make 6g constants behave as ken proposes. (i hope.)

various bug fixes and tests involving constants.

test/const1.go is the major new test case.

R=ken
OCL=26216
CL=26224

25 files changed, 966 insertions, 708 deletions

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index b8bf0cfe7..162617dca 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -146,11 +146,11 @@ cgen(Node *n, Node *res)
 	case ONOT:
 		p1 = gbranch(AJMP, T);
 		p2 = pc;
-		gmove(booltrue, res);
+		gmove(nodbool(1), res);
 		p3 = gbranch(AJMP, T);
 		patch(p1, pc);
 		bgen(n, 1, p2);
-		gmove(boolfalse, res);
+		gmove(nodbool(0), res);
 		patch(p3, pc);
 		goto ret;
 
@@ -408,7 +408,7 @@ agen(Node *n, Node *res)
 		if(nr->addable)
 			goto irad;
 		if(nl->addable) {
-			if(whatis(nr) != Wlitint) {
+			if(!isconst(nr, CTINT)) {
 				regalloc(&n1, nr->type, N);
 				cgen(nr, &n1);
 			}
@@ -423,7 +423,7 @@ agen(Node *n, Node *res)
 	irad:
 		regalloc(&n3, types[tptr], res);
 		agen(nl, &n3);
-		if(whatis(nr) != Wlitint) {
+		if(!isconst(nr, CTINT)) {
 			regalloc(&n1, nr->type, N);
 			cgen(nr, &n1);
 		}
@@ -438,7 +438,7 @@ agen(Node *n, Node *res)
 			fatal("index is zero width");
 
 		// constant index
-		if(whatis(nr) == Wlitint) {
+		if(isconst(nr, CTINT)) {
 			v = mpgetfix(nr->val.u.xval);
 			if(isslice(nl->type)) {
 
@@ -618,7 +618,7 @@ bgen(Node *n, int true, Prog *to)
 	}
 
 	if(n == N)
-		n = booltrue;
+		n = nodbool(1);
 
 	nl = n->left;
 	nr = n->right;
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index 4d091da64..c0822644e 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -345,15 +345,6 @@ nodconst(Node *n, Type *t, vlong v)
 	case TFLOAT64:
 	case TFLOAT80:
 		fatal("nodconst: bad type %T", t);
-
-	case TPTR32:
-	case TPTR64:
-	case TUINT8:
-	case TUINT16:
-	case TUINT32:
-	case TUINT64:
-		n->val.ctype = CTUINT;
-		break;
 	}
 }
 
@@ -1102,8 +1093,6 @@ naddr(Node *n, Addr *a)
 			a->dval = mpgetflt(n->val.u.fval);
 			break;
 		case CTINT:
-		case CTSINT:
-		case CTUINT:
 			a->sym = S;
 			a->type = D_CONST;
 			a->offset = mpgetfix(n->val.u.xval);
@@ -2057,7 +2046,7 @@ oindex:
 	}
 
 	w = n->type->width;
-	if(whatis(r) == Wlitint)
+	if(isconst(r, CTINT))
 		goto oindex_const;
 
 	switch(w) {
diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index 116341cdf..8b02de9b2 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -5,6 +5,16 @@
 #include	"go.h"
 #define	TUP(x,y)	(((x)<<16)|(y))
 
+static Val toflt(Val);
+static Val toint(Val);
+static Val tostr(Val);
+static void overflow(Val, Type*);
+static Val copyval(Val);
+
+/*
+ * truncate float literal fv to 32-bit or 64-bit precision
+ * according to type.
+ */
 void
 truncfltlit(Mpflt *fv, Type *t)
 {
@@ -33,12 +43,28 @@ truncfltlit(Mpflt *fv, Type *t)
 	}
 }
 
+/*
+ * convert n, if literal, to type t.
+ * implicit conversion.
+ */
 void
-convlit1(Node *n, Type *t, int conv)
+convlit(Node *n, Type *t)
+{
+	convlit1(n, t, 0);
+}
+
+/*
+ * convert n, if literal, to type t.
+ */
+void
+convlit1(Node *n, Type *t, int explicit)
 {
-	int et, wt;
+	int et, ct;
 
-	if(n == N || t == T)
+	if(n == N || t == T || n->type == T)
+		return;
+	et = t->etype;
+	if(et == TIDEAL || et == TNIL)
 		return;
 
 	switch(n->op) {
@@ -53,17 +79,37 @@ convlit1(Node *n, Type *t, int conv)
 		return;
 	}
 
-	et = t->etype;
-	wt = whatis(n);
+	// avoided repeated calculations, errors
+	if(eqtype(n->type, t, 0)) {
+		n->type = t;
+		return;
+	}
+
+	ct = consttype(n);
+	if(ct < 0)
+		goto bad;
 
-	switch(wt) {
+	if(et == TINTER) {
+		if(ct == CTNIL) {
+			n->type = t;
+			return;
+		}
+		defaultlit(n, T);
+		return;
+	}
+
+	// if already has non-ideal type, cannot change implicitly
+	if(n->type->etype != TIDEAL && n->type->etype != TNIL && !explicit)
+		goto bad;
+
+	switch(ct) {
 	default:
-		goto bad1;
+		goto bad;
 
-	case Wlitnil:
+	case CTNIL:
 		switch(et) {
 		default:
-			goto bad1;
+			goto bad;
 
 		case TPTR32:
 		case TPTR64:
@@ -76,450 +122,577 @@ convlit1(Node *n, Type *t, int conv)
 		}
 		break;
 
-	case Wlitstr:
-		if(isnilinter(t)) {
-			defaultlit(n);
-			return;
-		}
-		if(et == TSTRING)
-			break;
-		goto bad1;
-
-	case Wlitbool:
-		if(isnilinter(t)) {
-			defaultlit(n);
-			return;
-		}
-		if(et == TBOOL)
-			break;
-		goto bad1;
-
-	case Wlitint:
-		if(isnilinter(t)) {
-			defaultlit(n);
-			return;
-		}
-		if(isint[et]) {
-			// int to int
-			if(mpcmpfixfix(n->val.u.xval, minintval[et]) < 0)
-				goto bad2;
-			if(mpcmpfixfix(n->val.u.xval, maxintval[et]) > 0)
-				goto bad2;
-			break;
-		}
-		if(isfloat[et]) {
-			// int to float
-			Mpint *xv;
-			Mpflt *fv;
-
-			xv = n->val.u.xval;
-			if(mpcmpfixflt(xv, minfltval[et]) < 0)
-				goto bad2;
-			if(mpcmpfixflt(xv, maxfltval[et]) > 0)
-				goto bad2;
-			fv = mal(sizeof(*n->val.u.fval));
-			n->val.u.fval = fv;
-			mpmovefixflt(fv, xv);
-			n->val.ctype = CTFLT;
-			truncfltlit(fv, t);
-			break;
-		}
-		if(!conv)
-			goto bad1;
-
-		// only done as string(CONST)
-		if(et == TSTRING) {
-			Rune rune;
-			int l;
-			String *s;
-
-			rune = mpgetfix(n->val.u.xval);
-			l = runelen(rune);
-			s = mal(sizeof(*s)+l);
-			s->len = l;
-			runetochar((char*)(s->s), &rune);
-
-			n->val.u.sval = s;
-			n->val.ctype = CTSTR;
-			break;
-		}
-		goto bad1;
+	case CTSTR:
+	case CTBOOL:
+		if(et != n->type->etype)
+			goto bad;
+		break;
 
-	case Wlitfloat:
-		if(isnilinter(t)) {
-			defaultlit(n);
-			return;
-		}
+	case CTINT:
+	case CTFLT:
+		ct = n->val.ctype;
 		if(isint[et]) {
-			// float to int
-			Mpflt *fv;
-
-			fv = n->val.u.fval;
-			if(mpcmpfltfix(fv, minintval[et]) < 0)
-				goto bad2;
-			if(mpcmpfltfix(fv, maxintval[et]) > 0)
-				goto bad2;
-			if(floor(mpgetflt(fv)) != mpgetflt(fv))
-				goto bad3;
-			n->val.u.xval = mal(sizeof(*n->val.u.xval));
-			mpmovefltfix(n->val.u.xval, fv);
-			n->val.ctype = CTINT;
-			break;
-		}
-		if(isfloat[et]) {
-			// float to float
-			Mpflt *fv;
-
-			fv = n->val.u.fval;
-			if(mpcmpfltflt(fv, minfltval[et]) < 0)
-				goto bad2;
-			if(mpcmpfltflt(fv, maxfltval[et]) > 0)
-				goto bad2;
-			truncfltlit(fv, t);
-			break;
-		}
-		goto bad1;
+			if(ct == CTFLT)
+				n->val = toint(n->val);
+			else if(ct != CTINT)
+				goto bad;
+			overflow(n->val, t);
+		} else if(isfloat[et]) {
+			if(ct == CTINT)
+				n->val = toflt(n->val);
+			else if(ct != CTFLT)
+				goto bad;
+			overflow(n->val, t);
+			truncfltlit(n->val.u.fval, t);
+		} else if(et == TSTRING && ct == CTINT && explicit)
+			n->val = tostr(n->val);
+		else
+			goto bad;
 	}
 	n->type = t;
-
 	return;
 
-bad1:
-	yyerror("illegal conversion of %W to %T", wt, t);
+bad:
+	if(n->type->etype == TIDEAL)
+		defaultlit(n, T);
+	yyerror("cannot convert %T constant to %T", n->type, t);
+	n->type = T;
+	n->diag = 1;
 	return;
+}
 
-bad2:
-	yyerror("overflow converting constant to %T", t);
-	return;
+static Val
+copyval(Val v)
+{
+	Mpint *i;
+	Mpflt *f;
 
-bad3:
-	yyerror("cannot convert non-integer constant to %T", t);
-	return;
+	switch(v.ctype) {
+	case CTINT:
+		i = mal(sizeof(*i));
+		mpmovefixfix(i, v.u.xval);
+		v.u.xval = i;
+		break;
+	case CTFLT:
+		f = mal(sizeof(*f));
+		mpmovefltflt(f, v.u.fval);
+		v.u.fval = f;
+		break;
+	}
+	return v;
 }
 
