'users.users.root': Attribute not found
An error occurred while looking for attribute names. Are you sure that 'users.users.root' exists?
After e0780c5 but before this change, this query just printed out a raw
thing, which is behavior that belongs in "nix eval", "nix-instantiate
--eval", or "nix repl <<<":
$ nixos-option users.users.root
{
_module = {
args = { name = "root"; };
check = true;
};
createHome = false;
cryptHomeLuks = null;
description = "System administrator";
...
After this change:
$ nixos-option users.users.root
This attribute set contains:
createHome
cryptHomeLuks
description
extraGroups
group
hashedPassword
...
2. For aggregates of other types (not submodules), print out the option
that contains them rather than printing an error message.
Before:
$ nixos-option environment.shellAliases.l
error: At 'l' in path 'environment.shellAliases.l': Attribute not found
An error occurred while looking for attribute names. Are you sure that 'environment.shellAliases.l' exists?
After:
$ nixos-option environment.shellAliases.l
Note: showing environment.shellAliases instead of environment.shellAliases.l
Value:
{
l = "ls -alh";
ll = "ls -l";
ls = "ls --color=tty";
}
...
When running e.g. `nixos-option users.users.ma27`, the evaluation breaks
since `ma27` is the attribute name in `attrsOf (submodule {})`, but not
a part of the option tree and therefore breaks with the following
errors:
```
error: At 'ma27' in path 'users.users.ma27': Attribute not found
An error occurred while looking for attribute names. Are you sure that 'users.users.ma27' exists?
```
This happens since the option evaluator expects that either the option
exists or the option is a submodule and the "next" token in the
attribute path points to an option (e.g. `users.users.ma27.createHome`).
This patch checks in the `Attribute not found` condition if the attribute-path
actually exists in the config tree. If that's true, a dummy-attrset is created
which contains `{_type = "__nixos-option-submodule-attr";}`, in that case, the
entire entry of the submodule will be displayed.
Automated consumers can use 'sed 1d' or similar to remove this header.
This probably makes this output *easier* to consume correctly. Having
this header show up in consumers' terminal or log output is probably not
useful, but hiding it without hiding all error messages would have been
more troublesome that just stripping it from stdout.
I.e., previously, unsophisticated use would show undesired output:
$ some-other-tool
This attribute set contains:
This attribute set contains:
This attribute set contains:
This attribute set contains:
<Actual some-other-tool output>
The simplest way to hide this undesired output would have been
nixos-option ... 2>/dev/null, which would hide all error messages.
We do not wish to encourage that.
Correct use would have been something like:
nixos-option ... 2> >( grep --line-buffered -v 'This attribute set contains:')
After this change, correct use is simpler:
nixos-option ... | sed 1d
or
nixos-option ... | sed '1/This attribute set contains:/d'
if the caller don't know if this invocation of nixos-option will yield
an attribute listing or an option description.
Switch from convention "appease clang-tidy --checks='*'" to
"References are like non-nullptr pointers". The clang-tidy check
"google-runtime-references" complains about non-const reference
arguments, but this is not a convention used in Nix.
Switch from convention "appease clang-tidy --checks='*'" to
"References are like non-nullptr pointers". The clang-tidy check
"google-runtime-references" complains about non-const reference
arguments, but this is not a convention used in Nix.
Switch from convention "appease clang-tidy --checks='*'" to
"References are like non-nullptr pointers". The clang-tidy check
"google-runtime-references" complains about non-const reference
arguments, but this is not a convention used in Nix.
I don't think this matters. As long as one or the other of these is
a std::string, I get an operator== that looks at content rather than
pointer equality. I picked casting the constant over casting the dynamic
thing in hopes that the compiler would have a better chance at optimizing
away any runtime cost.
Deferring to reviewer.
This is important because this contains some code copied from nix (as an
interim expediency until that functionality can be exported via nix's
API). The license specified here must be compatible with this borrowing.
Select the same license that nix is released under: lgpl2Plus.
Specifically, with
clang-format --style='{ IndentWidth: 4, BreakBeforeBraces: Mozilla, ColumnLimit: 120, PointerAlignment: Middle }'
which was the clang-format invocation that produced the fewest diffs on
the nix source out of ~20 that I tried.
Also add --all, which shows the value of all options. Diffing the --all
output on either side of contemplated changes is a lovely way to better
understand what's going on inside nixos.
