From 762273f1fd48b2b2f2bbedca65abfd4c07b5af05 Mon Sep 17 00:00:00 2001 From: Matthew Bauer Date: Tue, 9 Jun 2020 01:23:37 -0500 Subject: [PATCH] Allow empty hash in derivations follow up of https://github.com/NixOS/nix/pull/3544 This allows hash="" so that it can be used for debugging purposes. For instance, this gives you an error message like: warning: found empty hash, assuming you wanted 'sha256:0000000000000000000000000000000000000000000000000000' hash mismatch in fixed-output derivation '/nix/store/asx6qw1r1xk6iak6y6jph4n58h4hdmbm-nix': wanted: sha256:0000000000000000000000000000000000000000000000000000 got: sha256:0fpfhipl9v1mfzw2ffmxiyyzqwlkvww22bh9wcy4qrfslb4jm429 --- src/libexpr/primops.cc | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index d458ab272..de04fd2be 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -719,7 +719,13 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * * throw Error(format("multiple outputs are not supported in fixed-output derivations, at %1%") % posDrvName); HashType ht = outputHashAlgo.empty() ? htUnknown : parseHashType(outputHashAlgo); - Hash h(*outputHash, ht); + + Hash h; + if (outputHash->empty()) { + h = Hash(ht); + printError("warning: found empty hash, assuming you wanted '%s'", h.to_string()); + } else + h = Hash(*outputHash, ht); auto outPath = state.store->makeFixedOutputPath(ingestionMethod, h, drvName); if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);