-void
-convlit(Node *n, Type *t)
+static Val
+toflt(Val v)
 {
-	convlit1(n, t, 0);
+	Mpflt *f;
+
+	if(v.ctype == CTINT) {
+		f = mal(sizeof(*f));
+		mpmovefixflt(f, v.u.xval);
+		v.ctype = CTFLT;
+		v.u.fval = f;
+	}
+	return v;
+}
+
+static Val
+toint(Val v)
+{
+	Mpint *i;
+
+	if(v.ctype == CTFLT) {
+		i = mal(sizeof(*i));
+		if(mpmovefltfix(i, v.u.fval) < 0)
+			yyerror("constant %#F truncated to integer", v.u.fval);
+		v.ctype = CTINT;
+		v.u.xval = i;
+	}
+	return v;
+}
+
+static void
+overflow(Val v, Type *t)
+{
+	// v has already been converted
+	// to appropriate form for t.
+	if(t == T || t->etype == TIDEAL)
+		return;
+	switch(v.ctype) {
+	case CTINT:
+		if(mpcmpfixfix(v.u.xval, minintval[t->etype]) < 0
+		|| mpcmpfixfix(v.u.xval, maxintval[t->etype]) > 0)
+			yyerror("constant %B overflows %T", v.u.xval, t);
+		break;
+	case CTFLT:
+		if(mpcmpfltflt(v.u.fval, minfltval[t->etype]) < 0
+		|| mpcmpfltflt(v.u.fval, maxfltval[t->etype]) > 0)
+			yyerror("constant %#F overflows %T", v.u.fval, t);
+		break;
+	}
+}
+
+static Val
+tostr(Val v)
+{
+	Rune rune;
+	int l;
+	String *s;
+
+	switch(v.ctype) {
+	case CTINT:
+		if(mpcmpfixfix(v.u.xval, minintval[TINT]) < 0
+		|| mpcmpfixfix(v.u.xval, maxintval[TINT]) > 0)
+			yyerror("overflow in int -> string");
+		rune = mpgetfix(v.u.xval);
+		l = runelen(rune);
+		s = mal(sizeof(*s)+l);
+		s->len = l;
+		runetochar((char*)s->s, &rune);
+		v.ctype = CTSTR;
+		v.u.sval = s;
+		break;
+
+	case CTFLT:
+		yyerror("no float -> string");
+	}
+	return v;
 }
 
+int
+consttype(Node *n)
+{
+	if(n == N || n->op != OLITERAL)
+		return -1;
+	return n->val.ctype;
+}
+
+int
+isconst(Node *n, int ct)
+{
+	return consttype(n) == ct;
+}
+
+/*
+ * if n is constant, rewrite as OLITERAL node.
+ */
 void
 evconst(Node *n)
 {
 	Node *nl, *nr;
 	int32 len;
 	String *str;
-	int wl, wr;
-	Mpint *xval;
-	Mpflt *fval;
-
-	xval = nil;
-	fval = nil;
+	int wl, wr, lno;
+	Val v;
 
 	nl = n->left;
-	if(nl == N)
+	if(nl == N || nl->type == T)
 		return;
-
-	wl = whatis(nl);
-	switch(wl) {
-	default:
+	if(consttype(nl) < 0)
 		return;
-
-	case Wlitint:
-	case Wlitfloat:
-	case Wlitbool:
-	case Wlitstr:
-	case Wlitnil:
-		break;
-	}
+	wl = nl->type->etype;
+	if(isint[wl] || isfloat[wl])
+		wl = TIDEAL;
 
 	nr = n->right;
 	if(nr == N)
 		goto unary;
-
-	wr = whatis(nr);
-	switch(wr) {
-	default:
+	if(nr->type == T)
 		return;
+	if(consttype(nr) < 0)
+		return;
+	wr = nr->type->etype;
+	if(isint[wr] || isfloat[wr])
+		wr = TIDEAL;
+
+	// check for compatible general types (numeric, string, etc)
+	if(wl != wr)
+		goto illegal;
 
-	case Wlitint:
-	case Wlitfloat:
-	case Wlitbool:
-	case Wlitstr:
-	case Wlitnil:
+	// check for compatible types.
+	switch(n->op) {
+	default:
+		// ideal const mixes with anything but otherwise must match.
+		if(nl->type->etype != TIDEAL)
+			defaultlit(nr, nl->type);
+		if(nr->type->etype != TIDEAL)
+			defaultlit(nl, nr->type);
+		if(nl->type->etype != nr->type->etype)
+			goto illegal;
 		break;
-	}
 
-	if(wl != wr) {
-		if(wl == Wlitfloat && wr == Wlitint) {
-			xval = nr->val.u.xval;
-			nr->val.u.fval = mal(sizeof(*nr->val.u.fval));
-			mpmovefixflt(nr->val.u.fval, xval);
-			nr->val.ctype = CTFLT;
-			wr = whatis(nr);
-		} else
-		if(wl == Wlitint && wr == Wlitfloat) {
-			xval = nl->val.u.xval;
-			nl->val.u.fval = mal(sizeof(*nl->val.u.fval));
-			mpmovefixflt(nl->val.u.fval, xval);
-			nl->val.ctype = CTFLT;
-			wl = whatis(nl);
-		} else {
-			yyerror("illegal combination of literals %O %W, %W", n->op, wl, wr);
-			return;
-		}
+	case OLSH:
+	case ORSH:
+		// right must be unsigned.
+		// left can be ideal.
+		defaultlit(nr, types[TUINT]);
+		break;
 	}
 
-	// dance to not modify left side
-	// this is because iota will reuse it
-	if(wl == Wlitint) {
-		xval = mal(sizeof(*xval));
-		mpmovefixfix(xval, nl->val.u.xval);
-	} else
-	if(wl == Wlitfloat) {
-		fval = mal(sizeof(*fval));
-		mpmovefltflt(fval, nl->val.u.fval);
+	// copy numeric value to avoid modifying
+	// n->left, in case someone still refers to it (e.g. iota).
+	v = nl->val;
+	if(wl == TIDEAL)
+		v = copyval(v);
+
+	// since wl == wr,
+	// the only way v.ctype != nr->val.ctype
+	// is when one is CTINT and the other CTFLT.
+	// make both CTFLT.
+	if(v.ctype != nr->val.ctype) {
+		v = toflt(v);
+		nr->val = toflt(nr->val);
 	}
 
-	switch(TUP(n->op, wl)) {
+	// run op
+	switch(TUP(n->op, v.ctype)) {
 	default:
-		yyerror("illegal literal %O %W", n->op, wl);
+	illegal:
+		yyerror("illegal constant expression %T %O %T",
+			nl->type, n->op, nr->type);
+		n->diag = 1;
 		return;
 
-	case TUP(OADD, Wlitint):
-		mpaddfixfix(xval, nr->val.u.xval);
+	case TUP(OADD, CTINT):
+		mpaddfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OSUB, Wlitint):
-		mpsubfixfix(xval, nr->val.u.xval);
+	case TUP(OSUB, CTINT):
+		mpsubfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OMUL, Wlitint):
-		mpmulfixfix(xval, nr->val.u.xval);
+	case TUP(OMUL, CTINT):
+		mpmulfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(ODIV, Wlitint):
-		mpdivfixfix(xval, nr->val.u.xval);
+	case TUP(ODIV, CTINT):
+		if(mpcmpfixc(nr->val.u.xval, 0) == 0) {
+			yyerror("division by zero");
+			mpmovecfix(v.u.xval, 1);
+			break;
+		}
+		mpdivfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OMOD, Wlitint):
-		mpmodfixfix(xval, nr->val.u.xval);
+	case TUP(OMOD, CTINT):
+		if(mpcmpfixc(nr->val.u.xval, 0) == 0) {
+			yyerror("division by zero");
+			mpmovecfix(v.u.xval, 1);
+			break;
+		}
+		mpmodfixfix(v.u.xval, nr->val.u.xval);
 		break;
 
-	case TUP(OLSH, Wlitint):
-		mplshfixfix(xval, nr->val.u.xval);
+	case TUP(OLSH, CTINT):
+		mplshfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(ORSH, Wlitint):
-		mprshfixfix(xval, nr->val.u.xval);
+	case TUP(ORSH, CTINT):
+		mprshfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OOR, Wlitint):
-		mporfixfix(xval, nr->val.u.xval);
+	case TUP(OOR, CTINT):
+		mporfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OAND, Wlitint):
-		mpandfixfix(xval, nr->val.u.xval);
+	case TUP(OAND, CTINT):
+		mpandfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OANDNOT, Wlitint):
-		mpandnotfixfix(xval, nr->val.u.xval);
+	case TUP(OANDNOT, CTINT):
+		mpandnotfixfix(v.u.xval, nr->val.u.xval);
 		break;
-	case TUP(OXOR, Wlitint):
-		mpxorfixfix(xval, nr->val.u.xval);
+	case TUP(OXOR, CTINT):
+		mpxorfixfix(v.u.xval, nr->val.u.xval);
 		break;
-
-	case TUP(OADD, Wlitfloat):
-		mpaddfltflt(fval, nr->val.u.fval);
+	case TUP(OADD, CTFLT):
+		mpaddfltflt(v.u.fval, nr->val.u.fval);
 		break;
-	case TUP(OSUB, Wlitfloat):
-		mpsubfltflt(fval, nr->val.u.fval);
+	case TUP(OSUB, CTFLT):
+		mpsubfltflt(v.u.fval, nr->val.u.fval);
 		break;
-	case TUP(OMUL, Wlitfloat):
-		mpmulfltflt(fval, nr->val.u.fval);
+	case TUP(OMUL, CTFLT):
+		mpmulfltflt(v.u.fval, nr->val.u.fval);
 		break;
-	case TUP(ODIV, Wlitfloat):
-		mpdivfltflt(fval, nr->val.u.fval);
+	case TUP(ODIV, CTFLT):
+		if(mpcmpfltc(nr->val.u.fval, 0) == 0) {
+			yyerror("division by zero");
+			mpmovecflt(v.u.fval, 1.0);
+			break;
+		}
+		mpdivfltflt(v.u.fval, nr->val.u.fval);
 		break;
 
-	case TUP(OEQ, Wlitnil):
+	case TUP(OEQ, CTNIL):
 		goto settrue;
-	case TUP(ONE, Wlitnil):
+	case TUP(ONE, CTNIL):
 		goto setfalse;
 
-	case TUP(OEQ, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) == 0)
+	case TUP(OEQ, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) == 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(ONE, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) != 0)
+	case TUP(ONE, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) != 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLT, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) < 0)
+	case TUP(OLT, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) < 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLE, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) <= 0)
+	case TUP(OLE, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) <= 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGE, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) >= 0)
+	case TUP(OGE, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) >= 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGT, Wlitint):
-		if(mpcmpfixfix(xval, nr->val.u.xval) > 0)
+	case TUP(OGT, CTINT):
+		if(mpcmpfixfix(v.u.xval, nr->val.u.xval) > 0)
 			goto settrue;
 		goto setfalse;
 
-	case TUP(OEQ, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) == 0)
+	case TUP(OEQ, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) == 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(ONE, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) != 0)
+	case TUP(ONE, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) != 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLT, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) < 0)
+	case TUP(OLT, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) < 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLE, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) <= 0)
+	case TUP(OLE, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) <= 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGE, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) >= 0)
+	case TUP(OGE, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) >= 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGT, Wlitfloat):
-		if(mpcmpfltflt(fval, nr->val.u.fval) > 0)
+	case TUP(OGT, CTFLT):
+		if(mpcmpfltflt(v.u.fval, nr->val.u.fval) > 0)
 			goto settrue;
 		goto setfalse;
 
