wcc/check: #25 reject overlong array-lit in a tuple return (wwstage)

selfhost/cmd/w6c/main.combined.ww

@@ -15123,6 +15123,19 @@ fn checkretassign(c: *checker, n: *node) void = {
 	if (n.lhs.kind == nkind.N_ARRLIT) {
 		checkarrlitfits(c, c.fnret, n.lhs);
 	};
+	// #25: array-typed element of a TUPLE RETURN with an overlong array
+	// literal — `fn f() ([2]int,i32) = { return ([1,2,3],5); }`. #20
+	// wired the tuple over-fill walk at the LET position only; the
+	// return path runs through checkretassign which never routed tuple
+	// elements through checkarrlitfits. Reuse the #26 helper. Fire
+	// BEFORE the isassignable/conf guards (a tuple return drives
+	// conf=false → short-circuit), same reason as the #12 array arm
+	// above. Alias/!-aware on the fnret tuple type.
+	let rrt: *node = resolvealias(c, unwrapbang(c.fnret));
+	if (rrt != nil && rrt.kind == nkind.N_TTUPLE
+	    && n.lhs.kind == nkind.N_TUPLE) {
+		checktuplearrfits(c, rrt, n.lhs);
+	};
 	let src: *node = exprtype(c, n.lhs, nil);
 	if (src == nil) { return; };
 	let conf: bool = false;

selfhost/cmd/wcc/check.ww

@@ -4842,6 +4842,19 @@ fn checkretassign(c: *checker, n: *node) void = {
 	if (n.lhs.kind == nkind.N_ARRLIT) {
 		checkarrlitfits(c, c.fnret, n.lhs);
 	};
+	// #25: array-typed element of a TUPLE RETURN with an overlong array
+	// literal — `fn f() ([2]int,i32) = { return ([1,2,3],5); }`. #20
+	// wired the tuple over-fill walk at the LET position only; the
+	// return path runs through checkretassign which never routed tuple
+	// elements through checkarrlitfits. Reuse the #26 helper. Fire
+	// BEFORE the isassignable/conf guards (a tuple return drives
+	// conf=false → short-circuit), same reason as the #12 array arm
+	// above. Alias/!-aware on the fnret tuple type.
+	let rrt: *node = resolvealias(c, unwrapbang(c.fnret));
+	if (rrt != nil && rrt.kind == nkind.N_TTUPLE
+	    && n.lhs.kind == nkind.N_TUPLE) {
+		checktuplearrfits(c, rrt, n.lhs);
+	};
 	let src: *node = exprtype(c, n.lhs, nil);
 	if (src == nil) { return; };
 	let conf: bool = false;

selfhost/cmd/wwdump/main.combined.ww

@@ -15123,6 +15123,19 @@ fn checkretassign(c: *checker, n: *node) void = {
 	if (n.lhs.kind == nkind.N_ARRLIT) {
 		checkarrlitfits(c, c.fnret, n.lhs);
 	};
+	// #25: array-typed element of a TUPLE RETURN with an overlong array
+	// literal — `fn f() ([2]int,i32) = { return ([1,2,3],5); }`. #20
+	// wired the tuple over-fill walk at the LET position only; the
+	// return path runs through checkretassign which never routed tuple
+	// elements through checkarrlitfits. Reuse the #26 helper. Fire
+	// BEFORE the isassignable/conf guards (a tuple return drives
+	// conf=false → short-circuit), same reason as the #12 array arm
+	// above. Alias/!-aware on the fnret tuple type.
+	let rrt: *node = resolvealias(c, unwrapbang(c.fnret));
+	if (rrt != nil && rrt.kind == nkind.N_TTUPLE
+	    && n.lhs.kind == nkind.N_TUPLE) {
+		checktuplearrfits(c, rrt, n.lhs);
+	};
 	let src: *node = exprtype(c, n.lhs, nil);
 	if (src == nil) { return; };
 	let conf: bool = false;

test/wcc/832_tuple_elem_overlong.c

@@ -25,6 +25,8 @@
  *   tuple_arr_over     | let t:([2]int,i32)=([1,2,3],5)                | b. FAIL
  *   tuple_nested_arr   | let t:([2][3]int,i32)=([[..],[..],[..]],5)    | b. FAIL
  *   tuple_in_tuple     | let t:([2]int,([2]int,i32))=([..],([1,2,3],.))| #26 FAIL
+ *   tuple_return_over  | fn()([2]int,i32){return([1,2,3],5)}          | #25 FAIL
+ *   tuple_return_nested| fn()([2]int,([2]int,i32)){return(..,([..3],.))| #25 FAIL
  *
  *   pos row            | shape                                        | want
  *   -------------------+----------------------------------------------+------
@@ -116,6 +118,25 @@ static const char *neg[] = {
 	"\tlet t: ([2]int, ([2]int, i32)) = ([1, 2], ([3, 4, 5], 6));\n"
 	"\treturn t.0[0]: i32;\n"
 	"};\n",
+	/* tuple_return_over (#25) — overlong [2]int in a tuple RETURN. */
+	"package main;\n"
+	"fn f() ([2]int, i32) = {\n"
+	"\treturn ([1, 2, 3], 5);\n"
+	"};\n"
+	"export fn main() i32 = {\n"
+	"\tlet t = f();\n"
+	"\treturn t.1;\n"
+	"};\n",
+	/* tuple_return_nested (#25 path × #26 recursion) — nested tuple in a
+	 * RETURN, inner [2]int over-filled. */
+	"package main;\n"
+	"fn f() ([2]int, ([2]int, i32)) = {\n"
+	"\treturn ([1, 2], ([3, 4, 5], 6));\n"
+	"};\n"
+	"export fn main() i32 = {\n"
+	"\tlet t = f();\n"
+	"\treturn t.0[0]: i32;\n"
+	"};\n",
 };
 
 static int