wcc/cgen: #64+#68 tuple-literal cursor-fill decl-blind — massign + call-arg widen (both-stage)

A tuple LITERAL with a declared-tagged element reached the cursor-fill
helper (cg_tuple_lit_to_cursor) through the generic cgexpr(N_TUPLE) arm
with no declared type, so the element was stored stamped-keyed at its
constructed scalar width rather than widened into the declared tagged box.
Both consumers ran silent and wrong on both stages (#263 gate-blind:
cs==ww byte-identical, both wrong — runtime is the only net).

#64 massign: N_MASSIGN derives a declared tuple type from the lvalue
binding types and threads it into cg_tuple_lit_to_cursor + the receive
loop (mirror of the #57 N_LET wire); a `_` target falls back to the rhs
literal element type for cursor stride.

#68 call-arg: the send is made param-aware (fill over the PARAM tuple) and
the restage guard graduates a declared-tagged element to a real widen
(reusing cg_widen_tagged_store); nested tuple/struct/array elements and
tagged elements with no param decl stay rule-7 loud. The matching
pop/drain is made param-aware too so push count == pop count: a
param-aware send pushes the box's N words, so the drain must pop N or the
SysV arg sequence skews. This is a push/pop balance requirement of the
send change, not a separate latent under-drain (the standalone trailing-
arg drain is already correct at HEAD).

Closed by construction: the only remaining cg_tuple_lit_to_cursor caller
passing NULL/nil is the generic cgexpr(N_TUPLE) arm, provably non-widening
(constructed type == governing type). The four widening consumers — LET,
RETURN, MASSIGN, call-arg — are all decl-wired. Whole-tuple single-ident
reassign from a tuple literal is rule-7 loud (task #49), not a silent
widening consumer, so the residual NULL arm stays non-widening.

Pin: 945_tuple_lit_declblind_run — massign / call-arg / `_`-control /
call-arg-drain / nested-tuple-ERR rows, each base-fail at abd97e6 and
post-pass with cs==ww byte-id.

Makefile

@@ -321,6 +321,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_peellint_gate \
 	  $(BIN)/test_tuple_nary_destructure_run \
 	  $(BIN)/test_rvalue_tuple_destructure_run \
+	  $(BIN)/test_tuple_lit_declblind_run \
 	  $(BIN)/test_overcap_tuple_field_store_run \
 	  $(BIN)/test_mixed_scalar_tuple_sret_run \
 	  $(BIN)/test_tuple_in_union_run \
@@ -1590,6 +1591,18 @@ $(BIN)/test_rvalue_tuple_destructure_run: test/wcc/945_rvalue_tuple_destructure_
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+# #64 + #68: tuple LITERAL fills the register cursor DECL-BLIND — the #57
+# decl wire (a declared-tagged element widens into its box) stopped at
+# N_LET/N_RETURN; destructure-REASSIGN (#64) and CALL-ARG send (#68) still
+# rode the decl-less route (box stored/sent word0-only, cursor skewed).
+# Both stages, #263 gate-blind (byte-id cs==ww, both ran wrong). Run +
+# cs==ww byte-id.
+$(BIN)/test_tuple_lit_declblind_run: test/wcc/945_tuple_lit_declblind_run.c \
+		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
+		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 # #234: over-cap tuple sret store into a local struct field / indexed local
 # (run + cs==ww byte-id), deferred forms loud-stop (builderr both drivers).
 $(BIN)/test_overcap_tuple_field_store_run: test/wcc/940_overcap_tuple_field_store_run.c \

cmd/w6c/cgen.c

@@ -250,6 +250,23 @@ node_tuplearg(Node *n)
 	return (u && u->kind == TY_TUPLE) ? u : NULL;
 }
 
