radiance · commit

lib/std/arch/rv64/tests/match.array.rad added +160 -0

1	+	//! Test array literal patterns in match statements.
2	+
3	+	/// All-binding array pattern: destructure into variables.
4	+	fn sum3(arr: [i32; 3]) -> i32 {
5	+	match arr {
6	+	case [a, b, c] => {
7	+	return a + b + c;
8	+	}
9	+	}
10	+	}
11	+
12	+	/// Mixed literal and binding: test first element, bind rest.
13	+	fn classify(arr: [i32; 3]) -> i32 {
14	+	match arr {
15	+	case [1, b, c] => {
16	+	return b + c;
17	+	}
18	+	case [2, b, c] => {
19	+	return (b + c) * 2;
20	+	}
21	+	else => {
22	+	return 0;
23	+	}
24	+	}
25	+	}
26	+
27	+	/// All-literal array pattern.
28	+	fn isOrigin(p: [i32; 2]) -> bool {
29	+	match p {
30	+	case [0, 0] => {
31	+	return true;
32	+	}
33	+	else => {
34	+	return false;
35	+	}
36	+	}
37	+	}
38	+
39	+	/// Placeholder inside array pattern.
40	+	fn firstOf3(arr: [i32; 3]) -> i32 {
41	+	match arr {
42	+	case [x, _, _] => {
43	+	return x;
44	+	}
45	+	}
46	+	}
47	+
48	+	/// Array pattern nested inside union variant.
49	+	union Shape {
50	+	Point { coords: [i32; 2] },
51	+	Line { start: [i32; 2], end: [i32; 2] },
52	+	None,
53	+	}
54	+
55	+	fn shapeSum(s: Shape) -> i32 {
56	+	match s {
57	+	case Shape::Point { coords: [x, y] } => {
58	+	return x + y;
59	+	}
60	+	case Shape::Line { start: [x1, y1], end: [x2, y2] } => {
61	+	return x1 + y1 + x2 + y2;
62	+	}
63	+	case Shape::None => {
64	+	return 0;
65	+	}
66	+	}
67	+	}
68	+
69	+	/// Array pattern with literal test inside union.
70	+	fn isAtOrigin(s: Shape) -> bool {
71	+	match s {
72	+	case Shape::Point { coords: [0, 0] } => {
73	+	return true;
74	+	}
75	+	else => {
76	+	return false;
77	+	}
78	+	}
79	+	}
80	+
81	+	/// Array pattern in if-let-case.
82	+	fn extractX(s: Shape) -> i32 {
83	+	if let case Shape::Point { coords: [x, _] } = s {
84	+	return x;
85	+	}
86	+	return -1;
87	+	}
88	+
89	+	/// Array pattern in let-else.
90	+	fn extractLine(s: Shape) -> i32 {
91	+	let case Shape::Line { start: [x1, _], end: [x2, _] } = s
92	+	else { return -1; };
93	+	return x2 - x1;
94	+	}
95	+
96	+	/// Nested array of arrays.
97	+	fn sumMatrix(m: [[i32; 2]; 2]) -> i32 {
98	+	match m {
99	+	case [[a, b], [c, d]] => {
100	+	return a + b + c + d;
101	+	}
102	+	}
103	+	}
104	+
105	+	/// Nested array with literal test.
106	+	fn isIdentity(m: [[i32; 2]; 2]) -> bool {
107	+	match m {
108	+	case [[1, 0], [0, 1]] => {
109	+	return true;
110	+	}
111	+	else => {
112	+	return false;
113	+	}
114	+	}
115	+	}
116	+
117	+	@default fn main() -> i32 {
118	+	// sum3
119	+	assert sum3([10, 20, 30]) == 60;
120	+
121	+	// classify
122	+	assert classify([1, 5, 6]) == 11;
123	+	assert classify([2, 3, 4]) == 14;
124	+	assert classify([9, 1, 1]) == 0;
125	+
126	+	// isOrigin
127	+	assert isOrigin([0, 0]);
128	+	assert not isOrigin([1, 0]);
129	+	assert not isOrigin([0, 1]);
130	+
131	+	// firstOf3
132	+	assert firstOf3([42, 0, 0]) == 42;
133	+
134	+	// shapeSum
135	+	assert shapeSum(Shape::Point { coords: [3, 4] }) == 7;
136	+	assert shapeSum(Shape::Line { start: [1, 2], end: [3, 4] }) == 10;
137	+	assert shapeSum(Shape::None) == 0;
138	+
139	+	// isAtOrigin
140	+	assert isAtOrigin(Shape::Point { coords: [0, 0] });
141	+	assert not isAtOrigin(Shape::Point { coords: [1, 0] });
142	+	assert not isAtOrigin(Shape::None);
143	+
144	+	// extractX
145	+	assert extractX(Shape::Point { coords: [5, 9] }) == 5;
146	+	assert extractX(Shape::None) == -1;
147	+
148	+	// extractLine
149	+	assert extractLine(Shape::Line { start: [2, 0], end: [8, 0] }) == 6;
150	+	assert extractLine(Shape::None) == -1;
151	+
152	+	// sumMatrix
153	+	assert sumMatrix([[1, 2], [3, 4]]) == 10;
154	+
155	+	// isIdentity
156	+	assert isIdentity([[1, 0], [0, 1]]);
157	+	assert not isIdentity([[1, 1], [0, 1]]);
158	+
159	+	return 0;
160	+	}

lib/std/arch/rv64/tests/match.char.rad added +66 -0

1	+	//! Test character literal patterns in match statements.
2	+
3	+	/// Top-level character match.
4	+	fn charClass(c: u8) -> i32 {
5	+	match c {
6	+	case 'a' => { return 1; }
7	+	case 'b' => { return 2; }
8	+	case 'z' => { return 26; }
9	+	case '0' => { return 100; }
10	+	else => { return 0; }
11	+	}
12	+	}
13	+
14	+	/// Character pattern nested inside a union variant field.
15	+	union Token {
16	+	Punct { ch: u8, pos: i32 },
17	+	Eof,
18	+	}
19	+
20	+	fn tokenVal(t: Token) -> i32 {
21	+	match t {
22	+	case Token::Punct { ch: '(', pos } => {
23	+	return pos;
24	+	}
25	+	case Token::Punct { ch: ')', pos } => {
26	+	return 0 - pos;
27	+	}
28	+	case Token::Punct { ch: '+', .. } => {
29	+	return 100;
30	+	}
31	+	else => {
32	+	return 0;
33	+	}
34	+	}
35	+	}
36	+
37	+	/// Character pattern in if-let-case.
38	+	fn isOpen(t: Token) -> bool {
39	+	if let case Token::Punct { ch: '(', .. } = t {
40	+	return true;
41	+	}
42	+	return false;
43	+	}
44	+
45	+	@default fn main() -> i32 {
46	+	// charClass
47	+	assert charClass('a') == 1;
48	+	assert charClass('b') == 2;
49	+	assert charClass('z') == 26;
50	+	assert charClass('0') == 100;
51	+	assert charClass('x') == 0;
52	+
53	+	// tokenVal
54	+	assert tokenVal(Token::Punct { ch: '(', pos: 5 }) == 5;
55	+	assert tokenVal(Token::Punct { ch: ')', pos: 10 }) == -10;
56	+	assert tokenVal(Token::Punct { ch: '+', pos: 0 }) == 100;
57	+	assert tokenVal(Token::Punct { ch: '-', pos: 0 }) == 0;
58	+	assert tokenVal(Token::Eof) == 0;
59	+
60	+	// isOpen
61	+	assert isOpen(Token::Punct { ch: '(', pos: 0 });
62	+	assert not isOpen(Token::Punct { ch: ')', pos: 0 });
63	+	assert not isOpen(Token::Eof);
64	+
65	+	return 0;
66	+	}

lib/std/arch/rv64/tests/match.nested.call.rad added +76 -0

1	+	//! Test nested patterns with tuple-style (Call) union variants.
2	+
3	+	union Dir { North, South }
4	+	union Opt { Some(i32), None }
5	+
6	+	/// Tuple-style variant with integer literal nested pattern.
7	+	fn checkOpt(o: Opt) -> i32 {
8	+	match o {
9	+	case Opt::Some(42) => {
10	+	return 1;
11	+	}
12	+	case Opt::Some(x) => {
13	+	return x;
14	+	}
15	+	case Opt::None => {
16	+	return 0;
17	+	}
18	+	}
19	+	}
20	+
21	+	/// Tuple-style variant in if-let-case.
22	+	fn extractSome(o: Opt) -> i32 {
23	+	if let case Opt::Some(x) = o {
24	+	return x;
25	+	}
26	+	return -1;
27	+	}
28	+
29	+	/// Tuple-style variant in let-else.
30	+	fn unwrapSome(o: Opt) -> i32 {
31	+	let case Opt::Some(x) = o
32	+	else { return -1; };
33	+	return x;
34	+	}
35	+
36	+	/// Nested union inside tuple-style variant.
37	+	union Wrapper { Wrap(Dir), Empty }
38	+
39	+	fn extractDir(w: Wrapper) -> i32 {
40	+	match w {
41	+	case Wrapper::Wrap(Dir::North) => {
42	+	return 10;
43	+	}
44	+	case Wrapper::Wrap(Dir::South) => {
45	+	return 20;
46	+	}
47	+	else => {
48	+	return 0;
49	+	}
50	+	}
51	+	}
52	+
53	+	@default fn main() -> i32 {
54	+	// checkOpt: literal 42 matches first arm
55	+	assert checkOpt(Opt::Some(42)) == 1;
56	+	// checkOpt: non-42 matches second arm
57	+	assert checkOpt(Opt::Some(7)) == 7;
58	+	assert checkOpt(Opt::Some(0)) == 0;
59	+	// checkOpt: None
60	+	assert checkOpt(Opt::None) == 0;
61	+
62	+	// extractSome
63	+	assert extractSome(Opt::Some(99)) == 99;
64	+	assert extractSome(Opt::None) == -1;
65	+
66	+	// unwrapSome
67	+	assert unwrapSome(Opt::Some(55)) == 55;
68	+	assert unwrapSome(Opt::None) == -1;
69	+
70	+	// extractDir
71	+	assert extractDir(Wrapper::Wrap(Dir::North)) == 10;
72	+	assert extractDir(Wrapper::Wrap(Dir::South)) == 20;
73	+	assert extractDir(Wrapper::Empty) == 0;
74	+
75	+	return 0;
76	+	}

lib/std/arch/rv64/tests/match.nested.deep.rad added +88 -0

1	+	//! Test deeply nested patterns: three levels of record nesting,
2	+	//! and nested unions inside records inside unions.
3	+
4	+	record Leaf {
5	+	val: i32,
6	+	}
7	+
8	+	record Branch {
9	+	leaf: Leaf,
10	+	extra: i32,
11	+	}
12	+
13	+	union Tree {
14	+	Node { branch: Branch, tag: i32 },
15	+	Empty,
16	+	}
17	+
18	+	/// Three levels deep: union -> record -> record -> record.
19	+	fn sumTree(t: Tree) -> i32 {
20	+	match t {
21	+	case Tree::Node { branch: Branch { leaf: Leaf { val }, extra }, tag } => {
22	+	return val + extra + tag;
23	+	}
24	+	case Tree::Empty => {
25	+	return 0;
26	+	}
27	+	}
28	+	}
29	+
30	+	/// Nested union inside a record inside a union.
31	+	union Color { Red, Green, Blue }
32	+
33	+	record Pixel {
34	+	color: Color,
35	+	brightness: i32,
36	+	}
37	+
38	+	union Canvas {
39	+	Filled { pixel: Pixel },
40	+	Blank,
41	+	}
42	+
43	+	fn getColor(cv: Canvas) -> i32 {
44	+	match cv {
45	+	case Canvas::Filled { pixel: Pixel { color: Color::Red, brightness } } => {
46	+	return brightness;
47	+	}
48	+	case Canvas::Filled { pixel: Pixel { color: Color::Green, brightness } } => {
49	+	return brightness * 2;
50	+	}
51	+	case Canvas::Filled { pixel: Pixel { color: Color::Blue, brightness } } => {
52	+	return brightness * 3;
53	+	}
54	+	else => {
55	+	return 0;
56	+	}
57	+	}
58	+	}
59	+
60	+	/// If-let-case with nested patterns.
61	+	fn ifLetNested(t: Tree) -> i32 {
62	+	if let case Tree::Node { branch: Branch { leaf: Leaf { val }, extra }, tag } = t {
63	+	return val + extra + tag;
64	+	}
65	+	return -1;
66	+	}
67	+
68	+	@default fn main() -> i32 {
69	+	// sumTree
70	+	let t = Tree::Node { branch: Branch { leaf: Leaf { val: 10 }, extra: 20 }, tag: 30 };
71	+	assert sumTree(t) == 60;
72	+	assert sumTree(Tree::Empty) == 0;
73	+
74	+	// getColor
75	+	let red = Canvas::Filled { pixel: Pixel { color: Color::Red, brightness: 5 } };
76	+	assert getColor(red) == 5;
77	+	let green = Canvas::Filled { pixel: Pixel { color: Color::Green, brightness: 7 } };
78	+	assert getColor(green) == 14;
79	+	let blue = Canvas::Filled { pixel: Pixel { color: Color::Blue, brightness: 3 } };
80	+	assert getColor(blue) == 9;
81	+	assert getColor(Canvas::Blank) == 0;
82	+
83	+	// ifLetNested
84	+	assert ifLetNested(t) == 60;
85	+	assert ifLetNested(Tree::Empty) == -1;
86	+
87	+	return 0;
88	+	}

