cmd/gc: fix call order in array literal of slice literal of make chan

Fixes #8761.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/144530045
diff --git a/test/fixedbugs/bug491.go b/test/fixedbugs/bug491.go
new file mode 100644
index 0000000..f4b58af
--- /dev/null
+++ b/test/fixedbugs/bug491.go
@@ -0,0 +1,110 @@
+// run
+
+// Copyright 2014 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.
+
+// Test order of calls to builtin functions.
+// Discovered during CL 144530045 review.
+
+package main
+
+func main() {
+	// append
+	{
+		x := make([]int, 0)
+		f := func() int { x = make([]int, 2); return 2 }
+		a, b, c := append(x, 1), f(), append(x, 1)
+		if len(a) != 1 || len(c) != 3 {
+			bug()
+			println("append call not ordered:", len(a), b, len(c))
+		}
+	}
+
+	// cap
+	{
+		x := make([]int, 1)
+		f := func() int { x = make([]int, 3); return 2 }
+		a, b, c := cap(x), f(), cap(x)
+		if a != 1 || c != 3 {
+			bug()
+			println("cap call not ordered:", a, b, c)
+		}
+	}
+
+	// complex
+	{
+		x := 1.0
+		f := func() int { x = 3; return 2 }
+		a, b, c := complex(x, 0), f(), complex(x, 0)
+		if real(a) != 1 || real(c) != 3 {
+			bug()
+			println("complex call not ordered:", a, b, c)
+		}
+	}
+
+	// copy
+	{
+		tmp := make([]int, 100)
+		x := make([]int, 1)
+		f := func() int { x = make([]int, 3); return 2 }
+		a, b, c := copy(tmp, x), f(), copy(tmp, x)
+		if a != 1 || c != 3 {
+			bug()
+			println("copy call not ordered:", a, b, c)
+		}
+	}
+
+	// imag
+	{
+		x := 1i
+		f := func() int { x = 3i; return 2 }
+		a, b, c := imag(x), f(), imag(x)
+		if a != 1 || c != 3 {
+			bug()
+			println("imag call not ordered:", a, b, c)
+		}
+	}
+
+	// len
+	{
+		x := make([]int, 1)
+		f := func() int { x = make([]int, 3); return 2 }
+		a, b, c := len(x), f(), len(x)
+		if a != 1 || c != 3 {
+			bug()
+			println("len call not ordered:", a, b, c)
+		}
+	}
+
+	// make
+	{
+		x := 1
+		f := func() int { x = 3; return 2 }
+		a, b, c := make([]int, x), f(), make([]int, x)
+		if len(a) != 1 || len(c) != 3 {
+			bug()
+			println("make call not ordered:", len(a), b, len(c))
+		}
+	}
+
+	// real
+	{
+		x := 1 + 0i
+		f := func() int { x = 3; return 2 }
+		a, b, c := real(x), f(), real(x)
+		if a != 1 || c != 3 {
+			bug()
+			println("real call not ordered:", a, b, c)
+		}
+	}
+}
+
+var bugged = false
+
+func bug() {
+	if !bugged {
+		println("BUG")
+		bugged = true
+	}
+}
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