+/* node_tuplearg_decl — #68: like node_tuplearg, but an N_TUPLE LITERAL arg
+ * with a tuple PARAM type reports the DECLARED param tuple (element widths
+ * keyed on the param, so a declared-tagged element's box words drive the
+ * send/drain). The literal's own type is element-constructed (a concrete
+ * rvalue under a tagged slot counts ONE word, not the box) — see the cgcall
+ * paramtup send. Every other source falls back to node_tuplearg. */
+static Type *
+node_tuplearg_decl(Node *n, Type *param)
+{
+	if (n && n->kind == N_TUPLE && param) {
+		Type *pu = type_chase_named(param);
+		if (pu && pu->kind == TY_TUPLE)
+			return pu;
+	}
+	return node_tuplearg(n);
+}
+
 /* #83: positional tuple register-return ABI. Tuple elements ride
  * consecutive eightbytes over tuple_rseq[]; a slice/str rides its 3-word
  * {ptr,len,cap} header (ref/hare/rt/ensure.ha:4-8, ty_str->size SSoT), a
@@ -8842,10 +8859,12 @@ cgexpr(Cg *c, Node *n, Local *locals)
 		int widen_sz[64] = {0};
 		Type *widen_param[64] = {0};
 		int memarg[64] = {0};
+		Type *argparam[64] = {0};	/* #68: declared param type per arg */
 		{
 			Tparam *p = callee_params;
 			for (int i = 0; i < argcount; i++) {
 				if (p == NULL) break;
+				argparam[i] = p->type;
 				Type *at = args[i] ? args[i]->type : NULL;
 				int psz = tagged_arg_size(p->type);
 				if (psz > 0) {
@@ -9207,8 +9226,26 @@ cgexpr(Cg *c, Node *n, Local *locals)
 				    args[i], widen_sz[i]);
 				continue;
 			}
-			cgexpr(c, args[i], locals);
+			/* #68: a tuple-LITERAL arg derives its DECLARED tuple
-			Type *tuparg_push = node_tuplearg(args[i]);
+			 * type from the callee PARAM (the #57 decl wire,
+			 * extended to call-arg send), so a declared-tagged
+			 * element's concrete rvalue widens into the box cursor;
+			 * the restage + push then key on the param tuple type,
+			 * not the literal's element-constructed type. */
+			Type *paramtup = NULL;
+			if (args[i] && args[i]->kind == N_TUPLE) {
+				Type *pcu = argparam[i]
+				    ? type_chase_named(argparam[i]) : NULL;
+				if (pcu && pcu->kind == TY_TUPLE)
+					paramtup = pcu;
+			}
+			if (paramtup)
+				cg_tuple_lit_to_cursor(c, &locals, args[i],
+				    paramtup);
+			else
+				cgexpr(c, args[i], locals);
+			Type *tuparg_push = paramtup
+			    ? paramtup : node_tuplearg(args[i]);
 			/* #32 (C-t2, rule 7): a tuple-typed arg from a source
 			 * shape whose cgexpr does NOT fill the return cursor
 			 * (chain reads, match exprs, ...) must die loud here —
@@ -9307,11 +9344,22 @@ cgexpr(Cg *c, Node *n, Local *locals)
 					 * cannot carry it; pre-guard it ran
 					 * WRONG (inner words skewed). Loud
 					 * until a consumer motivates wiring. */
+					/* #68: a declared-tagged element graduates
+					 * to a real widen — the decl-aware send
+					 * (cg_tuple_lit_to_cursor over the param
+					 * tuple type) already left the box words in
+					 * the cursor, so the count + tuple_store
+					 * below carry them. Only the param-decl
+					 * literal path is wired; nested tuple/
+					 * struct/array stay rule-7 loud, as does a
+					 * tagged element with no param decl (the
+					 * cursor was filled stamped-keyed). */
 					Type *cu = type_chase_named(p->type);
 					if (cu && (cu->kind == TY_TUPLE
 					    || cu->kind == TY_STRUCT
 					    || cu->kind == TY_ARRAY
-					    || cu->kind == TY_TAGGED))
+					    || (cu->kind == TY_TAGGED
+					        && !paramtup)))
 						fatal("#32: tuple arg element "
 						    "kind unsupported (nested "
 						    "tuple/struct/array/tagged; "
@@ -9549,7 +9597,8 @@ cgexpr(Cg *c, Node *n, Local *locals)
 					else
 						stackslots++;
 				}
-			} else if ((tu = node_tuplearg(args[i])) != NULL) {
+			} else if ((tu = node_tuplearg_decl(args[i],
+			    argparam[i])) != NULL) {
 				/* #163: drain the tuple's staged words (pushed
 				 * slot+0 first) into the SysV arg cursor by SysV
 				 * class — a float MOVSD/MOVSS off (SP) into the
@@ -9557,7 +9606,14 @@ cgexpr(Cg *c, Node *n, Local *locals)
 				 * next INTEGER arg reg (DI/SI/..); a slice/str its
 				 * 3-word {ptr,len,cap}. Reg overflow loud-stops
 				 * (rule 7): the partial-spill stitch is out of
-				 * scope (twin of #164's cap). */
+				 * scope (twin of #164's cap).
+				 *
+				 * #68: a tuple-LITERAL arg drains over the PARAM
+				 * tuple element widths (node_tuplearg_decl), so a
+				 * declared-tagged element's box words pop into the
+				 * arg cursor together with the i64 that follows —
+				 * the literal's element-constructed types undercount
+				 * a wide box. Mirrors the param-aware send. */
 				int ef32;
 				for (Tparam *p = tu->params; p; p = p->next) {
 					if (fld_isfloat(p->type, &ef32)) {
@@ -14084,15 +14140,42 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
 		 * SAME producer source the SEND walks. */
 		int sret_recv = (n->rhs && n->rhs->kind == N_CALL)
 		    ? cg_sret_retsize(n->rhs->type) : 0;
-		/* #64 (filed, rule 7): an N_TUPLE literal rhs rides this
-		 * decl-less cgexpr route, so a declared-TAGGED element's
-		 * concrete rvalue still fills the cursor stamped-keyed
-		 * (silent skew) — the #57 decl wire stops at return/let. */
-		cgexpr(c, n->rhs, *locals);
 		Type *rt = n->rhs ? n->rhs->type : NULL;
 		Type *ru = type_chase_named(rt);
 		Tparam *tp0 = (ru && ru->kind == TY_TUPLE) ? ru->params : NULL;
 		int mf32;
+		/* #64: a tuple-LITERAL rhs carries a DECLARED tuple type (built
+		 * from the lvalue binding types) into the cursor fill, so a
+		 * declared-tagged element's concrete rvalue widens into the box
+		 * instead of riding the decl-less stamped-keyed route — the #57
+		 * decl wire extended past N_LET/N_RETURN to destructure-reassign.
+		 * A `_` lvalue is never type-stamped (the checker skips it) —
+		 * fall back to the rhs literal element type for its cursor
+		 * stride so the next element stays aligned (harec `_` advance;
+		 * pinned by the R3 control row). */
+		int litrhs = (n->rhs && n->rhs->kind == N_TUPLE);
+		Tparam *declp = NULL;
+		if (litrhs) {
+			Tparam **dpp = &declp;
+			Tparam *tpw = tp0;
+			for (Node *l = n->list; l; l = l->next) {
+				Tparam *dpn = amalloc(c->a, sizeof *dpn);
+				dpn->name = NULL;
+				dpn->type = l->type ? l->type
+				    : (tpw ? tpw->type : NULL);
+				dpn->next = NULL;
+				dpn->variadic = 0;
+				*dpp = dpn;
+				dpp = &dpn->next;
+				if (tpw) tpw = tpw->next;
+			}
+			Type *decltt = newtype(c->a, TY_TUPLE);
+			decltt->params = declp;
+			cg_tuple_lit_to_cursor(c, locals, n->rhs, decltt);
+		} else {
+			cgexpr(c, n->rhs, *locals);
+		}
+		Tparam *recvp = litrhs ? declp : tp0;
 		if (sret_recv > 0) {
 			int scr = cg_sretscr_off;
 			int foff = 0;
@@ -14137,7 +14220,7 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
 		int gpcap = TUPLE_GPCAP;
 		int ssecap = TUPLE_SSECAP;
 		int gptotal = 0, ssetotal = 0;
-		for (Tparam *tp = tp0; tp; tp = tp->next) {
+		for (Tparam *tp = recvp; tp; tp = tp->next) {
 			if (fld_isfloat(tp->type, &mf32))
 				ssetotal++;
 			else
@@ -14152,7 +14235,7 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
 			    "capacity (%d eightbytes: X0,X1); see return-ABI #10",
 			    ssecap);
 		int gpcur = 0, ssecur = 0;
-		Tparam *tp = tp0;
+		Tparam *tp = recvp;
 		for (Node *l = n->list; l; l = l->next) {
 			Type *et = tp ? tp->type : NULL;
 			int isflt = fld_isfloat(et, &mf32);