lib/std/arch/rv64/tests/match.nested.guard.rad added +71 -0

1	+	//! Test nested patterns combined with guards.
2	+
3	+	record Pair {
4	+	a: i32,
5	+	b: i32,
6	+	}
7	+
8	+	union Opt {
9	+	Some { pair: Pair },
10	+	None,
11	+	}
12	+
13	+	/// Nested pattern with guard on bound variable.
14	+	fn filtered(o: Opt) -> i32 {
15	+	match o {
16	+	case Opt::Some { pair: Pair { a, b } } if a > 0 => {
17	+	return a + b;
18	+	}
19	+	case Opt::Some { pair: Pair { a, b } } => {
20	+	return 0 - a - b;
21	+	}
22	+	case Opt::None => {
23	+	return -1;
24	+	}
25	+	}
26	+	}
27	+
28	+	/// Nested union with guard.
29	+	union Tag { X, Y }
30	+
31	+	union Box {
32	+	Item { tag: Tag, val: i32 },
33	+	Empty,
34	+	}
35	+
36	+	fn guardedNested(bx: Box) -> i32 {
37	+	match bx {
38	+	case Box::Item { tag: Tag::X, val } if val > 10 => {
39	+	return val;
40	+	}
41	+	case Box::Item { tag: Tag::X, val } => {
42	+	return 0 - val;
43	+	}
44	+	case Box::Item { tag: Tag::Y, val } => {
45	+	return val * 2;
46	+	}
47	+	else => {
48	+	return 0;
49	+	}
50	+	}
51	+	}
52	+
53	+	@default fn main() -> i32 {
54	+	// filtered tests
55	+	let pos = Opt::Some { pair: Pair { a: 3, b: 4 } };
56	+	assert filtered(pos) == 7;
57	+	let neg = Opt::Some { pair: Pair { a: -2, b: 5 } };
58	+	assert filtered(neg) == -3;
59	+	assert filtered(Opt::None) == -1;
60	+
61	+	// guardedNested tests
62	+	let x_big = Box::Item { tag: Tag::X, val: 20 };
63	+	assert guardedNested(x_big) == 20;
64	+	let x_small = Box::Item { tag: Tag::X, val: 5 };
65	+	assert guardedNested(x_small) == -5;
66	+	let y = Box::Item { tag: Tag::Y, val: 8 };
67	+	assert guardedNested(y) == 16;
68	+	assert guardedNested(Box::Empty) == 0;
69	+
70	+	return 0;
71	+	}

lib/std/arch/rv64/tests/match.nested.iflet.guard.rad added +68 -0

1	+	//! Test nested patterns combined with guards in if-let-case.
2	+
3	+	record Pair {
4	+	a: i32,
5	+	b: i32,
6	+	}
7	+
8	+	union Opt {
9	+	Some { pair: Pair },
10	+	None,
11	+	}
12	+
13	+	/// Nested record pattern with guard on bound variable.
14	+	fn filteredRecord(o: Opt) -> i32 {
15	+	if let case Opt::Some { pair: Pair { a, b } } = o; a > 0 {
16	+	return a + b;
17	+	}
18	+	return -1;
19	+	}
20	+
21	+	/// Nested union variant with guard.
22	+	union Dir { North, South }
23	+
24	+	union Command {
25	+	Move { dir: Dir, speed: i32 },
26	+	Stop,
27	+	}
28	+
29	+	fn fastNorth(c: Command) -> i32 {
30	+	if let case Command::Move { dir: Dir::North, speed } = c; speed > 10 {
31	+	return speed;
32	+	}
33	+	return -1;
34	+	}
35	+
36	+	/// Nested record with guard and else branch.
37	+	fn filteredElse(o: Opt) -> i32 {
38	+	if let case Opt::Some { pair: Pair { a, b } } = o; a > 0 {
39	+	return a + b;
40	+	} else {
41	+	return 0;
42	+	}
43	+	}
44	+
45	+	@default fn main() -> i32 {
46	+	// filteredRecord
47	+	let pos = Opt::Some { pair: Pair { a: 3, b: 4 } };
48	+	assert filteredRecord(pos) == 7;
49	+	let neg = Opt::Some { pair: Pair { a: -2, b: 5 } };
50	+	assert filteredRecord(neg) == -1;
51	+	assert filteredRecord(Opt::None) == -1;
52	+
53	+	// fastNorth
54	+	let fast = Command::Move { dir: Dir::North, speed: 20 };
55	+	assert fastNorth(fast) == 20;
56	+	let slow = Command::Move { dir: Dir::North, speed: 5 };
57	+	assert fastNorth(slow) == -1;
58	+	let south = Command::Move { dir: Dir::South, speed: 15 };
59	+	assert fastNorth(south) == -1;
60	+	assert fastNorth(Command::Stop) == -1;
61	+
62	+	// filteredElse
63	+	assert filteredElse(pos) == 7;
64	+	assert filteredElse(neg) == 0;
65	+	assert filteredElse(Opt::None) == 0;
66	+
67	+	return 0;
68	+	}

lib/std/arch/rv64/tests/match.nested.iflet.rad added +63 -0

1	+	//! Test nested patterns in if-let-case and let-else contexts.
2	+
3	+	record Inner {
4	+	x: i32,
5	+	y: i32,
6	+	}
7	+
8	+	union Wrapper {
9	+	Some { inner: Inner, z: i32 },
10	+	None,
11	+	}
12	+
13	+	/// Nested if-let-case.
14	+	fn ifLetNested(w: Wrapper) -> i32 {
15	+	if let case Wrapper::Some { inner: Inner { x, y }, z } = w {
16	+	return x + y + z;
17	+	}
18	+	return -1;
19	+	}
20	+
21	+	/// Nested union variant in if-let-case.
22	+	union Kind { A, B }
23	+
24	+	union Tagged {
25	+	Item { kind: Kind, val: i32 },
26	+	Empty,
27	+	}
28	+
29	+	fn ifLetNestedUnion(t: Tagged) -> i32 {
30	+	if let case Tagged::Item { kind: Kind::A, val } = t {
31	+	return val;
32	+	}
33	+	return 0;
34	+	}
35	+
36	+	/// Nested patterns with placeholder in if-let-case.
37	+	fn ifLetPlaceholder(w: Wrapper) -> i32 {
38	+	if let case Wrapper::Some { inner: Inner { x, .. }, .. } = w {
39	+	return x;
40	+	}
41	+	return -1;
42	+	}
43	+
44	+	@default fn main() -> i32 {
45	+	let w = Wrapper::Some { inner: Inner { x: 10, y: 20 }, z: 30 };
46	+
47	+	// ifLetNested
48	+	assert ifLetNested(w) == 60;
49	+	assert ifLetNested(Wrapper::None) == -1;
50	+
51	+	// ifLetNestedUnion
52	+	let ta = Tagged::Item { kind: Kind::A, val: 42 };
53	+	assert ifLetNestedUnion(ta) == 42;
54	+	let tb = Tagged::Item { kind: Kind::B, val: 99 };
55	+	assert ifLetNestedUnion(tb) == 0;
56	+	assert ifLetNestedUnion(Tagged::Empty) == 0;
57	+
58	+	// ifLetPlaceholder
59	+	assert ifLetPlaceholder(w) == 10;
60	+	assert ifLetPlaceholder(Wrapper::None) == -1;
61	+
62	+	return 0;
63	+	}

lib/std/arch/rv64/tests/match.nested.letelse.rad added +37 -0

1	+	//! Test nested patterns in let-else statements.
2	+
3	+	record Inner {
4	+	x: i32,
5	+	y: i32,
6	+	}
7	+
8	+	union Wrapper {
9	+	Some { inner: Inner, z: i32 },
10	+	None,
11	+	}
12	+
13	+	/// Nested record destructuring in let-else.
14	+	fn extractSum(w: Wrapper) -> i32 {
15	+	let case Wrapper::Some { inner: Inner { x, y }, z } = w
16	+	else { return -1; };
17	+	return x + y + z;
18	+	}
19	+
20	+	/// Nested with placeholder in let-else.
21	+	fn extractPartial(w: Wrapper) -> i32 {
22	+	let case Wrapper::Some { inner: Inner { x, .. }, .. } = w
23	+	else { return -1; };
24	+	return x;
25	+	}
26	+
27	+	@default fn main() -> i32 {
28	+	let w = Wrapper::Some { inner: Inner { x: 10, y: 20 }, z: 30 };
29	+
30	+	assert extractSum(w) == 60;
31	+	assert extractSum(Wrapper::None) == -1;
32	+
33	+	assert extractPartial(w) == 10;
34	+	assert extractPartial(Wrapper::None) == -1;
35	+
36	+	return 0;
37	+	}

lib/std/arch/rv64/tests/match.nested.letelse.union.rad added +58 -0

1	+	//! Test nested union variant patterns in let-else statements.
2	+
3	+	union Dir { North, South }
4	+
5	+	union Command {
6	+	Move { dir: Dir, speed: i32 },
7	+	Stop,
8	+	}
9	+
10	+	/// Nested union variant in let-else.
11	+	fn extractNorth(c: Command) -> i32 {
12	+	let case Command::Move { dir: Dir::North, speed } = c
13	+	else { return -1; };
14	+	return speed;
15	+	}
16	+
17	+	/// Nested union variant in let-else, deeper nesting.
18	+	record Inner {
19	+	x: i32,
20	+	y: i32,
21	+	}
22	+
23	+	union Wrapper {
24	+	Some { inner: Inner, z: i32 },
25	+	None,
26	+	}
27	+
28	+	union Box {
29	+	Filled { w: Wrapper, tag: i32 },
30	+	Empty,
31	+	}
32	+
33	+	fn extractInner(b: Box) -> i32 {
34	+	let case Box::Filled { w: Wrapper::Some { inner: Inner { x, y }, z }, tag } = b
35	+	else { return -1; };
36	+	return x + y + z + tag;
37	+	}
38	+
39	+	@default fn main() -> i32 {
40	+	// extractNorth
41	+	let mn = Command::Move { dir: Dir::North, speed: 5 };
42	+	assert extractNorth(mn) == 5;
43	+	let ms = Command::Move { dir: Dir::South, speed: 3 };
44	+	assert extractNorth(ms) == -1;
45	+	assert extractNorth(Command::Stop) == -1;
46	+
47	+	// extractInner
48	+	let b = Box::Filled {
49	+	w: Wrapper::Some { inner: Inner { x: 10, y: 20 }, z: 30 },
50	+	tag: 40,
51	+	};
52	+	assert extractInner(b) == 100;
53	+	let b2 = Box::Filled { w: Wrapper::None, tag: 50 };
54	+	assert extractInner(b2) == -1;
55	+	assert extractInner(Box::Empty) == -1;
56	+
57	+	return 0;
58	+	}

lib/std/arch/rv64/tests/match.nested.literal.rad added +115 -0

1	+	//! Test literal patterns (integers, booleans) nested inside union variant fields.
2	+
3	+	union Action {
4	+	Set { code: i32, value: i32 },
5	+	Toggle { flag: bool },
6	+	None,
7	+	}
8	+
9	+	/// Match integer literals inside a union variant field.
10	+	fn handleCode(a: Action) -> i32 {
11	+	match a {
12	+	case Action::Set { code: 1, value } => {
13	+	return value * 10;
14	+	}
15	+	case Action::Set { code: 2, value } => {
16	+	return value * 20;
17	+	}
18	+	case Action::Set { code, value } => {
19	+	return code + value;
20	+	}
21	+	case Action::Toggle { flag: true } => {
22	+	return 100;
23	+	}
24	+	case Action::Toggle { flag: false } => {
25	+	return 200;
26	+	}
27	+	else => {
28	+	return 0;
29	+	}
30	+	}
31	+	}
32	+
33	+	/// Integer literal nested pattern in if-let-case.
34	+	fn isCodeOne(a: Action) -> bool {
35	+	if let case Action::Set { code: 1, .. } = a {
36	+	return true;
37	+	}
38	+	return false;
39	+	}
40	+
41	+	/// Integer literal nested pattern in let-else.
42	+	fn extractCodeTwo(a: Action) -> i32 {
43	+	let case Action::Set { code: 2, value } = a
44	+	else { return -1; };
45	+	return value;
46	+	}
47	+
48	+	/// Boolean literal nested in if-let-case.
49	+	fn isToggleOn(a: Action) -> bool {
50	+	if let case Action::Toggle { flag: true } = a {
51	+	return true;
52	+	}
53	+	return false;
54	+	}
55	+
56	+	/// Multiple literal fields in the same pattern.
57	+	union Pair {
58	+	Both { a: i32, b: i32 },
59	+	Empty,
60	+	}
61	+
62	+	fn matchBothLiterals(p: Pair) -> i32 {
63	+	match p {
64	+	case Pair::Both { a: 1, b: 2 } => {
65	+	return 12;
66	+	}
67	+	case Pair::Both { a: 1, b } => {
68	+	return 10 + b;
69	+	}
70	+	case Pair::Both { a, b: 2 } => {
71	+	return a + 20;
72	+	}
73	+	else => {
74	+	return 0;
75	+	}
76	+	}
77	+	}
78	+
79	+	@default fn main() -> i32 {
80	+	// handleCode: integer literal patterns
81	+	assert handleCode(Action::Set { code: 1, value: 5 }) == 50;
82	+	assert handleCode(Action::Set { code: 2, value: 3 }) == 60;
83	+	assert handleCode(Action::Set { code: 99, value: 1 }) == 100;
84	+
85	+	// handleCode: boolean literal patterns
86	+	assert handleCode(Action::Toggle { flag: true }) == 100;
87	+	assert handleCode(Action::Toggle { flag: false }) == 200;
88	+
89	+	// handleCode: void variant
90	+	assert handleCode(Action::None) == 0;
91	+
92	+	// isCodeOne
93	+	assert isCodeOne(Action::Set { code: 1, value: 42 });
94	+	assert not isCodeOne(Action::Set { code: 2, value: 42 });
95	+	assert not isCodeOne(Action::None);
96	+
97	+	// extractCodeTwo
98	+	assert extractCodeTwo(Action::Set { code: 2, value: 77 }) == 77;
99	+	assert extractCodeTwo(Action::Set { code: 1, value: 77 }) == -1;
100	+	assert extractCodeTwo(Action::None) == -1;
101	+
102	+	// isToggleOn
103	+	assert isToggleOn(Action::Toggle { flag: true });
104	+	assert not isToggleOn(Action::Toggle { flag: false });
105	+	assert not isToggleOn(Action::None);
106	+
107	+	// matchBothLiterals
108	+	assert matchBothLiterals(Pair::Both { a: 1, b: 2 }) == 12;
109	+	assert matchBothLiterals(Pair::Both { a: 1, b: 5 }) == 15;
110	+	assert matchBothLiterals(Pair::Both { a: 3, b: 2 }) == 23;
111	+	assert matchBothLiterals(Pair::Both { a: 3, b: 5 }) == 0;
112	+	assert matchBothLiterals(Pair::Empty) == 0;
113	+
114	+	return 0;
115	+	}