-	case TUP(OEQ, Wlitstr):
+	case TUP(OEQ, CTSTR):
 		if(cmpslit(nl, nr) == 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(ONE, Wlitstr):
+	case TUP(ONE, CTSTR):
 		if(cmpslit(nl, nr) != 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLT, Wlitstr):
+	case TUP(OLT, CTSTR):
 		if(cmpslit(nl, nr) < 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OLE, Wlitstr):
+	case TUP(OLE, CTSTR):
 		if(cmpslit(nl, nr) <= 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGE, Wlitstr):
+	case TUP(OGE, CTSTR):
 		if(cmpslit(nl, nr) >= 0l)
 			goto settrue;
 		goto setfalse;
-	case TUP(OGT, Wlitstr):
+	case TUP(OGT, CTSTR):
 		if(cmpslit(nl, nr) > 0)
 			goto settrue;
 		goto setfalse;
-	case TUP(OADD, Wlitstr):
-		len = nl->val.u.sval->len + nr->val.u.sval->len;
+	case TUP(OADD, CTSTR):
+		len = v.u.sval->len + nr->val.u.sval->len;
 		str = mal(sizeof(*str) + len);
 		str->len = len;
-		memcpy(str->s, nl->val.u.sval->s, nl->val.u.sval->len);
-		memcpy(str->s+nl->val.u.sval->len, nr->val.u.sval->s, nr->val.u.sval->len);
+		memcpy(str->s, v.u.sval->s, v.u.sval->len);
+		memcpy(str->s+v.u.sval->len, nr->val.u.sval->s, nr->val.u.sval->len);
 		str->len = len;
-		nl->val.u.sval = str;
+		v.u.sval = str;
 		break;
 
-	case TUP(OOROR, Wlitbool):
-		if(nl->val.u.bval || nr->val.u.bval)
+	case TUP(OOROR, CTBOOL):
+		if(v.u.bval || nr->val.u.bval)
 			goto settrue;
 		goto setfalse;
-	case TUP(OANDAND, Wlitbool):
-		if(nl->val.u.bval && nr->val.u.bval)
+	case TUP(OANDAND, CTBOOL):
+		if(v.u.bval && nr->val.u.bval)
+			goto settrue;
+		goto setfalse;
+	case TUP(OEQ, CTBOOL):
+		if(v.u.bval == nr->val.u.bval)
+			goto settrue;
+		goto setfalse;
+	case TUP(ONE, CTBOOL):
+		if(v.u.bval != nr->val.u.bval)
 			goto settrue;
 		goto setfalse;
 	}
 	goto ret;
 
-settrue:
-	*n = *booltrue;
-	return;
-
-setfalse:
-	*n = *boolfalse;
-	return;
-
 unary:
-	if(wl == Wlitint) {
-		xval = mal(sizeof(*xval));
-		mpmovefixfix(xval, nl->val.u.xval);
-	} else
-	if(wl == Wlitfloat) {
-		fval = mal(sizeof(*fval));
-		mpmovefltflt(fval, nl->val.u.fval);
-	}
+	// copy numeric value to avoid modifying
+	// nl, in case someone still refers to it (e.g. iota).
+	v = nl->val;
+	if(wl == TIDEAL)
+		v = copyval(v);
 
-	switch(TUP(n->op, wl)) {
+	switch(TUP(n->op, v.ctype)) {
 	default:
-		yyerror("illegal combination of literals %O %d", n->op, wl);
+		yyerror("illegal constant expression %O %T %d", n->op, nl->type, v.ctype);
 		return;
 
-	case TUP(OPLUS, Wlitint):
+	case TUP(OPLUS, CTINT):
 		break;
-	case TUP(OMINUS, Wlitint):
-		mpnegfix(xval);
+	case TUP(OMINUS, CTINT):
+		mpnegfix(v.u.xval);
 		break;
-	case TUP(OCOM, Wlitint):
-		mpcomfix(xval);
+	case TUP(OCOM, CTINT):
+		mpcomfix(v.u.xval);
 		break;
 
-	case TUP(OPLUS, Wlitfloat):
+	case TUP(OPLUS, CTFLT):
 		break;
-	case TUP(OMINUS, Wlitfloat):
-		mpnegflt(fval);
+	case TUP(OMINUS, CTFLT):
+		mpnegflt(v.u.fval);
 		break;
 
-	case TUP(ONOT, Wlitbool):
-		if(nl->val.u.bval)
+	case TUP(ONOT, CTBOOL):
+		if(!v.u.bval)
 			goto settrue;
 		goto setfalse;
 	}
 
 ret:
+	// rewrite n in place.
 	*n = *nl;
+	n->val = v;
+
+	// lose type name if any:
+	//	type T int
+	//	const A T = 1;
+	// A+0 has type int, not T.
+	n->type = types[n->type->etype];
+
+	// check range.
+	lno = lineno;
+	lineno = n->lineno;
+	overflow(v, n->type);
+	lineno = lno;
+
+	// truncate precision for non-ideal float.
+	if(v.ctype == CTFLT && n->type->etype != TIDEAL)
+		truncfltlit(v.u.fval, n->type);
+	return;
+
+settrue:
+	*n = *nodbool(1);
+	return;
+
+setfalse:
+	*n = *nodbool(0);
+	return;
+}
 
-	// second half of dance
-	if(wl == Wlitint) {
-		n->val.u.xval = xval;
-	} else
-	if(wl == Wlitfloat) {
-		n->val.u.fval = fval;
-		truncfltlit(fval, n->type);
+Node*
+nodlit(Val v)
+{
+	Node *n;
+
+	n = nod(OLITERAL, N, N);
+	n->val = v;
+	switch(v.ctype) {
+	default:
+		fatal("nodlit ctype %d", v.ctype);
+	case CTSTR:
+		n->type = types[TSTRING];
+		break;
+	case CTBOOL:
+		n->type = types[TBOOL];
+		break;
+	case CTINT:
+	case CTFLT:
+		n->type = types[TIDEAL];
+		break;
+	case CTNIL:
+		n->type = types[TNIL];
+		break;
 	}
+	return n;
 }
 
 void
-defaultlit(Node *n)
+defaultlit(Node *n, Type *t)
 {
+	int lno;
+
 	if(n == N)
 		return;
-	if(n->type != T)
+	if(n->type == T || n->type->etype != TIDEAL)
 		return;
-	if(n->op != OLITERAL)
+
+	switch(n->op) {
+	case OLITERAL:
+		break;
+	case OLSH:
+	case ORSH:
+		defaultlit(n->left, t);
+		n->type = n->left->type;
 		return;
+	}
 
+	lno = lineno;
+	lineno = n->lineno;
 	switch(n->val.ctype) {
 	default:
 		yyerror("defaultlit: unknown literal: %N", n);
 		break;
 	case CTINT:
-	case CTSINT:
-	case CTUINT:
 		n->type = types[TINT];
+		if(t != T) {
+			if(isint[t->etype])
+				n->type = t;
+			else if(isfloat[t->etype]) {
+				n->type = t;
+				n->val = toflt(n->val);
+			}
+		}
+		overflow(n->val, n->type);
 		break;
 	case CTFLT:
 		n->type = types[TFLOAT];
+		if(t != T) {
+			if(isfloat[t->etype])
+				n->type = t;
+			else if(isint[t->etype]) {
+				n->type = t;
+				n->val = toint(n->val);
+			}
+		}
+		overflow(n->val, n->type);
 		break;
-	case CTBOOL:
-		n->type = types[TBOOL];
-		break;
-	case CTSTR:
-		n->type = types[TSTRING];
-		break;
 	}
+	lineno = lno;
+}
+
+/*
+ * defaultlit on both nodes simultaneously;
+ * if they're both ideal going in they better
+ * get the same type going out.
+ */
+void
+defaultlit2(Node *l, Node *r)
+{
+	if(l->type == T || r->type == T)
+		return;
+	if(l->type->etype != TIDEAL && l->type->etype != TNIL) {
+		convlit(r, l->type);
+		return;
+	}
+	if(r->type->etype != TIDEAL && r->type->etype != TNIL) {
+		convlit(l, r->type);
+		return;
+	}
+	if(isconst(l, CTFLT) || isconst(r, CTFLT)) {
+		convlit(l, types[TFLOAT]);
+		convlit(r, types[TFLOAT]);
+		return;
+	}
+	convlit(l, types[TINT]);
+	convlit(r, types[TINT]);
 }
 
 int
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index fc977eba2..1f72442f5 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -23,6 +23,8 @@ dodclvar(Node *n, Type *t)
 	if(n == N)
 		return;
 
+	if(t != T && (t->etype == TIDEAL || t->etype == TNIL))
+		fatal("dodclvar %T", t);
 	for(; n->op == OLIST; n = n->right)
 		dodclvar(n->left, t);
 
@@ -1284,7 +1286,7 @@ fninit(Node *n)
 	r = list(r, a);
 
 	// (4)
-	a = nod(OAS, done, booltrue);
+	a = nod(OAS, done, nodbool(1));
 	r = list(r, a);
 
 	// (5)
@@ -1460,7 +1462,7 @@ loop:
 	a = nod(OAS, v, N);
 	if(t == T) {
 		gettype(e, a);
-		defaultlit(e);
+		defaultlit(e, T);
 		dodclvar(v, e->type);
 	} else
 		dodclvar(v, t);
@@ -1475,7 +1477,7 @@ loop:
 
 /*
  * declare constants from grammar
- * new_name_list [type] [= expr_list]
+ * new_name_list [[type] = expr_list]
  */
 void
 constiter(Node *vv, Type *t, Node *cc)
@@ -1483,9 +1485,14 @@ constiter(Node *vv, Type *t, Node *cc)
 	Iter viter, citer;
 	Node *v, *c;
 
-	if(cc == N)
+	if(cc == N) {
+		if(t != T)
+			yyerror("constdcl cannot have type without expr");
 		cc = lastconst;
+		t = lasttype;
+	}
 	lastconst = cc;
+	lasttype = t;
 	vv = rev(vv);
 	cc = rev(treecopy(cc));
 
@@ -1499,7 +1506,7 @@ loop:
 	}
 
 	if(v == N || c == N) {
-		yyerror("shape error in var dcl");
+		yyerror("shape error in const dcl");
 		iota += 1;
 		return;
 	}
@@ -1507,6 +1514,8 @@ loop:
 	gettype(c, N);
 	if(t != T)
 		convlit(c, t);
+	if(t == T)
+		lasttype = c->type;
 	dodclconst(v, c);
 
 	v = listnext(&viter);
@@ -1587,5 +1596,6 @@ yes:
 	mpmovecfix(val.u.xval, v);
 	n = nod(OLITERAL, N, N);
 	n->val = val;
+	n->type = types[TINT];
 	return n;
 }
diff --git a/src/cmd/gc/export.c b/src/cmd/gc/export.c
index 7697e3037..ae943daab 100644
--- a/src/cmd/gc/export.c
+++ b/src/cmd/gc/export.c
@@ -110,7 +110,7 @@ dumpexportconst(Sym *s)
 
 	Bprint(bout, "\t");
 	Bprint(bout, "const %lS", s);
-	if(t != T)
+	if(t != T && t->etype != TIDEAL)
 		Bprint(bout, " %#T", t);
 	Bprint(bout, " = ");
 
