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cmd/compile: Fix internal compiler: getinarg: not a func when returning invalid interface.

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Internal error arose from calling methodfunc on a invalid interface
field during the implements check. int obviously isn't a function,
and errors on getinarg...

for im := iface.Type; im != nil; im = im.Down {
  imtype = methodfunc(im.Type, nil)
  // ...
}

Fix handles the internal compiler error, but does not throw an
additional error, i.e. the following code will error on the I
interface, but type A will pass the implements check since
'Read(string) string' is implemented and 'int' is skipped

type I interface {
  Read(string) string
  int
}

type A struct {
}

func (a *A) Read(s string) string {
  return s
}

func New() I {
  return new(A)
}

Fixes #10975

Change-Id: I4b54013afb2814db3f315515f0c742d8631ca500
Reviewed-on: https://go-review.googlesource.com/13747
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
acanino 2015-08-21 22:24:20 -04:00 committed by Brad Fitzpatrick
parent 788eb99b76
commit acc90c53e8
2 changed files with 22 additions and 0 deletions
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3
src/cmd/compile/internal/gc/subr.go
View file

@ -2986,6 +2986,9 @@ func implements(t *Type, iface *Type, m **Type, samename **Type, ptr *int) bool
var followptr bool
var rcvr *Type
for im := iface.Type; im != nil; im = im.Down {
if im.Broke == 1 {
continue
}
imtype = methodfunc(im.Type, nil)
tm = ifacelookdot(im.Sym, t, &followptr, 0)
if tm == nil || tm.Nointerface || !Eqtype(methodfunc(tm.Type, nil), imtype) {

19
test/fixedbugs/issue10975.go Normal file
View file

@ -0,0 +1,19 @@
// errorcheck
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Issue 10975: Returning an invalid interface would cause
// `internal compiler error: getinarg: not a func`.
package main
type I interface {
int // ERROR "interface contains embedded non-interface int"
}
func New() I {
return struct{}{}
}