swiftlang/swift

[SR-4716] Better diagnostics for multifile executable without a main.swift file

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#47,293 创建于 2017年4月27日

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 (5 评论) (0 反应) (0 负责人)Swift (69,989 star) (10,719 fork)batch import
compilerdiagnostics qualitygood first issueimprovementlegacy driver

描述
Previous ID SR-4716
Radar None
Original Reporter @huonw
Type Improvement
Status In Progress
Resolution
Votes 0
Component/s Compiler
Labels Improvement, DiagnosticsQoI, Driver, StarterBug
Assignee None
Priority Medium

md5: 107a386ff1ef4614f95e66bc776c43f4

Issue Description:

$ touch file1.swift file2.swift
$ swiftc file1.swift file2.swift
Undefined symbols for architecture x86_64:
  "_main", referenced from:
     implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
<unknown>:0: error: link command failed with exit code 1 (use -v to see invocation)

The problem here is neither file is called main.swift, so the top-level-code `main` function doesn't get emitted. The compiler should check the file names and emit an error rather than going all the way through compilation to hit the link error.

贡献者指南

技术栈
swift
领域
developer experiencetooling
议题类型
feature
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
half day
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Swift compiler driver knowledgeFamiliarity with file name detection in compilation pipeline
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
50
研究方向
Investigate the Swift compiler driver code, specifically where it determines whether to emit the top level code entry point. The issue suggests adding a check for file names (e.g., main.swift) before the linking step to emit a clear diagnostic. Look for the driver's handling of multiple source files and the condition that checks for a main.swift file. The fix likely involves modifying the driver to produce an error when no main.swift is present among the input files.