cmd/gc: clearer error for defer/go of conversion or invalid function call

Fixes issue 4654.

R=ken2
CC=golang-dev
https://codereview.appspot.com/7229072

1 files changed, 71 insertions, 0 deletions

diff --git a/test/fixedbugs/issue4654.go b/test/fixedbugs/issue4654.go
new file mode 100644
index 000000000..ede7f56e7
--- /dev/null
+++ b/test/fixedbugs/issue4654.go
@@ -0,0 +1,71 @@
+// errorcheck
+
+// Copyright 2013 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 4654.
+// Check error for conversion and 'not used' in defer/go.
+
+package p
+
+import "unsafe"
+
+func f() {
+	defer int(0) // ERROR "defer requires function call, not conversion"
+	go string([]byte("abc")) // ERROR "go requires function call, not conversion"
+	
+	var c complex128
+	var f float64
+	var t struct {X int}
+
+	var x []int
+	defer append(x, 1) // ERROR "defer discards result of append"
+	defer cap(x) // ERROR "defer discards result of cap"
+	defer complex(1, 2) // ERROR "defer discards result of complex"
+	defer complex(f, 1) // ERROR "defer discards result of complex"
+	defer imag(1i) // ERROR "defer discards result of imag"
+	defer imag(c) // ERROR "defer discards result of imag"
+	defer len(x) // ERROR "defer discards result of len"
+	defer make([]int, 1) // ERROR "defer discards result of make"
+	defer make(chan bool) // ERROR "defer discards result of make"
+	defer make(map[string]int) // ERROR "defer discards result of make"
+	defer new(int) // ERROR "defer discards result of new"
+	defer real(1i) // ERROR "defer discards result of real"
+	defer real(c) // ERROR "defer discards result of real"
+	defer append(x, 1) // ERROR "defer discards result of append"
+	defer append(x, 1) // ERROR "defer discards result of append"
+	defer unsafe.Alignof(t.X) // ERROR "defer discards result of unsafe.Alignof"
+	defer unsafe.Offsetof(t.X) // ERROR "defer discards result of unsafe.Offsetof"
+	defer unsafe.Sizeof(t) // ERROR "defer discards result of unsafe.Sizeof"
+	
+	defer copy(x, x) // ok
+	m := make(map[int]int)
+	defer delete(m, 1) // ok
+	defer panic(1) // ok
+	defer print(1) // ok
+	defer println(1) // ok
+	defer recover() // ok
+
+	int(0) // ERROR "int\(0\) not used"
+	string([]byte("abc")) // ERROR "string\(\[\]byte literal\) not used"
+
+	append(x, 1) // ERROR "not used"
+	cap(x) // ERROR "not used"
+	complex(1, 2) // ERROR "not used"
+	complex(f, 1) // ERROR "not used"
+	imag(1i) // ERROR "not used"
+	imag(c) // ERROR "not used"
+	len(x) // ERROR "not used"
+	make([]int, 1) // ERROR "not used"
+	make(chan bool) // ERROR "not used"
+	make(map[string]int) // ERROR "not used"
+	new(int) // ERROR "not used"
+	real(1i) // ERROR "not used"
+	real(c) // ERROR "not used"
+	append(x, 1) // ERROR "not used"
+	append(x, 1) // ERROR "not used"
+	unsafe.Alignof(t.X) // ERROR "not used"
+	unsafe.Offsetof(t.X) // ERROR "not used"
+	unsafe.Sizeof(t) // ERROR "not used"
+}