gc: add ... T, rework plain ...

No longer a distinct type; now a property of func types.

R=ken2
CC=golang-dev
https://golang.org/cl/197042

21 files changed, 360 insertions, 109 deletions

diff --git a/src/cmd/5g/gsubr.c b/src/cmd/5g/gsubr.c
index 561d2ccceb..ad9cad67e0 100644
--- a/src/cmd/5g/gsubr.c
+++ b/src/cmd/5g/gsubr.c
@@ -178,7 +178,6 @@ isfat(Type *t)
 	case TARRAY:
 	case TSTRING:
 	case TINTER:	// maybe remove later
-	case TDDD:	// maybe remove later
 		return 1;
 	}
 	return 0;
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index 07471ffa7c..5549830e3f 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -174,7 +174,6 @@ isfat(Type *t)
 	case TARRAY:
 	case TSTRING:
 	case TINTER:	// maybe remove later
-	case TDDD:	// maybe remove later
 		return 1;
 	}
 	return 0;
diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index e09ba7b20d..07ad153e0c 100644
--- a/src/cmd/8g/gsubr.c
+++ b/src/cmd/8g/gsubr.c
@@ -176,7 +176,6 @@ isfat(Type *t)
 	case TARRAY:
 	case TSTRING:
 	case TINTER:	// maybe remove later
-	case TDDD:	// maybe remove later
 		return 1;
 	}
 	return 0;
diff --git a/src/cmd/gc/align.c b/src/cmd/gc/align.c
index ba84c4377f..7a27a040c9 100644
--- a/src/cmd/gc/align.c
+++ b/src/cmd/gc/align.c
@@ -176,9 +176,6 @@ dowidth(Type *t)
 		w = 8;
 		checkwidth(t->type);
 		break;
-	case TDDD:
-		w = 2*widthptr;
-		break;
 	case TINTER:		// implemented as 2 pointers
 		w = 2*widthptr;
 		offmod(t);
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index 4639eda8d2..aeb3e3916a 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -877,6 +877,7 @@ stotype(NodeList *l, int et, Type **t)
 		f->type = n->type;
 		f->note = note;
 		f->width = BADWIDTH;
+		f->isddd = n->isddd;
 
 		if(n->left != N && n->left->op == ONAME) {
 			f->nname = n->left;
@@ -1022,11 +1023,23 @@ checkarglist(NodeList *all, int input)
 		if(n != N)
 			n = newname(n->sym);
 		n = nod(ODCLFIELD, n, t);
-		if(n->right != N && n->right->op == OTYPE && isddd(n->right->type)) {
+		if(n->right != N && n->right->op == ODDD) {
 			if(!input)
 				yyerror("cannot use ... in output argument list");
 			else if(l->next != nil)
 				yyerror("can only use ... as final argument in list");
+			if(n->right->left == N) {
+				// TODO(rsc): Delete with DDD cleanup.
+				n->right->op = OTYPE;
+				n->right->type = typ(TINTER);
+			} else {
+				n->right->op = OTARRAY;
+				n->right->right = n->right->left;
+				n->right->left = N;
+			}
+			n->isddd = 1;
+			if(n->left != N)
+				n->left->isddd = 1;
 		}
 		l->n = n;
 	}
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index e5715e895e..d634d0d3a9 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -147,6 +147,7 @@ struct	Type
 	uchar	local;		// created in this file
 	uchar	deferwidth;
 	uchar	broke;
+	uchar	isddd;	// TFIELD is ... argument
 
 	Node*	nod;		// canonical OTYPE node
 	int		lineno;
@@ -205,6 +206,7 @@ struct	Node
 	uchar	dodata;		// compile literal assignment as data statement
 	uchar	used;
 	uchar	oldref;
+	uchar	isddd;
 
 	// most nodes
 	Node*	left;
@@ -401,6 +403,9 @@ enum
 	OTINTER,
 	OTFUNC,
 	OTARRAY,
+	
+	// misc
+	ODDD,
 
 	// for back ends
 	OCMP, ODEC, OEXTEND, OINC, OREGISTER, OINDREG,
@@ -425,21 +430,20 @@ enum
 
