[FEAT]: Introduce new error message for packages without `mainProgram` · NixOS/nix#15138

(1 评论) (0 反应) (0 负责人)C++ (9,803 star) (1,293 fork)batch import

error-messagesfeaturegood first issuenew-cli

描述

Is your feature request related to a problem?

Some packages have multiple binaries with different purposes therefore setting mainProgram is not desirable.

When mainProgram is not set for these packages nix run errors out with

error: unable to execute '/nix/store/abc/bin/xyz': No such file or directory

Proposed solution

A new error for packages that don't have the mainProgram attribute set, something like

error: in 'abc': 'mainProgram' isn't set

Alternative solutions

An option to set mainProgram to null for packages that desire to do so, leaving the default behavior of mainProgram = pname; intact. An error like

error: 'abc' doesn't have a default binary

would be better in this case.

Additional context

https://github.com/NixOS/nixpkgs/issues/486543

Checklist

checked latest Nix manual (source)
checked open feature issues and pull requests for possible duplicates

Add :+1: to issues you find important.

贡献者指南

技术栈: cpp
领域: cli
议题类型: feature
难度: 3
预计时间: 1-3 hours
活动状态: fresh
清晰度: mostly clear
前置要求: Basic understanding of NixFamiliarity with Nix error handling
新手友好度: 60
研究方向: Investigate where the error 'unable to execute ... No such file or directory' is produced (likely in src/libstore or src/libexpr). Look for how mainProgram is handled in drv evaluation. The goal is to add a check before that error is thrown when mainProgram is not set, emitting a clearer message like 'mainProgram isn't set'. Refer to the linked issue https://github.com/NixOS/nixpkgs/issues/486543 for context. The implementation may involve modifying the Nix expression evaluator or the build execution code path.