lib/std/arch/rv64/tests/match.nested.multi.rad added +75 -0

1	+	//! Test multiple nested refining fields in the same record pattern.
2	+
3	+	union Dir { North, South, East }
4	+	union Mode { Fast, Slow }
5	+
6	+	union Command {
7	+	Move { dir: Dir, mode: Mode, speed: i32 },
8	+	Stop,
9	+	}
10	+
11	+	/// Two union-typed fields refined simultaneously.
12	+	fn dispatch(c: Command) -> i32 {
13	+	match c {
14	+	case Command::Move { dir: Dir::North, mode: Mode::Fast, speed } => {
15	+	return speed * 4;
16	+	}
17	+	case Command::Move { dir: Dir::North, mode: Mode::Slow, speed } => {
18	+	return speed;
19	+	}
20	+	case Command::Move { dir: Dir::South, mode: Mode::Fast, speed } => {
21	+	return 0 - speed * 4;
22	+	}
23	+	case Command::Move { dir: Dir::South, mode: Mode::Slow, speed } => {
24	+	return 0 - speed;
25	+	}
26	+	else => {
27	+	return 0;
28	+	}
29	+	}
30	+	}
31	+
32	+	/// Multiple refining fields with guard.
33	+	fn dispatchGuarded(c: Command) -> i32 {
34	+	match c {
35	+	case Command::Move { dir: Dir::North, mode: Mode::Fast, speed } if speed > 10 => {
36	+	return speed * 3;
37	+	}
38	+	case Command::Move { dir: Dir::North, mode: Mode::Fast, speed } => {
39	+	return speed * 2;
40	+	}
41	+	case Command::Move { dir: Dir::South, mode: Mode::Slow, speed } => {
42	+	return 0 - speed;
43	+	}
44	+	else => {
45	+	return 0;
46	+	}
47	+	}
48	+	}
49	+
50	+	@default fn main() -> i32 {
51	+	// dispatch
52	+	let nf = Command::Move { dir: Dir::North, mode: Mode::Fast, speed: 5 };
53	+	assert dispatch(nf) == 20;
54	+	let ns = Command::Move { dir: Dir::North, mode: Mode::Slow, speed: 5 };
55	+	assert dispatch(ns) == 5;
56	+	let sf = Command::Move { dir: Dir::South, mode: Mode::Fast, speed: 3 };
57	+	assert dispatch(sf) == -12;
58	+	let ss = Command::Move { dir: Dir::South, mode: Mode::Slow, speed: 3 };
59	+	assert dispatch(ss) == -3;
60	+	// East falls to else.
61	+	let ef = Command::Move { dir: Dir::East, mode: Mode::Fast, speed: 7 };
62	+	assert dispatch(ef) == 0;
63	+	assert dispatch(Command::Stop) == 0;
64	+
65	+	// dispatchGuarded
66	+	let fast_big = Command::Move { dir: Dir::North, mode: Mode::Fast, speed: 20 };
67	+	assert dispatchGuarded(fast_big) == 60;
68	+	let fast_small = Command::Move { dir: Dir::North, mode: Mode::Fast, speed: 5 };
69	+	assert dispatchGuarded(fast_small) == 10;
70	+	let south_slow = Command::Move { dir: Dir::South, mode: Mode::Slow, speed: 4 };
71	+	assert dispatchGuarded(south_slow) == -4;
72	+	assert dispatchGuarded(Command::Stop) == 0;
73	+
74	+	return 0;
75	+	}

lib/std/arch/rv64/tests/match.nested.pattern.rad added +212 -0

1	+	//! Test nested patterns in match/case statements.
2	+
3	+	record Inner {
4	+	x: i32,
5	+	y: i32,
6	+	}
7	+
8	+	union Outer {
9	+	A { inner: Inner, z: i32 },
10	+	B,
11	+	}
12	+
13	+	/// Match a union variant and destructure its nested record field.
14	+	fn testNestedMatch(o: Outer) -> i32 {
15	+	match o {
16	+	case Outer::A { inner: Inner { x, y }, z } => {
17	+	return x + y + z;
18	+	}
19	+	case Outer::B => {
20	+	return 0;
21	+	}
22	+	}
23	+	}
24	+
25	+	/// Nested pattern in if-let-case.
26	+	fn testNestedIfLetCase(o: Outer) -> i32 {
27	+	if let case Outer::A { inner: Inner { x, y }, z } = o {
28	+	return x + y + z;
29	+	}
30	+	return 0;
31	+	}
32	+
33	+	/// Nested pattern with placeholder for unused fields.
34	+	fn testNestedPlaceholder(o: Outer) -> i32 {
35	+	match o {
36	+	case Outer::A { inner: Inner { x, .. }, z } => {
37	+	return x + z;
38	+	}
39	+	case Outer::B => {
40	+	return 0;
41	+	}
42	+	}
43	+	}
44	+
45	+	/// Multi-level nesting: three records deep.
46	+	record Deep {
47	+	val: i32,
48	+	}
49	+
50	+	record Mid {
51	+	deep: Deep,
52	+	extra: i32,
53	+	}
54	+
55	+	union Wrapper {
56	+	W { mid: Mid, tag: i32 },
57	+	Empty,
58	+	}
59	+
60	+	fn testDeepNesting(w: Wrapper) -> i32 {
61	+	match w {
62	+	case Wrapper::W { mid: Mid { deep: Deep { val }, extra }, tag } => {
63	+	return val + extra + tag;
64	+	}
65	+	case Wrapper::Empty => {
66	+	return 0;
67	+	}
68	+	}
69	+	}
70	+
71	+	/// Nested union inside a union variant.
72	+	union Direction {
73	+	North,
74	+	South,
75	+	}
76	+
77	+	union Command {
78	+	Move { dir: Direction, speed: i32 },
79	+	Stop,
80	+	}
81	+
82	+	fn testNestedUnionLiteral(c: Command) -> i32 {
83	+	match c {
84	+	case Command::Move { dir: Direction::North, speed } => {
85	+	return speed;
86	+	}
87	+	case Command::Move { dir: Direction::South, speed } => {
88	+	return 0 - speed;
89	+	}
90	+	else => {
91	+	return 0;
92	+	}
93	+	}
94	+	}
95	+
96	+	/// Mixed record and union nesting with multiple fields.
97	+	record Point {
98	+	x: i32,
99	+	y: i32,
100	+	}
101	+
102	+	union Shape {
103	+	Circle { center: Point, radius: i32 },
104	+	Rect { origin: Point, size: Point },
105	+	None,
106	+	}
107	+
108	+	fn testMixedNesting(s: Shape) -> i32 {
109	+	match s {
110	+	case Shape::Circle { center: Point { x, y }, radius } => {
111	+	return x + y + radius;
112	+	}
113	+	case Shape::Rect { origin: Point { x: ox, y: oy }, size: Point { x: sx, y: sy } } => {
114	+	return ox + oy + sx + sy;
115	+	}
116	+	case Shape::None => {
117	+	return 0;
118	+	}
119	+	}
120	+	}
121	+
122	+	/// Nested union variant pattern inside record field.
123	+	union Pair {
124	+	Val { a: i32, b: i32 },
125	+	Empty,
126	+	}
127	+
128	+	record Container {
129	+	pair: Pair,
130	+	label: i32,
131	+	}
132	+
133	+	union Boxed {
134	+	Some { c: Container },
135	+	None,
136	+	}
137	+
138	+	fn testNestedUnionInRecord(bx: Boxed) -> i32 {
139	+	match bx {
140	+	case Boxed::Some { c: Container { pair: Pair::Val { a, b }, label } } => {
141	+	return a + b + label;
142	+	}
143	+	case Boxed::Some { c: Container { pair: Pair::Empty, .. } } => {
144	+	return -1;
145	+	}
146	+	else => {
147	+	return 0;
148	+	}
149	+	}
150	+	}
151	+
152	+	/// Nested pattern binding -- bind intermediate record as a whole.
153	+	fn testPartialNesting(s: Shape) -> i32 {
154	+	match s {
155	+	case Shape::Circle { center, radius } => {
156	+	return center.x + center.y + radius;
157	+	}
158	+	case Shape::Rect { origin, size: Point { x, y } } => {
159	+	return origin.x + origin.y + x + y;
160	+	}
161	+	case Shape::None => {
162	+	return 0;
163	+	}
164	+	}
165	+	}
166	+
167	+	@default fn main() -> i32 {
168	+	// Basic nested match.
169	+	let o1 = Outer::A { inner: Inner { x: 10, y: 20 }, z: 30 };
170	+	assert testNestedMatch(o1) == 60;
171	+	assert testNestedMatch(Outer::B) == 0;
172	+
173	+	// If-let-case nested.
174	+	assert testNestedIfLetCase(o1) == 60;
175	+	assert testNestedIfLetCase(Outer::B) == 0;
176	+
177	+	// Placeholder in nested pattern.
178	+	assert testNestedPlaceholder(o1) == 40;
179	+
180	+	// Three-level deep nesting.
181	+	let w = Wrapper::W { mid: Mid { deep: Deep { val: 100 }, extra: 200 }, tag: 300 };
182	+	assert testDeepNesting(w) == 600;
183	+	assert testDeepNesting(Wrapper::Empty) == 0;
184	+
185	+	// Nested union literal inside union variant.
186	+	let north = Command::Move { dir: Direction::North, speed: 5 };
187	+	assert testNestedUnionLiteral(north) == 5;
188	+	let south = Command::Move { dir: Direction::South, speed: 3 };
189	+	assert testNestedUnionLiteral(south) == -3;
190	+	assert testNestedUnionLiteral(Command::Stop) == 0;
191	+
192	+	// Mixed nesting: record fields destructured in multiple arms.
193	+	let circ = Shape::Circle { center: Point { x: 1, y: 2 }, radius: 10 };
194	+	assert testMixedNesting(circ) == 13;
195	+	let rect = Shape::Rect { origin: Point { x: 3, y: 4 }, size: Point { x: 5, y: 6 } };
196	+	assert testMixedNesting(rect) == 18;
197	+	assert testMixedNesting(Shape::None) == 0;
198	+
199	+	// Nested union variant pattern inside record inside union.
200	+	let bx = Boxed::Some { c: Container { pair: Pair::Val { a: 7, b: 8 }, label: 100 } };
201	+	assert testNestedUnionInRecord(bx) == 115;
202	+	let bx2 = Boxed::Some { c: Container { pair: Pair::Empty, label: 99 } };
203	+	assert testNestedUnionInRecord(bx2) == -1;
204	+	assert testNestedUnionInRecord(Boxed::None) == 0;
205	+
206	+	// Partial nesting: bind one field whole, destructure another.
207	+	assert testPartialNesting(circ) == 13;
208	+	assert testPartialNesting(rect) == 18;
209	+	assert testPartialNesting(Shape::None) == 0;
210	+
211	+	return 0;
212	+	}

lib/std/arch/rv64/tests/match.nested.record.rad added +84 -0

1	+	//! Test nested record destructuring inside union variant patterns.
2	+
3	+	record Point {
4	+	x: i32,
5	+	y: i32,
6	+	}
7	+
8	+	record Rect {
9	+	origin: Point,
10	+	size: Point,
11	+	}
12	+
13	+	union Shape {
14	+	Circle { center: Point, radius: i32 },
15	+	Rectangle { rect: Rect },
16	+	None,
17	+	}
18	+
19	+	/// Nested record destructuring in multiple arms.
20	+	fn area(s: Shape) -> i32 {
21	+	match s {
22	+	case Shape::Circle { center: Point { x, y }, radius } => {
23	+	return x + y + radius;
24	+	}
25	+	case Shape::Rectangle { rect: Rect { origin: Point { x: ox, y: oy }, size: Point { x: w, y: h } } } => {
26	+	return ox + oy + w * h;
27	+	}
28	+	case Shape::None => {
29	+	return 0;
30	+	}
31	+	}
32	+	}
33	+
34	+	/// Partial nesting: bind intermediate record as a whole.
35	+	fn partial(s: Shape) -> i32 {
36	+	match s {
37	+	case Shape::Circle { center, radius } => {
38	+	return center.x + center.y + radius;
39	+	}
40	+	case Shape::Rectangle { rect } => {
41	+	return rect.origin.x + rect.size.x * rect.size.y;
42	+	}
43	+	case Shape::None => {
44	+	return -1;
45	+	}
46	+	}
47	+	}
48	+
49	+	/// Nested with placeholder to ignore fields.
50	+	fn withPlaceholder(s: Shape) -> i32 {
51	+	match s {
52	+	case Shape::Circle { center: Point { x, .. }, radius } => {
53	+	return x + radius;
54	+	}
55	+	case Shape::Rectangle { rect: Rect { size: Point { x: w, y: h }, .. } } => {
56	+	return w * h;
57	+	}
58	+	case Shape::None => {
59	+	return 0;
60	+	}
61	+	}
62	+	}
63	+
64	+	@default fn main() -> i32 {
65	+	let c = Shape::Circle { center: Point { x: 3, y: 4 }, radius: 5 };
66	+	let r = Shape::Rectangle { rect: Rect { origin: Point { x: 1, y: 2 }, size: Point { x: 10, y: 20 } } };
67	+
68	+	// area tests
69	+	assert area(c) == 12;
70	+	assert area(r) == 203;
71	+	assert area(Shape::None) == 0;
72	+
73	+	// partial tests
74	+	assert partial(c) == 12;
75	+	assert partial(r) == 201;
76	+	assert partial(Shape::None) == -1;
77	+
78	+	// withPlaceholder tests
79	+	assert withPlaceholder(c) == 8;
80	+	assert withPlaceholder(r) == 200;
81	+	assert withPlaceholder(Shape::None) == 0;
82	+
83	+	return 0;
84	+	}