 	TPTR32, TPTR64,		// 16
 
-	TDDD,			// 18
-	TFUNC,
+	TFUNC,		// 18
 	TARRAY,
 	T_old_DARRAY,
-	TSTRUCT,		// 22
+	TSTRUCT,		// 21
 	TCHAN,
 	TMAP,
-	TINTER,			// 25
+	TINTER,			// 24
 	TFORW,
 	TFIELD,
 	TANY,
 	TSTRING,
 
 	// pseudo-types for literals
-	TIDEAL,			// 30
+	TIDEAL,			// 29
 	TNIL,
 	TBLANK,
 	
@@ -844,7 +848,6 @@ int	isfixedarray(Type*);
 int	isslice(Type*);
 int	isinter(Type*);
 int	isnilinter(Type*);
-int	isddd(Type*);
 int	isideal(Type*);
 int	isblank(Node*);
 Type*	maptype(Type*, Type*);
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index c309d0d017..f2a037710b 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -76,7 +76,7 @@
 
 %type	<sym>	hidden_importsym hidden_pkg_importsym
 
-%type	<node>	hidden_constant hidden_dcl hidden_interfacedcl hidden_structdcl
+%type	<node>	hidden_constant hidden_dcl hidden_interfacedcl hidden_structdcl hidden_opt_sym
 
 %type	<list>	hidden_funres
 %type	<list>	ohidden_funres
@@ -896,10 +896,10 @@ convtype:
 		// array literal
 		$$ = nod(OTARRAY, $2, $4);
 	}
-|	'[' dotdotdot ']' ntype
+|	'[' LDDD ']' ntype
 	{
 		// array literal of nelem
-		$$ = nod(OTARRAY, $2, $4);
+		$$ = nod(OTARRAY, nod(ODDD, N, N), $4);
 	}
 |	LMAP '[' ntype ']' ntype
 	{
@@ -920,7 +920,11 @@ convtype:
 dotdotdot:
 	LDDD
 	{
-		$$ = typenod(typ(TDDD));
+		$$ = nod(ODDD, N, N);
+	}
+|	LDDD ntype
+	{
+		$$ = nod(ODDD, $2, N);
 	}
 
 ntype:
@@ -979,10 +983,10 @@ othertype:
 	{
 		$$ = nod(OTARRAY, $2, $4);
 	}
-|	'[' dotdotdot ']' ntype
+|	'[' LDDD ']' ntype
 	{
 		// array literal of nelem
-		$$ = nod(OTARRAY, $2, $4);
+		$$ = nod(OTARRAY, nod(ODDD, N, N), $4);
 	}
 |	LCHAN non_recvchantype
 	{
@@ -1651,10 +1655,6 @@ hidden_type_misc:
 		$$->type = $3;
 		$$->chan = Csend;
 	}
-|	LDDD
-	{
-		$$ = typ(TDDD);
-	}
 
 hidden_type_recv_chan:
 	LCOMM LCHAN hidden_type
@@ -1670,14 +1670,35 @@ hidden_type_func:
 		$$ = functype(nil, $3, $5);
 	}
 
+hidden_opt_sym:
+	sym
+	{
+		$$ = newname($1);
+	}
+|	'?'
+	{
+		$$ = N;
+	}
+
 hidden_dcl:
-	sym hidden_type
+	hidden_opt_sym hidden_type
 	{
-		$$ = nod(ODCLFIELD, newname($1), typenod($2));
+		$$ = nod(ODCLFIELD, $1, typenod($2));
+	}
+|	hidden_opt_sym LDDD
+	{
+		$$ = nod(ODCLFIELD, $1, typenod(typ(TINTER)));
+		$$->isddd = 1;
 	}
-|	'?' hidden_type
+|	hidden_opt_sym LDDD hidden_type
 	{
-		$$ = nod(ODCLFIELD, N, typenod($2));
+		Type *t;
+		
+		t = typ(TARRAY);
+		t->bound = -1;
+		t->type = $3;
+		$$ = nod(ODCLFIELD, $1, typenod(t));
+		$$->isddd = 1;
 	}
 
