From 48c758bbe7840295b30bd9358e07719ae548c2f8 Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Thu, 21 May 2026 21:10:58 +0900
Subject: [PATCH] selfhost/cmd/wcc: stamp e.type_ for N_RECV (A.6.2.0d)
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Port head-only of cstage cmd/wcc/check.c:1230-1236 to exprtype's
new N_RECV arm. Peel alias on the channel base; `chan T` → T.
N_TCHAN element lives in .lhs (cstage ww.h:279, ww typeeqast
L585).

One documented divergence: cstage L1234 errors on a non-chan
base; wwstage returns nil under the lenient-on-miss policy
(scruttype L656 / A.6.1.5b N_DOT precedent).

A.6.2 step 4 of 8 (γ order). Same shape as A.6.2.0a N_SLICE
scaffold — precedent-consistent.

`make test-unit` green; full `make test` batched per option B.
---
 selfhost/cmd/w6c/main.combined.ww    | 16 ++++++++++++++++
 selfhost/cmd/wcc/check.ww            | 16 ++++++++++++++++
 selfhost/cmd/wwdump/main.combined.ww | 16 ++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/selfhost/cmd/w6c/main.combined.ww b/selfhost/cmd/w6c/main.combined.ww
index 23656c27..678a94b2 100644
--- a/selfhost/cmd/w6c/main.combined.ww
+++ b/selfhost/cmd/w6c/main.combined.ww
@@ -8874,6 +8874,22 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 		e.type_ = tinfofornode(c, tt): *void;
 		return tt;
 	};
+	if (k == nkind.N_RECV) {
+		// A.6.2.0d — head-only stamp of the receive expression's
+		// overall type. Mirrors cstage cmd/wcc/check.c:1230-1236
+		// N_RECV: peel alias on the channel base; chan T → T.
+		// Documented cstage divergence: cstage L1234 errors on a
+		// non-chan base; wwstage returns nil (lenient on miss),
+		// matching scruttype L656 / A.6.1.5b N_DOT precedent.
+		let basetn: *node = exprtype(c, e.lhs, nil);
+		let bu: *node = resolvealias(c, unwrapbang(basetn));
+		if (bu == nil) { return nil; };
+		if (bu.kind == nkind.N_TCHAN) {
+			e.type_ = tinfofornode(c, bu.lhs): *void;
+			return bu.lhs;
+		};
+		return nil;
+	};
 	if (k == nkind.N_TRYPROP) {
 		// success unwrap: the success-variant type of operand's
 		// tagged union.
diff --git a/selfhost/cmd/wcc/check.ww b/selfhost/cmd/wcc/check.ww
index 73069c15..1b19efe1 100644
--- a/selfhost/cmd/wcc/check.ww
+++ b/selfhost/cmd/wcc/check.ww
@@ -1910,6 +1910,22 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 		e.type_ = tinfofornode(c, tt): *void;
 		return tt;
 	};
+	if (k == nkind.N_RECV) {
+		// A.6.2.0d — head-only stamp of the receive expression's
+		// overall type. Mirrors cstage cmd/wcc/check.c:1230-1236
+		// N_RECV: peel alias on the channel base; chan T → T.
+		// Documented cstage divergence: cstage L1234 errors on a
+		// non-chan base; wwstage returns nil (lenient on miss),
+		// matching scruttype L656 / A.6.1.5b N_DOT precedent.
+		let basetn: *node = exprtype(c, e.lhs, nil);
+		let bu: *node = resolvealias(c, unwrapbang(basetn));
+		if (bu == nil) { return nil; };
+		if (bu.kind == nkind.N_TCHAN) {
+			e.type_ = tinfofornode(c, bu.lhs): *void;
+			return bu.lhs;
+		};
+		return nil;
+	};
 	if (k == nkind.N_TRYPROP) {
 		// success unwrap: the success-variant type of operand's
 		// tagged union.
diff --git a/selfhost/cmd/wwdump/main.combined.ww b/selfhost/cmd/wwdump/main.combined.ww
index b2adafb4..6352b51a 100644
--- a/selfhost/cmd/wwdump/main.combined.ww
+++ b/selfhost/cmd/wwdump/main.combined.ww
@@ -8874,6 +8874,22 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 		e.type_ = tinfofornode(c, tt): *void;
 		return tt;
 	};
+	if (k == nkind.N_RECV) {
+		// A.6.2.0d — head-only stamp of the receive expression's
+		// overall type. Mirrors cstage cmd/wcc/check.c:1230-1236
+		// N_RECV: peel alias on the channel base; chan T → T.
+		// Documented cstage divergence: cstage L1234 errors on a
+		// non-chan base; wwstage returns nil (lenient on miss),
+		// matching scruttype L656 / A.6.1.5b N_DOT precedent.
+		let basetn: *node = exprtype(c, e.lhs, nil);
+		let bu: *node = resolvealias(c, unwrapbang(basetn));
+		if (bu == nil) { return nil; };
+		if (bu.kind == nkind.N_TCHAN) {
+			e.type_ = tinfofornode(c, bu.lhs): *void;
+			return bu.lhs;
+		};
+		return nil;
+	};
 	if (k == nkind.N_TRYPROP) {
 		// success unwrap: the success-variant type of operand's
 		// tagged union.