cmd/compile: declaring non-callable append then attempting to call crashes gc

[Xjs]

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

go version go1.11 windows/amd64 (also occurs under Linux or on the playground)

Does this issue reproduce with the latest release?

Yes

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

GOHOSTARCH=amd64
GOHOSTOS=windows

(also happens on playground)

What did you do?

MWE:

package main

func main() {
	var append bool
	append()
}

https://play.golang.org/p/Z36gAU5mgUY

What did you expect to see?

prog.go:5:9: cannot call non-function append (type bool)

What did you see instead?

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x70 pc=0xb7c7ee]

goroutine 1 [running]:
cmd/compile/internal/gc.typecheck1(0xc00032c180, 0x1, 0xc00032c080)
	/usr/local/go/src/cmd/compile/internal/gc/typecheck.go:1270 +0x3ece
cmd/compile/internal/gc.typecheck(0xc00032c180, 0x1, 0xc00032c080)
	/usr/local/go/src/cmd/compile/internal/gc/typecheck.go:238 +0x6ad
cmd/compile/internal/gc.typecheckslice(0xc0003201c0, 0x3, 0x4, 0x1)
	/usr/local/go/src/cmd/compile/internal/gc/typecheck.go:68 +0x50
cmd/compile/internal/gc.Main(0xcc2180)
	/usr/local/go/src/cmd/compile/internal/gc/main.go:518 +0x2059
main.main()
	/usr/local/go/src/cmd/compile/main.go:51 +0x96

Spotted by @Weiss91

[agnivade]

Fixed on tip. Also backported to 1.11.1

[Xjs]

@agnivade Still occurs on play.golang.org (as of now, see
https://play.golang.org/p/Z36gAU5mgUY), 1.11.1/windows, 1.11.1/linux. So not sure about that backport.

[Xjs]

Just checked with current master, still crashes. Please reopen.

PS C:\Users\jannis.schnitzer\src\stuff\panic-typecheck> cat .\main.go
package main

func main() {
        var append bool
        append()
}
PS C:\Users\jannis.schnitzer\src\stuff\panic-typecheck> C:\Users\jannis.schnitzer\src\go.googlesource.com\go\bin\go.exe build
# stuff/panic-typecheck
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x70 pc=0xb952c5]

goroutine 1 [running]:
cmd/compile/internal/gc.typecheck1(0xc000340200, 0x1, 0xc000340100)
        c:/go/src/cmd/compile/internal/gc/typecheck.go:1270 +0x3ed5
cmd/compile/internal/gc.typecheck(0xc000340200, 0x1, 0xc000340100)
        c:/go/src/cmd/compile/internal/gc/typecheck.go:238 +0x6b4
cmd/compile/internal/gc.typecheckslice(0xc00032a660, 0x3, 0x4, 0x1)
        c:/go/src/cmd/compile/internal/gc/typecheck.go:68 +0x57
cmd/compile/internal/gc.Main(0xcdfc60)
        c:/go/src/cmd/compile/internal/gc/main.go:518 +0x20d0
main.main()
        c:/go/src/cmd/compile/main.go:51 +0x9d
PS C:\Users\jannis.schnitzer\src\stuff\panic-typecheck> C:\Users\jannis.schnitzer\src\go.googlesource.com\go\bin\go.exe version
go version devel +93e27e01af Mon Oct 15 14:51:30 2018 +0000 windows/amd64
PS C:\Users\jannis.schnitzer\src\stuff\panic-typecheck>

[agnivade]

I cannot reproduce. Possibly a windows issue ?

21:33:16-agniva-~/play/go/src$gotip run append.go 
# command-line-arguments
./append.go:5:9: cannot call non-function append (type bool)
21:35:35-agniva-~/play/go/src$gotip version
go version devel +296b7aeae0 Mon Oct 15 16:01:56 2018 +0000 linux/amd64
21:35:37-agniva-~/play/go/src$cat append.go 
package main

func main() {
  var append bool
  append()
}

@griesemer

[griesemer]

I cannot reproduce this either. Also, @Xjs I don't quite believe you're running current master: Your stack dump indicates a crash at c:/go/src/cmd/compile/internal/gc/typecheck.go:1270 which is the middle of a comment. Can you please update (and make sure you're using the newest compiler) and try again, thanks.

[Xjs]

@griesemer Indeed, the go tool seems not to have called the freshly-built compile.exe. Can confirm that this error doesn't occur in tip on Windows anymore. Sorry for the confusion. (Can also confirm that 1.11.1's compile.exe does produce this error, though.)

[agnivade]

Reason why it didn't get included for 1.11.1 - #27973 (comment).

Closing it now.