From 688abd08744989098a9073ed707f45b8b7e51103 Mon Sep 17 00:00:00 2001
From: brent saner <brent.saner@gmail.com>
Date: Tue, 26 Aug 2025 20:39:29 -0400
Subject: [PATCH] v1.9.5

FIXED:
* HasFlag would inappropriately report true for m = A, flag = A | B.
  This has been rectified, and this behavior is now explicitly
  exposed via IsOneOf.
---
 bitmask/bitmask.go | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/bitmask/bitmask.go b/bitmask/bitmask.go
index 237fae8..95fcf3d 100644
--- a/bitmask/bitmask.go
+++ b/bitmask/bitmask.go
@@ -34,11 +34,47 @@ func NewMaskBitExplicit(value uint) (m *MaskBit) {
 	return
 }
 
-// HasFlag is true if m has MaskBit flag set/enabled.
+/*
+	HasFlag is true if m has MaskBit flag set/enabled.
+	THIS WILL RETURN FALSE FOR OR'd FLAGS.
+	For example:
+
+		flagA MaskBit = 0x01
+		flagB MaskBit = 0x02
+		flagComposite = flagA | flagB
+
+		m *MaskBit = NewMaskBitExplicit(uint(flagA))
+	
+	m.HasFlag(flagComposite) will return false even though flagComposite is an OR
+	that contains flagA.
+	Use [MaskBit.IsOneOf] instead if you do not desire this behavior,
+	and instead want to test composite flag *membership*.
+	(MaskBit.IsOneOf will also return true for non-composite equality.)
+*/
 func (m *MaskBit) HasFlag(flag MaskBit) (r bool) {
 
 	var b MaskBit = *m
 
+	if b&flag == flag {
+		r = true
+	}
+	return
+}
+
+/*
+	IsOneOf is like a "looser" form of [MaskBit.HasFlag]
+	in that it allows for testing composite membership.
+
+	See [MaskBit.HasFlag] for more information.
+
+	If composite is *not* an OR'd MaskBit (i.e.
+	it falls directly on a boundary -- 0, 1, 2, 4, 8, 16, etc.),
+	then IsOneOf will behave exactly like HasFlag.
+*/
+func (m *MaskBit) IsOneOf(composite MaskBit) (r bool) {
+
+	var b MaskBit = *m
+
 	if b&flag != 0 {
 		r = true
 	}