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cmd/compile/internal/gc: handle recursive interfaces better

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Previously, we handled recursive interfaces by deferring typechecking
of interface methods, while eagerly expanding interface embeddings.

This CL switches to eagerly evaluating interface methods, and
deferring expanding interface embeddings to dowidth. This allows us to
detect recursive interface embeddings with the same mechanism used for
detecting recursive struct embeddings.

Updates #16369.

Change-Id: If4c0320058047f8a2d9b52b9a79de47eb9887f95
Reviewed-on: https://go-review.googlesource.com/38391
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2017-03-20 11:56:15 -07:00
parent 4e35e5fcab
commit 07de3465be
9 changed files with 99 additions and 90 deletions
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56
src/cmd/compile/internal/gc/align.go
View file

@ -4,6 +4,10 @@
package gc
import (
"sort"
)
// machine size and rounding alignment is dictated around
// the size of a pointer, set in betypeinit (see ../amd64/galign.go).
var defercalc int
@ -15,6 +19,47 @@ func Rnd(o int64, r int64) int64 {
return (o + r - 1) &^ (r - 1)
}
// expandiface computes the method set for interface type t by
// expanding embedded interfaces.
func expandiface(t *Type) {
var fields []*Field
for _, m := range t.Methods().Slice() {
if m.Sym != nil {
fields = append(fields, m)
continue
}
if !m.Type.IsInterface() {
yyerrorl(m.Nname.Pos, "interface contains embedded non-interface %v", m.Type)
m.SetBroke(true)
t.SetBroke(true)
// Add to fields so that error messages
// include the broken embedded type when
// printing t.
// TODO(mdempsky): Revisit this.
fields = append(fields, m)
continue
}
// Embedded interface: duplicate all methods
// (including broken ones, if any) and add to t's
// method set.
for _, t1 := range m.Type.Fields().Slice() {
f := newField()
f.Type = t1.Type
f.SetBroke(t1.Broke())
f.Sym = t1.Sym
f.Nname = m.Nname // preserve embedding position
fields = append(fields, f)
}
}
sort.Sort(methcmp(fields))
// Access fields directly to avoid recursively calling dowidth
// within Type.Fields().
t.Extra.(*InterType).fields.Set(fields)
}
func offmod(t *Type) {
o := int32(0)
for _, f := range t.Fields().Slice() {
@ -203,9 +248,8 @@ func dowidth(t *Type) {
case TINTER: // implemented as 2 pointers
w = 2 * int64(Widthptr)
t.Align = uint8(Widthptr)
offmod(t)
expandiface(t)
case TCHAN: // implemented as pointer
w = int64(Widthptr)
@ -316,6 +360,14 @@ func dowidth(t *Type) {
t.Align = uint8(w)
}
if t.Etype == TINTER {
// We defer calling these functions until after
// setting t.Width and t.Align so the recursive calls
// to dowidth within t.Fields() will succeed.
checkdupfields("method", t)
offmod(t)
}
lineno = lno
if defercalc == 1 {