@@ -118,8 +118,6 @@ dumpexportconst(Sym *s)
 	default:
 		fatal("dumpexportconst: unknown ctype: %S", s);
 	case CTINT:
-	case CTSINT:
-	case CTUINT:
 		Bprint(bout, "%B\n", n->val.u.xval);
 		break;
 	case CTBOOL:
@@ -343,18 +341,14 @@ mypackage(Node *ss)
 }
 
 void
-importconst(Node *ss, Type *t, Val *v)
+importconst(Node *ss, Type *t, Node *n)
 {
-	Node *n;
 	Sym *s;
 
 	if(!exportname(ss->sym->name) && !mypackage(ss))
 		return;
 
-	n = nod(OLITERAL, N, N);
-	n->val = *v;
-	n->type = t;
-
+	convlit(n, t);
 	s = importsym(ss, LACONST);
 	if(s->oconst != N) {
 		// TODO: check if already the same.
@@ -363,7 +357,7 @@ importconst(Node *ss, Type *t, Val *v)
 
 	dodclconst(newname(s), n);
 
-	if(debug['e'])
+	if(debug['E'])
 		print("import const %S\n", s);
 }
 
@@ -385,7 +379,7 @@ importvar(Node *ss, Type *t, int ctxt)
 	checkwidth(t);
 	addvar(newname(s), t, ctxt);
 
-	if(debug['e'])
+	if(debug['E'])
 		print("import var %S %lT\n", s, t);
 }
 
@@ -410,7 +404,7 @@ importtype(Node *ss, Type *t)
 	s->otype->sym = s;
 	checkwidth(s->otype);
 
-	if(debug['e'])
+	if(debug['E'])
 		print("import type %S %lT\n", s, t);
 }
 
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 0306eabf7..46c99baeb 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -371,6 +371,10 @@ enum
 	TFORWSTRUCT,
 	TFORWINTER,
 
+	// pseudo-types for literals
+	TIDEAL,
+	TNIL,
+
 	NTYPE,
 };
 enum
@@ -378,10 +382,7 @@ enum
 	CTxxx,
 
 	CTINT,
-	CTSINT,
-	CTUINT,
 	CTFLT,
-
 	CTSTR,
 	CTBOOL,
 	CTNIL,
@@ -389,26 +390,6 @@ enum
 
 enum
 {
-	/* indications for whatis() */
-	Wnil	= 0,
-	Wtnil,
-
-	Wtfloat,
-	Wtint,
-	Wtbool,
-	Wtstr,
-
-	Wlitfloat,
-	Wlitint,
-	Wlitbool,
-	Wlitstr,
-	Wlitnil,
-
-	Wtunkn,
-};
-
-enum
-{
 	/* types of channel */
 	Cxxx,
 	Cboth,
@@ -518,10 +499,9 @@ EXTERN	int	dclcontext;	// PEXTERN/PAUTO
 EXTERN	int	importflag;
 EXTERN	int	inimportsys;
 
-EXTERN	Node*	booltrue;
-EXTERN	Node*	boolfalse;
 EXTERN	uint32	iota;
 EXTERN	Node*	lastconst;
+EXTERN	Type*	lasttype;
 EXTERN	int32	vargen;
 EXTERN	int32	exportgen;
 EXTERN	int32	maxarg;
@@ -594,7 +574,7 @@ void	mpdivfixfix(Mpint *a, Mpint *b);
 void	mpmodfixfix(Mpint *a, Mpint *b);
 void	mpatofix(Mpint *a, char *s);
 void	mpatoflt(Mpflt *a, char *s);
-void	mpmovefltfix(Mpint *a, Mpflt *b);
+int	mpmovefltfix(Mpint *a, Mpflt *b);
 void	mpmovefixflt(Mpflt *a, Mpint *b);
 int	Bconv(Fmt*);
 
@@ -611,7 +591,7 @@ void	mpdivmodfixfix(Mpint *q, Mpint *r, Mpint *n, Mpint *d);
 void	mpdivfract(Mpint *a, Mpint *b);
 void	mpnegfix(Mpint *a);
 void	mpandfixfix(Mpint *a, Mpint *b);
-void	mpnotandfixfix(Mpint *a, Mpint *b);
+void	mpandnotfixfix(Mpint *a, Mpint *b);
 void	mplshfixfix(Mpint *a, Mpint *b);
 void	mporfixfix(Mpint *a, Mpint *b);
 void	mprshfixfix(Mpint *a, Mpint *b);
@@ -651,6 +631,7 @@ void	fatal(char*, ...);
 void	linehist(char*, int32);
 int32	setlineno(Node*);
 Node*	nod(int, Node*, Node*);
+Node*	nodlit(Val);
 Node*	list(Node*, Node*);
 Type*	typ(int);
 Dcl*	dcl(void);
@@ -680,9 +661,10 @@ void	argtype(Node*, Type*);
 int	eqargs(Type*, Type*);
 uint32	typehash(Type*, int);
 void	frame(int);
-Node*	literal(int32);
 Node*	dobad(void);
-Node*	nodintconst(int32);
+Node*	nodintconst(int64);
+Node*	nodnil(void);
+Node*	nodbool(int);
 void	ullmancalc(Node*);
 void	badtype(int, Type*, Type*);
 Type*	ptrto(Type*);
@@ -735,7 +717,8 @@ void	dodclvar(Node*, Type*);
 Type*	dodcltype(Type*);
 void	updatetype(Type*, Type*);
 void	dodclconst(Node*, Node*);
-void	defaultlit(Node*);
+void	defaultlit(Node*, Type*);
+void	defaultlit2(Node*, Node*);
 int	listcount(Node*);
 void	addmethod(Node*, Type*, int);
 Node*	methodname(Node*, Type*);
@@ -806,7 +789,7 @@ void	doimport6(Node*, Node*);
 void	doimport7(Node*, Node*);
 void	doimport8(Node*, Val*, Node*);
 void	doimport9(Sym*, Node*);
-void	importconst(Node *ss, Type *t, Val *v);
+void	importconst(Node *ss, Type *t, Node *v);
 void	importmethod(Sym *s, Type *t);
 void	importtype(Node *ss, Type *t);
 void	importvar(Node *ss, Type *t, int ctxt);
@@ -826,7 +809,6 @@ void	walkas(Node*);
 void	walkbool(Node*);
 void	walkswitch(Node*);
 void	walkselect(Node*);
-int	whatis(Node*);
 void	walkdot(Node*);
 Node*	ascompatee(int, Node**, Node**);
 Node*	ascompatet(int, Node**, Type**, int);
@@ -871,6 +853,8 @@ void	convlit(Node*, Type*);
 void	evconst(Node*);
 int	cmpslit(Node *l, Node *r);
 int	smallintconst(Node*);
+int	consttype(Node*);
+int	isconst(Node*, int);
 
 /*
  *	gen.c/gsubr.c/obj.c
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index a68490fd8..bbffa34bb 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -73,7 +73,7 @@
 %type	<type>		indcl fnlitdcl dotdotdot
 %type	<val>		oliteral
 
-%type	<val>		hidden_constant
+%type	<node>		hidden_constant
 %type	<node>		hidden_dcl hidden_structdcl
 %type	<type>		hidden_type hidden_type1 hidden_type2
 %type	<node>		hidden_structdcl_list ohidden_structdcl_list hidden_structdcl_list_r
@@ -447,12 +447,12 @@ simple_stmt:
 	}
 |	expr LINC
 	{
-		$$ = nod(OASOP, $1, literal(1));
+		$$ = nod(OASOP, $1, nodintconst(1));
 		$$->etype = OADD;
 	}
 |	expr LDEC
 	{
-		$$ = nod(OASOP, $1, literal(1));
+		$$ = nod(OASOP, $1, nodintconst(1));
 		$$->etype = OSUB;
 	}
 
@@ -822,33 +822,32 @@ uexpr:
 pexpr:
 	LLITERAL
 	{
-		$$ = nod(OLITERAL, N, N);
-		$$->val = $1;
-		if($1.ctype == CTSTR)
-			$$->type = types[TSTRING];
-	}
-|	laconst
-	{
-		$$ = nod(OLITERAL, N, N);
-		$$->val = $1->oconst->val;
-		$$->type = $1->oconst->type;
+		$$ = nodlit($1);
 	}
 |	LNIL
 	{
-		$$ = nod(OLITERAL, N, N);
-		$$->val.ctype = CTNIL;
+		Val v;
+
+		v.ctype = CTNIL;
+		$$ = nodlit(v);
 	}
 |	LTRUE
 	{
-		$$ = booltrue;
+		$$ = nodbool(1);
 	}
 |	LFALSE
 	{
-		$$ = boolfalse;
+		$$ = nodbool(0);
+	}
+|	laconst
+	{
+		$$ = nod(OLITERAL, N, N);
+		$$->val = $1->oconst->val;
+		$$->type = $1->oconst->type;
 	}
 |	LIOTA
 	{
-		$$ = literal(iota);
+		$$ = nodintconst(iota);
 		$$->iota = 1;	// flag to reevaluate on copy
 	}
 |	name
@@ -1828,11 +1827,11 @@ hidden_import:
 	}
 |	LCONST hidden_pkg_importsym '=' hidden_constant
 	{
-		importconst($2, T, &$4);
+		importconst($2, types[TIDEAL], $4);
 	}
 |	LCONST hidden_pkg_importsym hidden_type '=' hidden_constant
 	{
-		importconst($2, $3, &$5);
+		importconst($2, $3, $5);
 	}
 |	LTYPE hidden_pkg_importsym hidden_type
 	{
@@ -1870,11 +1869,7 @@ hidden_type1:
 	}
 |	'[' LLITERAL ']' hidden_type
 	{
-		Node *n;
-
-		n = nod(OLITERAL, N, N);
-		n->val = $2;
-		$$ = aindex(n, $4);
+		$$ = aindex(nodlit($2), $4);
 	}
 |	LMAP '[' hidden_type ']' hidden_type
 	{
@@ -1978,15 +1973,18 @@ hidden_funres:
 
 hidden_constant:
 	LLITERAL
+	{
+		$$ = nodlit($1);
+	}
 |	'-' LLITERAL
 	{
-		$$ = $2;
-		switch($$.ctype){
+		$$ = nodlit($2);
+		switch($$->val.ctype){
 		case CTINT:
-			mpnegfix($$.u.xval);
+			mpnegfix($$->val.u.xval);
 			break;
 		case CTFLT:
-			mpnegflt($$.u.fval);
+			mpnegflt($$->val.u.fval);
 			break;
 		default:
 			yyerror("bad negated constant");
@@ -1994,11 +1992,11 @@ hidden_constant:
 	}
 |	LTRUE
 	{
-		$$ = booltrue->val;
+		$$ = nodbool(1);
 	}
 |	LFALSE
 	{
-		$$ = boolfalse->val;
+		$$ = nodbool(0);
 	}
 
 hidden_importsym:
diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index b31cf6f0c..cff5b3993 100644
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -58,7 +58,6 @@ mainlex(int argc, char *argv[])
 	fmtinstall('L', Lconv);		// line number
 	fmtinstall('B', Bconv);		// big numbers
 	fmtinstall('F', Fconv);		// big float numbers
-	fmtinstall('W', Wconv);		// whatis numbers (Wlitint)
 
 	lexinit();
 	lineno = 1;
@@ -115,13 +114,14 @@ usage:
 	print("flags:\n");
 	print("  -I DIR search for packages in DIR\n");
 	print("  -d print declarations\n");
+	print("  -e no limit on number of errors printed\n");
 	print("  -f print stack frame structure\n");
+	print("  -h panic on an error\n");
 	print("  -k name specify package name\n");
 	print("  -o file specify output file\n");
 	print("  -p print the assembly language\n");
 	print("  -w print the parse tree after typing\n");
 	print("  -x print lex tokens\n");
-	print("  -h panic on an error\n");
 	myexit(0);
 	return 0;
 }
@@ -1276,20 +1276,12 @@ lexinit(void)
 	/* for walk to use in error messages */
 	types[TFUNC] = functype(N, N, N);
 
