$ go tool vet go/types
go/types/scope.go:159: method WriteTo(w io.Writer, n int, recurse bool) should have signature WriteTo(io.Writer) (int64, error)
panic: interface conversion: ast.Spec is *ast.AliasSpec, not *ast.ValueSpec

goroutine 1 [running]:
panic(0x12804a0, 0xc420e23c40)
	/Users/josh/go/tip/src/runtime/panic.go:531 +0x1cf
main.checkCopyLocksGenDecl(0xc420e1e000, 0xc420e23a80)
	/Users/josh/go/tip/src/cmd/vet/copylock.go:64 +0x303
main.checkCopyLocks(0xc420e1e000, 0x13da720, 0xc420e23a80)
	/Users/josh/go/tip/src/cmd/vet/copylock.go:39 +0x188
main.(*File).Visit(0xc420e1e000, 0x13da720, 0xc420e23a80, 0x13d9760, 0xc420e1e000)
	/Users/josh/go/tip/src/cmd/vet/main.go:500 +0x106
go/ast.Walk(0x13d9760, 0xc420e1e000, 0x13da720, 0xc420e23a80)
	/Users/josh/go/tip/src/go/ast/walk.go:52 +0x66
go/ast.walkDeclList(0x13d9760, 0xc420e1e000, 0xc42001b480, 0x6, 0x8)
	/Users/josh/go/tip/src/go/ast/walk.go:38 +0x89
go/ast.Walk(0x13d9760, 0xc420e1e000, 0x13da620, 0xc42001b500)
	/Users/josh/go/tip/src/go/ast/walk.go:363 +0x2ce0
main.(*File).walkFile(0xc420e1e000, 0xc420a13f60, 0x1a, 0xc42001b500)
	/Users/josh/go/tip/src/cmd/vet/main.go:467 +0x120
main.doPackage(0xc420a126a0, 0x11, 0xc420e61980, 0x1, 0x1, 0x0, 0x0)
	/Users/josh/go/tip/src/cmd/vet/main.go:358 +0xbd1
main.doPackageDir(0xc420a126a0, 0x11)
	/Users/josh/go/tip/src/cmd/vet/main.go:287 +0x601
main.visit(0xc420a126a0, 0x11, 0x13dd480, 0xc420082ea0, 0x0, 0x0, 0x0, 0x0)
	/Users/josh/go/tip/src/cmd/vet/main.go:374 +0xe6
path/filepath.walk(0xc420a126a0, 0x11, 0x13dd480, 0xc420082ea0, 0x12ce4e8, 0x0, 0x0)
	/Users/josh/go/tip/src/path/filepath/path.go:351 +0x81
path/filepath.walk(0x7fff5fbff5bd, 0x8, 0x13dd480, 0xc42008fa00, 0x12ce4e8, 0x0, 0xc420043e78)
	/Users/josh/go/tip/src/path/filepath/path.go:376 +0x414
path/filepath.Walk(0x7fff5fbff5bd, 0x8, 0x12ce4e8, 0xc, 0xc42008f930)
	/Users/josh/go/tip/src/path/filepath/path.go:398 +0x14c
main.walkDir(0x7fff5fbff5bd, 0x8)
	/Users/josh/go/tip/src/cmd/vet/main.go:389 +0x41
main.main()
	/Users/josh/go/tip/src/cmd/vet/main.go:243 +0x308