go/types: go vet INTERNAL PANIC

[alberts]

What is the expected output?

go tool vet panics on some of our internal code.

Reducing it is quite a big job. If there isn't enough info here, let me know and I'll go
for it.

INTERNAL PANIC: runtime error: invalid memory address or nil pointer dereference
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x10 pc=0x4eb475]

goroutine 1 [running]:
code.google.com/p/go.tools/go/types.func·003()
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/check.go:447 +0x175
code.google.com/p/go.tools/go/types.identicalMethods(0xc2001e53e0, 0x1, 0x1,
0xc2001c9d90, 0x1, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/predicates.go:219 +0xe5
code.google.com/p/go.tools/go/types.IsIdentical(0xc20008db00, 0xc2001e2d80,
0xc20008db00, 0xc2001c6760, 0xc2000cd700, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/predicates.go:165 +0x8de
code.google.com/p/go.tools/go/types.(*operand).isAssignable(0xc2001b7ac0, 0xc2000cd980,
0xc20008db40, 0xc20020d420, 0xc20016d000, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/operand.go:144 +0x172
code.google.com/p/go.tools/go/types.(*checker).assignment(0xc2000af160, 0xc2001b7ac0,
0xc20008db40, 0xc20020d420, 0xc20008db40, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/stmt.go:36 +0x1dd
code.google.com/p/go.tools/go/types.(*checker).argument(0xc2000af160, 0xc2001c6f60, 0x0,
0xc2000cd680, 0xc20006dbc0, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/expr.go:984 +0x23a
code.google.com/p/go.tools/go/types.(*checker).rawExpr(0xc2000af160, 0xc2001b7ac0,
0xc2000cd700, 0xc2000cd800, 0x0, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/expr.go:1577 +0x353a
code.google.com/p/go.tools/go/types.(*checker).expr(0xc2000af160, 0xc2001b7ac0,
0xc2000cd700, 0xc2000cd800, 0x0, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/expr.go:1727 +0x88
code.google.com/p/go.tools/go/types.(*checker).assignNtoM(0xc2000af160, 0xc20006db40,
0x2, 0x2, 0xc2000aaa70, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/stmt.go:188 +0x1b4
code.google.com/p/go.tools/go/types.(*checker).stmt(0xc2000af160, 0xc2000cd7c0,
0xc2000cd840)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/stmt.go:375 +0x3846
code.google.com/p/go.tools/go/types.(*checker).stmtList(0xc2000af160, 0xc20006dbe0, 0x2,
0x2)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/stmt.go:247 +0x68
code.google.com/p/go.tools/go/types.check(0xc2000cd980, 0x6060a0, 0x1, 0xc2000cd440,
0xc200000268, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/check.go:485 +0x4cf
code.google.com/p/go.tools/go/types.(*Context).Check(0xc2000cd980, 0x6060a0, 0x1,
0xc2000cd440, 0xc200000268, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/go/types/api.go:112 +0x6c
main.(*Package).check(0xc2000cd8c0, 0xc2000cd440, 0xc200000268, 0x1, 0x1, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/cmd/vet/types.go:32 +0x168
main.doPackage(0x6060a0, 0x1, 0xc20006d010, 0x1, 0x1, ...)
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/cmd/vet/main.go:226 +0x8f5
main.main()
    /home/alberts/go/src/pkg/code.google.com/p/go.tools/cmd/vet/main.go:144 +0x665

Which compiler are you using (5g, 6g, 8g, gccgo)?

6g

Which operating system are you using?

linux

Which version are you using?  (run 'go version')

tip

[remyoudompheng]

Comment 1:

The crash location looks similar to issue #5512.
Do you see a similar pattern in your program?

[alberts]

Comment 2:

Yes, I think so. I reduced it down to two types (from other packages though) that
interact with each other through a function along the lines of a.foo(b).
I think we can close this as a duplicate for now.

[davecheney]

Comment 3:

Marking as duplicate as per #2

Status changed to Duplicate.

Merged into issue #5512.