cmd/compile: fix typechecking of untyped boolean expressions

Previously, if we typechecked a statement like

    var x bool = p1.f == p2.f && p1.g == p2.g

we would correctly update the '&&' node's type from 'untyped bool' to
'bool', but the '==' nodes would stay 'untyped bool'. This is
inconsistent, and caused consistency checks during walk to fail.

This CL doesn't pass toolstash because it seems to slightly affect the
register allocator's heuristics. (Presumably 'untyped bool's were
previously making it all the way through SSA?)

Fixes #23414.

Change-Id: Ia85f8cfc69b5ba35dfeb157f4edf57612ecc3285
Reviewed-on: https://go-review.googlesource.com/94022
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go
index dcc16b6decd83b3532be6fd37c3f519e0a33b1c8..af840059084dffaf4f75e719e93f65d6030ba017 100644 (file)
--- a/src/cmd/compile/internal/gc/const.go
+++ b/src/cmd/compile/internal/gc/const.go
@@ -232,11 +232,17 @@ func convlit1(n *Node, t *types.Type, explicit bool, reuse canReuseNode) *Node {
        switch n.Op {
        default:
                if n.Type == types.Idealbool {
-                       if t.IsBoolean() {
-                               n.Type = t
-                       } else {
-                               n.Type = types.Types[TBOOL]
+                       if !t.IsBoolean() {
+                               t = types.Types[TBOOL]
                        }
+                       switch n.Op {
+                       case ONOT:
+                               n.Left = convlit(n.Left, t)
+                       case OANDAND, OOROR:
+                               n.Left = convlit(n.Left, t)
+                               n.Right = convlit(n.Right, t)
+                       }
+                       n.Type = t
                }
 
                if n.Type.Etype == TIDEAL {

diff --git a/test/fixedbugs/issue23414.go b/test/fixedbugs/issue23414.go
new file mode 100644 (file)
index 0000000..7ef3d83
--- /dev/null
+++ b/test/fixedbugs/issue23414.go
@@ -0,0 +1,13 @@
+// compile
+
+// Copyright 2018 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 p
+
+var x struct{}
+
+func f() bool {
+       return x == x && x == x
+}