forked from lix-project/lix
22 lines
1.2 KiB
Markdown
22 lines
1.2 KiB
Markdown
|
---
|
||
|
|
synopsis: "Build failures caused by `allowSubstitutes = false` while being the wrong system now produce a decent error"
|
||
|
|
issues: [fj#484]
|
||
|
|
cls: [1841]
|
||
|
|
category: Fixes
|
||
|
|
credits: jade
|
||
|
|
---
|
||
|
|
|
||
|
|
Nix allows derivations to set `allowSubstitutes = false` in order to force them to be built locally without querying substituters for them.
|
||
|
|
This is useful for derivations that are very fast to build (especially if they produce large output).
|
||
|
|
However, this can shoot you in the foot if the derivation *has* to be substituted such as if the derivation is for another architecture, which is what `--always-allow-substitutes` is for.
|
||
|
|
|
||
|
|
Perhaps such derivations that are known to be impossible to build locally should ignore `allowSubstitutes` (irrespective of remote builders) in the future, but this at least reports the failure and solution directly.
|
||
|
|
|
||
|
|
```
|
||
|
|
$ nix build -f fail.nix
|
||
|
|
error: a 'unicornsandrainbows-linux' with features {} is required to build '/nix/store/...-meow.drv', but I am a 'x86_64-linux' with features {...}
|
||
|
|
|
||
|
|
Hint: the failing derivation has allowSubstitutes set to false, forcing it to be built rather than substituted.
|
||
|
|
Passing --always-allow-substitutes to force substitution may resolve this failure if the path is available in a substituter.
|
||
|
|
```
|