From 436a79e5dd4cbda2129930db3a660c99276d7357 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Mon, 20 Jul 2015 16:23:50 -0700
Subject: [PATCH] go/types: fix internal inInteger operand predicate

Backport of https://go-review.googlesource.com/#/c/12045/

Fixes golang/go#11594.

Change-Id: I3c81e2b1bbdc084d4a323fd963c1c780054ce223
Reviewed-on: https://go-review.googlesource.com/12046
Reviewed-by: Alan Donovan <adonovan@google.com>
---
 go/types/operand.go          | 5 +++--
 go/types/testdata/decls0.src | 1 +
 go/types/testdata/shifts.src | 8 ++++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/go/types/operand.go b/go/types/operand.go
index 0ac67672..d52b30e1 100644
--- a/go/types/operand.go
+++ b/go/types/operand.go
@@ -279,9 +279,10 @@ func (x *operand) assignableTo(conf *Config, T Type) bool {
 	return false
 }
 
-// isInteger reports whether x is a (typed or untyped) integer value.
+// isInteger reports whether x is a value of integer type
+// or an untyped constant representable as an integer.
 func (x *operand) isInteger() bool {
 	return x.mode == invalid ||
 		isInteger(x.typ) ||
-		x.mode == constant && representableConst(x.val, nil, UntypedInt, nil) // no *Config required for UntypedInt
+		isUntyped(x.typ) && x.mode == constant && representableConst(x.val, nil, UntypedInt, nil) // no *Config required for UntypedInt
 }
diff --git a/go/types/testdata/decls0.src b/go/types/testdata/decls0.src
index f1df3ea7..21baafe2 100644
--- a/go/types/testdata/decls0.src
+++ b/go/types/testdata/decls0.src
@@ -53,6 +53,7 @@ type (
 	iA1 [1 /* ERROR "invalid array length" */ <<100]int
 	iA2 [- /* ERROR "invalid array length" */ 1]complex128
 	iA3 ["foo" /* ERROR "must be integer" */ ]string
+	iA4 [float64 /* ERROR "must be integer" */ (0)]int
 )
 
 
diff --git a/go/types/testdata/shifts.src b/go/types/testdata/shifts.src
index 2df2ccde..fa4de9e8 100644
--- a/go/types/testdata/shifts.src
+++ b/go/types/testdata/shifts.src
@@ -331,3 +331,11 @@ func issue11325() {
 	_ = 1. >> 1.
 	_ = 1.1 /* ERROR "must be integer" */ >> 1
 }
+
+func issue11594() {
+	var _ = complex64 /* ERROR "must be integer" */ (1) << 2 // example from issue 11594
+	_ = float32 /* ERROR "must be integer" */ (0) << 1
+	_ = float64 /* ERROR "must be integer" */ (0) >> 2
+	_ = complex64 /* ERROR "must be integer" */ (0) << 3
+	_ = complex64 /* ERROR "must be integer" */ (0) >> 4
+}