selfhost/cmd/w6c/main.combined.ww

@@ -17065,22 +17065,40 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		emitline("\tX0, (SP)\n");
 		return rest + 1;
 	};
-	cgexpr(c, arg);
+	// #68: a tuple-LITERAL arg derives its DECLARED tuple type from the
-	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr
+	// callee PARAM type node (the #57 decl wire, extended to call-arg
-	// left the tuple in the return-ABI cursor (AX/DX/CX/R8 + X0/X1) for
+	// send), so a declared-tagged element's concrete rvalue widens into
-	// every nodetuplearg producer — call (return ABI), ident
+	// the box cursor; the restage + push then key on the param tuple type
-	// (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
+	// node (declared element widths), not the literal's element-
+	// constructed types. Mirrors cstage cgcall paramtup.
+	let paramtt: *node = nil;
+	if (arg.kind == nkind.N_TUPLE) { if (param != nil) {
+		if (param.kind == nkind.N_PARAM && param.lhs != nil) {
+			let ptn: *node = param.lhs;
+			for (ptn != nil && ptn.kind == nkind.N_TNAME) {
+				ptn = aliaslookup(c, ptn.str);
+			};
+			if (ptn != nil) { if (ptn.kind == nkind.N_TTUPLE) { paramtt = ptn; }; };
+		};
+	}; };
+	if (paramtt != nil) { cgtuplelittocursor(c, arg, paramtt); }
+	else { cgexpr(c, arg); };
+	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr /
+	// the decl-aware fill left the tuple in the return-ABI cursor (AX/DX/
+	// CX/R8 + X0/X1) for every nodetuplearg producer — call (return ABI),
+	// ident (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
 	// unwrap (payload shift); restage it into @tupargscr by SysV class
 	// (tupstore, the #164 helper) and push the slot words high->low so
 	// the pop drains slot+0 first into the SysV ARG cursor. The frame
 	// slot decouples the return-class regs from the overlapping
-	// arg-class regs. An N_TUPLE literal's elements are VALUE exprs —
+	// arg-class regs. When the PARAM tuple type is known (#68), walk its
-	// classify them the way cgtuplelittocursor does (nodeisstr/
+	// declared element type nodes (p.lhs); else an N_TUPLE literal's
-	// nodeisslice), kind-discriminated; the stride is the slot formula
+	// elements are VALUE exprs classified the way cgtuplelittocursor does.
-	// (wide ? header : 8), the same number slotsize() gives a type node.
+	let tuparg: *node = paramtt;
-	let tuparg: *node = nodetuplearg(c, arg);
+	if (tuparg == nil) { tuparg = nodetuplearg(c, arg); };
 	if (tuparg != nil) {
-		let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+		let tuplit: bool = false;
+		if (paramtt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 		let gptot: i32 = 0;
 		let sstot: i32 = 0;
 		let tsz: i32 = 0;
@@ -17099,23 +17117,34 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 			let eti: *tinfo = et.type_: *tinfo;
 			eti = tichase(eti);
 			if (eti != nil) {
-				if (eti.kind == tykind.TY_TUPLE
+				let bad: bool = eti.kind == tykind.TY_TUPLE
 				    || eti.kind == tykind.TY_STRUCT
-				    || eti.kind == tykind.TY_ARRAY
+				    || eti.kind == tykind.TY_ARRAY;
-				    || eti.kind == tykind.TY_TAGGED) {
+				// #68: a declared-tagged element graduates to a real
+				// widen — the decl-aware send (cgtuplelittocursor over
+				// the param tuple type) left the box words in the
+				// cursor, so tupstore below carries them. A tagged
+				// element with no param decl stays rule-7 loud (the
+				// cursor was filled stamped-keyed).
+				if (eti.kind == tykind.TY_TAGGED && paramtt == nil) { bad = true; };
+				if (bad) {
 					let mne: str = "#32: tuple arg element kind unsupported (nested tuple/struct/array/tagged; rule 7)\n";
 					os.write(2, mne.ptr, mne.len: u64);
 					os.exit(1);
 				};
 			};
-			// tagged is guarded loud above, so wide-vs-scalar is
+			// eslot — the full slot stride (str/slice header, tagged
-			// the full slot split here; eslot keeps the stride
+			// box, else 8); on the declared (non-tuplit) path tupeslotn
-			// arithmetic on the accessor scale (#22).
+			// reads the element TYPE node directly (#68 box-aware,
-			let wide: bool = false;
+			// mirrors cstage tuple_eslot). A literal element rides the
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
+			// wide-vs-scalar split off its VALUE node.
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			if (isfloattype(c, et)) { sstot += 1; }
 			else { gptot += eslot / 8; };
 			tsz += eslot;
@@ -17136,11 +17165,13 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		for (p != nil) {
 			let et: *node = p.lhs;
 			if (tuplit) { et = p; };
-			let wide: bool = false;
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			tupstore(c, gpcur, ssecur, scr + eoff, eslot, et);
 			if (isfloattype(c, et)) { ssecur += 1; }
 			else { gpcur += eslot / 8; };
@@ -28798,19 +28829,38 @@ fn cgcall(c: *cgen, n: *node) void = {
 				stackslots += 1;
 			};
 			popped += 1;
-		} else { let tuparg: *node = nodetuplearg(c, a);
+		} else {
+			// #68: drain over the PARAM tuple element widths for a
+			// tuple LITERAL arg (the declared-tagged box words pop
+			// together with the i64 that follows), mirroring the
+			// param-aware send; else the source tuple type.
+			let dptt: *node = nil;
+			if (a.kind == nkind.N_TUPLE) { if (dparam != nil) {
+				if (dparam.kind == nkind.N_PARAM && dparam.lhs != nil) {
+					let dtn2: *node = dparam.lhs;
+					for (dtn2 != nil && dtn2.kind == nkind.N_TNAME) {
+						dtn2 = aliaslookup(c, dtn2.str);
+					};
+					if (dtn2 != nil) { if (dtn2.kind == nkind.N_TTUPLE) { dptt = dtn2; }; };
+				};
+			}; };
+			let tuparg: *node = dptt;
+			if (tuparg == nil) { tuparg = nodetuplearg(c, a); };
 		    if (tuparg != nil) {
 			// #163/#32: drain the tuple's staged words (slot+0
 			// pushed first) into the SysV arg cursor by SysV class
 			// — a float MOVSD/MOVSS off (SP) into the next XMM,
 			// else POPQ into the next INTEGER arg reg; a slice/str
-			// its 3 words. Reg overflow loud-stops (rule 7); the
+			// its 3 words, a declared-tagged box its eslot words
+			// (#68). Reg overflow loud-stops (rule 7); the
 			// partial-spill stitch is out of scope (twin of #164).
 			// C-t2: nodetuplearg admits ident/literal/unwrap
 			// sources; a literal's elements are VALUE exprs,
 			// classified the way the @tupargscr restage classified
-			// them (kind-discriminated twin walk).
+			// them (kind-discriminated twin walk). The param-aware
-			let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+			// path (dptt) walks declared element TYPE nodes.
+			let tuplit: bool = false;
+			if (dptt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 			let p: *node = tuparg.list;
 			for (p != nil) {
 				let et: *node = p.lhs;
@@ -28832,14 +28882,17 @@ fn cgcall(c: *cgen, n: *node) void = {
 					fpidx += 1;
 					popped += 1;
 				} else {
-					// tagged is guarded loud at the restage, so
+					// eslot — full slot split; on the declared
-					// wide-vs-scalar is the full slot split here
+					// path tupeslotn reads the element TYPE node
-					// (#22 accessor scale).
+					// directly (#68 box-aware), else wide-vs-scalar
-					let wide: bool = false;
+					// off the literal VALUE node (#22 accessor scale).
-					if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-					else { wide = isstrtype(c, et) || isslicetype(c, et); };
 					let eb: i32 = 1;
-					if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					if (tuplit) {
+						let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+						if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					} else {
+						eb = tupeslotn(et) / 8;
+					};
 					if (intidx + eb > 6) {
 						let msg: str = "tuple arg element overflows integer arg regs (DI/SI/DX/CX/R8/R9); stitch out of scope, see #163\n";
 						os.write(2, msg.ptr, msg.len: u64);
@@ -36355,11 +36408,37 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 	};
 
-	// #64 (filed, rule 7): an N_TUPLE literal rhs rides this decl-less
+	// #64: a tuple-LITERAL rhs carries a DECLARED tuple type (built from
-	// cgexpr route, so a declared-TAGGED element's concrete rvalue
+	// the lvalue binding types) into the cursor fill, so a declared-tagged
-	// still fills the cursor stamped-keyed (silent skew) — the #57
+	// element's concrete rvalue widens into the box instead of riding the
-	// decl wire stops at return/let.
+	// decl-less stamped-keyed route — the #57 decl wire extended past
-	if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	// cgmlet/cgreturn to destructure-reassign. A `_` lvalue has no local
+	// (no declared type node); its decl element stays nil and the
+	// fill/receive fall back to the rhs literal element's own stamped type
+	// for the cursor stride (harec `_` advance; pinned by the R3 control).
+	let litrhs: bool = false;
+	if (n.rhs != nil) { if (n.rhs.kind == nkind.N_TUPLE) { litrhs = true; }; };
+	let synthdecl: *node = nil;
+	if (litrhs) {
+		synthdecl = newnode(nkind.N_TTUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+		let dtail: *node = nil;
+		let lb0: *node = n.list;
+		for (lb0 != nil) {
+			let w: *node = newnode(nkind.N_TUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+			w.lhs = nil;
+			if (lb0.kind == nkind.N_IDENT) {
+				let lc0: *local = localfindnode(c, lb0.str);
+				if (lc0 != nil) { w.lhs = lc0.tnode; };
+			};
+			w.next = nil;
+			if (dtail == nil) { synthdecl.list = w; } else { dtail.next = w; };
+			dtail = w;
+			lb0 = lb0.next;
+		};
+		cgtuplelittocursor(c, n.rhs, synthdecl);
+	} else {
+		if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	};
 
