From 70692d3c5feb2dd71b19393c21d0746c21cec5e9 Mon Sep 17 00:00:00 2001
From: Alan Donovan <adonovan@google.com>
Date: Wed, 13 Nov 2013 09:13:42 -0500
Subject: [PATCH] go.tools/pointer: fix constraint generation bug in
 *ssa.Select.

The previous code assumed that each channel item contained one field.

+ regression test.

R=crawshaw
CC=golang-dev
https://golang.org/cl/25480044
---
 pointer/gen.go               |  2 +-
 pointer/testdata/channels.go | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/pointer/gen.go b/pointer/gen.go
index 5a995342..89143c93 100644
--- a/pointer/gen.go
+++ b/pointer/gen.go
@@ -994,7 +994,7 @@ func (a *analysis) genInstr(cgn *cgnode, instr ssa.Instruction) {
 			switch st.Dir {
 			case ast.RECV:
 				a.genLoad(cgn, recv, st.Chan, 0, elemSize)
-				recv++
+				recv += nodeid(elemSize)
 
 			case ast.SEND:
 				a.genStore(cgn, st.Chan, a.valueNode(st.Send), 0, elemSize)
diff --git a/pointer/testdata/channels.go b/pointer/testdata/channels.go
index 001d7d23..db427d0b 100644
--- a/pointer/testdata/channels.go
+++ b/pointer/testdata/channels.go
@@ -90,9 +90,29 @@ func chan4() {
 	}
 }
 
+// Multi-word channel value in select with multiple receive cases.
+// (Regtest for a crash.)
+func chan5() {
+	type T struct {
+		x *int
+		y interface{}
+	}
+	ch := make(chan T)
+	ch <- T{new(int), incr} // @line ch5new
+	select {
+	case a := <-ch:
+		print(a.x) // @pointsto new@ch5new:13
+		print(a.y) // @types func(x int) int
+	case b := <-ch:
+		print(b.x) // @pointsto new@ch5new:13
+		print(b.y) // @types func(x int) int
+	}
+}
+
 func main() {
 	chan1()
 	chan2()
 	chan3()
 	chan4()
+	chan5()
 }