+	/* types used in front end */
+	types[TNIL] = typ(TNIL);
+	types[TIDEAL] = typ(TIDEAL);
+
 	/* pick up the backend typedefs */
 	belexinit(LBASETYPE);
-
-	booltrue = nod(OLITERAL, N, N);
-	booltrue->val.u.bval = 1;
-	booltrue->val.ctype = CTBOOL;
-	booltrue->type = types[TBOOL];
-	booltrue->addable = 1;
-
-	boolfalse = nod(OLITERAL, N, N);
-	boolfalse->val.u.bval = 0;
-	boolfalse->val.ctype = CTBOOL;
-	boolfalse->type = types[TBOOL];
-	boolfalse->addable = 1;
 }
 
 struct
diff --git a/src/cmd/gc/mparith1.c b/src/cmd/gc/mparith1.c
index 1fd8d7f0f..c4dbf9f08 100644
--- a/src/cmd/gc/mparith1.c
+++ b/src/cmd/gc/mparith1.c
@@ -154,10 +154,22 @@ mpmovefixflt(Mpflt *a, Mpint *b)
 	mpnorm(a);
 }
 
-void
+// convert (truncate) b to a.
+// return -1 (but still convert) if b was non-integer.
+int
 mpmovefltfix(Mpint *a, Mpflt *b)
 {
-	mpmovecfix(a, mpgetflt(b));
+	Mpflt f;
+	*a = b->val;
+	mpshiftfix(a, b->exp);
+	if(b->exp < 0) {
+		f.val = *a;
+		f.exp = 0;
+		mpnorm(&f);
+		if(mpcmpfltflt(b, &f) != 0)
+			return -1;
+	}
+	return 0;
 }
 
 void
@@ -303,7 +315,7 @@ bad:
 //
 // fixed point input
 // required syntax is [+-][0[x]]d*
-// 
+//
 void
 mpatofix(Mpint *a, char *as)
 {
@@ -422,8 +434,20 @@ Fconv(Fmt *fp)
 {
 	char buf[500];
 	Mpflt *fvp, fv;
+	double d;
 
 	fvp = va_arg(fp->args, Mpflt*);
+	if(fp->flags & FmtSharp) {
+		// alternate form - decimal for error messages.
+		// for well in range, convert to double and use print's %g
+		if(-900 < fvp->exp && fvp->exp < 900) {
+			d = mpgetflt(fvp);
+			return fmtprint(fp, "%g", d);
+		}
+		// TODO(rsc): for well out of range, print
+		// an approximation like 1.234e1000
+	}
+
 	if(sigfig(fvp) == 0) {
 		snprint(buf, sizeof(buf), "0p+0");
 		goto out;
diff --git a/src/cmd/gc/mparith2.c b/src/cmd/gc/mparith2.c
index 622a7c58d..2765ff5c2 100644
--- a/src/cmd/gc/mparith2.c
+++ b/src/cmd/gc/mparith2.c
@@ -159,6 +159,7 @@ mpneg(Mpint *a)
 	}
 }
 
+// shift left by s (or right by -s)
 void
 mpshiftfix(Mpint *a, int s)
 {
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 59bf93492..80405e37c 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -29,7 +29,7 @@ yyerror(char *fmt, ...)
 		*(int*)0 = 0;
 
 	nerrors++;
-	if(nerrors >= 10)
+	if(nerrors >= 10 && !debug['e'])
 		fatal("too many errors");
 }
 
@@ -351,7 +351,7 @@ dobad(void)
 }
 
 Node*
-nodintconst(int32 v)
+nodintconst(int64 v)
 {
 	Node *c;
 
@@ -360,12 +360,35 @@ nodintconst(int32 v)
 	c->val.u.xval = mal(sizeof(*c->val.u.xval));
 	mpmovecfix(c->val.u.xval, v);
 	c->val.ctype = CTINT;
-	c->type = types[TINT];
+	c->type = types[TIDEAL];
 	ullmancalc(c);
 	return c;
 }
 
 Node*
+nodnil(void)
+{
+	Node *c;
+
+	c = nodintconst(0);
+	c->val.ctype = CTNIL;
+	c->type = types[TNIL];
+	return c;
+}
+
+Node*
+nodbool(int b)
+{
+	Node *c;
+
+	c = nodintconst(0);
+	c->val.ctype = CTBOOL;
+	c->val.u.bval = b;
+	c->type = types[TBOOL];
+	return c;
+}
+
+Node*
 rev(Node *na)
 {
 	Node *i, *n;
@@ -437,19 +460,17 @@ aindex(Node *b, Type *t)
 
 	bound = -1;	// open bound
 	walktype(b, Erv);
-	switch(whatis(b)) {
-	default:	// variable bound
-		yyerror("array bound must be an integer expression");
-		break;
-
-	case Wnil:	// open bound
-		break;
-
-	case Wlitint:	// fixed bound
-		bound = mpgetfix(b->val.u.xval);
-		if(bound < 0)
-			yyerror("array bound must be non negative");
-		break;
+	if(b != nil) {
+		switch(consttype(b)) {
+		default:
+			yyerror("array bound must be an integer expression");
+			break;
+		case CTINT:
+			bound = mpgetfix(b->val.u.xval);
+			if(bound < 0)
+				yyerror("array bound must be non negative");
+			break;
+		}
 	}
 
 	// fixed array
@@ -569,64 +590,6 @@ dump(char *s, Node *n)
 	dodump(n, 1);
 }
 
-int
-whatis(Node *n)
-{
-	Type *t;
-
-	if(n == N)
-		return Wnil;
-
-	if(n->op == OLITERAL) {
-		switch(n->val.ctype) {
-		default:
-			break;
-		case CTINT:
-		case CTSINT:
-		case CTUINT:
-			return Wlitint;
-		case CTFLT:
-			return Wlitfloat;
-		case CTBOOL:
-			return Wlitbool;
-		case CTSTR:
-			return Wlitstr;
-		case CTNIL:
-			return Wlitnil;	// not used
-		}
-		return Wtunkn;
-	}
-
-	t = n->type;
-	if(t == T)
-		return Wtnil;
-
-	switch(t->etype) {
-	case TINT:
-	case TINT8:
-	case TINT16:
-	case TINT32:
-	case TINT64:
-	case TUINT:
-	case TUINT8:
-	case TUINT16:
-	case TUINT32:
-	case TUINT64:
-	case TUINTPTR:
-		return Wtint;
-	case TFLOAT:
-	case TFLOAT32:
-	case TFLOAT64:
-	case TFLOAT80:
-		return Wtfloat;
-	case TBOOL:
-		return Wtbool;
-	case TSTRING:
-		return Wtstr;
-	}
-	return Wtunkn;
-}
-
 /*
 s%,%,\n%g
 s%\n+%\n%g
@@ -1013,6 +976,8 @@ basicnames[] =
 	[TANY]		= "any",
 	[TDDD]		= "...",
 	[TSTRING]		= "string",
+	[TNIL]		= "nil",
+	[TIDEAL]		= "ideal",
 };
 
 int
@@ -1302,8 +1267,6 @@ Nconv(Fmt *fp)
 			snprint(buf1, sizeof(buf1), "LITERAL-ctype=%d", n->val.ctype);
 			break;
 		case CTINT:
-		case CTSINT:
-		case CTUINT:
 			snprint(buf1, sizeof(buf1), "I%B", n->val.u.xval);
 			break;
 		case CTFLT:
@@ -1363,7 +1326,7 @@ treecopy(Node *n)
 
 	case OLITERAL:
 		if(n->iota) {
-			m = literal(iota);
+			m = nodintconst(iota);
 			break;
 		}
 		m = nod(OXXX, N, N);
@@ -1416,34 +1379,6 @@ Zconv(Fmt *fp)
 	return 0;
 }
 
-static char*
-wnames[] =
-{
-	[Wnil] =	"Wnil",
-	[Wtnil] =	"Wtnil",
-
-	[Wtfloat] =	"Wtfloat",
-	[Wtint] =	"Wtint",
-	[Wtbool] =	"Wtbool",
-	[Wtstr] =	"Wtstr",
-
-	[Wlitfloat] =	"float constant",
-	[Wlitint] =	"int constant",
-	[Wlitbool] =	"bool",
-	[Wlitstr] =	"string",
-	[Wlitnil] =	"nil",
-};
-
-int
-Wconv(Fmt *fp)
-{
-	int w;
-
-	w = va_arg(fp->args, int);
-	if(w < 0 || w >= nelem(wnames) || wnames[w] == nil)
-		return fmtprint(fp, "W-%d", w);
-	return fmtstrcpy(fp, wnames[w]);
-}
 int
 isnil(Node *n)
 {
@@ -2043,18 +1978,6 @@ ptrto(Type *t)
 	return t1;
 }
 
-Node*
-literal(int32 v)
-{
-	Node *n;
-
-	n = nod(OLITERAL, N, N);
-	n->val.u.xval = mal(sizeof(*n->val.u.xval));
-	n->val.ctype = CTINT;
-	mpmovecfix(n->val.u.xval, v);
-	return n;
-}
-
 void
 frame(int context)
 {
diff --git a/src/cmd/gc/swt.c b/src/cmd/gc/swt.c
index 0c5e5eed8..408904ff1 100644
--- a/src/cmd/gc/swt.c
+++ b/src/cmd/gc/swt.c
@@ -448,7 +448,7 @@ walkswitch(Node *sw)
 	 */
 	walkstate(sw->ninit);
 	if(sw->ntest == N)
-		sw->ntest = booltrue;
+		sw->ntest = nodbool(1);
 	casebody(sw);
 
 	/*
@@ -466,7 +466,7 @@ walkswitch(Node *sw)
 		return;
 	}
 	arg = Snorm;
-	if(whatis(sw->ntest) == Wlitbool) {
+	if(isconst(sw->ntest, CTBOOL)) {
 		arg = Strue;
 		if(sw->ntest->val.u.xval == 0)
 			arg = Sfalse;
@@ -523,10 +523,10 @@ iscaseconst(Node *t)
 {
 	if(t == N || t->left == N)
 		return 0;
-	switch(whatis(t->left)) {
-	case Wlitfloat:
-	case Wlitint:
-	case Wlitstr:
+	switch(consttype(t->left)) {
+	case CTFLT:
+	case CTINT:
+	case CTSTR:
 		return 1;
 	}
 	return 0;
@@ -616,19 +616,23 @@ csort(Case *l, int(*f)(Case*, Case*))
 int
 casecmp(Case *c1, Case *c2)
 {
-	int w;
+	int ct;
+	Node *n1, *n2;
 