lib/std/arch/rv64/tests/match.nested.union.rad added +81 -0

1	+	//! Test nested union variant patterns inside record fields.
2	+
3	+	union Dir { North, South, East, West }
4	+
5	+	union Command {
6	+	Move { dir: Dir, speed: i32 },
7	+	Turn { dir: Dir },
8	+	Stop,
9	+	}
10	+
11	+	/// Match nested union variants within record field patterns.
12	+	fn dispatch(c: Command) -> i32 {
13	+	match c {
14	+	case Command::Move { dir: Dir::North, speed } => {
15	+	return speed;
16	+	}
17	+	case Command::Move { dir: Dir::South, speed } => {
18	+	return 0 - speed;
19	+	}
20	+	case Command::Move { dir: Dir::East, speed } => {
21	+	return speed * 2;
22	+	}
23	+	case Command::Move { dir: Dir::West, speed } => {
24	+	return speed * 3;
25	+	}
26	+	case Command::Turn { dir: Dir::North } => {
27	+	return 100;
28	+	}
29	+	case Command::Turn { dir: Dir::South } => {
30	+	return 200;
31	+	}
32	+	else => {
33	+	return 0;
34	+	}
35	+	}
36	+	}
37	+
38	+	/// Same outer variant appears multiple times with different nested patterns.
39	+	fn moveOnly(c: Command) -> i32 {
40	+	match c {
41	+	case Command::Move { dir: Dir::North, speed } => {
42	+	return speed + 10;
43	+	}
44	+	case Command::Move { dir: Dir::South, speed } => {
45	+	return speed + 20;
46	+	}
47	+	else => {
48	+	return -1;
49	+	}
50	+	}
51	+	}
52	+
53	+	@default fn main() -> i32 {
54	+	// dispatch tests
55	+	let mn = Command::Move { dir: Dir::North, speed: 5 };
56	+	assert dispatch(mn) == 5;
57	+	let ms = Command::Move { dir: Dir::South, speed: 3 };
58	+	assert dispatch(ms) == -3;
59	+	let me = Command::Move { dir: Dir::East, speed: 7 };
60	+	assert dispatch(me) == 14;
61	+	let mw = Command::Move { dir: Dir::West, speed: 4 };
62	+	assert dispatch(mw) == 12;
63	+	let tn = Command::Turn { dir: Dir::North };
64	+	assert dispatch(tn) == 100;
65	+	let ts = Command::Turn { dir: Dir::South };
66	+	assert dispatch(ts) == 200;
67	+	let te = Command::Turn { dir: Dir::East };
68	+	assert dispatch(te) == 0;
69	+	assert dispatch(Command::Stop) == 0;
70	+
71	+	// moveOnly tests
72	+	let mn2 = Command::Move { dir: Dir::North, speed: 5 };
73	+	assert moveOnly(mn2) == 15;
74	+	let ms2 = Command::Move { dir: Dir::South, speed: 3 };
75	+	assert moveOnly(ms2) == 23;
76	+	let me2 = Command::Move { dir: Dir::East, speed: 1 };
77	+	assert moveOnly(me2) == -1;
78	+	assert moveOnly(Command::Stop) == -1;
79	+
80	+	return 0;
81	+	}

lib/std/arch/rv64/tests/match.nested.whilelet.rad added +103 -0

1	+	//! Test nested patterns in while-let loops.
2	+
3	+	record Pair {
4	+	a: i32,
5	+	b: i32,
6	+	}
7	+
8	+	union Opt {
9	+	Some { pair: Pair },
10	+	None,
11	+	}
12	+
13	+	fn get(items: *[Opt], idx: u32) -> Opt {
14	+	if idx < items.len {
15	+	return items[idx];
16	+	}
17	+	return Opt::None;
18	+	}
19	+
20	+	/// While-let with nested record destructuring.
21	+	fn sumPairs(items: *[Opt]) -> i32 {
22	+	let mut sum: i32 = 0;
23	+	let mut i: u32 = 0;
24	+	while let case Opt::Some { pair: Pair { a, b } } = get(items, i) {
25	+	sum = sum + a + b;
26	+	i = i + 1;
27	+	}
28	+	return sum;
29	+	}
30	+
31	+	/// While-let with nested record and guard.
32	+	fn sumPositive(items: *[Opt]) -> i32 {
33	+	let mut sum: i32 = 0;
34	+	let mut i: u32 = 0;
35	+	while let case Opt::Some { pair: Pair { a, b } } = get(items, i); a > 0 {
36	+	sum = sum + a + b;
37	+	i = i + 1;
38	+	}
39	+	return sum;
40	+	}
41	+
42	+	union Dir { North, South }
43	+
44	+	union Command {
45	+	Move { dir: Dir, speed: i32 },
46	+	Stop,
47	+	}
48	+
49	+	fn getCmd(items: *[Command], idx: u32) -> Command {
50	+	if idx < items.len {
51	+	return items[idx];
52	+	}
53	+	return Command::Stop;
54	+	}
55	+
56	+	/// While-let with nested union variant pattern.
57	+	fn sumNorthSpeeds(items: *[Command]) -> i32 {
58	+	let mut sum: i32 = 0;
59	+	let mut i: u32 = 0;
60	+	while let case Command::Move { dir: Dir::North, speed } = getCmd(items, i) {
61	+	sum = sum + speed;
62	+	i = i + 1;
63	+	}
64	+	return sum;
65	+	}
66	+
67	+	@default fn main() -> i32 {
68	+	// sumPairs
69	+	let items: *[Opt] = &[
70	+	Opt::Some { pair: Pair { a: 1, b: 2 } },
71	+	Opt::Some { pair: Pair { a: 3, b: 4 } },
72	+	];
73	+	assert sumPairs(items) == 10;
74	+
75	+	// sumPairs: empty
76	+	let empty: *[Opt] = &[];
77	+	assert sumPairs(empty) == 0;
78	+
79	+	// sumPositive: stops at first non-positive a.
80	+	let mixed: *[Opt] = &[
81	+	Opt::Some { pair: Pair { a: 3, b: 4 } },
82	+	Opt::Some { pair: Pair { a: -1, b: 5 } },
83	+	Opt::Some { pair: Pair { a: 2, b: 6 } },
84	+	];
85	+	assert sumPositive(mixed) == 7;
86	+
87	+	// sumNorthSpeeds
88	+	let cmds: *[Command] = &[
89	+	Command::Move { dir: Dir::North, speed: 5 },
90	+	Command::Move { dir: Dir::North, speed: 10 },
91	+	];
92	+	assert sumNorthSpeeds(cmds) == 15;
93	+
94	+	// sumNorthSpeeds: stops at South.
95	+	let cmds2: *[Command] = &[
96	+	Command::Move { dir: Dir::North, speed: 3 },
97	+	Command::Move { dir: Dir::South, speed: 7 },
98	+	Command::Move { dir: Dir::North, speed: 9 },
99	+	];
100	+	assert sumNorthSpeeds(cmds2) == 3;
101	+
102	+	return 0;
103	+	}

lib/std/arch/rv64/tests/match.string.rad added +80 -0

1	+	//! Test string literal patterns in match statements.
2	+
3	+	/// Top-level string match.
4	+	fn classify(s: *[u8]) -> i32 {
5	+	match s {
6	+	case "red" => {
7	+	return 1;
8	+	}
9	+	case "green" => {
10	+	return 2;
11	+	}
12	+	case "blue" => {
13	+	return 3;
14	+	}
15	+	else => {
16	+	return 0;
17	+	}
18	+	}
19	+	}
20	+
21	+	/// String pattern nested inside a union variant field.
22	+	union Cmd {
23	+	Say { msg: *[u8], count: i32 },
24	+	Quit,
25	+	}
26	+
27	+	fn dispatch(c: Cmd) -> i32 {
28	+	match c {
29	+	case Cmd::Say { msg: "hello", count } => {
30	+	return count;
31	+	}
32	+	case Cmd::Say { msg: "bye", count } => {
33	+	return 0 - count;
34	+	}
35	+	else => {
36	+	return 0;
37	+	}
38	+	}
39	+	}
40	+
41	+	/// String pattern in if-let-case.
42	+	fn isHello(c: Cmd) -> bool {
43	+	if let case Cmd::Say { msg: "hello", .. } = c {
44	+	return true;
45	+	}
46	+	return false;
47	+	}
48	+
49	+	/// String pattern in let-else.
50	+	fn extractBye(c: Cmd) -> i32 {
51	+	let case Cmd::Say { msg: "bye", count } = c
52	+	else { return -1; };
53	+	return count;
54	+	}
55	+
56	+	@default fn main() -> i32 {
57	+	// classify
58	+	assert classify("red") == 1;
59	+	assert classify("green") == 2;
60	+	assert classify("blue") == 3;
61	+	assert classify("other") == 0;
62	+
63	+	// dispatch
64	+	assert dispatch(Cmd::Say { msg: "hello", count: 3 }) == 3;
65	+	assert dispatch(Cmd::Say { msg: "bye", count: 5 }) == -5;
66	+	assert dispatch(Cmd::Say { msg: "other", count: 1 }) == 0;
67	+	assert dispatch(Cmd::Quit) == 0;
68	+
69	+	// isHello
70	+	assert isHello(Cmd::Say { msg: "hello", count: 1 });
71	+	assert not isHello(Cmd::Say { msg: "bye", count: 1 });
72	+	assert not isHello(Cmd::Quit);
73	+
74	+	// extractBye
75	+	assert extractBye(Cmd::Say { msg: "bye", count: 7 }) == 7;
76	+	assert extractBye(Cmd::Say { msg: "hello", count: 7 }) == -1;
77	+	assert extractBye(Cmd::Quit) == -1;
78	+
79	+	return 0;
80	+	}

lib/std/lang/lower.rad +200 -49

    subject: *MatchSubject,
    pattern: *ast::Node,
    matchBlock: BlockId,
    fallthrough: BlockId
) throws (LowerError) {
    // Wildcard `_` always matches.
    // Wildcards always match; array patterns are tested element-by-element
    // during binding, so they also unconditionally enter the match block.
    if isWildcardPattern(pattern) {
        try emitJmp(self, matchBlock);
        return;
    }
    if let case ast::NodeValue::ArrayLit(_) = pattern.value {
        try emitJmp(self, matchBlock);
        return;
    }
    let isNil = pattern.value == ast::NodeValue::Nil;

    match subject.kind {
        case MatchSubjectKind::OptionalPtr if isNil => {
            // Null pointer optimization: branch on the data pointer being null.

                let tagReg = tvalTagReg(self, base);

                try emitBrCmp(self, il::CmpOp::Eq, il::Type::W8, il::Val::Reg(tagReg), il::Val::Imm(variantTag as i64), matchBlock, fallthrough);
            }
        }
        else => { // Scalar comparison.
        else => { // Value comparison.
            assert not isNil;
            let pattVal = try lowerExpr(self, pattern);
            try emitBrCmp(self, il::CmpOp::Eq, subject.ilType, subject.val, pattVal, matchBlock, fallthrough);
            if isAggregateType(subject.type) {
                // Aggregate types need structural comparison rather than
                // scalar compare.
                let subjectReg = emitValToReg(self, subject.val);
                let pattReg = emitValToReg(self, pattVal);
                let eq = try lowerAggregateEq(self, subject.type, subjectReg, pattReg, 0);
                let eqReg = emitValToReg(self, eq);

                try emitBr(self, eqReg, matchBlock, fallthrough);
            } else {
                try emitBrCmp(self, il::CmpOp::Eq, subject.ilType, subject.val, pattVal, matchBlock, fallthrough);
            }
        }
    }
}

/// Emit branches for multiple patterns. The first pattern that matches

    // Declare the variable in the current block's scope.
    return newVar(self, name, ilType(self.low, subject.bindType), mutable, subject.val);
}

/// Bind variables from inside case patterns (union variants, records, slices).
fn bindPatternVariables(self: *mut FnLowerer, subject: *MatchSubject, patterns: *mut [*ast::Node]) throws (LowerError) {
/// `failBlock` is passed when nested patterns may require additional tests
/// that branch on mismatch (e.g. nested union variant tests).
fn bindPatternVariables(self: *mut FnLowerer, subject: *MatchSubject, patterns: *mut [*ast::Node], failBlock: BlockId) throws (LowerError) {
    for pattern in patterns {

        // Handle simple variant patterns like `Variant(x)`.
        // TODO: Why is this handled differently from the cases below?
        if let arg = resolver::variantPatternBinding(self.low.resolver, pattern) {
            if let case ast::NodeValue::Ident(name) = arg.value {
                if let bindType = resolver::typeFor(self.low.resolver, arg) {
                    let case MatchSubjectKind::Union(unionInfo) = subject.kind
                        else panic "bindPatternVariables: expected union subject";
                    let valOffset = unionInfo.valOffset as i32;

                    try bindPayloadVariable(self, name, subject.val, bindType, subject.by, valOffset, false);
            if let bindType = resolver::typeFor(self.low.resolver, arg) {
                let case MatchSubjectKind::Union(unionInfo) = subject.kind
                    else panic "bindPatternVariables: expected union subject";
                let valOffset = unionInfo.valOffset as i32;

                match arg.value {
                    case ast::NodeValue::Ident(name) => {
                        try bindPayloadVariable(self, name, subject.val, bindType, subject.by, valOffset, false);
                    }
                    case ast::NodeValue::Placeholder => {}
                    else => {
                        // Nested pattern inside a variant call, e.g. `Variant(Inner { x, y })`.
                        let base = emitValToReg(self, subject.val);
                        let payloadBase = emitPtrOffset(self, base, valOffset);
                        let fieldInfo = resolver::RecordField {
                            name: nil,
                            fieldType: bindType,
                            offset: 0,
                        };
                        try bindFieldVariable(self, arg, payloadBase, fieldInfo, subject.by, failBlock);
                    }
                }
            }
        }
        match pattern.value {
            // Compound variant patterns like `Variant { a, b }`.
            case ast::NodeValue::RecordLit(lit) =>
                try bindRecordPatternFields(self, subject, pattern, lit),
                try bindRecordPatternFields(self, subject, pattern, lit, failBlock),
            // Array patterns like `[a, b, c]`.
            case ast::NodeValue::ArrayLit(_) =>
                panic "bindPatternVariables: array patterns not yet implemented",
            case ast::NodeValue::ArrayLit(items) =>
                try bindArrayPatternElements(self, subject, items, failBlock),
            // Literals, wildcards, identifiers: no bindings needed.
            else => {},
        }
    }
}

/// Bind variables from a record literal pattern (e.g., `Variant { op, a, b }`).
// TODO: Currently only handles union variant payloads. Standalone record patterns are not
// yet supported.
fn bindRecordPatternFields(self: *mut FnLowerer, subject: *MatchSubject, pattern: *ast::Node, lit: ast::RecordLit) throws (LowerError) {
/// Bind variables from an array literal pattern (e.g., `[a, 1, c]`).
/// Each element is either bound as a variable, skipped (placeholder), or
/// tested against the subject element, branching to `failBlock` on mismatch.
fn bindArrayPatternElements(
    self: *mut FnLowerer,
    subject: *MatchSubject,
    items: *mut [*ast::Node],
    failBlock: BlockId
) throws (LowerError) {
    let case resolver::Type::Array(arrInfo) = subject.type
        else throw LowerError::ExpectedSliceOrArray;

    let elemTy = *arrInfo.item;
    let elemLayout = resolver::getTypeLayout(elemTy);
    let stride = elemLayout.size as i32;
    let base = emitValToReg(self, subject.val);

    for elem, i in items {
        let fieldInfo = resolver::RecordField {
            name: nil,
            fieldType: elemTy,
            offset: (i as i32) * stride,
        };
        try bindFieldVariable(self, elem, base, fieldInfo, subject.by, failBlock);
    }
}

fn bindRecordPatternFields(self: *mut FnLowerer, subject: *MatchSubject, pattern: *ast::Node, lit: ast::RecordLit, failBlock: BlockId) throws (LowerError) {
    // No fields to bind (e.g., `{ .. }`).
    if lit.fields.len == 0 {
        return;
    }
    // Get the union type info from the subject.

