selfhost/cmd/wcc: N_CALL intercepts for len/append/free (A.6.2.1b)

Three Hare pseudo-builtins (len/append/free) were resolving via the
generic N_CALL path and leaving e.type_ nil, blocking #15's post-
checker assertion. Add inline intercepts in exprtype that stamp e.type_
to mktname("i32")/mktname("void") and return the same tnode, matching
the cstage shape at cmd/wcc/check.c:896-1011 (rule 10 stage byte-id).

No shadow guard: cstage's len/append/free intercepts have none either,
and L85-88 seeds the names into c.top so a same-module decl dup-
silences. No arg-walk: resolvewalk descends children before dispatching
the parent N_CALL (check.ww:404-417), so args are stamped before the
intercept fires.

insert/delete deferred — not implemented in either stage. The cstage
divergence from harec (len → i32 not size; append → void not tagged)
pre-dates this task; #19 (dedicated AST kinds) is the Hare-faithful
path. Behavior is transitively covered by the 990-997 byte-id corpus
(append used in progs 16, 19, 20); the stamp side gates on #15.

selfhost/cmd/w6c/main.combined.ww

@@ -8663,6 +8663,32 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 				};
 			};
 		};
+		// len(x) / append(s,...) / free(p) — Hare pseudo-builtins.
+		// Mirror cstage cmd/wcc/check.c:896-1011 (rule 10 requires
+		// stage byte-id; both stages stamp the same shape). No shadow
+		// guard: cstage's len/append/free intercepts have none either
+		// (check.c:901/962/1005), and the names are seeded into c.top
+		// at L85-88 so a user same-module decl dup-silences. Harec
+		// models these as dedicated AST kinds — EXPR_LEN at
+		// ref/harec/src/check.c:2630 (result `&builtin_type_size`),
+		// EXPR_APPEND at :745 (result `(nomem | void)`), EXPR_FREE at
+		// :2443 (result `&builtin_type_void`). The cstage divergence
+		// (len → i32 not size, append → void not tagged) pre-dates
+		// this task; #19 (Drew's δ — dedicated AST kinds) is the
+		// Hare-faithful path. This is the intercept-shim minimum to
+		// unblock #15 (A.6.2.1e assertion enable).
+		if (callee.kind == nkind.N_IDENT) {
+			if (streq(callee.str, "len")) {
+				let tn: *node = mktname(c, "i32");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+			if (streq(callee.str, "append") || streq(callee.str, "free")) {
+				let tn: *node = mktname(c, "void");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+		};
 		let nm: str;
 		nm.ptr = nil; nm.len = 0;
 		if (callee.kind == nkind.N_IDENT) { nm = callee.str; };

selfhost/cmd/wcc/check.ww

@@ -1699,6 +1699,32 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 				};
 			};
 		};
+		// len(x) / append(s,...) / free(p) — Hare pseudo-builtins.
+		// Mirror cstage cmd/wcc/check.c:896-1011 (rule 10 requires
+		// stage byte-id; both stages stamp the same shape). No shadow
+		// guard: cstage's len/append/free intercepts have none either
+		// (check.c:901/962/1005), and the names are seeded into c.top
+		// at L85-88 so a user same-module decl dup-silences. Harec
+		// models these as dedicated AST kinds — EXPR_LEN at
+		// ref/harec/src/check.c:2630 (result `&builtin_type_size`),
+		// EXPR_APPEND at :745 (result `(nomem | void)`), EXPR_FREE at
+		// :2443 (result `&builtin_type_void`). The cstage divergence
+		// (len → i32 not size, append → void not tagged) pre-dates
+		// this task; #19 (Drew's δ — dedicated AST kinds) is the
+		// Hare-faithful path. This is the intercept-shim minimum to
+		// unblock #15 (A.6.2.1e assertion enable).
+		if (callee.kind == nkind.N_IDENT) {
+			if (streq(callee.str, "len")) {
+				let tn: *node = mktname(c, "i32");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+			if (streq(callee.str, "append") || streq(callee.str, "free")) {
+				let tn: *node = mktname(c, "void");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+		};
 		let nm: str;
 		nm.ptr = nil; nm.len = 0;
 		if (callee.kind == nkind.N_IDENT) { nm = callee.str; };

selfhost/cmd/wwdump/main.combined.ww

@@ -8663,6 +8663,32 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
 				};
 			};
 		};
+		// len(x) / append(s,...) / free(p) — Hare pseudo-builtins.
+		// Mirror cstage cmd/wcc/check.c:896-1011 (rule 10 requires
+		// stage byte-id; both stages stamp the same shape). No shadow
+		// guard: cstage's len/append/free intercepts have none either
+		// (check.c:901/962/1005), and the names are seeded into c.top
+		// at L85-88 so a user same-module decl dup-silences. Harec
+		// models these as dedicated AST kinds — EXPR_LEN at
+		// ref/harec/src/check.c:2630 (result `&builtin_type_size`),
+		// EXPR_APPEND at :745 (result `(nomem | void)`), EXPR_FREE at
+		// :2443 (result `&builtin_type_void`). The cstage divergence
+		// (len → i32 not size, append → void not tagged) pre-dates
+		// this task; #19 (Drew's δ — dedicated AST kinds) is the
+		// Hare-faithful path. This is the intercept-shim minimum to
+		// unblock #15 (A.6.2.1e assertion enable).
+		if (callee.kind == nkind.N_IDENT) {
+			if (streq(callee.str, "len")) {
+				let tn: *node = mktname(c, "i32");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+			if (streq(callee.str, "append") || streq(callee.str, "free")) {
+				let tn: *node = mktname(c, "void");
+				e.type_ = tinfofornode(c, tn): *void;
+				return tn;
+			};
+		};
 		let nm: str;
 		nm.ptr = nil; nm.len = 0;
 		if (callee.kind == nkind.N_IDENT) { nm = callee.str; };