[C2y] Claim conformance to WG14 N3496

This was a clarification for C23's N2412, primarily about the
BOOL_WIDTH macro. It should expand to the number of bits in the value
representation, not the object representation. Clang 20 implements the
correct value.

Author: AaronBallman

clang/test/C/C2y/n3496.c

@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -verify -std=c2y -ffreestanding %s
+// RUN: %clang_cc1 -verify -std=c23 -ffreestanding %s
+
+/* WG14 N3496: Clang 20
+ * Clarify the specification of the width macros
+ *
+ * C23 N2412 mandated a two's complement sign representation for integers, and
+ * added *_WIDTH macros for all of the various integer types. There was
+ * confusion as to whether BOOL_WIDTH specified the minimum number of bits or
+ * an exact number of bits. N3496 clarified that it's an exact number of bits.
+ */
+// expected-no-diagnostics
+
+#include <limits.h>
+
+static_assert(BOOL_WIDTH == 1);
+

clang/www/c_status.html

@@ -319,7 +319,7 @@ <h2 id="c2y">C2y implementation status</h2>
     <tr>
       <td>Clarify the specification of the width macros</td>
       <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3496.htm">N3496</a></td>
-      <td class="unknown" align="center">Unknown</td>
+      <td class="full" align="center">Clang 20</td>
 	</tr>
     <tr>
       <td>Complex operators</td>