-	w = whatis(c1->node->left);
-	if(w != whatis(c2->node->left))
+	n1 = c1->node->left;
+	n2 = c2->node->left;
+
+	ct = n1->val.ctype;
+	if(ct != n2->val.ctype)
 		fatal("casecmp1");
 
-	switch(w) {
-	case Wlitfloat:
-		return mpcmpfltflt(c1->node->left->val.u.fval, c2->node->left->val.u.fval);
-	case Wlitint:
-		return mpcmpfixfix(c1->node->left->val.u.xval, c2->node->left->val.u.xval);
-	case Wlitstr:
-		return cmpslit(c1->node->left, c2->node->left);
+	switch(ct) {
+	case CTFLT:
+		return mpcmpfltflt(n1->val.u.fval, n2->val.u.fval);
+	case CTINT:
+		return mpcmpfixfix(n1->val.u.xval, n2->val.u.xval);
+	case CTSTR:
+		return cmpslit(n1, n2);
 	}
 
 	fatal("casecmp2");
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index c113858d7..07af51407 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -356,7 +356,7 @@ loop:
 			goto ret;
 
 		walktype(n->left, Erv);
-		convlit(n->left, types[TFUNC]);
+		defaultlit(n->left, T);
 
 		t = n->left->type;
 		if(t == T)
@@ -367,11 +367,8 @@ loop:
 		if(n->left->op == ODOTINTER)
 			n->op = OCALLINTER;
 
-		if(isptr[t->etype])
-			t = t->type;
-
 		if(t->etype != TFUNC) {
-			yyerror("call of a non-function %T", t);
+			yyerror("call of a non-function: %T", t);
 			goto ret;
 		}
 
@@ -406,7 +403,9 @@ loop:
 			n->right = reorder1(l);
 			if(isselect(n)) {
 				// clear output bool - special prob with selectsend
-				r = ascompatte(n->op, getoutarg(t), &boolfalse, 0);
+				Node *b;
+				b = nodbool(0);
+				r = ascompatte(n->op, getoutarg(t), &b, 0);
 				n->right = list(n->right, r);
 			}
 			break;
@@ -586,7 +585,7 @@ loop:
 		if(l == N)
 			goto ret;
 		walktype(l, Erv);
-	
+
 		// structure literal
 		if(t->etype == TSTRUCT) {
 			indir(n, structlit(n, N));
@@ -623,6 +622,9 @@ loop:
 	case ONOT:
 		if(top != Erv)
 			goto nottop;
+		evconst(n);
+		if(n->op == OLITERAL)
+			goto ret;
 		walktype(n->left, Erv);
 		if(n->left == N || n->left->type == T)
 			goto ret;
@@ -634,15 +636,11 @@ loop:
 			goto nottop;
 		walktype(n->left, Elv);
 		l = n->left;
-		if(l->op != OINDEX) {
-			if(n->etype == OLSH || n->etype == ORSH)
-				goto shft;
-			goto com;
-		}
-		if(!istype(l->left->type, TMAP))
-			goto com;
-		indir(n, mapop(n, top));
-		goto ret;
+		if(l->op == OINDEX && istype(l->left->type, TMAP))
+			indir(n, mapop(n, top));
+		if(n->etype == OLSH || n->etype == ORSH)
+			goto shft;
+		goto com;
 
 	case OLSH:
 	case ORSH:
@@ -657,14 +655,14 @@ loop:
 		evconst(n);
 		if(n->op == OLITERAL)
 			goto ret;
-		if(n->left->type == T)
-			convlit(n->left, types[TINT]);
-		if(n->right->type == T)
-			convlit(n->right, types[TUINT]);
+		// do NOT defaultlit n->left.
+		// let parent defaultlit or convlit instead.
+		defaultlit(n->right, types[TUINT]);
 		if(n->left->type == T || n->right->type == T)
 			goto ret;
 		if(issigned[n->right->type->etype])
 			goto badt;
+		// check of n->left->type happens in second switch.
 		break;
 
 	case OMOD:
@@ -695,8 +693,7 @@ loop:
 		evconst(n);
 		if(n->op == OLITERAL)
 			goto ret;
-		convlit(n->left, n->right->type);
-		convlit(n->right, n->left->type);
+		defaultlit2(n->left, n->right);
 		if(n->left->type == T || n->right->type == T)
 			goto ret;
 		if(!eqtype(n->left->type, n->right->type, 0))
@@ -749,6 +746,7 @@ loop:
 		if(top != Erv)
 			goto nottop;
 		walktype(n->left, Erv);
+		defaultlit(n->left, T);
 		implicitstar(&n->left);
 		t = n->left->type;
 		if(t == T)
@@ -757,7 +755,7 @@ loop:
 		default:
 			goto badt;
 		case TSTRING:
-			if(whatis(n->left) == Wlitstr)
+			if(isconst(n->left, CTSTR))
 				nodconst(n, types[TINT], n->left->val.u.sval->len);
 			break;
 		case TMAP:
@@ -774,8 +772,8 @@ loop:
 		if(top != Erv)
 			goto nottop;
 		walktype(n->left, Erv);
+		defaultlit(n->left, T);
 		implicitstar(&n->left);
-		evconst(n);
 		t = n->left->type;
 		if(t == T)
 			goto ret;
@@ -800,7 +798,7 @@ loop:
 		if(n->left == N || n->right == N)
 			goto ret;
 
-		defaultlit(n->left);
+		defaultlit(n->left, T);
 		implicitstar(&n->left);
 
 		t = n->left->type;
@@ -809,17 +807,16 @@ loop:
 
 		switch(t->etype) {
 		default:
+			defaultlit(n->right, T);
 			goto badt;
 
 		case TSTRING:
 			// right side must be an int
 			if(top != Erv)
 				goto nottop;
-			if(n->right->type == T) {
-				convlit(n->right, types[TINT]);
-				if(n->right->type == T)
-					break;
-			}
+			defaultlit(n->right, types[TINT]);
+			if(n->right->type == T)
+				break;
 			if(!isint[n->right->type->etype])
 				goto badt;
 			indir(n, stringop(n, top));
@@ -827,11 +824,9 @@ loop:
 
 		case TMAP:
 			// right side must be map type
-			if(n->right->type == T) {
-				convlit(n->right, t->down);
-				if(n->right->type == T)
-					break;
-			}
+			defaultlit(n->right, t->down);
+			if(n->right->type == T)
+				break;
 			if(!eqtype(n->right->type, t->down, 0))
 				goto badt;
 			n->type = t->type;
@@ -841,14 +836,11 @@ loop:
 
 		case TARRAY:
 			// right side must be an int
-			if(n->right->type == T) {
-				convlit(n->right, types[TINT]);
-				if(n->right->type == T)
-					break;
-			}
+			defaultlit(n->right, types[TINT]);
+			if(n->right->type == T)
+				break;
 			if(!isint[n->right->type->etype])
 				goto badt;
-
 			n->type = t->type;
 			break;
 		}
@@ -871,7 +863,7 @@ loop:
 	case OSEND:
 		if(top == Elv)
 			goto nottop;
-		walktype(n->left, Erv);		// chan
+		walktype(n->left, Erv);	// chan
 		walktype(n->right, Erv);	// e
 		indir(n, chanop(n, top));
 		goto ret;
@@ -897,7 +889,9 @@ loop:
 		walktype(n->right, Erv);
 		if(n->left == N || n->right == N)
 			goto ret;
-		convlit(n->left, types[TSTRING]);
+		defaultlit(n->left, T);
+		defaultlit(n->right->left, types[TUINT]);
+		defaultlit(n->right->right, types[TUINT]);
 		implicitstar(&n->left);
 		t = n->left->type;
 		if(t == T)
@@ -919,12 +913,14 @@ loop:
 	case ODOTINTER:
 		if(top == Etop)
 			goto nottop;
+		defaultlit(n->left, T);
 		walkdot(n);
 		goto ret;
 
 	case OADDR:
 		if(top != Erv)
 			goto nottop;
+		defaultlit(n->left, T);
 		if(n->left->op == OCOMPOS && n->left->type != T) {
 			// turn &Point(1, 2) or &[]int(1, 2) or &[...]int(1, 2) into allocation.
 			// initialize with
@@ -968,13 +964,13 @@ loop:
 				yyerror("cannot take address of function");
 			}
 		}
-		walktype(n->left, Elv);
-		addrescapes(n->left);
 		if(n->left == N)
 			goto ret;
+		walktype(n->left, Elv);
 		t = n->left->type;
 		if(t == T)
 			goto ret;
+		addrescapes(n->left);
 		n->type = ptrto(t);
 		goto ret;
 
@@ -984,6 +980,7 @@ loop:
 		if(top == Elv)	// even if n is lvalue, n->left is rvalue
 			top = Erv;
 		walktype(n->left, top);
+		defaultlit(n->left, T);
 		if(n->left == N)
 			goto ret;
 		t = n->left->type;
@@ -1041,12 +1038,8 @@ loop:
 	case ONE:
 		if(n->left->type == T)
 			goto ret;
-		if(isslice(n->left->type)) {
-			t = types[TBOOL];
-			break;
-		}
 		et = n->left->type->etype;
-		if(!okforeq[et])
+		if(!okforeq[et] && !isslice(n->left->type))
 			goto badt;
 		if(isinter(n->left->type)) {
 			indir(n, ifaceop(T, n, n->op));
@@ -1085,18 +1078,14 @@ loop:
 		et = n->left->type->etype;
 		if(!okforadd[et])
 			goto badt;
-		if(!isfloat[et])
-			break;
-
-		l = nod(OLITERAL, N, N);
-		l->val.u.fval = mal(sizeof(*l->val.u.fval));
-		l->val.ctype = CTFLT;
-		mpmovecflt(l->val.u.fval, 0.0);
-
-		l = nod(OSUB, l, n->left);
-		indir(n, l);
-		walktype(n, Erv);
-		goto ret;
+		if(isfloat[et]) {
+			// TODO(rsc): Can do this more efficiently,
+			// but OSUB is wrong.  Should be in back end anyway.
+			indir(n, nod(OMUL, n->left, nodintconst(-1)));
+			walktype(n, Erv);
+			goto ret;
+		}
+		break;
 
 	case OLSH:
 	case ORSH:
@@ -1109,17 +1098,27 @@ loop:
 		if(n->left->type == T)
 			goto ret;
 		et = n->left->type->etype;
-		if(!okforand[et])
+		if(et != TIDEAL && !okforand[et])
 			goto badt;
 		break;
 	}
 