 hidden_structdcl:
diff --git a/src/cmd/gc/print.c b/src/cmd/gc/print.c
index 91f012d8b8..57ebe3f1cf 100644
--- a/src/cmd/gc/print.c
+++ b/src/cmd/gc/print.c
@@ -243,7 +243,19 @@ exprfmt(Fmt *f, Node *n, int prec)
 		break;
 
 	case OCOMPLIT:
-		fmtprint(f, "<compos>");
+		fmtprint(f, "composite literal");
+		break;
+	
+	case OARRAYLIT:
+		fmtprint(f, "slice literal");
+		break;
+	
+	case OMAPLIT:
+		fmtprint(f, "map literal");
+		break;
+	
+	case OSTRUCTLIT:
+		fmtprint(f, "struct literal");
 		break;
 
 	case ODOT:
@@ -338,9 +350,6 @@ exprfmt(Fmt *f, Node *n, int prec)
 	case OMAKEMAP:
 		fmtprint(f, "make(%#T)", n->type);
 		break;
-
-	case OMAPLIT:
-		fmtprint(f, "map literal");
 	}
 
 	if(prec > nprec)
diff --git a/src/cmd/gc/reflect.c b/src/cmd/gc/reflect.c
index e1dba06b8c..3f90f68e93 100644
--- a/src/cmd/gc/reflect.c
+++ b/src/cmd/gc/reflect.c
@@ -391,7 +391,6 @@ enum {
 	KindFloat64,
 	KindArray,
 	KindChan,
-	KindDotDotDot,
 	KindFunc,
 	KindInterface,
 	KindMap,
@@ -423,7 +422,6 @@ kinds[] =
 	[TFLOAT64]	= KindFloat64,
 	[TBOOL]		= KindBool,
 	[TSTRING]		= KindString,
-	[TDDD]		= KindDotDotDot,
 	[TPTR32]		= KindPtr,
 	[TPTR64]		= KindPtr,
 	[TSTRUCT]	= KindStruct,
@@ -453,7 +451,6 @@ structnames[] =
 	[TFLOAT64]	= "*runtime.Float64Type",
 	[TBOOL]		= "*runtime.BoolType",
 	[TSTRING]		= "*runtime.StringType",
-	[TDDD]		= "*runtime.DotDotDotType",
 
 	[TPTR32]		= "*runtime.PtrType",
 	[TPTR64]		= "*runtime.PtrType",
@@ -518,7 +515,6 @@ haspointers(Type *t)
 				return 1;
 		return 0;
 	case TSTRING:
-	case TDDD:
 	case TPTR32:
 	case TPTR64:
 	case TINTER:
@@ -637,7 +633,7 @@ typename(Type *t)
 static Sym*
 dtypesym(Type *t)
 {
-	int ot, n;
+	int ot, n, isddd;
 	Sym *s, *s1, *s2;
 	Sig *a, *m;
 	Type *t1;
@@ -709,14 +705,19 @@ ok:
 	case TFUNC:
 		for(t1=getthisx(t)->type; t1; t1=t1->down)
 			dtypesym(t1->type);
-		for(t1=getinargx(t)->type; t1; t1=t1->down)
+		isddd = 0;
+		for(t1=getinargx(t)->type; t1; t1=t1->down) {
+			isddd = t1->isddd;
 			dtypesym(t1->type);
+		}
 		for(t1=getoutargx(t)->type; t1; t1=t1->down)
 			dtypesym(t1->type);
 
 		ot = dcommontype(s, ot, t);
+		ot = duint8(s, ot, isddd);
 
 		// two slice headers: in and out.
+		ot = rnd(ot, widthptr);
 		ot = dsymptr(s, ot, s, ot+2*(widthptr+2*4));
 		n = t->thistuple + t->intuple;
 		ot = duint32(s, ot, n);
@@ -855,7 +856,6 @@ dumptypestructs(void)
 		for(i=1; i<=TBOOL; i++)
 			dtypesym(ptrto(types[i]));
 		dtypesym(ptrto(types[TSTRING]));
-		dtypesym(typ(TDDD));
 		dtypesym(ptrto(pkglookup("Pointer", unsafepkg)->def->type));
 		