 	if (sretrecv > 0) {
 		let scr: i32 = localfind(c, "@sretscr");
@@ -36438,9 +36517,20 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	let l: *node = n.list;
 	let pt: *node = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	// #64: a tuple-LITERAL rhs keys element WIDTH on the DECLARED lvalue
+	// type (synthdecl), not the rettuple (nil for a literal); a `_` slot
+	// (declared type nil) falls back to the rhs literal element's own
+	// stamped type for the cursor stride.
+	let dp: *node = nil;
+	let re: *node = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		if (isfloattype(c, tn)) {
 			ssetotal = ssetotal + 1;
 		} else {
@@ -36448,6 +36538,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	if (gptotal > TUPLE_GPCAP) {	// AX,DX,CX,R8 capacity
 		// pinned loud-stop, inline like cgen.ww:604 (cstage uses
@@ -36467,9 +36559,16 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	l = n.list;
 	pt = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	dp = nil;
+	re = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		let isflt: bool = isfloattype(c, tn);
 		let eslot: i32 = tupeslotn(tn);
 		let off: i32 = 0;
@@ -36486,6 +36585,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	c.lastwasreturn = 0;
 	return;

selfhost/cmd/wcc/cgenexpr.ww

@@ -7363,19 +7363,38 @@ fn cgcall(c: *cgen, n: *node) void = {
 				stackslots += 1;
 			};
 			popped += 1;
-		} else { let tuparg: *node = nodetuplearg(c, a);
+		} else {
+			// #68: drain over the PARAM tuple element widths for a
+			// tuple LITERAL arg (the declared-tagged box words pop
+			// together with the i64 that follows), mirroring the
+			// param-aware send; else the source tuple type.
+			let dptt: *node = nil;
+			if (a.kind == nkind.N_TUPLE) { if (dparam != nil) {
+				if (dparam.kind == nkind.N_PARAM && dparam.lhs != nil) {
+					let dtn2: *node = dparam.lhs;
+					for (dtn2 != nil && dtn2.kind == nkind.N_TNAME) {
+						dtn2 = aliaslookup(c, dtn2.str);
+					};
+					if (dtn2 != nil) { if (dtn2.kind == nkind.N_TTUPLE) { dptt = dtn2; }; };
+				};
+			}; };
+			let tuparg: *node = dptt;
+			if (tuparg == nil) { tuparg = nodetuplearg(c, a); };
 		    if (tuparg != nil) {
 			// #163/#32: drain the tuple's staged words (slot+0
 			// pushed first) into the SysV arg cursor by SysV class
 			// — a float MOVSD/MOVSS off (SP) into the next XMM,
 			// else POPQ into the next INTEGER arg reg; a slice/str
-			// its 3 words. Reg overflow loud-stops (rule 7); the
+			// its 3 words, a declared-tagged box its eslot words
+			// (#68). Reg overflow loud-stops (rule 7); the
 			// partial-spill stitch is out of scope (twin of #164).
 			// C-t2: nodetuplearg admits ident/literal/unwrap
 			// sources; a literal's elements are VALUE exprs,
 			// classified the way the @tupargscr restage classified
-			// them (kind-discriminated twin walk).
+			// them (kind-discriminated twin walk). The param-aware
-			let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+			// path (dptt) walks declared element TYPE nodes.
+			let tuplit: bool = false;
+			if (dptt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 			let p: *node = tuparg.list;
 			for (p != nil) {
 				let et: *node = p.lhs;
@@ -7397,14 +7416,17 @@ fn cgcall(c: *cgen, n: *node) void = {
 					fpidx += 1;
 					popped += 1;
 				} else {
-					// tagged is guarded loud at the restage, so
+					// eslot — full slot split; on the declared
-					// wide-vs-scalar is the full slot split here
+					// path tupeslotn reads the element TYPE node
-					// (#22 accessor scale).
+					// directly (#68 box-aware), else wide-vs-scalar
-					let wide: bool = false;
+					// off the literal VALUE node (#22 accessor scale).
-					if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-					else { wide = isstrtype(c, et) || isslicetype(c, et); };
 					let eb: i32 = 1;
-					if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					if (tuplit) {
+						let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+						if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					} else {
+						eb = tupeslotn(et) / 8;
+					};
 					if (intidx + eb > 6) {
 						let msg: str = "tuple arg element overflows integer arg regs (DI/SI/DX/CX/R8/R9); stitch out of scope, see #163\n";
 						os.write(2, msg.ptr, msg.len: u64);

selfhost/cmd/wcc/cgenstmt.ww

@@ -3171,11 +3171,37 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 	};
 
-	// #64 (filed, rule 7): an N_TUPLE literal rhs rides this decl-less
+	// #64: a tuple-LITERAL rhs carries a DECLARED tuple type (built from
-	// cgexpr route, so a declared-TAGGED element's concrete rvalue
+	// the lvalue binding types) into the cursor fill, so a declared-tagged
-	// still fills the cursor stamped-keyed (silent skew) — the #57
+	// element's concrete rvalue widens into the box instead of riding the
-	// decl wire stops at return/let.
+	// decl-less stamped-keyed route — the #57 decl wire extended past
-	if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	// cgmlet/cgreturn to destructure-reassign. A `_` lvalue has no local
+	// (no declared type node); its decl element stays nil and the
+	// fill/receive fall back to the rhs literal element's own stamped type
+	// for the cursor stride (harec `_` advance; pinned by the R3 control).
+	let litrhs: bool = false;
+	if (n.rhs != nil) { if (n.rhs.kind == nkind.N_TUPLE) { litrhs = true; }; };
+	let synthdecl: *node = nil;
+	if (litrhs) {
+		synthdecl = newnode(nkind.N_TTUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+		let dtail: *node = nil;
+		let lb0: *node = n.list;
+		for (lb0 != nil) {
+			let w: *node = newnode(nkind.N_TUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+			w.lhs = nil;
+			if (lb0.kind == nkind.N_IDENT) {
+				let lc0: *local = localfindnode(c, lb0.str);
+				if (lc0 != nil) { w.lhs = lc0.tnode; };
+			};
+			w.next = nil;
+			if (dtail == nil) { synthdecl.list = w; } else { dtail.next = w; };
+			dtail = w;
+			lb0 = lb0.next;
+		};
+		cgtuplelittocursor(c, n.rhs, synthdecl);
+	} else {
+		if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	};
 
 	if (sretrecv > 0) {
 		let scr: i32 = localfind(c, "@sretscr");
@@ -3254,9 +3280,20 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	let l: *node = n.list;
 	let pt: *node = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	// #64: a tuple-LITERAL rhs keys element WIDTH on the DECLARED lvalue
+	// type (synthdecl), not the rettuple (nil for a literal); a `_` slot
+	// (declared type nil) falls back to the rhs literal element's own
+	// stamped type for the cursor stride.
+	let dp: *node = nil;
+	let re: *node = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		if (isfloattype(c, tn)) {
 			ssetotal = ssetotal + 1;
 		} else {
@@ -3264,6 +3301,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	if (gptotal > TUPLE_GPCAP) {	// AX,DX,CX,R8 capacity
 		// pinned loud-stop, inline like cgen.ww:604 (cstage uses
@@ -3283,9 +3322,16 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	l = n.list;
 	pt = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	dp = nil;
+	re = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		let isflt: bool = isfloattype(c, tn);
 		let eslot: i32 = tupeslotn(tn);
 		let off: i32 = 0;
@@ -3302,6 +3348,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	c.lastwasreturn = 0;
 	return;