-	if(t == T)
+	if(t == T) {
 		t = n->left->type;
+		// throw away name:
+		//	type MyInt int
+		//	var x MyInt = 0;
+		// -x has type int, not MyInt.
+		if(t != T)
+			t = types[t->etype];
+	}
 	n->type = t;
 	goto ret;
 
 nottop:
+	if(n->diag)
+		goto ret;
+	n->diag = 1;
 	switch(top) {
 	default:
 		yyerror("didn't expect %O here", n->op);
@@ -1137,6 +1136,9 @@ nottop:
 	goto ret;
 
 badt:
+	if(n->diag)
+		goto ret;
+	n->diag = 1;
 	if(n->right == N) {
 		if(n->left == N) {
 			badtype(n->op, T, T);
@@ -1160,14 +1162,13 @@ void
 walkbool(Node *n)
 {
 	walktype(n, Erv);
+	defaultlit(n, T);
 	addtotop(n);
 	if(n != N && n->type != T)
 		if(!eqtype(n->type, types[TBOOL], 0))
 			yyerror("IF and FOR require a boolean type");
 }
 
-
-
 void
 walkconv(Node *n)
 {
@@ -1182,12 +1183,15 @@ walkconv(Node *n)
 	if(l == N)
 		return;
 	walktype(l, Erv);
-
-	convlit1(l, t, 1);
+	if(l->type == T)
+		return;
 
 	// if using .(T), interface assertion.
 	if(n->op == ODOTTYPE) {
 		// interface conversion
+		defaultlit(l, T);
+		if(!isinter(l->type))
+			yyerror("type assertion requires interface on left, have %T", l->type);
 		et = ifaceas(n->type, l->type, 1);
 		if(et != Inone) {
 			indir(n, ifaceop(n->type, l, et));
@@ -1197,6 +1201,9 @@ walkconv(Node *n)
 	}
 
 	// otherwise, conversion.
+	convlit1(l, t, 1);
+	if(l->type == T)
+		return;
 
 	// nil conversion
 	if(eqtype(t, l->type, 0)) {
@@ -1208,7 +1215,6 @@ walkconv(Node *n)
 	}
 
 	// simple fix-float
-	if(l->type != T)
 	if(isint[l->type->etype] || isfloat[l->type->etype])
 	if(isint[t->etype] || isfloat[t->etype]) {
 		evconst(n);
@@ -1324,6 +1330,7 @@ recv:
 	a = c->left;			// nil elem
 	a = nod(OLITERAL, N, N);
 	a->val.ctype = CTNIL;
+	a->type = types[TNIL];
 
 	r = a;
 	a = c->left;			// chan
@@ -1797,7 +1804,7 @@ mkdotargs(Node *r, Node *rr, Iter *saver, Node *nn, Type *l, int fp)
 	st = typ(TSTRUCT);	// generated structure
 	ft = T;			// last field
 	while(r != N) {
-		defaultlit(r);
+		defaultlit(r, T);
 
 		// generate the next structure field
 		t = typ(TFIELD);
@@ -1968,7 +1975,7 @@ prcompat(Node *n, int fmt)
 	Node *on;
 	Type *t;
 	Iter save;
-	int w, notfirst;
+	int notfirst, et;
 
 	r = N;
 	l = listfirst(&save, &n);
@@ -1989,49 +1996,42 @@ loop:
 		r = list(r, nod(OCALL, on, N));
 	}
 
-	w = whatis(l);
-	switch(w) {
-	default:
-		if(l->type == T)
-			goto out;
-		if(isinter(l->type)) {
-			on = syslook("printinter", 1);
-			argtype(on, l->type);		// any-1
-			break;
-		}
-		if(isptr[l->type->etype]
-		|| l->type->etype == TCHAN
-		|| l->type->etype == TMAP
-		|| l->type->etype == TFUNC) {
-			on = syslook("printpointer", 1);
-			argtype(on, l->type);	// any-1
+	walktype(l, Erv);
+	if(l->op == OLITERAL) {
+		switch(l->val.ctype) {
+		case CTINT:
+			defaultlit(l, types[TINT64]);
 			break;
-		}
-		if(isslice(l->type)) {
-			on = syslook("printarray", 1);
-			argtype(on, l->type);	// any-1
+		case CTFLT:
+			defaultlit(l, types[TFLOAT64]);
 			break;
 		}
-		badtype(OPRINT, l->type, T);
-		l = listnext(&save);
-		goto loop;
+	}
+	if(l->type == T)
+		goto out;
 
-	case Wlitint:
-	case Wtint:
+	et = l->type->etype;
+	if(isinter(l->type)) {
+		on = syslook("printinter", 1);
+		argtype(on, l->type);		// any-1
+	} else if(isptr[et] || et == TCHAN || et == TMAP || et == TFUNC) {
+		on = syslook("printpointer", 1);
+		argtype(on, l->type);	// any-1
+	} else if(isslice(l->type)) {
+		on = syslook("printarray", 1);
+		argtype(on, l->type);	// any-1
+	} else if(isint[et]) {
 		on = syslook("printint", 0);
-		break;
-	case Wlitfloat:
-	case Wtfloat:
+	} else if(isfloat[et]) {
 		on = syslook("printfloat", 0);
-		break;
-	case Wlitbool:
-	case Wtbool:
+	} else if(et == TBOOL) {
 		on = syslook("printbool", 0);
-		break;
-	case Wlitstr:
-	case Wtstr:
+	} else if(et == TSTRING) {
 		on = syslook("printstring", 0);
-		break;
+	} else {
+		badtype(OPRINT, l->type, T);
+		l = listnext(&save);
+		goto loop;
 	}
 
 	t = *getinarg(on->type);
@@ -2538,6 +2538,7 @@ chanop(Node *n, int top)
 			goto shape;
 
 		// chanrecv2(hchan *chan any) (elem any, pres bool);
+		defaultlit(n->right->left, T);
 		t = fixchan(n->right->left->type);
 		if(t == T)
 			break;
@@ -2560,7 +2561,7 @@ chanop(Node *n, int top)
 			goto recv2;
 
 		// chanrecv1(hchan *chan any) (elem any);
-
+		defaultlit(n->left, T);
 		t = fixchan(n->left->type);
 		if(t == T)
 			break;
@@ -2588,6 +2589,7 @@ chanop(Node *n, int top)
 		if(a == N) {
 			a = nod(OLITERAL, N, N);
 			a->val.ctype = CTNIL;
+			a->type = types[TNIL];
 		} else
 			a = nod(OADDR, a, N);
 
@@ -3072,7 +3074,7 @@ colas(Node *nl, Node *nr)
 
 	while(l != N) {
 		walktype(r, Erv);
-		defaultlit(r);
+		defaultlit(r, T);
 		a = old2new(l, r->type);
 		n = list(n, a);
 
@@ -3215,9 +3217,9 @@ ary:
 	hk = nod(OXXX, N, N);		// hidden key
 	tempname(hk, types[TINT]);	// maybe TINT32
 
-	n->ninit = nod(OAS, hk, literal(0));
+	n->ninit = nod(OAS, hk, nodintconst(0));
 	n->ntest = nod(OLT, hk, nod(OLEN, m, N));
-	n->nincr = nod(OASOP, hk, literal(1));
+	n->nincr = nod(OASOP, hk, nodintconst(1));
 	n->nincr->etype = OADD;
 
 	if(local)
@@ -3250,9 +3252,10 @@ map:
 	r = nod(OCALL, on, r);
 	n->ninit = r;
 
-	r = nod(OINDEX, hk, literal(0));
+	r = nod(OINDEX, hk, nodintconst(0));
 	a = nod(OLITERAL, N, N);
 	a->val.ctype = CTNIL;
+	a->type = types[TNIL];
 	r = nod(ONE, r, a);
 	n->ntest = r;
 
@@ -3678,19 +3681,14 @@ loop:
  * the current function returns.  mark any local vars
  * as needing to move to the heap.
  */
-static char *pnames[] = {
-[PAUTO]	"auto",
-[PPARAM]	"param",
-[PPARAMOUT] "param_out",
-};
-
 void
 addrescapes(Node *n)
 {
 	char buf[100];
 	switch(n->op) {
 	default:
-		dump("addrescapes", n);
+		// probably a type error already.
+		// dump("addrescapes", n);
 		break;
 
 	case ONAME:
@@ -3702,8 +3700,6 @@ addrescapes(Node *n)
 			break;
 		case PAUTO:
 		case PPARAM:
-			if(debug['E'])
-				print("%L %s %S escapes %p\n", n->lineno, pnames[n->class], n->sym, n);
 			// if func param, need separate temporary
 			// to hold heap pointer.
 			if(n->class == PPARAM) {
diff --git a/src/lib/syscall/errstr_darwin.go b/src/lib/syscall/errstr_darwin.go
index 780ce71b1..1ea357601 100644
--- a/src/lib/syscall/errstr_darwin.go
+++ b/src/lib/syscall/errstr_darwin.go
@@ -235,7 +235,7 @@ func str(val int64) string {  // do it here rather than with fmt to avoid depend
 }
 
 func Errstr(errno int64) string {
-	if errno < 0 || errno >= len(error) {
+	if errno < 0 || errno >= int64(len(error)) {
 		return "Error " + str(errno)
 	}
 	return error[errno]
diff --git a/src/lib/syscall/errstr_linux.go b/src/lib/syscall/errstr_linux.go
index 2a6a5b813..61ac4b56e 100644
--- a/src/lib/syscall/errstr_linux.go
+++ b/src/lib/syscall/errstr_linux.go
@@ -285,7 +285,7 @@ func str(val int64) string {  // do it here rather than with fmt to avoid depend
 }
 
 func Errstr(errno int64) string {
-	if errno < 0 || errno >= len(error) {
+	if errno < 0 || errno >= int64(len(error)) {
 		return "Error " + str(errno)
 	}
 	return error[errno]
diff --git a/test/const.go b/test/const.go
index 85c0a91b6..8e587cfe5 100644
--- a/test/const.go
+++ b/test/const.go
@@ -14,6 +14,9 @@ const (
 	c1 = chuge >> 100;
 	c3div2 = 3/2;
 	c1e3 = 1e3;
+
+	ctrue = true;
+	cfalse = !ctrue;
 )
 
