go - 为什么 go build 会因为 regexp.MustCompile 解析错误而成功？

Question

go run 或 go test(编译然后运行)失败，但go build(仅编译)失败。我本以为 MustCompile 与编译有关，而不是运行时。

---

package main

import (
    "regexp"
)

var someInvalidRegex = regexp.MustCompile(`(?!`)

func main() {
    someInvalidRegex.MatchString("foo")
}

运行时失败:

$ go run main.go
panic: regexp: Compile(`(?!`): error parsing regexp: invalid or unsupported Perl syntax: `(?!`

goroutine 1 [running]:
regexp.MustCompile(0x10b7d19, 0x3, 0xc420022070)
    /usr/local/Cellar/go/1.10.3/libexec/src/regexp/regexp.go:240 +0x171
exit status 2

编译成功:

$ go build -o foo
$ echo $?
0

运行时再次失败:

$ ./foo
panic: regexp: Compile(`(?!`): error parsing regexp: invalid or unsupported Perl syntax: `(?!`

goroutine 1 [running]:
regexp.MustCompile(0x10b7d19, 0x3, 0xc420022070)
    /usr/local/Cellar/go/1.10.3/libexec/src/regexp/regexp.go:240 +0x171

Answer 1

编译器不会分析您的正则表达式。它是在运行时完成的。“MustCompile”函数名中的“Compile”部分代表正则表达式的编译。