cmd/compile: nil pointer dereference for receivers has wrong line number

[dhowden]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?

go version go1.6.3 darwin/amd64

1. What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"

1. What did you do?

https://play.golang.org/p/qNwU6hT1YS

Force nil-pointer dereference on receiver in method. The nil-dereference is reported as happening on the method call - line 25 - rather than on the actual deference which is inside the method (line 12).

1. What did you expect to see?

0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0xffffffff addr=0x0 pc=0x20146]

goroutine 1 [running]:
panic(0x13f4a0, 0x1040a038)
/usr/local/go/src/runtime/panic.go:481 +0x700
main.main()
/tmp/sandbox599323765/main.go:12 +0xe6

1. What did you see instead?

0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0xffffffff addr=0x0 pc=0x20146]

goroutine 1 [running]:
panic(0x13f4a0, 0x1040a038)
/usr/local/go/src/runtime/panic.go:481 +0x700
main.main()
/tmp/sandbox599323765/main.go:25 +0xe6

[dominikh]

This is a duplicate of #10152 and caused by inlining.

[davecheney]

What happens if you disable inlining? -gcflags=-N

On Fri, 22 Jul 2016, 10:24 David Howden [email protected] wrote:

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?

go version go1.6.3 darwin/amd64

1. What operating system and processor architecture are you using (go
   env)?

GOARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"

1. What did you do?

https://play.golang.org/p/qNwU6hT1YS

Force nil-pointer dereference on receiver in method. The nil-dereference
is reported as happening on the method call - line 25 - rather than on the
actual deference which is inside the method (line 12).

1. What did you expect to see?

0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0xffffffff addr=0x0 pc=0x20146]

goroutine 1 [running]:
panic(0x13f4a0, 0x1040a038)
/usr/local/go/src/runtime/panic.go:481 +0x700
main.main()
/tmp/sandbox599323765/main.go:12 +0xe6

1. What did you see instead?

0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0xffffffff addr=0x0 pc=0x20146]

goroutine 1 [running]:
panic(0x13f4a0, 0x1040a038)
/usr/local/go/src/runtime/panic.go:481 +0x700
main.main()
/tmp/sandbox599323765/main.go:25 +0xe6

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[dhowden]

@davecheney Still incorrect with inlining disabled.

$ go build -gcflags=-N example.go
$ ./example
0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x231f]

goroutine 1 [running]:
panic(0xda980, 0xc82000a0f0)
    /usr/local/go/src/runtime/panic.go:481 +0x3e6
main.main()
    example.go:25 +0x26f

[dominikh]

-N does not disable inlining, -l does.

[dhowden]

Yeah, sorry. Just seen that too. With inlining disabled it shows the correct position.

$ go build -gcflags="-N -l" example.go
$ ./example
0
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x205d]

goroutine 1 [running]:
panic(0xda920, 0xc82000a0f0)
    /usr/local/go/src/runtime/panic.go:481 +0x3e6
main.(*Example).Value(0x0, 0x0)
    example.go:12 +0x1d
main.main()
    example.go:25 +0x12a

[davecheney]

My mistake, I thought -N was a superset of -l. Show's how much I've used
that flag.

On Fri, Jul 22, 2016 at 2:41 PM, Dominik Honnef [email protected]
wrote:

-N does not disable inlining, -l does.

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[quentinmit]

Closing as dupe of #10152, please comment if you think it's not.