 		// add paths for runtime and main, which 6l imports implicitly.
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 9d0c84ac41..a938424704 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -941,7 +941,6 @@ etnames[] =
 	[TBOOL]		= "BOOL",
 	[TPTR32]	= "PTR32",
 	[TPTR64]	= "PTR64",
-	[TDDD]		= "DDD",
 	[TFUNC]		= "FUNC",
 	[TARRAY]	= "ARRAY",
 	[TSTRUCT]	= "STRUCT",
@@ -1088,7 +1087,6 @@ basicnames[] =
 	[TFLOAT64]	= "float64",
 	[TBOOL]		= "bool",
 	[TANY]		= "any",
-	[TDDD]		= "...",
 	[TSTRING]		= "string",
 	[TNIL]		= "nil",
 	[TIDEAL]		= "ideal",
@@ -1166,9 +1164,16 @@ Tpretty(Fmt *fp, Type *t)
 			fmtprint(fp, "func");
 		fmtprint(fp, "(");
 		for(t1=getinargx(t)->type; t1; t1=t1->down) {
-			if(noargnames && t1->etype == TFIELD)
-				fmtprint(fp, "%T", t1->type);
-			else
+			if(noargnames && t1->etype == TFIELD) {
+				if(t1->isddd) {
+					// TODO(rsc): Delete with DDD cleanup.
+					if(t1->type->etype == TINTER)
+						fmtprint(fp, "...");
+					else
+						fmtprint(fp, "... %T", t1->type->type);
+				} else
+					fmtprint(fp, "%T", t1->type);
+			} else
 				fmtprint(fp, "%T", t1);
 			if(t1->down)
 				fmtprint(fp, ", ");
@@ -1246,9 +1251,16 @@ Tpretty(Fmt *fp, Type *t)
 		if(t->sym == S || t->embedded) {
 			if(exporting)
 				fmtprint(fp, "? ");
-			fmtprint(fp, "%T", t->type);
 		} else
-			fmtprint(fp, "%hS %T", t->sym, t->type);
+			fmtprint(fp, "%hS ", t->sym);
+		if(t->isddd) {
+			// TODO(rsc): delete with DDD cleanup.
+			if(t->type->etype == TINTER)
+				fmtprint(fp, "...");
+			else
+				fmtprint(fp, "... %T", t->type->type);
+		} else
+			fmtprint(fp, "%T", t->type);
 		if(t->note)
 			fmtprint(fp, " \"%Z\"", t->note);
 		return 0;
@@ -1608,13 +1620,7 @@ isselect(Node *n)
 int
 isinter(Type *t)
 {
-	if(t != T) {
-		if(t->etype == TINTER)
-			return 1;
-		if(t->etype == TDDD)
-			return 1;
-	}
-	return 0;
+	return t != T && t->etype == TINTER;
 }
 
 int
@@ -1628,14 +1634,6 @@ isnilinter(Type *t)
 }
 
 int
-isddd(Type *t)
-{
-	if(t != T && t->etype == TDDD)
-		return 1;
-	return 0;
-}
-
-int
 isideal(Type *t)
 {
 	if(t == T)
@@ -1756,7 +1754,7 @@ eqtype1(Type *t1, Type *t2, int d, int names)
 			while(ta != tb) {
 				if(ta == T || tb == T)
 					return 0;
-				if(ta->etype != TFIELD || tb->etype != TFIELD)
+				if(ta->etype != TFIELD || tb->etype != TFIELD || ta->isddd != tb->isddd)
 					return 0;
 				if(!eqtype1(ta->type, tb->type, d+1, names))
 					return 0;
@@ -2193,19 +2191,24 @@ out:
 void
 badtype(int o, Type *tl, Type *tr)
 {
-	yyerror("illegal types for operand: %O", o);
+	Fmt fmt;
+	char *s;
+	
+	fmtstrinit(&fmt);
 	if(tl != T)
-		print("	%T\n", tl);
+		fmtprint(&fmt, "\n	%T", tl);
 	if(tr != T)
-		print("	%T\n", tr);
+		fmtprint(&fmt, "\n	%T", tr);
 