    // Get the payload base pointer which points to the record within the tagged union.
    let base = emitValToReg(self, subject.val);
    let valOffset = unionInfo.valOffset as i32;
    let payloadBase = emitPtrOffset(self, base, valOffset);

    // Bind each field.
    try bindNestedRecordFields(self, payloadBase, lit, recInfo, subject.by, failBlock);
}

/// Emit a field read from a base pointer.
fn emitFieldRead(self: *mut FnLowerer, base: il::Reg, fieldInfo: resolver::RecordField, matchBy: resolver::MatchBy) -> il::Val {
    match matchBy {
        case resolver::MatchBy::Value => {
            return emitRead(self, base, fieldInfo.offset, fieldInfo.fieldType);
        }
        case resolver::MatchBy::Ref, resolver::MatchBy::MutRef => {
            return il::Val::Reg(emitPtrOffset(self, base, fieldInfo.offset));
        }
    }
}

/// Bind a single record field to a pattern variable, with support for nested
/// pattern tests that branch to `failBlock` on mismatch.
fn bindFieldVariable(
    self: *mut FnLowerer,
    binding: *ast::Node,
    base: il::Reg,
    fieldInfo: resolver::RecordField,
    matchBy: resolver::MatchBy,
    failBlock: BlockId
) throws (LowerError) {
    match binding.value {
        case ast::NodeValue::Ident(name) => {
            let val = emitFieldRead(self, base, fieldInfo, matchBy);
            newVar(self, name, ilType(self.low, fieldInfo.fieldType), false, val);
        }
        case ast::NodeValue::Placeholder => {}
        case ast::NodeValue::RecordLit(lit) => {
            // Check if this record literal is a union variant pattern.
            if let keyNode = resolver::patternVariantKeyNode(binding) {
                if let case resolver::NodeExtra::UnionVariant { .. } = resolver::nodeData(self.low.resolver, keyNode).extra {
                    try emitNestedFieldTest(self, binding, base, fieldInfo, matchBy, failBlock);
                    return;
                }
            }
            // Plain nested record destructuring pattern.
            let recInfo = resolver::getRecord(fieldInfo.fieldType)
                else throw LowerError::ExpectedRecord;
            let nestedBase = emitPtrOffset(self, base, fieldInfo.offset);

            try bindNestedRecordFields(self, nestedBase, lit, recInfo, matchBy, failBlock);
        }
        else => {
            // Nested pattern requiring a test (union variant scope access, literal, etc).
            try emitNestedFieldTest(self, binding, base, fieldInfo, matchBy, failBlock);
        }
    }
}

/// Emit a nested pattern test for a record field value, branching to
/// `failBlock` if the pattern does not match. On success, continues in
/// a fresh block and binds any nested variables.
fn emitNestedFieldTest(
    self: *mut FnLowerer,
    pattern: *ast::Node,
    base: il::Reg,
    fieldInfo: resolver::RecordField,
    matchBy: resolver::MatchBy,
    failBlock: BlockId
) throws (LowerError) {
    let fieldType = fieldInfo.fieldType;
    let fieldPtr = emitPtrOffset(self, base, fieldInfo.offset);

    // Build a MatchSubject for the nested field.
    let ilTy = ilType(self.low, fieldType);
    let kind = matchSubjectKind(fieldType);

    // For aggregate subjects, the value must be a pointer.
    let mut val = il::Val::Reg(fieldPtr);
    if not isAggregateType(fieldType) {
        val = emitRead(self, base, fieldInfo.offset, fieldType);
    }
    let nestedSubject = MatchSubject {
        val,
        type: fieldType,
        ilType: ilTy,
        bindType: fieldType,
        kind,
        by: matchBy,
    };

    // Emit the pattern test: on success jump to `continueBlock`, on fail to `failBlock`.
    let continueBlock = try createBlock(self, "nest");
    try emitPatternMatch(self, &nestedSubject, pattern, continueBlock, failBlock);
    try switchToAndSeal(self, continueBlock);

    // After the test succeeds, bind any nested variables.
    let patterns: *mut [*ast::Node] = &mut [pattern];
    try bindPatternVariables(self, &nestedSubject, patterns, failBlock);
}

/// Bind variables from a nested record literal pattern.
fn bindNestedRecordFields(
    self: *mut FnLowerer,
    base: il::Reg,
    lit: ast::RecordLit,
    recInfo: resolver::RecordType,
    matchBy: resolver::MatchBy,
    failBlock: BlockId
) throws (LowerError) {
    for fieldNode in lit.fields {
        let case ast::NodeValue::RecordLitField(field) = fieldNode.value else {
            throw LowerError::UnexpectedNodeValue(fieldNode);
        };
        let fieldIdx = resolver::recordFieldIndexFor(self.low.resolver, fieldNode)

        if fieldIdx >= recInfo.fields.len {
            throw LowerError::MissingMetadata;
        }
        let fieldInfo = recInfo.fields[fieldIdx];

        bindFieldVariable(self, field.value, payloadBase, fieldInfo, subject.by);
        try bindFieldVariable(self, field.value, base, fieldInfo, matchBy, failBlock);
    }
}

/// Bind a single record field to a pattern variable.
fn bindFieldVariable(
    self: *mut FnLowerer,
    binding: *ast::Node,
    base: il::Reg,
    fieldInfo: resolver::RecordField,
    matchBy: resolver::MatchBy
) {
    let case ast::NodeValue::Ident(name) = binding.value else {
        return; // Not an identifier binding.
    };
    let mut val: il::Val = undefined;
    match matchBy {
        case resolver::MatchBy::Value => {
            val = emitRead(self, base, fieldInfo.offset, fieldInfo.fieldType);
        },
        case resolver::MatchBy::Ref, resolver::MatchBy::MutRef => {
            val = il::Val::Reg(emitPtrOffset(self, base, fieldInfo.offset));
        },
    }
    let _ = newVar(self, name, ilType(self.low, fieldInfo.fieldType), false, val);
}

/// Lower function body to a list of basic blocks.
fn lowerFnBody(self: *mut FnLowerer, body: *ast::Node) -> *[il::Block] throws (LowerError) {
    // Create and switch to entry block.
    let entry = try createBlock(self, "entry");
    self.entryBlock = entry;

        // Body block: where the case body lives.
        let mut bodyLabel = "case";
        if prong.arm == ast::ProngArm::Else {
            bodyLabel = "else";
        }
        let bodyBlock = try createBlock(self, bodyLabel);
        let mut bodyBlock = try createBlock(self, bodyLabel);
        if not hasGuard {
            entryBlock = bodyBlock;
        }
        // Fallthrough block: jumped to when pattern or guard fails.
        let nextArm = try createBlock(self, "arm");

        }
        // Switch to entry block, where any variable bindings need to be created.
        try switchToAndSeal(self, entryBlock);

        // Bind pattern variables after successful match. Note that the guard
        // has not been evaluated yet.
        // has not been evaluated yet. Nested patterns may emit additional
        // tests that branch to `nextArm` on failure, switching the current
        // block.
        match prong.arm {
            case ast::ProngArm::Binding(pat) =>
                try bindMatchVariable(self, &subject, pat, false),
            case ast::ProngArm::Case(patterns) =>
                try bindPatternVariables(self, &subject, patterns),
                try bindPatternVariables(self, &subject, patterns, nextArm),
            else => {},
        }

        // Evaluate guard if present; can still fail to next arm.
        if let g = prong.guard {
            try emitCondBranch(self, g, bodyBlock, nextArm);
        } else if currentBlock(self).n != bodyBlock.n {
            // Nested tests changed the current block. Create a new body block
            // after the nest blocks to maintain RPO ordering, and jump to it.
            bodyBlock = try createBlock(self, bodyLabel);
            try emitJmp(self, bodyBlock);
        }
        // Lower prong body and jump to merge if unterminated.
        try switchToAndSeal(self, bodyBlock);
        try lowerNode(self, prong.body);
        try emitMergeIfUnterminated(self, &mut mergeBlock);

        case ast::PatternKind::Case => {
            let patterns: *mut [*ast::Node] = &mut [pat.pattern];
            // Jump to `targetBlock` if the pattern matches, `failBlock` otherwise.
            try emitPatternMatches(self, subject, patterns, targetBlock, failBlock);
            try switchToAndSeal(self, targetBlock);
            // Bind any variables inside the pattern.
            try bindPatternVariables(self, subject, patterns);
            // Bind any variables inside the pattern. Nested patterns may
            // emit additional tests that branch to `failBlock`, switching
            // the current block.
            try bindPatternVariables(self, subject, patterns, failBlock);
        }
        case ast::PatternKind::Binding => {
            // Jump to `targetBlock` if there is a value present, `failBlock` otherwise.
            try emitBindingTest(self, subject, targetBlock, failBlock);
            try switchToAndSeal(self, targetBlock);

    }
    // Handle guard: on success jump to `successBlock`, on failure jump to `failBlock`.
    if let g = pat.guard {
        try emitCondBranch(self, g, *successBlock, failBlock);
        try switchToAndSeal(self, *successBlock);
    } else if currentBlock(self).n != targetBlock.n {
        // Nested tests changed the current block. Create a new success block
        // after the nest blocks to maintain RPO ordering, and jump to it.
        *successBlock = try createBlock(self, successLabel);

        try emitJmp(self, *successBlock);
        try switchToAndSeal(self, *successBlock);
    }
}

/// Lower a `let-else` statement.
fn lowerLetElse(self: *mut FnLowerer, letElse: ast::LetElse) throws (LowerError) {

lib/std/lang/lower/tests/match.nested.iflet.rad added +18 -0

1	+	/// Nested record pattern in if-let-case.
2	+	record Inner {
3	+	x: i32,
4	+	y: i32,
5	+	}
6	+
7	+	union Outer {
8	+	A { inner: Inner, z: i32 },
9	+	B,
10	+	}
11	+
12	+	/// If-let-case with nested record destructuring.
13	+	fn extract(o: Outer) -> i32 {
14	+	if let case Outer::A { inner: Inner { x, y }, z } = o {
15	+	return x + y + z;
16	+	}
17	+	return 0;
18	+	}

lib/std/lang/lower/tests/match.nested.iflet.ril added +19 -0

1	+	fn w32 $extract(w64 %0) {
2	+	@entry0
3	+	reserve %1 16 4;
4	+	blit %1 %0 16;
5	+	load w8 %2 %1 0;
6	+	br.eq w8 %2 0 @then1 @else2;
7	+	@then1
8	+	add w64 %3 %1 4;
9	+	sload w32 %4 %3 0;
10	+	sload w32 %5 %3 4;
11	+	sload w32 %6 %3 8;
12	+	add w32 %7 %4 %5;
13	+	add w32 %8 %7 %6;
14	+	ret %8;
15	+	@else2
16	+	jmp @merge3;
17	+	@merge3
18	+	ret 0;
19	+	}

lib/std/lang/lower/tests/match.nested.pattern.rad added +18 -0

1	+	/// Nested pattern matching in case arms.
2	+	record Inner {
3	+	x: i32,
4	+	y: i32,
5	+	}
6	+
7	+	union Outer {
8	+	A { inner: Inner, z: i32 },
9	+	B,
10	+	}
11	+
12	+	/// Destructure a nested record inside a union variant pattern.
13	+	fn nested(o: Outer) -> i32 {
14	+	match o {
15	+	case Outer::A { inner: Inner { x, y }, z } => return x + y + z,
16	+	case Outer::B => return 0,
17	+	}
18	+	}

lib/std/lang/lower/tests/match.nested.pattern.ril added +21 -0

1	+	fn w32 $nested(w64 %0) {
2	+	@entry0
3	+	reserve %1 16 4;
4	+	blit %1 %0 16;
5	+	jmp @arm1;
6	+	@arm1
7	+	load w8 %2 %1 0;
8	+	br.eq w8 %2 0 @case2 @arm3;
9	+	@case2
10	+	add w64 %3 %1 4;
11	+	sload w32 %4 %3 0;
12	+	sload w32 %5 %3 4;
13	+	sload w32 %6 %3 8;
14	+	add w32 %7 %4 %5;
15	+	add w32 %8 %7 %6;
16	+	ret %8;
17	+	@arm3
18	+	jmp @case4;
19	+	@case4
20	+	ret 0;
21	+	}

lib/std/lang/lower/tests/match.nested.record.rad added +18 -0

1	+	/// Nested record destructuring inside a union variant.
2	+	record Point {
3	+	x: i32,
4	+	y: i32,
5	+	}
6	+
7	+	union Shape {
8	+	Circle { center: Point, radius: i32 },
9	+	None,
10	+	}
11	+
12	+	/// Destructure nested record fields in both arms.
13	+	fn getX(s: Shape) -> i32 {
14	+	match s {
15	+	case Shape::Circle { center: Point { x, .. }, .. } => return x,
16	+	case Shape::None => return 0,
17	+	}
18	+	}

lib/std/lang/lower/tests/match.nested.record.ril added +17 -0

1	+	fn w32 $getX(w64 %0) {
2	+	@entry0
3	+	reserve %1 16 4;
4	+	blit %1 %0 16;
5	+	jmp @arm1;
6	+	@arm1
7	+	load w8 %2 %1 0;
8	+	br.eq w8 %2 0 @case2 @arm3;
9	+	@case2
10	+	add w64 %3 %1 4;
11	+	sload w32 %4 %3 0;
12	+	ret %4;
13	+	@arm3
14	+	jmp @case4;
15	+	@case4
16	+	ret 0;
17	+	}

