go compile_error ai_generated true

append(s, x) 已求值但未使用

append(s, x) evaluated but not used

ID: go/append-to-slice-without-assignment

其他格式: JSON · Markdown 中文 · English
95%修复率
90%置信度
1证据数
2023-02-28首次发现

版本兼容性

版本状态引入弃用备注
Go 1.20 active — — —
Go 1.21 active — — —
Go 1.22 active — — —

根因分析

append() 函数返回一个新切片；忽略返回值会丢弃结果，原始切片保持不变，导致编译时错误。

English

The append() function returns a new slice; ignoring the return value discards the result and the original slice remains unchanged, leading to a compile-time error.

generic

官方文档

https://go.dev/ref/spec#Appending_and_copying_slices

解决方案

  1. Assign the result of append back to the slice: s = append(s, x). Ensure s is used later in the code.
  2. If you want to modify the slice in place, use copy or index assignment instead: s = append(s[:len(s):len(s)], x) to extend capacity.
  3. Use a pointer to the slice if you need to modify it inside a function: func foo(s *[]int) { *s = append(*s, x) }

无效尝试

常见但无效的做法:

  1. 70% 失败

    The error 'evaluated but not used' will still occur because s is not used after assignment.

  2. 90% 失败

    The same compile-time error occurs regardless of goroutine; append still returns an unused value.

  3. 50% 失败

    This compiles but discards the result, which is likely a logic bug; the original slice s remains unchanged.