 	// common mistake: *struct and *interface.
 	if(tl && tr && isptr[tl->etype] && isptr[tr->etype]) {
 		if(tl->type->etype == TSTRUCT && tr->type->etype == TINTER)
-			print("	(*struct vs *interface)\n");
+			fmtprint(&fmt, "\n	(*struct vs *interface)");
 		else if(tl->type->etype == TINTER && tr->type->etype == TSTRUCT)
-			print("	(*interface vs *struct)\n");
+			fmtprint(&fmt, "\n	(*interface vs *struct)");
 	}
+	s = fmtstrflush(&fmt);
+	yyerror("illegal types for operand: %O%s", o, s);
 }
 
 /*
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index e8ed1dc941..dfd67b71cb 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -140,6 +140,9 @@ reswitch:
 			n = n->right;
 		goto redo;
 
+	case ODDD:
+		break;
+
 	/*
 	 * types (OIND is with exprs)
 	 */
@@ -157,7 +160,8 @@ reswitch:
 		if(l == nil) {
 			t->bound = -1;
 		} else {
-			typecheck(&l, Erv | Etype);
+			if(l->op != ODDD)
+				typecheck(&l, Erv | Etype);
 			switch(l->op) {
 			default:
 				yyerror("invalid array bound %#N", l);
@@ -173,13 +177,7 @@ reswitch:
 				}
 				break;
 
-			case OTYPE:
-				if(l->type == T)
-					goto error;
-				if(l->type->etype != TDDD) {
-					yyerror("invalid array bound %T", l->type);
-					goto error;
-				}
+			case ODDD:
 				t->bound = -100;
 				break;
 			}
@@ -1496,12 +1494,18 @@ typecheckaste(int op, Type *tstruct, NodeList *nl, char *desc)
 		tn = n->type->type;
 		for(tl=tstruct->type; tl; tl=tl->down) {
 			int xx, yy;
+			if(tl->isddd) {
+				// TODO(rsc): delete if (but not body) in DDD cleanup.
+				if(tl->type->etype != TINTER)
+					for(; tn; tn=tn->down)
+						if(checkconv(tn->type, tl->type->type, 0, &xx, &yy, desc) < 0)
+							yyerror("cannot use %T as type %T in %s", tn->type, tl->type->type, desc);
+				goto out;
+			}
 			if(tn == T) {
 				yyerror("not enough arguments to %#O", op);
 				goto out;
 			}
-			if(isddd(tl->type))
-				goto out;
 			if(checkconv(tn->type, tl->type, 0, &xx, &yy, desc) < 0)
 				yyerror("cannot use type %T as type %T in %s", tn->type, tl->type, desc);
 			tn = tn->down;
@@ -1513,10 +1517,17 @@ typecheckaste(int op, Type *tstruct, NodeList *nl, char *desc)
 
 	for(tl=tstruct->type; tl; tl=tl->down) {
 		t = tl->type;
-		if(isddd(t)) {
+		if(tl->isddd) {
+			if(nl != nil && nl->next == nil && nl->n->isddd && eqtype(nl->n->type, t))
+				goto out;
 			for(; nl; nl=nl->next) {
+				int xx, yy;
 				setlineno(nl->n);
-				defaultlit(&nl->n, T);
+				defaultlit(&nl->n, t->type);
+				// TODO(rsc): drop first if in DDD cleanup
+				if(t->etype != TINTER)
+				if(checkconv(nl->n->type, t->type, 0, &xx, &yy, desc) < 0)
+					yyerror("cannot use %#N as type %T in %s", nl->n, t->type, desc);					
 			}
 			goto out;
 		}
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index e142814f7b..9a84acce36 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1368,6 +1368,31 @@ mkdotargs(NodeList *lr0, NodeList *nn, Type *l, int fp, NodeList **init)
 	return nn;
 }
 
