2259 error message - "auto-call" error #4240
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bburdette
changed the title
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Some slight changes:
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I think very long error messages should be avoided since then we just end up duplicating the manual. The error message can also get out of date, for instance it talks about It's probably better to have a shorter message that links to the manual for more information (not Nix pills which are not an authoritative reference for Nix). |
src/libexpr/eval.cc
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| throwTypeError("cannot auto-call a function that has an argument without a default value ('%1%')", i.name); | ||
| throwUndefinedVarError(i.pos, R"(cannot auto-call a function that has an argument without a default value ('%1%') | ||
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| An 'auto-call' is when a nix expression is evaluated without any external arguments. |
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This is not correct. An auto-call is when a top-level function is called with external arguments or with default values if no matching argument is provided.
It's probably better to say something like `you need to pass "--arg %1% ...' or '--argstr %1% ...'".
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UndefinedVarError is probably misleading. There is no undefined variable, just a missing argument.
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Thanks for the feedback!
Here's the result:
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Thanks for the merge! |
The PR #4240 changed messag of the error that was thrown when an auto-called function was missing an argument. However this change also changed the type of the error, from `EvalError` to a new `MissingArgumentError`. This broke hydra which was relying on an `EvalError` being thrown. Make `MissingArgumentError` a subclass of `EvalError` to un-break hydra.
revised this "auto-call" error which I've found to be somewhat inscrutable in the past. This is intended to address (in part) issue #2259.
Current output is like this:
Revised error output is like so:
This reflect my perhaps imperfect understanding of autoCall, feedback on that is welcome.