ww: hare-feature batch (_, const, [_]T, ..., size/offset, assert, for-else)

selfhost/cmd/wcc/cgenexpr.ww

@@ -736,6 +736,19 @@ fn cgcall(c: *cgen, n: *node) void = {
 
 fn cgassign(c: *cgen, n: *node) void = {
 	let lhs: *node = n.lhs;
+	// Discard lvalue `_ = expr;` — evaluate rhs for side effects,
+	// write nothing. Detected by lhs being an N_IDENT with empty str
+	// (planted by parseprimary on the TK_UNDER token).
+	if (lhs != nil) {
+		if (lhs.kind == N_IDENT) {
+			if (lhs.str.len == 0) {
+				if (n.op == TK_ASSIGN) {
+					cgexpr(c, n.rhs);
+					return;
+				};
+			};
+		};
+	};
 	// `*p = v` — deref-assign. Element width comes from the
 	// pointer's declared type. Mirrors C cgen: eval rhs (AX,
 	// and BX if str), push, eval pointer, pop value, store.