selfhost/cmd/wcc/cgenutil.ww

@@ -829,22 +829,40 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		emitline("\tX0, (SP)\n");
 		return rest + 1;
 	};
-	cgexpr(c, arg);
+	// #68: a tuple-LITERAL arg derives its DECLARED tuple type from the
-	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr
+	// callee PARAM type node (the #57 decl wire, extended to call-arg
-	// left the tuple in the return-ABI cursor (AX/DX/CX/R8 + X0/X1) for
+	// send), so a declared-tagged element's concrete rvalue widens into
-	// every nodetuplearg producer — call (return ABI), ident
+	// the box cursor; the restage + push then key on the param tuple type
-	// (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
+	// node (declared element widths), not the literal's element-
+	// constructed types. Mirrors cstage cgcall paramtup.
+	let paramtt: *node = nil;
+	if (arg.kind == nkind.N_TUPLE) { if (param != nil) {
+		if (param.kind == nkind.N_PARAM && param.lhs != nil) {
+			let ptn: *node = param.lhs;
+			for (ptn != nil && ptn.kind == nkind.N_TNAME) {
+				ptn = aliaslookup(c, ptn.str);
+			};
+			if (ptn != nil) { if (ptn.kind == nkind.N_TTUPLE) { paramtt = ptn; }; };
+		};
+	}; };
+	if (paramtt != nil) { cgtuplelittocursor(c, arg, paramtt); }
+	else { cgexpr(c, arg); };
+	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr /
+	// the decl-aware fill left the tuple in the return-ABI cursor (AX/DX/
+	// CX/R8 + X0/X1) for every nodetuplearg producer — call (return ABI),
+	// ident (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
 	// unwrap (payload shift); restage it into @tupargscr by SysV class
 	// (tupstore, the #164 helper) and push the slot words high->low so
 	// the pop drains slot+0 first into the SysV ARG cursor. The frame
 	// slot decouples the return-class regs from the overlapping
-	// arg-class regs. An N_TUPLE literal's elements are VALUE exprs —
+	// arg-class regs. When the PARAM tuple type is known (#68), walk its
-	// classify them the way cgtuplelittocursor does (nodeisstr/
+	// declared element type nodes (p.lhs); else an N_TUPLE literal's
-	// nodeisslice), kind-discriminated; the stride is the slot formula
+	// elements are VALUE exprs classified the way cgtuplelittocursor does.
-	// (wide ? header : 8), the same number slotsize() gives a type node.
+	let tuparg: *node = paramtt;
-	let tuparg: *node = nodetuplearg(c, arg);
+	if (tuparg == nil) { tuparg = nodetuplearg(c, arg); };
 	if (tuparg != nil) {
-		let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+		let tuplit: bool = false;
+		if (paramtt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 		let gptot: i32 = 0;
 		let sstot: i32 = 0;
 		let tsz: i32 = 0;
@@ -863,23 +881,34 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 			let eti: *tinfo = et.type_: *tinfo;
 			eti = tichase(eti);
 			if (eti != nil) {
-				if (eti.kind == tykind.TY_TUPLE
+				let bad: bool = eti.kind == tykind.TY_TUPLE
 				    || eti.kind == tykind.TY_STRUCT
-				    || eti.kind == tykind.TY_ARRAY
+				    || eti.kind == tykind.TY_ARRAY;
-				    || eti.kind == tykind.TY_TAGGED) {
+				// #68: a declared-tagged element graduates to a real
+				// widen — the decl-aware send (cgtuplelittocursor over
+				// the param tuple type) left the box words in the
+				// cursor, so tupstore below carries them. A tagged
+				// element with no param decl stays rule-7 loud (the
+				// cursor was filled stamped-keyed).
+				if (eti.kind == tykind.TY_TAGGED && paramtt == nil) { bad = true; };
+				if (bad) {
 					let mne: str = "#32: tuple arg element kind unsupported (nested tuple/struct/array/tagged; rule 7)\n";
 					os.write(2, mne.ptr, mne.len: u64);
 					os.exit(1);
 				};
 			};
-			// tagged is guarded loud above, so wide-vs-scalar is
+			// eslot — the full slot stride (str/slice header, tagged
-			// the full slot split here; eslot keeps the stride
+			// box, else 8); on the declared (non-tuplit) path tupeslotn
-			// arithmetic on the accessor scale (#22).
+			// reads the element TYPE node directly (#68 box-aware,
-			let wide: bool = false;
+			// mirrors cstage tuple_eslot). A literal element rides the
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
+			// wide-vs-scalar split off its VALUE node.
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			if (isfloattype(c, et)) { sstot += 1; }
 			else { gptot += eslot / 8; };
 			tsz += eslot;
@@ -900,11 +929,13 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		for (p != nil) {
 			let et: *node = p.lhs;
 			if (tuplit) { et = p; };
-			let wide: bool = false;
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			tupstore(c, gpcur, ssecur, scr + eoff, eslot, et);
 			if (isfloattype(c, et)) { ssecur += 1; }
 			else { gpcur += eslot / 8; };

