cmd/compile: omit unnecessary interface method expression wrappers

We'll always generate method expression wrappers for declared
interface types in their own package, so no need to generate them in
downstream packages.

Noticed by gri@ while looking into #21282.

Change-Id: I4fb7051b4e15297933da05fdd2b111d6b8f4178e
Reviewed-on: https://go-review.googlesource.com/106175
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 49c1b485c95c63ebbe314013e2d0a44ed79393e1..f46279cf6e5f0f2acee2e226e8156f615c6b4880 100644 (file)
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -1633,6 +1633,11 @@ func genwrapper(rcvr *types.Type, method *types.Field, newnam *types.Sym) {
                return
        }
 
+       // Only generate I.M wrappers for I in I's own package.
+       if rcvr.IsInterface() && rcvr.Sym != nil && rcvr.Sym.Pkg != localpkg {
+               return
+       }
+
        lineno = autogeneratedPos
 
        dclcontext = PEXTERN