From 29a22abfc8c81be7c3676f385fb0f2caf3029543 Mon Sep 17 00:00:00 2001

From: Russ Cox <[email protected]>

Date: Tue, 17 Nov 2015 16:34:06 -0500

Subject: [PATCH 49/63] [release-branch.go1.5] cmd/compile: fix Val vs Opt

 collision

Fixes #12686.

Change-Id: I7a9f49dbd1f60b1d0240de57787753b425f9548c

Reviewed-on: https://go-review.googlesource.com/17031

Reviewed-by: Ian Lance Taylor <[email protected]>

Reviewed-on: https://go-review.googlesource.com/17124

---

 src/cmd/compile/internal/gc/const.go | 16 ++++++++++++----

 test/fixedbugs/issue12686.go         | 16 ++++++++++++++++

 2 files changed, 28 insertions(+), 4 deletions(-)

 create mode 100644 test/fixedbugs/issue12686.go

diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go

index 9eb4983..5095e5e 100644

--- a/src/cmd/compile/internal/gc/const.go

+++ b/src/cmd/compile/internal/gc/const.go

@@ -1279,20 +1279,28 @@ func defaultlit(np **Node, t *Type) {

 	return

 num:

+	// Note: n.Val().Ctype() can be CTxxx (not a constant) here

+	// in the case of an untyped non-constant value, like 1<<i.

+	v1 := n.Val()

 	if t != nil {

 		if Isint[t.Etype] {

 			t1 = t

-			n.SetVal(toint(n.Val()))

+			v1 = toint(n.Val())

 		} else if Isfloat[t.Etype] {

 			t1 = t

-			n.SetVal(toflt(n.Val()))

+			v1 = toflt(n.Val())

 		} else if Iscomplex[t.Etype] {

 			t1 = t

-			n.SetVal(tocplx(n.Val()))

+			v1 = tocplx(n.Val())

+		}

+		if n.Val().Ctype() != CTxxx {

+			n.SetVal(v1)

 		}

 	}

-	overflow(n.Val(), t1)

+	if n.Val().Ctype() != CTxxx {

+		overflow(n.Val(), t1)

+	}

 	Convlit(np, t1)

 	lineno = int32(lno)

 	return

diff --git a/test/fixedbugs/issue12686.go b/test/fixedbugs/issue12686.go

new file mode 100644

index 0000000..5783c99

--- /dev/null

+++ b/test/fixedbugs/issue12686.go

@@ -0,0 +1,16 @@

+// compile

+

+// Copyright 2015 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.

+

+// golang.org/issue/12686.

+// interesting because it's a non-constant but ideal value

+// and we used to incorrectly attach a constant Val to the Node.

+

+package p

+

+func f(i uint) uint {

+	x := []uint{1 << i}

+	return x[0]

+}

-- 

2.6.1