selfhost/cmd/wwdump/main.combined.ww

@@ -17065,22 +17065,40 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		emitline("\tX0, (SP)\n");
 		return rest + 1;
 	};
-	cgexpr(c, arg);
+	// #68: a tuple-LITERAL arg derives its DECLARED tuple type from the
-	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr
+	// callee PARAM type node (the #57 decl wire, extended to call-arg
-	// left the tuple in the return-ABI cursor (AX/DX/CX/R8 + X0/X1) for
+	// send), so a declared-tagged element's concrete rvalue widens into
-	// every nodetuplearg producer — call (return ABI), ident
+	// the box cursor; the restage + push then key on the param tuple type
-	// (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
+	// node (declared element widths), not the literal's element-
+	// constructed types. Mirrors cstage cgcall paramtup.
+	let paramtt: *node = nil;
+	if (arg.kind == nkind.N_TUPLE) { if (param != nil) {
+		if (param.kind == nkind.N_PARAM && param.lhs != nil) {
+			let ptn: *node = param.lhs;
+			for (ptn != nil && ptn.kind == nkind.N_TNAME) {
+				ptn = aliaslookup(c, ptn.str);
+			};
+			if (ptn != nil) { if (ptn.kind == nkind.N_TTUPLE) { paramtt = ptn; }; };
+		};
+	}; };
+	if (paramtt != nil) { cgtuplelittocursor(c, arg, paramtt); }
+	else { cgexpr(c, arg); };
+	// #163/#32 (C-t2): tuple ARG (param twin of #164's return). cgexpr /
+	// the decl-aware fill left the tuple in the return-ABI cursor (AX/DX/
+	// CX/R8 + X0/X1) for every nodetuplearg producer — call (return ABI),
+	// ident (cgtupleslottocursor), literal (cgtuplelittocursor), `?`/`!`
 	// unwrap (payload shift); restage it into @tupargscr by SysV class
 	// (tupstore, the #164 helper) and push the slot words high->low so
 	// the pop drains slot+0 first into the SysV ARG cursor. The frame
 	// slot decouples the return-class regs from the overlapping
-	// arg-class regs. An N_TUPLE literal's elements are VALUE exprs —
+	// arg-class regs. When the PARAM tuple type is known (#68), walk its
-	// classify them the way cgtuplelittocursor does (nodeisstr/
+	// declared element type nodes (p.lhs); else an N_TUPLE literal's
-	// nodeisslice), kind-discriminated; the stride is the slot formula
+	// elements are VALUE exprs classified the way cgtuplelittocursor does.
-	// (wide ? header : 8), the same number slotsize() gives a type node.
+	let tuparg: *node = paramtt;
-	let tuparg: *node = nodetuplearg(c, arg);
+	if (tuparg == nil) { tuparg = nodetuplearg(c, arg); };
 	if (tuparg != nil) {
-		let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+		let tuplit: bool = false;
+		if (paramtt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 		let gptot: i32 = 0;
 		let sstot: i32 = 0;
 		let tsz: i32 = 0;
@@ -17099,23 +17117,34 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 			let eti: *tinfo = et.type_: *tinfo;
 			eti = tichase(eti);
 			if (eti != nil) {
-				if (eti.kind == tykind.TY_TUPLE
+				let bad: bool = eti.kind == tykind.TY_TUPLE
 				    || eti.kind == tykind.TY_STRUCT
-				    || eti.kind == tykind.TY_ARRAY
+				    || eti.kind == tykind.TY_ARRAY;
-				    || eti.kind == tykind.TY_TAGGED) {
+				// #68: a declared-tagged element graduates to a real
+				// widen — the decl-aware send (cgtuplelittocursor over
+				// the param tuple type) left the box words in the
+				// cursor, so tupstore below carries them. A tagged
+				// element with no param decl stays rule-7 loud (the
+				// cursor was filled stamped-keyed).
+				if (eti.kind == tykind.TY_TAGGED && paramtt == nil) { bad = true; };
+				if (bad) {
 					let mne: str = "#32: tuple arg element kind unsupported (nested tuple/struct/array/tagged; rule 7)\n";
 					os.write(2, mne.ptr, mne.len: u64);
 					os.exit(1);
 				};
 			};
-			// tagged is guarded loud above, so wide-vs-scalar is
+			// eslot — the full slot stride (str/slice header, tagged
-			// the full slot split here; eslot keeps the stride
+			// box, else 8); on the declared (non-tuplit) path tupeslotn
-			// arithmetic on the accessor scale (#22).
+			// reads the element TYPE node directly (#68 box-aware,
-			let wide: bool = false;
+			// mirrors cstage tuple_eslot). A literal element rides the
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
+			// wide-vs-scalar split off its VALUE node.
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			if (isfloattype(c, et)) { sstot += 1; }
 			else { gptot += eslot / 8; };
 			tsz += eslot;
@@ -17136,11 +17165,13 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node, memphase: bool) i32 = {
 		for (p != nil) {
 			let et: *node = p.lhs;
 			if (tuplit) { et = p; };
-			let wide: bool = false;
-			if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-			else { wide = isstrtype(c, et) || isslicetype(c, et); };
 			let eslot: i32 = 8;
-			if (wide) { eslot = tyslicesize(): i32; };
+			if (tuplit) {
+				let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+				if (wide) { eslot = tyslicesize(): i32; };
+			} else {
+				eslot = tupeslotn(et);
+			};
 			tupstore(c, gpcur, ssecur, scr + eoff, eslot, et);
 			if (isfloattype(c, et)) { ssecur += 1; }
 			else { gpcur += eslot / 8; };
@@ -28798,19 +28829,38 @@ fn cgcall(c: *cgen, n: *node) void = {
 				stackslots += 1;
 			};
 			popped += 1;
-		} else { let tuparg: *node = nodetuplearg(c, a);
+		} else {
+			// #68: drain over the PARAM tuple element widths for a
+			// tuple LITERAL arg (the declared-tagged box words pop
+			// together with the i64 that follows), mirroring the
+			// param-aware send; else the source tuple type.
+			let dptt: *node = nil;
+			if (a.kind == nkind.N_TUPLE) { if (dparam != nil) {
+				if (dparam.kind == nkind.N_PARAM && dparam.lhs != nil) {
+					let dtn2: *node = dparam.lhs;
+					for (dtn2 != nil && dtn2.kind == nkind.N_TNAME) {
+						dtn2 = aliaslookup(c, dtn2.str);
+					};
+					if (dtn2 != nil) { if (dtn2.kind == nkind.N_TTUPLE) { dptt = dtn2; }; };
+				};
+			}; };
+			let tuparg: *node = dptt;
+			if (tuparg == nil) { tuparg = nodetuplearg(c, a); };
 		    if (tuparg != nil) {
 			// #163/#32: drain the tuple's staged words (slot+0
 			// pushed first) into the SysV arg cursor by SysV class
 			// — a float MOVSD/MOVSS off (SP) into the next XMM,
 			// else POPQ into the next INTEGER arg reg; a slice/str
-			// its 3 words. Reg overflow loud-stops (rule 7); the
+			// its 3 words, a declared-tagged box its eslot words
+			// (#68). Reg overflow loud-stops (rule 7); the
 			// partial-spill stitch is out of scope (twin of #164).
 			// C-t2: nodetuplearg admits ident/literal/unwrap
 			// sources; a literal's elements are VALUE exprs,
 			// classified the way the @tupargscr restage classified
-			// them (kind-discriminated twin walk).
+			// them (kind-discriminated twin walk). The param-aware
-			let tuplit: bool = tuparg.kind == nkind.N_TUPLE;
+			// path (dptt) walks declared element TYPE nodes.
+			let tuplit: bool = false;
+			if (dptt == nil) { if (tuparg.kind == nkind.N_TUPLE) { tuplit = true; }; };
 			let p: *node = tuparg.list;
 			for (p != nil) {
 				let et: *node = p.lhs;
@@ -28832,14 +28882,17 @@ fn cgcall(c: *cgen, n: *node) void = {
 					fpidx += 1;
 					popped += 1;
 				} else {
-					// tagged is guarded loud at the restage, so
+					// eslot — full slot split; on the declared
-					// wide-vs-scalar is the full slot split here
+					// path tupeslotn reads the element TYPE node
-					// (#22 accessor scale).
+					// directly (#68 box-aware), else wide-vs-scalar
-					let wide: bool = false;
+					// off the literal VALUE node (#22 accessor scale).
-					if (tuplit) { wide = nodeisstr(c, et) || nodeisslice(c, et); }
-					else { wide = isstrtype(c, et) || isslicetype(c, et); };
 					let eb: i32 = 1;
-					if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					if (tuplit) {
+						let wide: bool = nodeisstr(c, et) || nodeisslice(c, et);
+						if (wide) { eb = (tyslicesize() / 8i64): i32; };
+					} else {
+						eb = tupeslotn(et) / 8;
+					};
 					if (intidx + eb > 6) {
 						let msg: str = "tuple arg element overflows integer arg regs (DI/SI/DX/CX/R8/R9); stitch out of scope, see #163\n";
 						os.write(2, msg.ptr, msg.len: u64);
@@ -36355,11 +36408,37 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 	};
 
-	// #64 (filed, rule 7): an N_TUPLE literal rhs rides this decl-less
+	// #64: a tuple-LITERAL rhs carries a DECLARED tuple type (built from
-	// cgexpr route, so a declared-TAGGED element's concrete rvalue
+	// the lvalue binding types) into the cursor fill, so a declared-tagged
-	// still fills the cursor stamped-keyed (silent skew) — the #57
+	// element's concrete rvalue widens into the box instead of riding the
-	// decl wire stops at return/let.
+	// decl-less stamped-keyed route — the #57 decl wire extended past
-	if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	// cgmlet/cgreturn to destructure-reassign. A `_` lvalue has no local
+	// (no declared type node); its decl element stays nil and the
+	// fill/receive fall back to the rhs literal element's own stamped type
+	// for the cursor stride (harec `_` advance; pinned by the R3 control).
+	let litrhs: bool = false;
+	if (n.rhs != nil) { if (n.rhs.kind == nkind.N_TUPLE) { litrhs = true; }; };
+	let synthdecl: *node = nil;
+	if (litrhs) {
+		synthdecl = newnode(nkind.N_TTUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+		let dtail: *node = nil;
+		let lb0: *node = n.list;
+		for (lb0 != nil) {
+			let w: *node = newnode(nkind.N_TUPLE, n.rhs.file, n.rhs.line, n.rhs.col);
+			w.lhs = nil;
+			if (lb0.kind == nkind.N_IDENT) {
+				let lc0: *local = localfindnode(c, lb0.str);
+				if (lc0 != nil) { w.lhs = lc0.tnode; };
+			};
+			w.next = nil;
+			if (dtail == nil) { synthdecl.list = w; } else { dtail.next = w; };
+			dtail = w;
+			lb0 = lb0.next;
+		};
+		cgtuplelittocursor(c, n.rhs, synthdecl);
+	} else {
+		if (n.rhs != nil) { cgexpr(c, n.rhs); };
+	};
 
