Now type checks the resulting function values and allows mkMerge and co.
Also indicates that the type check is done in the function body
Co-Authored-By: Robert Hensing <robert@roberthensing.nl>
This reverts commit 4ff1ab5a56.
We need this to type options like:
services.xserver.windowManager.xmonad.extraPackages that specify functions that
take an attribute set containing packages / plugins and return a list containing
a selection of the values in this set.
The reason we need a dedicated type for this is to have the correct merge
behaviour. Without the functionTo type merging multiple function option
definitions results in an evaluation error. The functionTo type merges
definitions by returning a new function that applies the functions of all the
definitions to the given input and merges the result.
(cherry picked from commit 7ed41ff5e7)
I think there was a silent (i.e. semantic) merge conflict between PR #101139 and
PR #100456. This commit should fix the error, which manifests as follows:
error: undefined variable 'boolToString' at /home/kkini/src/nixpkgs/lib/types.nix:552:42
Nix can perform static scope checking, but whenever code is inside
a `with` expression, the analysis breaks down, because it can't
know statically what's in the attribute set whose attributes were
brought into scope. In those cases, Nix has to assume that
everything works out.
Except it doesnt. Removing `with` from lib/ revealed an undefined
variable in an error message.
If that doesn't convince you that we're better off without `with`,
I can tell you that this PR results in a 3% evaluation performance
improvement because Nix can look up local variables by index.
This adds up with applications like the module system.
Furthermore, removing `with` makes the binding site of each
variable obvious, which helps with comprehension.
This new type has unsurprising merge behavior: Only attribute sets are
merged together (recursively), and only if they don't conflict.
This is in contrast to the existing types:
- types.attrs is problematic because later definitions completely
override attributes of earlier definitions, and it doesn't support
mkIf and co.
- types.unspecified is very similar to types.attrs, but it has smart
merging behavior that often doesn't make sense, and it doesn't support
all types
Previously the only way to deprecate a type was using
theType = lib.warn "deprecated" (mkOptionType ...)
This caused the warning to be emitted when the type was evaluated, but
the error didn't include which option actually used that type.
With this commit, types can specify a deprecationMessage, which when
non-null, is printed along with the option that uses the type
Submodules that have a freeform type set behave as if that was the type
of the option itself (for values that don't have an option). Since the
submodules options are shown as separate entries in the manual, it makes
sense to show the freeform type as the submodule type.
Not all modules use name attribute as the name of the submodule, for example,
environment.etc uses target. We will need to maintain a list of exceptions.
The standard attrsOf is strict in its *values*, meaning it's impossible to
access only one attribute value without evaluating all others as well.
lazyAttrsOf is a version that doesn't have that problem, at the expense
of conditional definitions not properly working anymore.
Previously when this function was called without a value coercible to a
string it would throw an error instead of returning false. Now it does.
As a result this now allows the use of a type like `either path attrs`
without it erroring out when a definition is an attribute set.
The warning about there not being a isPath primop was removed because
this is not the case anymore, there is builtins.isPath. But also there
always was `builtins.typeOf x == "path"` that could've been used
instead. However the path type now stands for more than just path types,
but absolute paths in general.
This reverts commit eec83d41e3.
This broke hydra evaluation because with this commit submodule values
are allowed to be paths, however the certmgr module uses `either
(submodule ...) path` in its type, meaning it already used paths for
something else which would now be interpreted as a submodule.
The explicit remove helped to uncover some hidden uses of `optionSet`
in NixOps. However it makes life harder for end-users of NixOps - it will
be impossible to deploy 19.03 systems with old NixOps, but there is no
new release of NixOps with `optionSet` fixes.
Also, "deprecation" process isn't well defined. Even that `optionSet` was
declared "deprecated" for many years, it was never announced. Hence, I
leave "deprecation" announce. Then, 3 releases after announce,
we can announce removal of this feature.
This type has to be removed, not `throw`-ed in runtime, because it makes
some perfectly fine code to fail. For example:
```
$ nix-instantiate --eval -E '(import <nixpkgs/lib>).types' --strict
trace: `types.list` is deprecated; use `types.listOf` instead
error: types.optionSet is deprecated; use types.submodule instead
(use '--show-trace' to show detailed location information)
```