+ /*
+ * package all the arguments that match a ... T parameter into a []T.
+ */
+NodeList*
+mkdotargslice(NodeList *lr0, NodeList *nn, Type *l, int fp, NodeList **init)
+{
+	Node *a, *n;
+	Type *tslice;
+	
+	tslice = typ(TARRAY);
+	tslice->type = l->type->type;
+	tslice->bound = -1;
+	
+	n = nod(OCOMPLIT, N, typenod(tslice));
+	n->list = lr0;
+	typecheck(&n, Erv);
+	if(n->type == T)
+		fatal("mkdotargslice: typecheck failed");
+	walkexpr(&n, init);
+	
+	a = nod(OAS, nodarg(l, fp), n);
+	nn = list(nn, convas(a, init));
+	return nn;
+}
+
 /*
  * helpers for shape errors
  */
@@ -1466,7 +1491,7 @@ ascompatte(int op, Type **nl, NodeList *lr, int fp, NodeList **init)
 	}
 
 loop:
-	if(l != T && isddd(l->type)) {
+	if(l != T && l->isddd) {
 		// the ddd parameter must be last
 		ll = structnext(&savel);
 		if(ll != T)
@@ -1476,7 +1501,7 @@ loop:
 		// only if we are assigning a single ddd
 		// argument to a ddd parameter then it is
 		// passed thru unencapsulated
-		if(r != N && lr->next == nil && isddd(r->type)) {
+		if(r != N && lr->next == nil && r->isddd && eqtype(l->type, r->type)) {
 			a = nod(OAS, nodarg(l, fp), r);
 			a = convas(a, init);
 			nn = list(nn, a);
@@ -1486,7 +1511,11 @@ loop:
 		// normal case -- make a structure of all
 		// remaining arguments and pass a pointer to
 		// it to the ddd parameter (empty interface)
-		nn = mkdotargs(lr, nn, l, fp, init);
+		// TODO(rsc): delete in DDD cleanup.
+		if(l->type->etype == TINTER)
+			nn = mkdotargs(lr, nn, l, fp, init);
+		else
+			nn = mkdotargslice(lr, nn, l, fp, init);
 		goto ret;
 	}
 
diff --git a/src/pkg/exp/datafmt/datafmt.go b/src/pkg/exp/datafmt/datafmt.go
index 0a2354286b..cd9af2b6ac 100644
--- a/src/pkg/exp/datafmt/datafmt.go
+++ b/src/pkg/exp/datafmt/datafmt.go
@@ -415,8 +415,6 @@ func typename(typ reflect.Type) string {
 		return "array"
 	case *reflect.ChanType:
 		return "chan"
-	case *reflect.DotDotDotType:
-		return "ellipsis"
 	case *reflect.FuncType:
 		return "func"
 	case *reflect.InterfaceType:
diff --git a/src/pkg/exp/eval/bridge.go b/src/pkg/exp/eval/bridge.go
index 43a6fd30d6..d494421a43 100644
--- a/src/pkg/exp/eval/bridge.go
+++ b/src/pkg/exp/eval/bridge.go
@@ -75,12 +75,9 @@ func TypeFromNative(t reflect.Type) Type {
 	case *reflect.FuncType:
 		nin := t.NumIn()
 		// Variadic functions have DotDotDotType at the end
-		varidic := false
-		if nin > 0 {
-			if _, ok := t.In(nin - 1).(*reflect.DotDotDotType); ok {
-				varidic = true
-				nin--
-			}
+		variadic := t.DotDotDot()
+		if variadic {
+			nin--
 		}
 		in := make([]Type, nin)
 		for i := range in {
@@ -90,7 +87,7 @@ func TypeFromNative(t reflect.Type) Type {
 		for i := range out {
 			out[i] = TypeFromNative(t.Out(i))
 		}
-		et = NewFuncType(in, varidic, out)
+		et = NewFuncType(in, variadic, out)
 	case *reflect.InterfaceType:
 		log.Crashf("%T not implemented", t)
 	case *reflect.MapType:
diff --git a/src/pkg/reflect/type.go b/src/pkg/reflect/type.go
index cd838d7289..1e2772f66b 100644
--- a/src/pkg/reflect/type.go
+++ b/src/pkg/reflect/type.go
@@ -139,12 +139,6 @@ type UintptrType struct {
 	commonType
 }
 
