From d8ef423a189b95f9f6e0a385a0f4474bebf297ef Mon Sep 17 00:00:00 2001 From: Ben Burdette Date: Mon, 9 Nov 2020 19:16:50 -0700 Subject: [PATCH] error message formatting --- src/libexpr/eval.cc | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 0446376f3..2b697882b 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -1366,29 +1366,30 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res) actualArgs->attrs->push_back(*j); } else if (!i.def) { throwUndefinedVarError(i.pos, R"(cannot auto-call a function that has an argument without a default value ('%1%') - An 'auto-call' is when a nix expression is evaluated without any external arguments. - If that nix expression is a function, and that function's arguments all have default - values, then all is well. - But if the function arguments don't have default values, evaluation fails. +An 'auto-call' is when a nix expression is evaluated without any external arguments. +If that nix expression is a function, and that function's arguments all have default +values, then all is well. - The classic case for this error is evaluating a nix file with nix-build that expects - to be evaluated by callPackage. - # in 'callPackage' format: expression is a function that takes an argument 'stdenv'. - # callPackage would implicitly pull 'stdenv' from nixpkgs, then call this function. - { stdenv }: - stdenv.mkDerivation { - ... +But if the function arguments don't have default values, evaluation fails. - # in 'auto-call' format: nixpkgs is imported explicitly, and used directly. - let - nixpkgs = import {}; - in - nixpkgs.stdenv.mkDerivation { - ... +The classic case for this error is evaluating a nix file with nix-build that expects +to be evaluated by callPackage. + # in 'callPackage' format: expression is a function that takes an argument 'stdenv'. + # callPackage would implicitly pull 'stdenv' from nixpkgs, then call this function. + { stdenv }: + stdenv.mkDerivation { + ... - See this nix pill for more information re callPackage format: - https://nixos.org/guides/nix-pills/callpackage-design-pattern.html)", i.name); + # in 'auto-call' format: nixpkgs is imported explicitly, and used directly. + let + nixpkgs = import {}; + in + nixpkgs.stdenv.mkDerivation { + ... + +More about callPackage: +https://nixos.org/guides/nix-pills/callpackage-design-pattern.html)", i.name); } } }