flag/flag.go panic: runtime error: index out of range [0] with length 0

[develerltd]

panic: runtime error: index out of range [0] with length 0
goroutine 1 [running]:
flag.init()
/usr/local/go/src/flag/flag.go:1199 +0xfc

go/src/flag/flag.go

Line 1199 in 6d89b38

var CommandLine = NewFlagSet(os.Args[0], ExitOnError)

len(os.Args) > 1 is not always true, at least in Linux and macOS. If you compile a go program and then write a C program to exec it with execl("/path/to/exec", NULL), it will have no arguments at all, not even the executable name

[seankhliao]

This seems like an appropriate panic, the environment violates a fundamental part of what flag needs to work.

[develerltd]

This seems like an appropriate panic, the environment violates a fundamental part of what flag needs to work.

but this is at package level, so its unavoidable? so any package that imports "flag" will crash if the executable is ran like in my example?

that's not an appropriate panic

[gopherbot]

Change https://go.dev/cl/597075 mentions this issue: flag: handle nil os.Args when setting CommandLine at package level Fixes #68340

[gabyhelp]

Related Issues and Documentation

• flag: index out of range when argc is 0 #32775 (closed)
• cmd/link: panic with empty or short -B argument #14636 (closed)
• flag panics on empty os.Args #16812 (closed)

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