-// DotDotDotType represents the ... that can
-// be used as the type of the final function parameter.
-type DotDotDotType struct {
-	commonType
-}
-
 // UnsafePointerType represents an unsafe.Pointer type.
 type UnsafePointerType struct {
 	commonType
@@ -176,8 +170,9 @@ type ChanType struct {
 // FuncType represents a function type.
 type FuncType struct {
 	commonType
-	in  []*runtime.Type
-	out []*runtime.Type
+	dotdotdot bool
+	in        []*runtime.Type
+	out       []*runtime.Type
 }
 
 // Method on interface type
@@ -377,6 +372,19 @@ func (t *FuncType) In(i int) Type {
 	return toType(*t.in[i])
 }
 
+// DotDotDot returns true if the final function input parameter
+// is a "..." parameter.  If so, the parameter's underlying static
+// type - either interface{} or []T - is returned by t.In(t.NumIn() - 1).
+//
+// For concreteness, if t is func(x int, y ... float), then
+//
+//	t.NumIn() == 2
+//	t.In(0) is the reflect.Type for "int"
+//	t.In(1) is the reflect.Type for "[]float"
+//	t.DotDotDot() == true
+//
+func (t *FuncType) DotDotDot() bool { return t.dotdotdot }
+
 // NumIn returns the number of input parameters.
 func (t *FuncType) NumIn() int { return len(t.in) }
 
@@ -571,8 +579,6 @@ func toType(i interface{}) Type {
 		return nil
 	case *runtime.BoolType:
 		return (*BoolType)(unsafe.Pointer(v))
-	case *runtime.DotDotDotType:
-		return (*DotDotDotType)(unsafe.Pointer(v))
 	case *runtime.FloatType:
 		return (*FloatType)(unsafe.Pointer(v))
 	case *runtime.Float32Type:
diff --git a/src/pkg/runtime/type.go b/src/pkg/runtime/type.go
index bf757c7631..d76edeba4b 100644
--- a/src/pkg/runtime/type.go
+++ b/src/pkg/runtime/type.go
@@ -55,7 +55,6 @@ const (
 	kindFloat64
 	kindArray
 	kindChan
-	kindDotDotDot
 	kindFunc
 	kindInterface
 	kindMap
@@ -136,10 +135,6 @@ type StringType commonType
 // UintptrType represents a uintptr type.
 type UintptrType commonType
 
-// DotDotDotType represents the ... that can
-// be used as the type of the final function parameter.
-type DotDotDotType commonType
-
 // UnsafePointerType represents an unsafe.Pointer type.
 type UnsafePointerType commonType
 
@@ -175,8 +170,9 @@ type ChanType struct {
 // FuncType represents a function type.
 type FuncType struct {
 	commonType
-	in  []*Type // input parameter types
-	out []*Type // output parameter types
+	dotdotdot bool    // last input parameter is ...
+	in        []*Type // input parameter types
+	out       []*Type // output parameter types
 }
 
