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lib.derivations: remove throwIfNot usage

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throwIfNot sends our error message through a function call, even if the
error condition doesn't trigger. This requires a lot of thunk allocation
that can be easily avoided.
This commit is contained in:
Eman Resu 2026-05-26 13:37:09 -04:00
commit 079b1a7d07
1 changed files with 13 additions and 13 deletions
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26
lib/derivations.nix
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@ -6,7 +6,6 @@ let
isString
mapAttrs
removeAttrs
throwIfNot
;
showMaybeAttrPosPre =
@ -108,18 +107,18 @@ in
# attrset spine returned by lazyDerivation does not depend on it.
# Instead, the individual derivation attributes do depend on it.
checked =
throwIfNot (derivation.type or null == "derivation") "lazyDerivation: input must be a derivation."
throwIfNot
# NOTE: Technically we could require our outputs to be a subset of the
# actual ones, or even leave them unchecked and fail on a lazy basis.
# However, consider the case where an output is added in the underlying
# derivation, such as dev. lazyDerivation would remove it and cause it
# to fail as a buildInputs item, without any indication as to what
# happened. Hence the more stringent condition. We could consider
# adding a flag to control this behavior if there's a valid case for it,
# but the documentation must have a note like this.
(derivation.outputs == outputs)
''
if derivation.type or null != "derivation" then
throw "lazyDerivation: input must be a derivation."
# NOTE: Technically we could require our outputs to be a subset of the
# actual ones, or even leave them unchecked and fail on a lazy basis.
# However, consider the case where an output is added in the underlying
# derivation, such as dev. lazyDerivation would remove it and cause it
# to fail as a buildInputs item, without any indication as to what
# happened. Hence the more stringent condition. We could consider
# adding a flag to control this behavior if there's a valid case for it,
# but the documentation must have a note like this.
else if derivation.outputs != outputs then
throw ''
lib.lazyDerivation: The derivation ${derivation.name or "<unknown>"} has outputs that don't match the assumed outputs.
Assumed outputs passed to lazyDerivation${showMaybeAttrPosPre ",\n at " "outputs" args}:
@ -142,6 +141,7 @@ in
If none of the above works for you, replace the lib.lazyDerivation call by the
expression in the derivation argument.
''
else
derivation;
in
{