 	if (sretrecv > 0) {
 		let scr: i32 = localfind(c, "@sretscr");
@@ -36438,9 +36517,20 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	let l: *node = n.list;
 	let pt: *node = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	// #64: a tuple-LITERAL rhs keys element WIDTH on the DECLARED lvalue
+	// type (synthdecl), not the rettuple (nil for a literal); a `_` slot
+	// (declared type nil) falls back to the rhs literal element's own
+	// stamped type for the cursor stride.
+	let dp: *node = nil;
+	let re: *node = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		if (isfloattype(c, tn)) {
 			ssetotal = ssetotal + 1;
 		} else {
@@ -36448,6 +36538,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	if (gptotal > TUPLE_GPCAP) {	// AX,DX,CX,R8 capacity
 		// pinned loud-stop, inline like cgen.ww:604 (cstage uses
@@ -36467,9 +36559,16 @@ fn cgmassign(c: *cgen, n: *node) void = {
 	l = n.list;
 	pt = nil;
 	if (rettuple != nil) { pt = rettuple.list; };
+	dp = nil;
+	re = nil;
+	if (litrhs) { dp = synthdecl.list; re = n.rhs.list; };
 	for (l != nil) {
 		let tn: *node = nil;
-		if (pt != nil) { tn = pt.lhs; };
+		if (litrhs) {
+			if (dp != nil && dp.lhs != nil) { tn = dp.lhs; } else { tn = re; };
+		} else {
+			if (pt != nil) { tn = pt.lhs; };
+		};
 		let isflt: bool = isfloattype(c, tn);
 		let eslot: i32 = tupeslotn(tn);
 		let off: i32 = 0;
@@ -36486,6 +36585,8 @@ fn cgmassign(c: *cgen, n: *node) void = {
 		};
 		l = l.next;
 		if (pt != nil) { pt = pt.next; };
+		if (dp != nil) { dp = dp.next; };
+		if (re != nil) { re = re.next; };
 	};
 	c.lastwasreturn = 0;
 	return;

