go/types, govet: panics when encountering (string constant) + string(rune constant)

[alberts]

What steps will reproduce the problem?

Seems to depend on a lot of packages in our internal code unfortunately.

Here's the panic for now. I can try to narrow it down somehow if this isn't enough of a
clue.

What do you see instead?

INTERNAL PANIC: interface conversion: interface is int64, not string
panic: interface conversion: interface is int64, not string [recovered]
    panic: interface conversion: interface is int64, not string

goroutine 1 [running]:
go/types.func·003()
    /build/go/go/src/pkg/go/types/check.go:445 +0x175
go/types.binaryOpConst(0x563bf0, 0xc200150f30, 0x563830, 0x3039, 0xc, ...)
    /build/go/go/src/pkg/go/types/const.go:580 +0x10b9
go/types.(*checker).binary(0xc2000b43c0, 0xc2001ecdc0, 0xc2000b7e00, 0xc2000cf4a0,
0xc2000b7c40, ...)
    /build/go/go/src/pkg/go/types/expr.go:601 +0x4e2
go/types.(*checker).rawExpr(0xc2000b43c0, 0xc2001ecdc0, 0xc2000b7d80, 0xc2000c2990,
0xc20009b5d0, ...)
    /build/go/go/src/pkg/go/types/expr.go:1394 +0x2972
go/types.(*checker).expr(0xc2000b43c0, 0xc2001ecdc0, 0xc2000b7d80, 0xc2000c2990,
0xc20009b5d0, ...)
    /build/go/go/src/pkg/go/types/expr.go:1476 +0x88
go/types.(*checker).argument(0xc2000b43c0, 0xc2000ff6c0, 0x0, 0xc2000b7d80,
0xc2000c2990, ...)
    /build/go/go/src/pkg/go/types/expr.go:729 +0x10a
go/types.(*checker).rawExpr(0xc2000b43c0, 0xc2001ecdc0, 0xc2000b7c40, 0xc2000cd9c0, 0x0,
...)
    /build/go/go/src/pkg/go/types/expr.go:1331 +0x3403
go/types.(*checker).expr(0xc2000b43c0, 0xc2001ecdc0, 0xc2000b7c40, 0xc2000cd9c0, 0x0,
...)
    /build/go/go/src/pkg/go/types/expr.go:1476 +0x88
go/types.(*checker).assign1to1(0xc2000b43c0, 0xc2000b78c0, 0xc2000cf400, 0xc2000b7c40,
0xc2000cd9c0, ...)
    /build/go/go/src/pkg/go/types/stmt.go:103 +0x670
go/types.(*checker).assignNtoM(0xc2000b43c0, 0xc200085e00, 0x1, 0x1, 0xc200085e40, ...)
    /build/go/go/src/pkg/go/types/stmt.go:196 +0x100
go/types.(*checker).stmt(0xc2000b43c0, 0xc2000b7f40, 0xc2000cda00)
    /build/go/go/src/pkg/go/types/stmt.go:394 +0x396a
go/types.(*checker).stmtList(0xc2000b43c0, 0xc2000b8780, 0x5, 0x8)
    /build/go/go/src/pkg/go/types/stmt.go:266 +0x68
go/types.check(0xc2000d37c0, 0xc2000b76c0, 0xc200000838, 0x1, 0x1, ...)
    /build/go/go/src/pkg/go/types/check.go:483 +0x437
go/types.(*Context).Check(0xc2000d37c0, 0xc2000b76c0, 0xc200000838, 0x1, 0x1, ...)
    /build/go/go/src/pkg/go/types/api.go:98 +0x52
main.doPackage(0xc200065010, 0x1, 0x1)
    /home/alberts/go/src/cmd/vet/main.go:221 +0x955
main.main()
    /home/alberts/go/src/cmd/vet/main.go:136 +0x651

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')

go version devel +67fc3cb0d3aa Mon Mar 04 14:54:36 2013 +1100 linux/amd64

[remyoudompheng]

Comment 1:

You could improve the debugging experience by:
 * choosing a function in the trace (for example checker.stmt)
 * add a recover there:
x := recover()
switch x.(type) {
case nil:
    // nothing
case bailout:
    panic(x)
default:
    buf := new(bytes.Buffer)
    format.Node(buf, token.NewFileSet(), stmt /* the ast.Stmt argument */)
    printf("PANIC during checking %q: %v", x)
    panic(x)
}
Anyway, the crash is easy to reproduce:
package main
import "fmt"
const A = "hello"
const B = 142
func main() {
    fmt.Println(A + string(B))
}

[remyoudompheng]

Comment 2:

Please try CL 7474043 and check if that fixes your issue.
https://golang.org/cl/7474043

Labels changed: added go1.1, removed go1.1maybe.

Owner changed to @remyoudompheng.

Status changed to Started.

[alberts]

Comment 3:

works for me

[robpike]

Comment 4:

Owner changed to @griesemer.

Status changed to Accepted.

[robpike]

Comment 5:

Labels changed: added priority-soon, removed priority-triage.

[griesemer]

Comment 6:

This issue was closed by revision 0b2caf2.

Status changed to Fixed.