lib/std/lang/lower/tests/match.nested.union.rad added +16 -0

1	+	/// Nested union variant pattern inside a record field.
2	+	union Dir { N, S }
3	+
4	+	union Cmd {
5	+	Move { dir: Dir, speed: i32 },
6	+	Stop,
7	+	}
8	+
9	+	/// Match nested union variants inside record fields.
10	+	fn dispatch(c: Cmd) -> i32 {
11	+	match c {
12	+	case Cmd::Move { dir: Dir::N, speed } => return speed,
13	+	case Cmd::Move { dir: Dir::S, speed } => return 0 - speed,
14	+	else => return 0,
15	+	}
16	+	}

lib/std/lang/lower/tests/match.nested.union.ril added +35 -0

1	+	fn w32 $dispatch(w64 %0) {
2	+	@entry0
3	+	reserve %1 12 4;
4	+	blit %1 %0 12;
5	+	jmp @arm1;
6	+	@arm1
7	+	load w8 %2 %1 0;
8	+	br.eq w8 %2 0 @case2 @arm3;
9	+	@case2
10	+	add w64 %3 %1 4;
11	+	load w8 %4 %3 0;
12	+	br.eq w8 %4 0 @nest4 @arm3;
13	+	@arm3
14	+	load w8 %6 %1 0;
15	+	br.eq w8 %6 0 @case6 @arm7;
16	+	@nest4
17	+	sload w32 %5 %3 4;
18	+	jmp @case5;
19	+	@case5
20	+	ret %5;
21	+	@case6
22	+	add w64 %7 %1 4;
23	+	load w8 %8 %7 0;
24	+	br.eq w8 %8 1 @nest8 @arm7;
25	+	@arm7
26	+	jmp @else10;
27	+	@nest8
28	+	sload w32 %9 %7 4;
29	+	jmp @case9;
30	+	@case9
31	+	sub w32 %10 0 %9;
32	+	ret %10;
33	+	@else10
34	+	ret 0;
35	+	}

lib/std/lang/resolver.rad +147 -15

                } else => {}
            }
        }
        case Type::Array(arrayInfo) => {
            if let case ast::NodeValue::ArrayLit(items) = pattern.value {
                if items.len as u32 != arrayInfo.length {
                    throw emitError(self, pattern, ErrorKind::RecordFieldCountMismatch(
                        CountMismatch { expected: arrayInfo.length, actual: items.len as u32 }
                    ));
                }
                let elemTy = *arrayInfo.item;
                for item in items {
                    try resolveCasePattern(self, item, elemTy, IdentMode::Bind, matchBy);
                }
                setNodeType(self, pattern, scrutineeTy);
                return;
            }
        } else => {}
    }
    // Handle non-binding patterns (literals, placeholders) and bindings.

    try visitOptional(self, forStmt.elseBranch, Type::Void);

    return setNodeType(self, node, Type::Void);
}

/// Check whether any pattern in a case prong is a wildcard `_`.
/// Get the node within a pattern that carries the `UnionVariant` extra.
/// For `ScopeAccess` it is the pattern itself, for `RecordLit` it is the
/// type name, and for `Call` it is the callee.
pub fn patternVariantKeyNode(pattern: *ast::Node) -> ?*ast::Node {
    match pattern.value {
        case ast::NodeValue::ScopeAccess(_) => return pattern,
        case ast::NodeValue::RecordLit(lit) => return lit.typeName,
        case ast::NodeValue::Call(call) => return call.callee,
        else => return nil,
    }
}

/// Get the i-th sub-pattern element from a compound pattern.
/// For `RecordLit` this is the i-th field's value; for `Call` it is the
/// i-th argument.
fn patternSubElement(pattern: *ast::Node, idx: u32) -> ?*ast::Node {
    match pattern.value {
        case ast::NodeValue::RecordLit(lit) => {
            if idx < lit.fields.len as u32 {
                if let case ast::NodeValue::RecordLitField(field) = lit.fields[idx].value {
                    return field.value;
                }
            }
        }
        case ast::NodeValue::Call(call) => {
            if idx < call.args.len as u32 {
                return call.args[idx];
            }
        }
        else => {}
    }
    return nil;
}

/// Get the number of sub-pattern elements in a compound pattern.
fn patternSubCount(pattern: *ast::Node) -> u32 {
    match pattern.value {
        case ast::NodeValue::RecordLit(lit) => return lit.fields.len as u32,
        case ast::NodeValue::Call(call) => return call.args.len as u32,
        else => return 0,
    }
}

/// Check whether a pattern contains nested sub-patterns that further
/// refine the match beyond the outer variant (e.g. nested union variant
/// tests or literal comparisons). Used to allow the same outer variant
/// to appear in multiple match arms.
fn hasNestedRefiningPattern(self: *Resolver, pattern: *ast::Node) -> bool {
    for i in 0..patternSubCount(pattern) {
        if let sub = patternSubElement(pattern, i) {
            if isRefiningPattern(self, sub) {
                return true;
            }
        }
    }
    return false;
}

/// Check whether a single pattern node is a refining pattern that tests
/// a value rather than just binding it. Union variants, literals, and
/// scope accesses are refining; identifiers, placeholders, and plain
/// record destructurings are not.
fn isRefiningPattern(self: *Resolver, pattern: *ast::Node) -> bool {
    match pattern.value {
        case ast::NodeValue::Ident(_), ast::NodeValue::Placeholder =>
            return false,
        case ast::NodeValue::RecordLit(_), ast::NodeValue::Call(_) => {
            if let keyNode = patternVariantKeyNode(pattern) {
                if let case NodeExtra::UnionVariant { .. } = self.nodeData.entries[keyNode.id].extra {
                    return true;
                }
            }
            // Plain record destructuring / non-variant call is not directly
            // refining; recurse to check sub-patterns.
            return hasNestedRefiningPattern(self, pattern);
        }
        case ast::NodeValue::ArrayLit(items) => {
            for item in items {
                if isRefiningPattern(self, item) {
                    return true;
                }
            }
            return false;
        }
        case ast::NodeValue::ScopeAccess(_) =>
            return true,
        else =>
            return true,
    }
}

/// Check whether any pattern in a case prong matches unconditionally.
/// A plain `_` or an all-binding array pattern (e.g. `[x, y]`) qualifies.
/// Note: top-level identifiers in `case` are comparisons, not bindings,
/// so they do not count as wildcards.
fn hasWildcardPattern(patterns: *mut [*ast::Node]) -> bool {
    for pattern in patterns {
        if let case ast::NodeValue::Placeholder = pattern.value {
            return true;
        match pattern.value {
            case ast::NodeValue::Placeholder => return true,
            case ast::NodeValue::ArrayLit(items) => {
                if isIrrefutableArrayPattern(items) {
                    return true;
                }
            }
            else => {}
        }
    }
    return false;
}

/// Check whether all elements of an array pattern are irrefutable.
/// Inside array patterns, identifiers are bindings, not comparisons.
fn isIrrefutableArrayPattern(items: *mut [*ast::Node]) -> bool {
    for item in items {
        match item.value {
            case ast::NodeValue::Ident(_), ast::NodeValue::Placeholder => {}
            case ast::NodeValue::ArrayLit(inner) => {
                if not isIrrefutableArrayPattern(inner) {
                    return false;
                }
            }
            else => return false,
        }
    }
    return true;
}

/// Analyze a match prong, checking for duplicate catch-alls. Returns the
/// unified match type.
fn resolveMatchProng(
    self: *mut Resolver,
    prongNode: *ast::Node,

        let case ast::NodeValue::MatchProng(prong) = prongNode.value
            else panic "resolveMatchUnion: expected match prong";

        matchType = try resolveMatchProng(self, prongNode, prong, subjectTy, &mut state, matchType, matchBy);

        // Record covered variants. Guarded prongs don't count as covering.
        // Guarded prongs don't count as covering. Patterns with nested
        // refining sub-patterns (e.g. matching different inner union variants)
        // don't count as duplicates or as fully covering.
        if prong.guard == nil {
            if let case ast::ProngArm::Case(patterns) = prong.arm {
                for pattern in patterns {
                    if let case NodeExtra::UnionVariant { ordinal: ix, .. } = self.nodeData.entries[pattern.id].extra {
                        if covered[ix] {
                            throw emitError(self, pattern, ErrorKind::DuplicateMatchPattern);
                        if not hasNestedRefiningPattern(self, pattern) {
                            if covered[ix] {
                                throw emitError(self, pattern, ErrorKind::DuplicateMatchPattern);
                            }
                            covered[ix] = true;
                            coveredCount += 1;
                        }
                        covered[ix] = true;
                        coveredCount += 1;
                    }
                }
            }
        }
    }

                        } else {
                            hasFalse = true;
                        }
                    }
                }
                // Constant case values are required for the match to be
                // considered static.
                if constValueEntry(self, p) == nil {
                    state.isConst = false;
                } else {
                    hasConstCase = true;
                // Scalar constant patterns allow the match to be lowered
                // to a switch instruction.
                if let c = constValueEntry(self, p) {
                    match c {
                        case ConstValue::Bool(_), ConstValue::Char(_), ConstValue::Int(_) =>
                            hasConstCase = true,
                        else =>
                            state.isConst = false,
                    }
                }
            }
        }
    }


        }
        case ast::NodeValue::Ident(_) => {
            try bindValueIdent(self, binding, binding, bindTy, false, 0, 0);
        }
        else => {
            throw emitError(self, binding, ErrorKind::ExpectedIdentifier);
            // Nested pattern: recursively resolve (record destructuring,
            // union variant, scope access, call, literals, etc).
            try resolveCasePattern(self, binding, ty, IdentMode::Bind, matchBy);
        }
    }
}

/// Bind record pattern fields to variables in the current scope.

lib/std/lang/resolver/tests.rad +2 -2


/// Test array pattern matching with element bindings.
/// Pattern syntax: `[x, y]` matches an array and binds elements.
@test fn testResolveMatchArrayPattern() throws (testing::TestError) {
    let mut a = testResolver();
    let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [x, y] => return x + y, else => return 0 } }";
    let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [x, y] => return x + y } }";
    let result = try resolveProgramStr(&mut a, program);
    try expectNoErrors(&result);
}

/// Test array pattern with placeholder elements.
/// Pattern syntax: `[_, y]` ignores first element.
@test fn testResolveMatchArrayPatternPlaceholder() throws (testing::TestError) {
    let mut a = testResolver();
    let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [_, y] => return y, else => return 0 } }";
    let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [_, y] => return y } }";
    let result = try resolveProgramStr(&mut a, program);
    try expectNoErrors(&result);
}

/// Test identifier pattern that binds the whole value.

2158	2158		subject: *MatchSubject,
2159	2159		pattern: *ast::Node,
2160	2160		matchBlock: BlockId,
2161	2161		fallthrough: BlockId
2162	2162		) throws (LowerError) {
2163		-	// Wildcard `_` always matches.
	2163	+	// Wildcards always match; array patterns are tested element-by-element
	2164	+	// during binding, so they also unconditionally enter the match block.
2164	2165		if isWildcardPattern(pattern) {
2165	2166		try emitJmp(self, matchBlock);
2166	2167		return;
2167	2168		}
	2169	+	if let case ast::NodeValue::ArrayLit(_) = pattern.value {
	2170	+	try emitJmp(self, matchBlock);
	2171	+	return;
	2172	+	}
2168	2173		let isNil = pattern.value == ast::NodeValue::Nil;
2169	2174
2170	2175		match subject.kind {
2171	2176		case MatchSubjectKind::OptionalPtr if isNil => {
2172	2177		// Null pointer optimization: branch on the data pointer being null.

2218	2223		let tagReg = tvalTagReg(self, base);
2219	2224
2220	2225		try emitBrCmp(self, il::CmpOp::Eq, il::Type::W8, il::Val::Reg(tagReg), il::Val::Imm(variantTag as i64), matchBlock, fallthrough);
2221	2226		}
2222	2227		}
2223		-	else => { // Scalar comparison.
	2228	+	else => { // Value comparison.
2224	2229		assert not isNil;
2225	2230		let pattVal = try lowerExpr(self, pattern);
2226		-	try emitBrCmp(self, il::CmpOp::Eq, subject.ilType, subject.val, pattVal, matchBlock, fallthrough);
	2231	+	if isAggregateType(subject.type) {
	2232	+	// Aggregate types need structural comparison rather than
	2233	+	// scalar compare.
	2234	+	let subjectReg = emitValToReg(self, subject.val);
	2235	+	let pattReg = emitValToReg(self, pattVal);
	2236	+	let eq = try lowerAggregateEq(self, subject.type, subjectReg, pattReg, 0);
	2237	+	let eqReg = emitValToReg(self, eq);
	2238	+
	2239	+	try emitBr(self, eqReg, matchBlock, fallthrough);
	2240	+	} else {
	2241	+	try emitBrCmp(self, il::CmpOp::Eq, subject.ilType, subject.val, pattVal, matchBlock, fallthrough);
	2242	+	}
2227	2243		}
2228	2244		}
2229	2245		}
2230	2246
2231	2247		/// Emit branches for multiple patterns. The first pattern that matches

