From 686120ee4a34f658b2f19dcac9f9dc44dbc98b93 Mon Sep 17 00:00:00 2001 From: Jade Lovelace Date: Thu, 22 Aug 2024 17:07:14 -0700 Subject: fix: good errors for failures caused by allowSubstitutes This caused an absolute saga which I would not like anyone else to have to experience. Let's put in a laser targeted error message that diagnoses this exact problem. Fixes: https://git.lix.systems/lix-project/lix/issues/484 Change-Id: I2a79f04aeb4a1b67c10115e5e39501d958836298 --- doc/manual/rl-next/allowsubstitutes-errors.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 doc/manual/rl-next/allowsubstitutes-errors.md (limited to 'doc') diff --git a/doc/manual/rl-next/allowsubstitutes-errors.md b/doc/manual/rl-next/allowsubstitutes-errors.md new file mode 100644 index 000000000..47b0555b1 --- /dev/null +++ b/doc/manual/rl-next/allowsubstitutes-errors.md @@ -0,0 +1,21 @@ +--- +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. +``` -- cgit v1.2.3