From 686d680ea3e295c584def7e7b98e5d263873f2d2 Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Fri, 22 Jan 2021 16:38:25 +0100
Subject: [PATCH] io/key,io/pointer: forbid nil tags for InputOps

Forcing a non-nil tag ensures that all handler tags are either unique,
or intentionally equal. Additionally, a nil tag has special meaning in
FocusOps.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 io/key/key.go         | 3 +++
 io/pointer/pointer.go | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/io/key/key.go b/io/key/key.go
index 8b11caf7..8d951d9f 100644
--- a/io/key/key.go
+++ b/io/key/key.go
@@ -121,6 +121,9 @@ func (m Modifiers) Contain(m2 Modifiers) bool {
 }
 
 func (h InputOp) Add(o *op.Ops) {
+	if h.Tag == nil {
+		panic("Tag must be non-nil")
+	}
 	data := o.Write1(opconst.TypeKeyInputLen, h.Tag)
 	data[0] = byte(opconst.TypeKeyInput)
 }
diff --git a/io/pointer/pointer.go b/io/pointer/pointer.go
index 9e054fbc..b112bfde 100644
--- a/io/pointer/pointer.go
+++ b/io/pointer/pointer.go
@@ -189,6 +189,9 @@ func (op CursorNameOp) Add(o *op.Ops) {
 }
 
 func (h InputOp) Add(o *op.Ops) {
+	if h.Tag == nil {
+		panic("Tag must be non-nil")
+	}
 	data := o.Write1(opconst.TypePointerInputLen, h.Tag)
 	data[0] = byte(opconst.TypePointerInput)
 	if h.Grab {