 // Method on interface type
diff --git a/src/pkg/runtime/type.h b/src/pkg/runtime/type.h
index 9dc7881db5..36a3b6acf4 100644
--- a/src/pkg/runtime/type.h
+++ b/src/pkg/runtime/type.h
@@ -45,7 +45,6 @@ enum {
 	KindFloat64,
 	KindArray,
 	KindChan,
-	KindDotDotDot,
 	KindFunc,
 	KindInterface,
 	KindMap,
@@ -116,4 +115,3 @@ struct SliceType
 	Type;
 	Type *elem;
 };
-
diff --git a/test/ddd.go b/test/ddd.go
new file mode 100644
index 0000000000..682f22ffe3
--- /dev/null
+++ b/test/ddd.go
@@ -0,0 +1,105 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func sum(args ...int) int {
+	s := 0
+	for _, v := range args {
+		s += v
+	}
+	return s
+}
+
+func sumA(args []int) int {
+	s := 0
+	for _, v := range args {
+		s += v
+	}
+	return s
+}
+
+func sum2(args ...int) int { return 2 * sum(args) }
+
+func sum3(args ...int) int { return 3 * sumA(args) }
+
+func intersum(args ...interface{}) int {
+	s := 0
+	for _, v := range args {
+		s += v.(int)
+	}
+	return s
+}
+
+type T []T
+
+func ln(args ...T) int { return len(args) }
+
+func ln2(args ...T) int { return 2 * ln(args) }
+
+func main() {
+	if x := sum(1, 2, 3); x != 6 {
+		panicln("sum 6", x)
+	}
+	if x := sum(); x != 0 {
+		panicln("sum 0", x)
+	}
+	if x := sum(10); x != 10 {
+		panicln("sum 10", x)
+	}
+	if x := sum(1, 8); x != 9 {
+		panicln("sum 9", x)
+	}
+	if x := sum2(1, 2, 3); x != 2*6 {
+		panicln("sum 6", x)
+	}
+	if x := sum2(); x != 2*0 {
+		panicln("sum 0", x)
+	}
+	if x := sum2(10); x != 2*10 {
+		panicln("sum 10", x)
+	}
+	if x := sum2(1, 8); x != 2*9 {
+		panicln("sum 9", x)
+	}
+	if x := sum3(1, 2, 3); x != 3*6 {
+		panicln("sum 6", x)
+	}
+	if x := sum3(); x != 3*0 {
+		panicln("sum 0", x)
+	}
+	if x := sum3(10); x != 3*10 {
+		panicln("sum 10", x)
+	}
+	if x := sum3(1, 8); x != 3*9 {
+		panicln("sum 9", x)
+	}
+	if x := intersum(1, 2, 3); x != 6 {
+		panicln("intersum 6", x)
+	}
+	if x := intersum(); x != 0 {
+		panicln("intersum 0", x)
+	}
+	if x := intersum(10); x != 10 {
+		panicln("intersum 10", x)
+	}
+	if x := intersum(1, 8); x != 9 {
+		panicln("intersum 9", x)
+	}
+
+	if x := ln(nil, nil, nil); x != 3 {
+		panicln("ln 3", x)
+	}
+	if x := ln([]T{}); x != 1 {
+		panicln("ln 1", x)
+	}
+	if x := ln2(nil, nil, nil); x != 2*3 {
+		panicln("ln2 3", x)
+	}
+	if x := ln2([]T{}); x != 2*1 {
+		panicln("ln2 1", x)
+	}
+}
diff --git a/test/ddd1.go b/test/ddd1.go
new file mode 100644
index 0000000000..da03a70c9d
--- /dev/null
+++ b/test/ddd1.go
@@ -0,0 +1,28 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func sum(args ...int) int { return 0 }
+
+var (
+	_ = sum(1, 2, 3)
+	_ = sum()
+	_ = sum(1.0, 2.0)
+	_ = sum(1.5)      // ERROR "integer"
+	_ = sum("hello")  // ERROR "convert"
+	_ = sum([]int{1}) // ERROR "slice literal as type int"
+)
+
+type T []T
+
+func funny(args ...T) int { return 0 }
+
+var (
+	_ = funny(nil)
+	_ = funny(nil, nil)
+	_ = funny([]T{}) // ok because []T{} is a T; passes []T{[]T{}}
+)
diff --git a/test/ddd2.go b/test/ddd2.go
new file mode 100644
index 0000000000..a06af0c065
--- /dev/null
+++ b/test/ddd2.go
@@ -0,0 +1,16 @@
+// true
+
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ddd
+
+func Sum(args ...int) int {
+	s := 0
+	for _, v := range args {
+		s += v
+	}
+	return s
+}
+
diff --git a/test/ddd3.go b/test/ddd3.go
new file mode 100644
index 0000000000..f5f9952d3f
--- /dev/null
+++ b/test/ddd3.go
@@ -0,0 +1,24 @@
+// $G $D/ddd2.go && $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "./ddd2"
+
+func main() {
+	if x := ddd.Sum(1, 2, 3); x != 6 {
+		panicln("ddd.Sum 6", x)
+	}
+	if x := ddd.Sum(); x != 0 {
+		panicln("ddd.Sum 0", x)
+	}
+	if x := ddd.Sum(10); x != 10 {
+		panicln("ddd.Sum 10", x)
+	}
+	if x := ddd.Sum(1, 8); x != 9 {
+		panicln("ddd.Sum 9", x)
+	}
+}