3042	3058		// Declare the variable in the current block's scope.
3043	3059		return newVar(self, name, ilType(self.low, subject.bindType), mutable, subject.val);
3044	3060		}
3045	3061
3046	3062		/// Bind variables from inside case patterns (union variants, records, slices).
3047		-	fn bindPatternVariables(self: mut FnLowerer, subject: MatchSubject, patterns: mut [ast::Node]) throws (LowerError) {
	3063	+	/// `failBlock` is passed when nested patterns may require additional tests
	3064	+	/// that branch on mismatch (e.g. nested union variant tests).
	3065	+	fn bindPatternVariables(self: mut FnLowerer, subject: MatchSubject, patterns: mut [ast::Node], failBlock: BlockId) throws (LowerError) {
3048	3066		for pattern in patterns {
3049	3067
3050	3068		// Handle simple variant patterns like `Variant(x)`.
3051		-	// TODO: Why is this handled differently from the cases below?
3052	3069		if let arg = resolver::variantPatternBinding(self.low.resolver, pattern) {
3053		-	if let case ast::NodeValue::Ident(name) = arg.value {
3054		-	if let bindType = resolver::typeFor(self.low.resolver, arg) {
3055		-	let case MatchSubjectKind::Union(unionInfo) = subject.kind
3056		-	else panic "bindPatternVariables: expected union subject";
3057		-	let valOffset = unionInfo.valOffset as i32;
3058		-
3059		-	try bindPayloadVariable(self, name, subject.val, bindType, subject.by, valOffset, false);
	3070	+	if let bindType = resolver::typeFor(self.low.resolver, arg) {
	3071	+	let case MatchSubjectKind::Union(unionInfo) = subject.kind
	3072	+	else panic "bindPatternVariables: expected union subject";
	3073	+	let valOffset = unionInfo.valOffset as i32;
	3074	+
	3075	+	match arg.value {
	3076	+	case ast::NodeValue::Ident(name) => {
	3077	+	try bindPayloadVariable(self, name, subject.val, bindType, subject.by, valOffset, false);
	3078	+	}
	3079	+	case ast::NodeValue::Placeholder => {}
	3080	+	else => {
	3081	+	// Nested pattern inside a variant call, e.g. `Variant(Inner { x, y })`.
	3082	+	let base = emitValToReg(self, subject.val);
	3083	+	let payloadBase = emitPtrOffset(self, base, valOffset);
	3084	+	let fieldInfo = resolver::RecordField {
	3085	+	name: nil,
	3086	+	fieldType: bindType,
	3087	+	offset: 0,
	3088	+	};
	3089	+	try bindFieldVariable(self, arg, payloadBase, fieldInfo, subject.by, failBlock);
	3090	+	}
3060	3091		}
3061	3092		}
3062	3093		}
3063	3094		match pattern.value {
3064	3095		// Compound variant patterns like `Variant { a, b }`.
3065	3096		case ast::NodeValue::RecordLit(lit) =>
3066		-	try bindRecordPatternFields(self, subject, pattern, lit),
	3097	+	try bindRecordPatternFields(self, subject, pattern, lit, failBlock),
3067	3098		// Array patterns like `[a, b, c]`.
3068		-	case ast::NodeValue::ArrayLit(_) =>
3069		-	panic "bindPatternVariables: array patterns not yet implemented",
	3099	+	case ast::NodeValue::ArrayLit(items) =>
	3100	+	try bindArrayPatternElements(self, subject, items, failBlock),
3070	3101		// Literals, wildcards, identifiers: no bindings needed.
3071	3102		else => {},
3072	3103		}
3073	3104		}
3074	3105		}
3075	3106
3076		-	/// Bind variables from a record literal pattern (e.g., `Variant { op, a, b }`).
3077		-	// TODO: Currently only handles union variant payloads. Standalone record patterns are not
3078		-	// yet supported.
3079		-	fn bindRecordPatternFields(self: mut FnLowerer, subject: MatchSubject, pattern: *ast::Node, lit: ast::RecordLit) throws (LowerError) {
	3107	+	/// Bind variables from an array literal pattern (e.g., `[a, 1, c]`).
	3108	+	/// Each element is either bound as a variable, skipped (placeholder), or
	3109	+	/// tested against the subject element, branching to `failBlock` on mismatch.
	3110	+	fn bindArrayPatternElements(
	3111	+	self: *mut FnLowerer,
	3112	+	subject: *MatchSubject,
	3113	+	items: mut [ast::Node],
	3114	+	failBlock: BlockId
	3115	+	) throws (LowerError) {
	3116	+	let case resolver::Type::Array(arrInfo) = subject.type
	3117	+	else throw LowerError::ExpectedSliceOrArray;
	3118	+
	3119	+	let elemTy = *arrInfo.item;
	3120	+	let elemLayout = resolver::getTypeLayout(elemTy);
	3121	+	let stride = elemLayout.size as i32;
	3122	+	let base = emitValToReg(self, subject.val);
	3123	+
	3124	+	for elem, i in items {
	3125	+	let fieldInfo = resolver::RecordField {
	3126	+	name: nil,
	3127	+	fieldType: elemTy,
	3128	+	offset: (i as i32) * stride,
	3129	+	};
	3130	+	try bindFieldVariable(self, elem, base, fieldInfo, subject.by, failBlock);
	3131	+	}
	3132	+	}
	3133	+
	3134	+	fn bindRecordPatternFields(self: mut FnLowerer, subject: MatchSubject, pattern: *ast::Node, lit: ast::RecordLit, failBlock: BlockId) throws (LowerError) {
3080	3135		// No fields to bind (e.g., `{ .. }`).
3081	3136		if lit.fields.len == 0 {
3082	3137		return;
3083	3138		}
3084	3139		// Get the union type info from the subject.

3098	3153		// Get the payload base pointer which points to the record within the tagged union.
3099	3154		let base = emitValToReg(self, subject.val);
3100	3155		let valOffset = unionInfo.valOffset as i32;
3101	3156		let payloadBase = emitPtrOffset(self, base, valOffset);
3102	3157
3103		-	// Bind each field.
	3158	+	try bindNestedRecordFields(self, payloadBase, lit, recInfo, subject.by, failBlock);
	3159	+	}
	3160	+
	3161	+	/// Emit a field read from a base pointer.
	3162	+	fn emitFieldRead(self: *mut FnLowerer, base: il::Reg, fieldInfo: resolver::RecordField, matchBy: resolver::MatchBy) -> il::Val {
	3163	+	match matchBy {
	3164	+	case resolver::MatchBy::Value => {
	3165	+	return emitRead(self, base, fieldInfo.offset, fieldInfo.fieldType);
	3166	+	}
	3167	+	case resolver::MatchBy::Ref, resolver::MatchBy::MutRef => {
	3168	+	return il::Val::Reg(emitPtrOffset(self, base, fieldInfo.offset));
	3169	+	}
	3170	+	}
	3171	+	}
	3172	+
	3173	+	/// Bind a single record field to a pattern variable, with support for nested
	3174	+	/// pattern tests that branch to `failBlock` on mismatch.
	3175	+	fn bindFieldVariable(
	3176	+	self: *mut FnLowerer,
	3177	+	binding: *ast::Node,
	3178	+	base: il::Reg,
	3179	+	fieldInfo: resolver::RecordField,
	3180	+	matchBy: resolver::MatchBy,
	3181	+	failBlock: BlockId
	3182	+	) throws (LowerError) {
	3183	+	match binding.value {
	3184	+	case ast::NodeValue::Ident(name) => {
	3185	+	let val = emitFieldRead(self, base, fieldInfo, matchBy);
	3186	+	newVar(self, name, ilType(self.low, fieldInfo.fieldType), false, val);
	3187	+	}
	3188	+	case ast::NodeValue::Placeholder => {}
	3189	+	case ast::NodeValue::RecordLit(lit) => {
	3190	+	// Check if this record literal is a union variant pattern.
	3191	+	if let keyNode = resolver::patternVariantKeyNode(binding) {
	3192	+	if let case resolver::NodeExtra::UnionVariant { .. } = resolver::nodeData(self.low.resolver, keyNode).extra {
	3193	+	try emitNestedFieldTest(self, binding, base, fieldInfo, matchBy, failBlock);
	3194	+	return;
	3195	+	}
	3196	+	}
	3197	+	// Plain nested record destructuring pattern.
	3198	+	let recInfo = resolver::getRecord(fieldInfo.fieldType)
	3199	+	else throw LowerError::ExpectedRecord;
	3200	+	let nestedBase = emitPtrOffset(self, base, fieldInfo.offset);
	3201	+
	3202	+	try bindNestedRecordFields(self, nestedBase, lit, recInfo, matchBy, failBlock);
	3203	+	}
	3204	+	else => {
	3205	+	// Nested pattern requiring a test (union variant scope access, literal, etc).
	3206	+	try emitNestedFieldTest(self, binding, base, fieldInfo, matchBy, failBlock);
	3207	+	}
	3208	+	}
	3209	+	}
	3210	+
	3211	+	/// Emit a nested pattern test for a record field value, branching to
	3212	+	/// `failBlock` if the pattern does not match. On success, continues in
	3213	+	/// a fresh block and binds any nested variables.
	3214	+	fn emitNestedFieldTest(
	3215	+	self: *mut FnLowerer,
	3216	+	pattern: *ast::Node,
	3217	+	base: il::Reg,
	3218	+	fieldInfo: resolver::RecordField,
	3219	+	matchBy: resolver::MatchBy,
	3220	+	failBlock: BlockId
	3221	+	) throws (LowerError) {
	3222	+	let fieldType = fieldInfo.fieldType;
	3223	+	let fieldPtr = emitPtrOffset(self, base, fieldInfo.offset);
	3224	+
	3225	+	// Build a MatchSubject for the nested field.
	3226	+	let ilTy = ilType(self.low, fieldType);
	3227	+	let kind = matchSubjectKind(fieldType);
	3228	+
	3229	+	// For aggregate subjects, the value must be a pointer.
	3230	+	let mut val = il::Val::Reg(fieldPtr);
	3231	+	if not isAggregateType(fieldType) {
	3232	+	val = emitRead(self, base, fieldInfo.offset, fieldType);
	3233	+	}
	3234	+	let nestedSubject = MatchSubject {
	3235	+	val,
	3236	+	type: fieldType,
	3237	+	ilType: ilTy,
	3238	+	bindType: fieldType,
	3239	+	kind,
	3240	+	by: matchBy,
	3241	+	};
	3242	+
	3243	+	// Emit the pattern test: on success jump to `continueBlock`, on fail to `failBlock`.
	3244	+	let continueBlock = try createBlock(self, "nest");
	3245	+	try emitPatternMatch(self, &nestedSubject, pattern, continueBlock, failBlock);
	3246	+	try switchToAndSeal(self, continueBlock);
	3247	+
	3248	+	// After the test succeeds, bind any nested variables.
	3249	+	let patterns: mut [ast::Node] = &mut [pattern];
	3250	+	try bindPatternVariables(self, &nestedSubject, patterns, failBlock);
	3251	+	}
	3252	+
	3253	+	/// Bind variables from a nested record literal pattern.
	3254	+	fn bindNestedRecordFields(
	3255	+	self: *mut FnLowerer,
	3256	+	base: il::Reg,
	3257	+	lit: ast::RecordLit,
	3258	+	recInfo: resolver::RecordType,
	3259	+	matchBy: resolver::MatchBy,
	3260	+	failBlock: BlockId
	3261	+	) throws (LowerError) {
3104	3262		for fieldNode in lit.fields {
3105	3263		let case ast::NodeValue::RecordLitField(field) = fieldNode.value else {
3106	3264		throw LowerError::UnexpectedNodeValue(fieldNode);
3107	3265		};
3108	3266		let fieldIdx = resolver::recordFieldIndexFor(self.low.resolver, fieldNode)

3110	3268		if fieldIdx >= recInfo.fields.len {
3111	3269		throw LowerError::MissingMetadata;
3112	3270		}
3113	3271		let fieldInfo = recInfo.fields[fieldIdx];
3114	3272
3115		-	bindFieldVariable(self, field.value, payloadBase, fieldInfo, subject.by);
	3273	+	try bindFieldVariable(self, field.value, base, fieldInfo, matchBy, failBlock);
3116	3274		}
3117	3275		}
3118	3276
3119		-	/// Bind a single record field to a pattern variable.
3120		-	fn bindFieldVariable(
3121		-	self: *mut FnLowerer,
3122		-	binding: *ast::Node,
3123		-	base: il::Reg,
3124		-	fieldInfo: resolver::RecordField,
3125		-	matchBy: resolver::MatchBy
3126		-	) {
3127		-	let case ast::NodeValue::Ident(name) = binding.value else {
3128		-	return; // Not an identifier binding.
3129		-	};
3130		-	let mut val: il::Val = undefined;
3131		-	match matchBy {
3132		-	case resolver::MatchBy::Value => {
3133		-	val = emitRead(self, base, fieldInfo.offset, fieldInfo.fieldType);
3134		-	},
3135		-	case resolver::MatchBy::Ref, resolver::MatchBy::MutRef => {
3136		-	val = il::Val::Reg(emitPtrOffset(self, base, fieldInfo.offset));
3137		-	},
3138		-	}
3139		-	let _ = newVar(self, name, ilType(self.low, fieldInfo.fieldType), false, val);
3140		-	}
3141		-
3142	3277		/// Lower function body to a list of basic blocks.
3143	3278		fn lowerFnBody(self: mut FnLowerer, body: ast::Node) -> *[il::Block] throws (LowerError) {
3144	3279		// Create and switch to entry block.
3145	3280		let entry = try createBlock(self, "entry");
3146	3281		self.entryBlock = entry;

3315	3450		// Body block: where the case body lives.
3316	3451		let mut bodyLabel = "case";
3317	3452		if prong.arm == ast::ProngArm::Else {
3318	3453		bodyLabel = "else";
3319	3454		}
3320		-	let bodyBlock = try createBlock(self, bodyLabel);
	3455	+	let mut bodyBlock = try createBlock(self, bodyLabel);
3321	3456		if not hasGuard {
3322	3457		entryBlock = bodyBlock;
3323	3458		}
3324	3459		// Fallthrough block: jumped to when pattern or guard fails.
3325	3460		let nextArm = try createBlock(self, "arm");

3335	3470		}
3336	3471		// Switch to entry block, where any variable bindings need to be created.
3337	3472		try switchToAndSeal(self, entryBlock);
3338	3473
3339	3474		// Bind pattern variables after successful match. Note that the guard
3340		-	// has not been evaluated yet.
	3475	+	// has not been evaluated yet. Nested patterns may emit additional
	3476	+	// tests that branch to `nextArm` on failure, switching the current
	3477	+	// block.
3341	3478		match prong.arm {
3342	3479		case ast::ProngArm::Binding(pat) =>
3343	3480		try bindMatchVariable(self, &subject, pat, false),
3344	3481		case ast::ProngArm::Case(patterns) =>
3345		-	try bindPatternVariables(self, &subject, patterns),
	3482	+	try bindPatternVariables(self, &subject, patterns, nextArm),
3346	3483		else => {},
3347	3484		}
3348	3485
3349	3486		// Evaluate guard if present; can still fail to next arm.
3350	3487		if let g = prong.guard {
3351	3488		try emitCondBranch(self, g, bodyBlock, nextArm);
	3489	+	} else if currentBlock(self).n != bodyBlock.n {
	3490	+	// Nested tests changed the current block. Create a new body block
	3491	+	// after the nest blocks to maintain RPO ordering, and jump to it.
	3492	+	bodyBlock = try createBlock(self, bodyLabel);
	3493	+	try emitJmp(self, bodyBlock);
3352	3494		}
3353	3495		// Lower prong body and jump to merge if unterminated.
3354	3496		try switchToAndSeal(self, bodyBlock);
3355	3497		try lowerNode(self, prong.body);
3356	3498		try emitMergeIfUnterminated(self, &mut mergeBlock);

