runtime: make iface/eface handling more type safe

Change compiler-invoked interface functions to directly take
iface/eface parameters instead of fInterface/interface{} to avoid
needing to always convert.

For the handful of functions that legitimately need to take an
interface{} parameter, add efaceOf to type-safely convert *interface{}
to *eface.

Change-Id: I8928761a12fd3c771394f36adf93d3006a9fcf39
Reviewed-on: https://go-review.googlesource.com/16166
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go
index a753ceda52..24f35d2163 100644
--- a/src/runtime/mfinal.go
+++ b/src/runtime/mfinal.go
@@ -187,7 +187,7 @@ func runfinq() {
 					if len(ityp.mhdr) != 0 {
 						// convert to interface with methods
 						// this conversion is guaranteed to succeed - we checked in SetFinalizer
-						assertE2I(ityp, *(*interface{})(frame), (*fInterface)(frame))
+						assertE2I(ityp, *(*eface)(frame), (*iface)(frame))
 					}
 				default:
 					throw("bad kind in runfinq")
@@ -264,7 +264,7 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 		// (and we don't have the data structures to record them).
 		return
 	}
-	e := (*eface)(unsafe.Pointer(&obj))
+	e := efaceOf(&obj)
 	etyp := e._type
 	if etyp == nil {
 		throw("runtime.SetFinalizer: first argument is nil")
@@ -313,7 +313,7 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 		}
 	}
 
-	f := (*eface)(unsafe.Pointer(&finalizer))
+	f := efaceOf(&finalizer)
 	ftyp := f._type
 	if ftyp == nil {
 		// switch to system stack and remove finalizer
@@ -347,7 +347,7 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 			// ok - satisfies empty interface
 			goto okarg
 		}
-		if assertE2I2(ityp, obj, nil) {
+		if assertE2I2(ityp, *efaceOf(&obj), nil) {
 			goto okarg
 		}
 	}