test/wcc/945_tuple_lit_declblind_run.c

@@ -0,0 +1,285 @@
+/*
+ * 945_tuple_lit_declblind_run — #64 + #68: a tuple LITERAL fills the
+ * register cursor DECL-BLIND. The #57 decl wire (a declared-tagged element's
+ * concrete rvalue widens into its box) stopped at N_LET / N_RETURN; the
+ * other two tuple-literal consumers — destructure-REASSIGN (N_MASSIGN, #64)
+ * and CALL-ARG send (#68) — still rode the decl-less route, so a declared-
+ * tagged element was stored/sent WORD-0 ONLY (the box tag never set) and the
+ * cursor skewed every later element. Both stages, #263 gate-blind: the asm
+ * was byte-identical cs==ww and both ran wrong, so only RUNTIME catches it.
+ *
+ * Fix (both stages, byte-identical per rule 10): N_MASSIGN builds a DECLARED
+ * tuple type from the lvalue binding types and threads it into the cursor
+ * fill + receive (a `_` lvalue, never type-stamped, falls back to the rhs
+ * literal element type for its stride); the call-arg send/restage/drain key
+ * on the PARAM tuple type (the literal's element-constructed type undercounts
+ * a wide tagged box). The single residual generic cgexpr(N_TUPLE) arm is
+ * provably non-widening (the constructed type IS the governing type there).
+ *
+ * Every RUN row reads the box PAYLOAD back (binds n and asserts its VALUE),
+ * not merely which match arm fired — a skew that sets the tag right but
+ * corrupts the payload still fails. Rows (RUN unless marked ERR):
+ *   massign_tagged  `a,b=(7i64,99)` into a:(i32|i64); n==7 ⇒ 1, else 3;
+ *                   wrong arm ⇒ 0; garbage-tag fall-through ⇒ 2 (base).
+ *   callarg_tagged  `f((7i64,99))` param (ev,i64); match t.0, n==7 ⇒ 1.
+ *                   base: garbage tag ⇒ fall-through ⇒ 2.
+ *   massign_blank   `_,a=(99,7i64)` — `_` stride + named box widen; the box
+ *                   is element 1 (off the `_`-aligned cursor). n==7 ⇒ 1.
+ *                   base: word-0-only store corrupts a's tag ⇒ fall-through ⇒
+ *                   2 (the box's tag sits at word0; the lone scalar word
+ *                   overwrites it — verified on pristine abd97e6).
+ *   callarg_drain   `g((7i64, 35))` param (ev,i64); g returns (box payload)
+ *                   + t.1. This is the #68 DRAIN teeth (ken's verified probe
+ *                   shape): the param-aware drain must pop the box's 2 words
+ *                   AND the trailing i64 together. base: box is word-0 only
+ *                   so the i64 arm never fires (payload 0) ⇒ 0 + 35 = 35;
+ *                   post: 7 + 35 = 42. base 35 ≠ 42, and the +35 simultaneously
+ *                   proves the trailing arg still lands in its reg.
+ *   nested_tuple_arg [ERR] `h(((1,2),3))` param ((i32,i32),i64): a NESTED-
+ *                   TUPLE tuple-arg element has no transport and stays rule-7
+ *                   LOUD (the fix graduates ONLY a declared-tagged element;
+ *                   the TY_TUPLE/STRUCT/ARRAY arms are preserved). Asserts the
+ *                   build FAILS (nonzero) on BOTH drivers — locks the
+ *                   preserved loudness so a future widen-everything regresses.
+ *
+ * RUN rows: build+run on BOTH drivers AND cs==ww .s byte-identical (rule 10).
+ * NNN<950, self-contained (/tmp, no imports), so rule-14's selfhost-sibling
+ * race does not apply (903/940/945 precedent).
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+static int
+runwait(const char *cmd)
+{
+	int rc = system(cmd);
+	if (rc == -1) return -1;
+	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
+	return -1;
+}
+
+static int
+slurp_eq(const char *a, const char *b)
+{
+	FILE *fa = fopen(a, "rb");
+	FILE *fb = fopen(b, "rb");
+	if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
+	int rc = 0;
+	for (;;) {
+		int ca = fgetc(fa), cb = fgetc(fb);
+		if (ca != cb) { rc = -1; break; }
+		if (ca == EOF) break;
+	}
+	fclose(fa); fclose(fb);
+	return rc;
+}
+
+/* builderr: the build must FAIL (rule-7 loud); RUN rows leave it 0. */
+struct row { const char *label; const char *src; int want; int builderr; };
+
+static const struct row rows[] = {
+	{ "massign_tagged",
+	  "package main;\n"
+	  "type ev = (i32 | i64);\n"
+	  "export fn main() i32 = {\n"
+	  "	let a: ev = 5i32;\n"
+	  "	let b: i64 = 0;\n"
+	  "	a, b = (7i64, 99);\n"
+	  "	match (a) {\n"
+	  "	case let n: i64 => { if (n == 7) { return 1; }; return 3; };\n"
+	  "	case let m: i32 => { return 0; };\n"
+	  "	};\n"
+	  "	return 2;\n"
+	  "};\n", 1, 0 },
+	{ "callarg_tagged",
+	  "package main;\n"
+	  "type ev = (i32 | i64);\n"
+	  "fn f(t: (ev, i64)) i32 = {\n"
+	  "	match (t.0) {\n"
+	  "	case let n: i64 => { if (n == 7) { return 1; }; return 3; };\n"
+	  "	case let m: i32 => { return 0; };\n"
+	  "	};\n"
+	  "	return 2;\n"
+	  "};\n"
+	  "export fn main() i32 = {\n"
+	  "	return f((7i64, 99));\n"
+	  "};\n", 1, 0 },
+	{ "massign_blank",
+	  "package main;\n"
+	  "type ev = (i32 | i64);\n"
+	  "export fn main() i32 = {\n"
+	  "	let a: ev = 5i32;\n"
+	  "	_, a = (99, 7i64);\n"
+	  "	match (a) {\n"
+	  "	case let n: i64 => { if (n == 7) { return 1; }; return 3; };\n"
+	  "	case let m: i32 => { return 0; };\n"
+	  "	};\n"
+	  "	return 2;\n"
+	  "};\n", 1, 0 },
+	{ "callarg_drain",
+	  "package main;\n"
+	  "type ev = (i32 | i64);\n"
+	  "fn g(t: (ev, i64)) i32 = {\n"
+	  "	let bp: i64 = 0;\n"
+	  "	match (t.0) {\n"
+	  "	case let n: i64 => { bp = n; };\n"
+	  "	case let m: i32 => { bp = 0; };\n"
+	  "	};\n"
+	  "	return (bp + t.1): i32;\n"
+	  "};\n"
+	  "export fn main() i32 = {\n"
+	  "	return g((7i64, 35));\n"
+	  "};\n", 42, 0 },
+	{ "nested_tuple_arg",
+	  "package main;\n"
+	  "fn h(t: ((i32, i32), i64)) i32 = {\n"
+	  "	return 0;\n"
+	  "};\n"
+	  "export fn main() i32 = {\n"
+	  "	return h(((1, 2), 3));\n"
+	  "};\n", 0, 1 },
+};
+
+/* build+run via a driver (ww / ww_ww); returns 0 pass, nonzero fail. */
+static int
+run_driver(const char *driver, const struct row *r, int i)
+{
+	char src[96], tmpdir[96], errf[96], cmd[1024];
+	snprintf(src, sizeof src, "/tmp/tldb_%d_%d.ww", getpid(), i);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/tldb_%d_d_%d", getpid(), i);
+	snprintf(errf, sizeof errf, "/tmp/tldb_%d_e_%d", getpid(), i);
+
+	FILE *f = fopen(src, "wb");
+	if (!f) return -1;
+	fputs(r->src, f);
+	fclose(f);
+
+	mkdir(tmpdir, 0755);
+	snprintf(cmd, sizeof cmd, "cd %s && %s build %s >/dev/null 2>%s",
+	    tmpdir, driver, src, errf);
+	int brc = runwait(cmd);
+	/* ERR row: the rule-7 loud arm must fire — build FAILS (nonzero). A
+	 * clean build means the preserved loudness regressed. */
+	if (r->builderr) {
+		int ok = (brc != 0);
+		if (!ok)
+			fprintf(stderr, "row[%s]: %s built clean, expected "
+			    "rule-7 loud build-fail\n", r->label, driver);
+		unlink(src); unlink(errf); rmdir(tmpdir);
+		return ok ? 0 : 1;
+	}
+	if (brc != 0) {
+		fprintf(stderr, "row[%s]: build via %s failed\n",
+		    r->label, driver);
+		unlink(src); unlink(errf); rmdir(tmpdir);
+		return -1;
+	}
+
+	const char *base = strrchr(src, '/');
+	base = base ? base + 1 : src;
+	char outbin[256];
+	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
+	char *dot = strrchr(outbin, '.');
+	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
+	int got = runwait(outbin);
+
+	unlink(src); unlink(outbin); unlink(errf); rmdir(tmpdir);
+	if (got != r->want) {
+		fprintf(stderr, "row[%s]: %s exit %d, want %d\n",
+		    r->label, driver, got, r->want);
+		return 1;
+	}
+	return 0;
+}
+
+/* cs==ww .s byte-id (rule 10). */
+static int
+byteid(const char *w6c, const char *w6c_ww, const struct row *r, int i)
+{
+	char src[96], cs_s[96], ws_s[96], cmd[1024];
+	snprintf(src, sizeof src, "/tmp/tldb_bi_%d_%d.ww", getpid(), i);
+	snprintf(cs_s, sizeof cs_s, "/tmp/tldb_bi_%d_%d_cs.s", getpid(), i);
+	snprintf(ws_s, sizeof ws_s, "/tmp/tldb_bi_%d_%d_ww.s", getpid(), i);
+
+	FILE *f = fopen(src, "wb");
+	if (!f) return -1;
+	fputs(r->src, f);
+	fclose(f);
+
+	int rc = 0;
+	snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, cs_s, src);
+	if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c failed\n", r->label); rc = 1; }
+	else {
+		snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c_ww, ws_s, src);
+		if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c_ww failed\n", r->label); rc = 1; }
+		else if (slurp_eq(cs_s, ws_s) != 0) {
+			fprintf(stderr, "row[%s]: cstage/wwstage .s DIFFER "
+			    "(rule-10 byte-id)\n", r->label);
+			rc = 1;
+		}
+	}
+	unlink(src); unlink(cs_s); unlink(ws_s);
+	return rc;
+}
+
+int
+main(void)
+{
+	const char *bin = getenv("BIN");
+	if (!bin) bin = "out/bin";
+	char absbin[512];
+	if (bin[0] != '/') {
+		char cwd[256];
+		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
+		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
+		bin = absbin;
+	}
+
+	char cdrv[640], wdrv[640], w6c[640], w6c_ww[640];
+	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
+	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
+	snprintf(w6c, sizeof w6c, "%s/w6c", bin);
+	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);
+
+	struct { const char *name; const char *path; int gated; }
+	drivers[] = {
+		{ "cstage",  cdrv, 0 },
+		{ "wwstage", wdrv, 1 },
+		{ NULL, NULL, 0 },
+	};
+
+	int n = (int)(sizeof rows / sizeof rows[0]);
+	int total = 0, fail = 0;
+
+	for (int d = 0; drivers[d].name; d++) {
+		if (drivers[d].gated && access(drivers[d].path, X_OK) != 0) {
+			fprintf(stderr, "tuple_lit_declblind: skip %s (no %s)\n",
+			    drivers[d].name, drivers[d].path);
+			continue;
+		}
+		for (int i = 0; i < n; i++) {
+			total++;
+			if (run_driver(drivers[d].path, &rows[i], i) != 0) fail++;
+		}
+	}
+
+	if (access(w6c_ww, X_OK) == 0) {
+		for (int i = 0; i < n; i++) {
+			if (rows[i].builderr) continue;	/* no .s to compare */
+			total++;
+			if (byteid(w6c, w6c_ww, &rows[i], i) != 0) fail++;
+		}
+	}
+
+	if (fail) {
+		fprintf(stderr, "tuple_lit_declblind: %d/%d checks failed\n",
+		    fail, total);
+		return 1;
+	}
+	printf("tuple_lit_declblind: %d/%d ok\n", total, total);
+	return 0;
+}