runtime: confusing stack trace in case of deferring <nil> function #15466
Comments
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Here is the function for the stack trace above: |
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Thanks for your error report. Can you please tell us the version of Go you On Wed, 27 Apr 2016, 19:15 Alexey Nezhdanov, notifications@github.com
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The play.golang.org (used to create this thread) reports version "go1.6.2". |
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Thank you. I've confirmed that with 093ac15 the backtrace message also On Wed, Apr 27, 2016 at 8:58 PM, Alexey Nezhdanov notifications@github.com
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ianlancetaylor
changed the title
Deferring a nil function pointer produces a stack trace that does not mention the deferred function. This could be quite time-consuming to debug in case of, say, this use case:
cancel, err := Open(ctx)
if err!=nil {
log.Error(err)
// note that I forgot to put 'return' in here
}
defer cancel()
// many lines of code here
return nil
The snippet above will generate a panic() pointing to the 'return nil' line as the last line of user code.
Perhaps the error message could be improved.
Example: https://play.golang.org/p/jx3SBaSNlt
Current stack trace:
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0xffffffff addr=0x0 pc=0x93074]
goroutine 1 [running]:
panic(0x13f3e0, 0x1040a038)
/usr/local/go/src/runtime/panic.go:481 +0x700
main.a(0xfef70018, 0x1040a120)
/tmp/sandbox234618258/main.go:11 +0xfb
main.main()
/tmp/sandbox234618258/main.go:15 +0x20
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