cmd/gc: add diagnostic for var, type, const named init
Before this CL, defining the variable worked fine, but then when
the implicit package-level init func was created, that caused a
name collision and a confusing error about the redeclaration.
Also add a test for issue 3705 (func init() needs body).
Fixes #4517.
R=ken2
CC=golang-dev
https://golang.org/cl/7008045
diff --git a/test/fixedbugs/issue3705.go b/test/fixedbugs/issue3705.go
new file mode 100644
index 0000000..c19bcea
--- /dev/null
+++ b/test/fixedbugs/issue3705.go
@@ -0,0 +1,9 @@
+// errorcheck
+
+// Copyright 2012 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.
+
+package p
+
+func init() // ERROR "missing function body"
diff --git a/test/fixedbugs/issue4517a.go b/test/fixedbugs/issue4517a.go
new file mode 100644
index 0000000..a1b6b57
--- /dev/null
+++ b/test/fixedbugs/issue4517a.go
@@ -0,0 +1,9 @@
+// errorcheck
+
+// Copyright 2012 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.
+
+package p
+
+var init = 1 // ERROR "cannot declare init - must be func"
diff --git a/test/fixedbugs/issue4517b.go b/test/fixedbugs/issue4517b.go
new file mode 100644
index 0000000..f04103f
--- /dev/null
+++ b/test/fixedbugs/issue4517b.go
@@ -0,0 +1,9 @@
+// errorcheck
+
+// Copyright 2012 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.
+
+package p
+
+const init = 1 // ERROR "cannot declare init - must be func"
diff --git a/test/fixedbugs/issue4517c.go b/test/fixedbugs/issue4517c.go
new file mode 100644
index 0000000..47b21cf
--- /dev/null
+++ b/test/fixedbugs/issue4517c.go
@@ -0,0 +1,9 @@
+// errorcheck
+
+// Copyright 2012 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.
+
+package p
+
+type init byte // ERROR "cannot declare init - must be func"
