cmd/internal/gc: omit non-explicit capacity in errors with map/chan make

Fixes #9083.

Change-Id: Ifbdebafb39a73a1dacf7e67171e8e88028d1f10b
Reviewed-on: https://go-review.googlesource.com/1219
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Chris Manghane <cmang@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/internal/gc/fmt.go

@@ -1639,7 +1639,7 @@ func exprfmt(n *Node, prec int) string {
 			f += fmt.Sprintf("make(%v, %v, %v)", Tconv(n.Type, 0), Nconv(n.Left, 0), Nconv(n.Right, 0))
 			return f
 		}
-		if n.Left != nil {
+		if n.Left != nil && (n.Op == OMAKESLICE || !isideal(n.Left.Type)) {
 			var f string
 			f += fmt.Sprintf("make(%v, %v)", Tconv(n.Type, 0), Nconv(n.Left, 0))
 			return f

test/escape2.go

@@ -1753,7 +1753,7 @@ func slicerunetostring2() {
 }
 
 func makemap0() {
-	m := make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) does not escape"
+	m := make(map[int]int) // ERROR "make\(map\[int\]int\) does not escape"
 	m[0] = 0
 	m[1]++
 	delete(m, 1)
@@ -1761,10 +1761,10 @@ func makemap0() {
 }
 
 func makemap1() map[int]int {
-	return make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) escapes to heap"
+	return make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap"
 }
 
 func makemap2() {
-	m := make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) escapes to heap"
+	m := make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap"
 	sink = m
 }

test/escape2n.go

@@ -1753,7 +1753,7 @@ func slicerunetostring2() {
 }
 
 func makemap0() {
-	m := make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) does not escape"
+	m := make(map[int]int) // ERROR "make\(map\[int\]int\) does not escape"
 	m[0] = 0
 	m[1]++
 	delete(m, 1)
@@ -1761,10 +1761,10 @@ func makemap0() {
 }
 
 func makemap1() map[int]int {
-	return make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) escapes to heap"
+	return make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap"
 }
 
 func makemap2() {
-	m := make(map[int]int) // ERROR "make\(map\[int\]int\, 0\) escapes to heap"
+	m := make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap"
 	sink = m
 }

test/fixedbugs/issue9083.go

@@ -0,0 +1,22 @@
+// errorcheck
+
+// 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.
+
+// Issue 9083: map/chan error messages show non-explicit capacity.
+
+package main
+
+// untyped constant
+const zero = 0
+
+func main() {
+	var x int
+	x = make(map[int]int) // ERROR "cannot use make\(map\[int\]int\)|incompatible"
+	x = make(map[int]int, 0) // ERROR "cannot use make\(map\[int\]int, 0\)|incompatible"
+	x = make(map[int]int, zero) // ERROR "cannot use make\(map\[int\]int, zero\)|incompatible"
+	x = make(chan int) // ERROR "cannot use make\(chan int\)|incompatible"
+	x = make(chan int, 0) // ERROR "cannot use make\(chan int, 0\)|incompatible"
+	x = make(chan int, zero) // ERROR "cannot use make\(chan int, zero\)|incompatible"
+}