test/949: pin nullable (*T|void) tagged-element read byte-id (#261 deviation)

test/wcc/949_dotbase_addr_slice_run.c

@@ -657,6 +657,41 @@ static const struct row rows[] = {
 	  "	case void => yield 1: i32;\n"
 	  "	};\n"
 	  "};\n", 33, 1 },
+	/* #261 NULLABLE-fold deviation: a (*T | void) element is the 8B
+	 * one-word fold, NOT the 16B tag+payload slot. The fix mirrors
+	 * cstage exactly — classify TY_TAGGED for ANY base WITHOUT excluding
+	 * the nullable fold (slot_sz=8 degrades the copy arm to a single
+	 * MOVQ). These rows pin that the no-exclusion path is byte-id for the
+	 * fold too. The pointer-present / void cases prove the discriminant
+	 * (the pointer value itself) survives materialization. The variant
+	 * payload is read by constant (no `*p` deref) only to dodge an
+	 * ORTHOGONAL pre-existing wwstage checker bug (asserttyped: un on a
+	 * deref of a match-bound pointer) — distinct from #261's cgen axis. */
+	{ "tagged_null_ptr_rd",
+	  "package main;\n"
+	  "type e = struct { o: [4](*i32 | void) };\n"
+	  "export fn main() i32 = {\n"
+	  "	let k: i32 = 7;\n"
+	  "	let x: e;\n"
+	  "	x.o[1] = &k;\n"
+	  "	let v: (*i32 | void) = x.o[1];\n"
+	  "	return match (v) {\n"
+	  "	case let p: *i32 => yield 55: i32;\n"
+	  "	case void => yield 1: i32;\n"
+	  "	};\n"
+	  "};\n", 55, 1 },
+	{ "tagged_null_void_rd",
+	  "package main;\n"
+	  "type e = struct { o: [4](*i32 | void) };\n"
+	  "export fn main() i32 = {\n"
+	  "	let x: e;\n"
+	  "	x.o[1] = void;\n"
+	  "	let v: (*i32 | void) = x.o[1];\n"
+	  "	return match (v) {\n"
+	  "	case let p: *i32 => yield 99: i32;\n"
+	  "	case void => yield 1: i32;\n"
+	  "	};\n"
+	  "};\n", 1, 1 },
 	{ NULL, NULL, 0, 0 }
 };