cmd/gc: inlining of functions with local variables is broken with shadowing.

[remyoudompheng]

1. What is a short input program that triggers the error?

Here are two examples:

$ cat p1.go
package p1

type O map[string]map[string]string

func (opts O) RemoveOption(sect, opt string) bool {
    if _, ok := opts[sect]; !ok {
        return false
    }
    _, ok := opts[sect][opt]
    delete(opts[sect], opt)
    return ok
}
$ cat p2.go
package p2

import "./p1"

func NewO() p1.O { return nil }
$ cat main.go
package main

import "./p2"

func main() {
    p2.NewO().RemoveOption("hello", "world")
}

$ cat q1.go
package q1

func Deref(typ interface{}) interface{} {
      if typ, ok := typ.(*int); ok {
            return *typ
      }
      return typ
}
$ cat q2.go
package main

import "./q1"

func main() {
      x := 1
      y := q1.Deref(&x)
      if y != 1 {
            panic("y != 1")
      }
}

2. What is the full compiler output?

$ go tool 8g -I. p1.go
$ go tool 8g -I. p2.go
$ go tool 8g -I. main.go
main.go:3: p1.ok redeclared in this block
    previous declaration at main.go:3
go tool 8g: exit status 1

$ go tool 8g -I. q1.go
$ go tool 8g -I. q2.go
q2.go:3: invalid type assertion: q1.typ.(*int) (non-interface type *int on left)
q2.go:7: tempname called with nil type
q2.go:7: internal compiler error: typename <T>
go tool 8g: exit status 1

3. What version of the compiler are you using?  (Run it with the -V flag.)

8g version devel +5bc48b616305 Thu Nov 01 13:04:08 2012 +1100

Attachments:

1. inlining.tar.gz (530 bytes)

[dvyukov]

Comment 1:

Just debugged the same issue.
Note how {} disappear around  {  var @"".ok bool; _, @"".ok = @"".s.@"".lo.(@"".Int); if
@"".ok { return true }} after inlining:
//pkg1
        func (@"".s *@"".Interval "esc:0x0") IsInt() (? bool) { if @"".s == nil { return false }; {  var @"".ok bool; _, @"".ok = @"".s.@"".lo.(@"".Int); if @"".ok { return true }}; {  var @"".ok bool; _, @"".ok = @"".s.@"".hi.(@"".Int); if @"".ok { return true }}; return false }
//pkg2
        func (@"bugtest/pkg".s *@"bugtest/pkg".Interval "esc:0x0") IsInt2() (? bool) { if @"bugtest/pkg".s == nil { return false }; var @"bugtest/pkg".ok bool; ; _, @"bugtest/pkg".ok = @"bugtest/pkg".s.@"bugtest/pkg".lo.(@"bugtest/pkg".Int); if @"bugtest/pkg".ok { return true }; var @"bugtest/pkg".ok bool; ; _, @"bugtest/pkg".ok = @"bugtest/pkg".s.@"bugtest/pkg".hi.(@"bugtest/pkg".Int); if @"bugtest/pkg".ok { return true }; return false }
The error message is:
main.go:4: pkg.ok redeclared in this block

Labels changed: added compilerbug.

[rsc]

Comment 2:

I'll try to take a look at this today.

[rsc]

Comment 3:

This issue was closed by revision cb856ad.

Status changed to Fixed.