From 6db93d58cffc8bfd2a320111d96f7ca5a1751519 Mon Sep 17 00:00:00 2001
From: Jesse Rosenstock <jmr@google.com>
Date: Mon, 17 Aug 2020 09:22:15 +0200
Subject: [PATCH] Add test of union of bit-field from mailing list

https://sourceforge.net/p/cc65/mailman/message/36152700/

This currently works, but add a test to prevent future regressions.
---
 test/val/bitfield-union.c | 71 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 test/val/bitfield-union.c

diff --git a/test/val/bitfield-union.c b/test/val/bitfield-union.c
new file mode 100644
index 000000000..1fd201456
--- /dev/null
+++ b/test/val/bitfield-union.c
@@ -0,0 +1,71 @@
+/*
+  Copyright 2020 The cc65 Authors
+
+  This software is provided 'as-is', without any express or implied
+  warranty. In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/*
+  Tests of union of bit-fields; see https://sourceforge.net/p/cc65/mailman/message/36152700/
+*/
+
+#include <stdio.h>
+
+typedef union {
+     unsigned int bf;
+
+     struct {
+         unsigned int a : 1;
+         unsigned int b : 1;
+         unsigned int c : 1;
+     };
+} bitfield_t;
+
+static unsigned char failures = 0;
+
+int main (void)
+{
+     bitfield_t bitfield = {0};
+
+     printf ("Bitfield: %u\n", bitfield.bf);
+     if (bitfield.bf != 0) failures++;
+
+     bitfield.a = bitfield.a ^ 1;
+     printf ("a=1: %u\n", bitfield.bf);
+     if (bitfield.bf != 1) failures++;
+
+     bitfield.a = bitfield.a ^ 1;
+     printf ("a=0: %u\n\n", bitfield.bf);
+     if (bitfield.bf != 0) failures++;
+
+     bitfield.b = bitfield.b ^ 1;
+     printf ("b=1: %u\n", bitfield.bf);
+     if (bitfield.bf != 2) failures++;
+
+     bitfield.b = bitfield.b ^ 1;
+     printf ("b=0: %u\n\n", bitfield.bf);
+     if (bitfield.bf != 0) failures++;
+
+     bitfield.c = bitfield.c ^ 1;
+     printf ("c=1: %u\n", bitfield.bf);
+     if (bitfield.bf != 4) failures++;
+
+     bitfield.c = bitfield.c ^ 1;
+     printf ("c=0: %u\n\n", bitfield.bf);
+     if (bitfield.bf != 0) failures++;
+
+     return failures;
+}