This is to avoid stealing keys from submodules. `class` might be
common enough that reinterpreting existing `class` attributes in
configurations as a declaration leads to fairly widespread problems.
This is appears to be a fairly common mistake for beginners who want
to build larger things from the system configurations, such as NixOps
networks, etc. Further explanation seems appropriate.
The supposedly public nature of these functions has been holding
back module system maintenance, while usages of these functions
are expected to be rare. If used anywhere, presumably they're
emulating module system behavior because some use case isn't supported
properly. We should try to support such a use case directly, if it
even exists.
Previously, there was no way to unset an option when overriding a
kernel, apart from writing out the attrset yourself. Now it's
possible with lib.mkForce lib.kernel.unset. It's important to be able
to do this, because setting an option in the override may cause other
options to become unused, which would fail the config build unless
they were overridden too.
ofborg relies on the behavior that existed prior to
1c00bf3948, where evaluation would
immediately abort due to a missing argument (whether it be an aliased
package when `allowAliases = false;` or a typo'd or otherwise
nonexistent package).
If `callPackageWith` `throw`s instead of `abort`s, the following
`nix-env` invocation does not fail fast but instead silently skips the
attribute (assuming there is a package that has an aliased package in
its `autoArgs`):
$ nix-env -qa --json --file . --arg config '{ allowAliases = false; }' &>/dev/null
$ echo $?
0
This does change the error output when there is a missing package (for
any of the reasons mentioned above), though. Before this change, the
errors looked like this:
$ nix-build -A hello --arg config '{ allowAliases = false; }'
error:
… while calling the 'throw' builtin
at /home/vin/workspace/vcs/nixpkgs/master/lib/customisation.nix:179:65:
178|
179| in if missingArgs == [] then makeOverridable f allArgs else throw error;
| ^
180|
error: Function called without required argument "bash_5" at /home/vin/workspace/vcs/nixpkgs/master/pkgs/applications/misc/hello/default.nix:8, did you mean "bash" or "bashdb"?
And the errors now look like this:
$ nix-build -A hello --arg config '{ allowAliases = false; }'
error:
… while calling the 'abort' builtin
at /home/vin/workspace/vcs/nixpkgs/master/lib/customisation.nix:179:65:
178|
179| in if missingArgs == [] then makeOverridable f allArgs else abort error;
| ^
180|
error: evaluation aborted with the following error message: 'Function called without required argument "bash_5" at /home/vin/workspace/vcs/nixpkgs/master/pkgs/applications/misc/hello/default.nix:8, did you mean "bash" or "bashdb"?'
TimescaleDB provides two types of licenses, Apache 2.0 and Timescale Community License (TSL), with different feature sets. While all the code is in the same repository, the build
system can build both versions depending on the build parameters set in.
Co-authored-by: Emily Lange <git@indeednotjames.com>
lib.{hasPrefix,hasInfix,hasSuffix} would otherwise return an
always-false result, which can be very unexpected:
nix-repl> lib.strings.hasPrefix ./lib ./lib/meta.nix
false
