Revert "cmd/compile: properly handle map assignments for OAS2DOTTYPE"

This reverts commit 9d7c9b43.

For #15602.

Change-Id: I464184b05babe4cb8dedab6161efa730cea6ee2d
Reviewed-on: https://go-review.googlesource.com/22930
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/order.go

@@ -569,24 +569,18 @@ func orderstmt(n *Node, order *Order) {
 
 		orderexprlist(n.List, order)
 		n.Rlist.First().Left = orderexpr(n.Rlist.First().Left, order, nil) // i in i.(T)
-
-		results := n.List.Slice()
-		var assigns [2]*Node
-
-		for r, res := range results {
-			if !isblank(res) {
-				results[r] = ordertemp(res.Type, order, haspointers(res.Type))
-				assigns[r] = Nod(OAS, res, results[r])
-			}
+		if isblank(n.List.First()) {
+			order.out = append(order.out, n)
+		} else {
+			typ := n.Rlist.First().Type
+			tmp1 := ordertemp(typ, order, haspointers(typ))
+			order.out = append(order.out, n)
+			r := Nod(OAS, n.List.First(), tmp1)
+			r = typecheck(r, Etop)
+			ordermapassign(r, order)
+			n.List.Set([]*Node{tmp1, n.List.Second()})
 		}
-		order.out = append(order.out, n)
 
-		for _, assign := range assigns {
-			if assign != nil {
-				assign = typecheck(assign, Etop)
-				ordermapassign(assign, order)
-			}
-		}
 		cleantemp(t, order)
 
 		// Special: use temporary variables to hold result,

test/fixedbugs/issue14678.go

-// run
-
-// Copyright 2016 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.
-
-package main
-
-func main() {
-	m := make(map[int]bool)
-	i := interface{}(1)
-	var v int
-
-	// Ensure map is updated properly
-	_, m[1] = i.(int)
-	v, m[2] = i.(int)
-
-	if v != 1 {
-		panic("fail: v should be 1")
-	}
-	if m[1] == false {
-		panic("fail: m[1] should be true")
-	}
-	if m[2] == false {
-		panic("fail: m[2] should be true")
-	}
-}