3430	3572		case ast::PatternKind::Case => {
3431	3573		let patterns: mut [ast::Node] = &mut [pat.pattern];
3432	3574		// Jump to `targetBlock` if the pattern matches, `failBlock` otherwise.
3433	3575		try emitPatternMatches(self, subject, patterns, targetBlock, failBlock);
3434	3576		try switchToAndSeal(self, targetBlock);
3435		-	// Bind any variables inside the pattern.
3436		-	try bindPatternVariables(self, subject, patterns);
	3577	+	// Bind any variables inside the pattern. Nested patterns may
	3578	+	// emit additional tests that branch to `failBlock`, switching
	3579	+	// the current block.
	3580	+	try bindPatternVariables(self, subject, patterns, failBlock);
3437	3581		}
3438	3582		case ast::PatternKind::Binding => {
3439	3583		// Jump to `targetBlock` if there is a value present, `failBlock` otherwise.
3440	3584		try emitBindingTest(self, subject, targetBlock, failBlock);
3441	3585		try switchToAndSeal(self, targetBlock);

3445	3589		}
3446	3590		// Handle guard: on success jump to `successBlock`, on failure jump to `failBlock`.
3447	3591		if let g = pat.guard {
3448	3592		try emitCondBranch(self, g, *successBlock, failBlock);
3449	3593		try switchToAndSeal(self, *successBlock);
	3594	+	} else if currentBlock(self).n != targetBlock.n {
	3595	+	// Nested tests changed the current block. Create a new success block
	3596	+	// after the nest blocks to maintain RPO ordering, and jump to it.
	3597	+	*successBlock = try createBlock(self, successLabel);
	3598	+
	3599	+	try emitJmp(self, *successBlock);
	3600	+	try switchToAndSeal(self, *successBlock);
3450	3601		}
3451	3602		}
3452	3603
3453	3604		/// Lower a `let-else` statement.
3454	3605		fn lowerLetElse(self: *mut FnLowerer, letElse: ast::LetElse) throws (LowerError) {

3893	3893		} else => {}
3894	3894		}
3895	3895		}
3896	3896		case Type::Array(arrayInfo) => {
3897	3897		if let case ast::NodeValue::ArrayLit(items) = pattern.value {
	3898	+	if items.len as u32 != arrayInfo.length {
	3899	+	throw emitError(self, pattern, ErrorKind::RecordFieldCountMismatch(
	3900	+	CountMismatch { expected: arrayInfo.length, actual: items.len as u32 }
	3901	+	));
	3902	+	}
3898	3903		let elemTy = *arrayInfo.item;
3899	3904		for item in items {
3900	3905		try resolveCasePattern(self, item, elemTy, IdentMode::Bind, matchBy);
3901	3906		}
	3907	+	setNodeType(self, pattern, scrutineeTy);
3902	3908		return;
3903	3909		}
3904	3910		} else => {}
3905	3911		}
3906	3912		// Handle non-binding patterns (literals, placeholders) and bindings.

4017	4023		try visitOptional(self, forStmt.elseBranch, Type::Void);
4018	4024
4019	4025		return setNodeType(self, node, Type::Void);
4020	4026		}
4021	4027
4022		-	/// Check whether any pattern in a case prong is a wildcard `_`.
	4028	+	/// Get the node within a pattern that carries the `UnionVariant` extra.
	4029	+	/// For `ScopeAccess` it is the pattern itself, for `RecordLit` it is the
	4030	+	/// type name, and for `Call` it is the callee.
	4031	+	pub fn patternVariantKeyNode(pattern: ast::Node) -> ?ast::Node {
	4032	+	match pattern.value {
	4033	+	case ast::NodeValue::ScopeAccess(_) => return pattern,
	4034	+	case ast::NodeValue::RecordLit(lit) => return lit.typeName,
	4035	+	case ast::NodeValue::Call(call) => return call.callee,
	4036	+	else => return nil,
	4037	+	}
	4038	+	}
	4039	+
	4040	+	/// Get the i-th sub-pattern element from a compound pattern.
	4041	+	/// For `RecordLit` this is the i-th field's value; for `Call` it is the
	4042	+	/// i-th argument.
	4043	+	fn patternSubElement(pattern: ast::Node, idx: u32) -> ?ast::Node {
	4044	+	match pattern.value {
	4045	+	case ast::NodeValue::RecordLit(lit) => {
	4046	+	if idx < lit.fields.len as u32 {
	4047	+	if let case ast::NodeValue::RecordLitField(field) = lit.fields[idx].value {
	4048	+	return field.value;
	4049	+	}
	4050	+	}
	4051	+	}
	4052	+	case ast::NodeValue::Call(call) => {
	4053	+	if idx < call.args.len as u32 {
	4054	+	return call.args[idx];
	4055	+	}
	4056	+	}
	4057	+	else => {}
	4058	+	}
	4059	+	return nil;
	4060	+	}
	4061	+
	4062	+	/// Get the number of sub-pattern elements in a compound pattern.
	4063	+	fn patternSubCount(pattern: *ast::Node) -> u32 {
	4064	+	match pattern.value {
	4065	+	case ast::NodeValue::RecordLit(lit) => return lit.fields.len as u32,
	4066	+	case ast::NodeValue::Call(call) => return call.args.len as u32,
	4067	+	else => return 0,
	4068	+	}
	4069	+	}
	4070	+
	4071	+	/// Check whether a pattern contains nested sub-patterns that further
	4072	+	/// refine the match beyond the outer variant (e.g. nested union variant
	4073	+	/// tests or literal comparisons). Used to allow the same outer variant
	4074	+	/// to appear in multiple match arms.
	4075	+	fn hasNestedRefiningPattern(self: Resolver, pattern: ast::Node) -> bool {
	4076	+	for i in 0..patternSubCount(pattern) {
	4077	+	if let sub = patternSubElement(pattern, i) {
	4078	+	if isRefiningPattern(self, sub) {
	4079	+	return true;
	4080	+	}
	4081	+	}
	4082	+	}
	4083	+	return false;
	4084	+	}
	4085	+
	4086	+	/// Check whether a single pattern node is a refining pattern that tests
	4087	+	/// a value rather than just binding it. Union variants, literals, and
	4088	+	/// scope accesses are refining; identifiers, placeholders, and plain
	4089	+	/// record destructurings are not.
	4090	+	fn isRefiningPattern(self: Resolver, pattern: ast::Node) -> bool {
	4091	+	match pattern.value {
	4092	+	case ast::NodeValue::Ident(_), ast::NodeValue::Placeholder =>
	4093	+	return false,
	4094	+	case ast::NodeValue::RecordLit(_), ast::NodeValue::Call(_) => {
	4095	+	if let keyNode = patternVariantKeyNode(pattern) {
	4096	+	if let case NodeExtra::UnionVariant { .. } = self.nodeData.entries[keyNode.id].extra {
	4097	+	return true;
	4098	+	}
	4099	+	}
	4100	+	// Plain record destructuring / non-variant call is not directly
	4101	+	// refining; recurse to check sub-patterns.
	4102	+	return hasNestedRefiningPattern(self, pattern);
	4103	+	}
	4104	+	case ast::NodeValue::ArrayLit(items) => {
	4105	+	for item in items {
	4106	+	if isRefiningPattern(self, item) {
	4107	+	return true;
	4108	+	}
	4109	+	}
	4110	+	return false;
	4111	+	}
	4112	+	case ast::NodeValue::ScopeAccess(_) =>
	4113	+	return true,
	4114	+	else =>
	4115	+	return true,
	4116	+	}
	4117	+	}
	4118	+
	4119	+	/// Check whether any pattern in a case prong matches unconditionally.
	4120	+	/// A plain `_` or an all-binding array pattern (e.g. `[x, y]`) qualifies.
	4121	+	/// Note: top-level identifiers in `case` are comparisons, not bindings,
	4122	+	/// so they do not count as wildcards.
4023	4123		fn hasWildcardPattern(patterns: mut [ast::Node]) -> bool {
4024	4124		for pattern in patterns {
4025		-	if let case ast::NodeValue::Placeholder = pattern.value {
4026		-	return true;
	4125	+	match pattern.value {
	4126	+	case ast::NodeValue::Placeholder => return true,
	4127	+	case ast::NodeValue::ArrayLit(items) => {
	4128	+	if isIrrefutableArrayPattern(items) {
	4129	+	return true;
	4130	+	}
	4131	+	}
	4132	+	else => {}
4027	4133		}
4028	4134		}
4029	4135		return false;
4030	4136		}
4031	4137
	4138	+	/// Check whether all elements of an array pattern are irrefutable.
	4139	+	/// Inside array patterns, identifiers are bindings, not comparisons.
	4140	+	fn isIrrefutableArrayPattern(items: mut [ast::Node]) -> bool {
	4141	+	for item in items {
	4142	+	match item.value {
	4143	+	case ast::NodeValue::Ident(_), ast::NodeValue::Placeholder => {}
	4144	+	case ast::NodeValue::ArrayLit(inner) => {
	4145	+	if not isIrrefutableArrayPattern(inner) {
	4146	+	return false;
	4147	+	}
	4148	+	}
	4149	+	else => return false,
	4150	+	}
	4151	+	}
	4152	+	return true;
	4153	+	}
	4154	+
4032	4155		/// Analyze a match prong, checking for duplicate catch-alls. Returns the
4033	4156		/// unified match type.
4034	4157		fn resolveMatchProng(
4035	4158		self: *mut Resolver,
4036	4159		prongNode: *ast::Node,

4186	4309		let case ast::NodeValue::MatchProng(prong) = prongNode.value
4187	4310		else panic "resolveMatchUnion: expected match prong";
4188	4311
4189	4312		matchType = try resolveMatchProng(self, prongNode, prong, subjectTy, &mut state, matchType, matchBy);
4190	4313
4191		-	// Record covered variants. Guarded prongs don't count as covering.
	4314	+	// Guarded prongs don't count as covering. Patterns with nested
	4315	+	// refining sub-patterns (e.g. matching different inner union variants)
	4316	+	// don't count as duplicates or as fully covering.
4192	4317		if prong.guard == nil {
4193	4318		if let case ast::ProngArm::Case(patterns) = prong.arm {
4194	4319		for pattern in patterns {
4195	4320		if let case NodeExtra::UnionVariant { ordinal: ix, .. } = self.nodeData.entries[pattern.id].extra {
4196		-	if covered[ix] {
4197		-	throw emitError(self, pattern, ErrorKind::DuplicateMatchPattern);
	4321	+	if not hasNestedRefiningPattern(self, pattern) {
	4322	+	if covered[ix] {
	4323	+	throw emitError(self, pattern, ErrorKind::DuplicateMatchPattern);
	4324	+	}
	4325	+	covered[ix] = true;
	4326	+	coveredCount += 1;
4198	4327		}
4199		-	covered[ix] = true;
4200		-	coveredCount += 1;
4201	4328		}
4202	4329		}
4203	4330		}
4204	4331		}
4205	4332		}

4250	4377		} else {
4251	4378		hasFalse = true;
4252	4379		}
4253	4380		}
4254	4381		}
4255		-	// Constant case values are required for the match to be
4256		-	// considered static.
4257		-	if constValueEntry(self, p) == nil {
4258		-	state.isConst = false;
4259		-	} else {
4260		-	hasConstCase = true;
	4382	+	// Scalar constant patterns allow the match to be lowered
	4383	+	// to a switch instruction.
	4384	+	if let c = constValueEntry(self, p) {
	4385	+	match c {
	4386	+	case ConstValue::Bool(_), ConstValue::Char(_), ConstValue::Int(_) =>
	4387	+	hasConstCase = true,
	4388	+	else =>
	4389	+	state.isConst = false,
	4390	+	}
4261	4391		}
4262	4392		}
4263	4393		}
4264	4394		}
4265	4395

4421	4551		}
4422	4552		case ast::NodeValue::Ident(_) => {
4423	4553		try bindValueIdent(self, binding, binding, bindTy, false, 0, 0);
4424	4554		}
4425	4555		else => {
4426		-	throw emitError(self, binding, ErrorKind::ExpectedIdentifier);
	4556	+	// Nested pattern: recursively resolve (record destructuring,
	4557	+	// union variant, scope access, call, literals, etc).
	4558	+	try resolveCasePattern(self, binding, ty, IdentMode::Bind, matchBy);
4427	4559		}
4428	4560		}
4429	4561		}
4430	4562
4431	4563		/// Bind record pattern fields to variables in the current scope.

4004	4004
4005	4005		/// Test array pattern matching with element bindings.
4006	4006		/// Pattern syntax: `[x, y]` matches an array and binds elements.
4007	4007		@test fn testResolveMatchArrayPattern() throws (testing::TestError) {
4008	4008		let mut a = testResolver();
4009		-	let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [x, y] => return x + y, else => return 0 } }";
	4009	+	let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [x, y] => return x + y } }";
4010	4010		let result = try resolveProgramStr(&mut a, program);
4011	4011		try expectNoErrors(&result);
4012	4012		}
4013	4013
4014	4014		/// Test array pattern with placeholder elements.
4015	4015		/// Pattern syntax: `[_, y]` ignores first element.
4016	4016		@test fn testResolveMatchArrayPatternPlaceholder() throws (testing::TestError) {
4017	4017		let mut a = testResolver();
4018		-	let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [_, y] => return y, else => return 0 } }";
	4018	+	let program = "fn f(arr: [i32; 2]) -> i32 { match arr { case [_, y] => return y } }";
4019	4019		let result = try resolveProgramStr(&mut a, program);
4020	4020		try expectNoErrors(&result);
4021	4021		}
4022	4022
4023	4023		/// Test identifier pattern that binds the whole value.