 const (
@@ -111,4 +114,7 @@ func floats() {
 func main() {
 	ints();
 	floats();
+
+	assert(ctrue == true, "ctrue == true");
+	assert(cfalse == false, "cfalse == false");
 }
diff --git a/test/const1.go b/test/const1.go
new file mode 100644
index 000000000..09125a121
--- /dev/null
+++ b/test/const1.go
@@ -0,0 +1,79 @@
+// errchk $G -e $F.go
+
+// Copyright 2009 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
+
+type I interface {}
+const (
+	// assume all types behave similarly to int8/uint8
+	Int8 int8 = 101;
+	Minus1 int8 = -1;
+	Uint8 uint8 = 102;
+	Const = 103;
+
+	Float32 float32 = 104.5;
+	Float float = 105.5;
+	ConstFloat = 106.5;
+	Big float64 = 1e300;
+
+	String = "abc";
+	Bool = true;
+)
+
+var (
+	a1 = Int8 * 100;	// ERROR "overflows"
+	a2 = Int8 * -1;	// OK
+	a3 = Int8 * 1000;	// ERROR "overflows"
+	a4 = Int8 * int8(1000);	// ERROR "overflows"
+	a5 = int8(Int8 * 1000);	// ERROR "overflows"
+	a6 = int8(Int8 * int8(1000));	// ERROR "overflows"
+	a7 = Int8 - 2*Int8 - 2*Int8;	// ERROR "overflows"
+	a8 = Int8 * Const / 100;	// ERROR "overflows"
+	a9 = Int8 * (Const / 100);	// OK
+
+	b1 = Uint8 * Uint8;	// ERROR "overflows"
+	b2 = Uint8 * -1;	// ERROR "overflows"
+	b3 = Uint8 - Uint8;	// OK
+	b4 = Uint8 - Uint8 - Uint8;	// ERROR "overflows"
+	b5 = uint8(^0);	// ERROR "overflows"
+	b6 = ^uint8(0);	// ERROR "overflows"
+	b7 = uint8(Minus1);	// ERROR "overflows"
+	b8 = uint8(int8(-1));	// ERROR "overflows"
+	b8a = uint8(-1);	// ERROR "overflows"
+	b9 byte = (1<<10) >> 8;	// OK
+	b10 byte = (1<<10);	// ERROR "overflows"
+	b11 byte = (byte(1)<<10) >> 8;	// ERROR "overflows"
+	b12 byte = 1000;	// ERROR "overflows"
+	b13 byte = byte(1000);	// ERROR "overflows"
+	b14 byte = byte(100) * byte(100);	// ERROR "overflows"
+	b15 byte = byte(100) * 100;	// ERROR "overflows"
+	b16 byte = byte(0) * 1000;	// ERROR "overflows"
+	b16a byte = 0 * 1000;	// OK
+	b17 byte = byte(0) * byte(1000);	// ERROR "overflows"
+	b18 byte = Uint8/0;	// ERROR "division by zero"
+
+	c1 float64 = Big;
+	c2 float64 = Big*Big;	// ERROR "overflows"
+	c3 float64 = float64(Big)*Big;	// ERROR "overflows"
+	c4 = Big*Big;	// ERROR "overflows"
+	c5 = Big/0;	// ERROR "division by zero"
+)
+
+func f(int);
+
+func main() {
+	f(Int8);	// ERROR "convert"
+	f(Minus1);	// ERROR "convert"
+	f(Uint8);	// ERROR "convert"
+	f(Const);	// OK
+	f(Float32);	// ERROR "convert"
+	f(Float);	// ERROR "convert"
+	f(ConstFloat);	// ERROR "truncate"
+	f(ConstFloat - 0.5);	// OK
+	f(Big);	// ERROR "convert"
+	f(String);	// ERROR "convert"
+	f(Bool);	// ERROR "convert"
+}
diff --git a/test/const2.go b/test/const2.go
new file mode 100644
index 000000000..b3b10de8e
--- /dev/null
+++ b/test/const2.go
@@ -0,0 +1,12 @@
+// errchk $G $D/$F.go
+
+// Copyright 2009 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
+
+const (
+	A int = 1;
+	B byte;	// ERROR "type without expr"
+)
diff --git a/test/const3.go b/test/const3.go
new file mode 100644
index 000000000..fc734377e
--- /dev/null
+++ b/test/const3.go
@@ -0,0 +1,29 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 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 "fmt"
+
+type T int
+func (t T) String() string {
+	return fmt.Sprintf("T%d", t);
+}
+
+const (
+	A T = 1<<(1<<iota);
+	B;
+	C;
+	D;
+	E;
+)
+
+func main() {
+	s := fmt.Sprintf("%v %v %v %v %v", A, B, C, D, E);
+	if s != "T2 T4 T16 T256 T65536" {
+		panicln("type info didn't propagate in const: got", s);
+	}
+}
diff --git a/test/convert.go b/test/convert.go
new file mode 100644
index 000000000..11369e521
--- /dev/null
+++ b/test/convert.go
@@ -0,0 +1,53 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 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 "unsafe"
+
+func typeof(x interface{}) string {
+	val, typ, indir := sys.Reflect(x);
+	return typ;
+}
+
+func f() int {
+	return 0;
+}
+
+func g() int {
+	return 0;
+}
+
+type T func() int
+
+var m = map[string] T {
+	"f": f
+}
+
+type A int
+type B int
+
+var a A = 1;
+var b B = 2;
+var x int;
+
+func main() {
+	want := typeof(g);
+	if t := typeof(f); t != want {
+		panicln("type of f is", t, "want", want);
+	}
+
+	want = typeof(x);
+	if t := typeof(+a); t != want {
+		panicln("type of +a is", t, "want", want);
+	}
+	if t := typeof(a+0); t != want {
+		panicln("type of a+0 is", t, "want", want);
+	}
+	if t := typeof(a+b); t != want {
+		panicln("type of a+b is", t, "want", want);
+	}
+}
diff --git a/test/convlit.go b/test/convlit.go
index 23dab0a9c..cfa772712 100644
--- a/test/convlit.go
+++ b/test/convlit.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// ! errchk $G -e $D/$F.go
+
 package main
 
 // explicit conversions are okay, even if they overflow
@@ -20,10 +22,10 @@ var s string;
 var bad1 string = 1;	// ERROR "conver|incompatible"
 var bad2 = s + 1;		// ERROR "conver|incompatible"
 var bad3 = s + 'a';	// ERROR "conver|incompatible"
-var bad4 = "a" + 1;	// ERROR "literals|incompatible"
-var bad5 = "a" + 'a';	// ERROR "literals|incompatible"
+var bad4 = "a" + 1;	// ERROR "literals|incompatible|convert"
+var bad5 = "a" + 'a';	// ERROR "literals|incompatible|convert"
 
-var bad6 int = 1.5;	// ERROR "convert"
+var bad6 int = 1.5;	// ERROR "convert|truncate"
 var bad7 int = 1e100;	// ERROR "overflow"
 var bad8 float32 = 1e200;	// ERROR "overflow"
 
diff --git a/test/errchk b/test/errchk
index 2b602c3c7..c85f36f9b 100755
--- a/test/errchk
+++ b/test/errchk
@@ -63,11 +63,11 @@ pr -n -t $SOURCEFILE | grep '// ERROR' | while read line; do
   mv -f $TMPTMP $TMPALL
   if test -z "$errmsg"; then
     bug
-    echo 1>&2 "errchk: $SOURCEFILE: missing expected error message on line $lineno: '$regexp'"
+    echo 1>&2 "errchk: $SOURCEFILE:$lineno: missing expected error: '$regexp'"
     echo 1 > $TMPSTAT
   elif ! echo "$errmsg" | egrep -q "$regexp"; then
     bug
-    echo 1>&2 "errchk: $SOURCEFILE: error message on line $lineno does not match '$regexp'"
+    echo 1>&2 "errchk: $SOURCEFILE:$lineno: error message does not match '$regexp'"
     echo 1>&2 $errmsg
     echo 1 > $TMPSTAT
   fi
diff --git a/test/fixedbugs/bug090.go b/test/fixedbugs/bug090.go
index 0654cff9d..2b6f7deb8 100644
--- a/test/fixedbugs/bug090.go
+++ b/test/fixedbugs/bug090.go
@@ -33,13 +33,14 @@ func main() {
 	f = f3div2;
 	assert(f == f3div2, "f == f3div2");
 
-	i = f3div2;	// BUG: probably shouldn't compile
+	i = f3div2;	// ERROR "truncate"
 	assert(i == c3div2, "i == c3div2 from f3div2");
-	assert(i != f3div2, "i != f3div2");	// BUG: certainly shouldn't fail
+	assert(i != f3div2, "i != f3div2");	// ERROR "truncate"
 
 	const g float64 = 1.0;
-	i = g;  // BUG: shouldn't compile
+	i = g;  // ERROR "convert"
 
 	const h float64 = 3.14;
-	i = h;  // BUG: certainly shouldn't compile
+	i = h;  // ERROR "convert"
+	i = int(h);	// ERROR "truncate"
 }
diff --git a/test/fixedbugs/bug127.go b/test/fixedbugs/bug127.go
index b463d233c..604b43eff 100644
--- a/test/fixedbugs/bug127.go
+++ b/test/fixedbugs/bug127.go
@@ -7,6 +7,6 @@
 package main
 func main() {
         var x int64 = 0;
-        println(x != nil);	// ERROR "illegal|incompatible"
-        println(0 != nil);	// ERROR "illegal|incompatible"
+        println(x != nil);	// ERROR "illegal|incompatible|nil constant"
+        println(0 != nil);	// ERROR "illegal|incompatible|nil constant"
 }
diff --git a/test/golden.out b/test/golden.out
index df7be75c1..c91bb450f 100644
--- a/test/golden.out
+++ b/test/golden.out
@@ -32,17 +32,12 @@ pc: xxx
 
 
 =========== ./convlit.go
-BUG: errchk: ./convlit.go: missing expected error message on line 16: 'conver|incompatible'
-errchk: ./convlit.go: missing expected error message on line 22: 'convert'
-errchk: ./convlit.go: missing expected error message on line 23: 'overflow'
-errchk: ./convlit.go: missing expected error message on line 24: 'overflow'
-errchk: ./convlit.go: unmatched error messages:
+BUG: errchk: ./convlit.go: unmatched error messages:
 ==================================================
-./convlit.go:8: cannot convert non-integer constant to int
-./convlit.go:11: overflow converting constant to int
-./convlit.go:12: overflow converting constant to float
-./convlit.go:8: cannot convert non-integer constant to int
-./convlit.go:8: fatal error: too many errors
+./convlit.go:8: constant 1.5 truncated to integer
+./convlit.go:11: constant 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows int
+./convlit.go:12: constant 34911850510716223476646871064527264675788468424693128821036252992306087892081078460155404277013793117885253p+2968 overflows float
+./convlit.go:9: constant 1.5 truncated to integer
 ==================================================
 
 =========== ./helloworld.go
@@ -116,7 +111,7 @@ bugs/bug108.go:4: stupid shift: 1025
 BUG: errchk: command succeeded unexpectedly:  6g bugs/bug108.go
 
 =========== bugs/bug115.go
-bugs/bug115.go:8: overflow converting constant to uint
+bugs/bug115.go:8: constant -1 overflows uint
 BUG: bug115 should compile
 
 =========== bugs/bug117.go
@@ -129,7 +124,9 @@ BUG: should compile
 BUG: errchk: command succeeded unexpectedly:  6g bugs/bug125.go
 
 =========== bugs/bug131.go
-BUG: should not compile
+bugs/bug131.go:7: cannot convert uint64 constant to int64
+bugs/bug131.go:7: illegal types for operand: AS
+	int64
 
 =========== bugs/bug132.go
 BUG: compilation succeeds incorrectly
@@ -138,12 +135,11 @@ BUG: compilation succeeds incorrectly
 BUG: should not compile
 
 =========== bugs/bug138.go
-bugs/bug138.go:8: overflow converting constant to uint
-bugs/bug138.go:8: illegal combination of literals CONV 7
+bugs/bug138.go:8: constant -1 overflows uint
 BUG should compile
 
 =========== fixedbugs/bug016.go
-fixedbugs/bug016.go:7: overflow converting constant to uint
+fixedbugs/bug016.go:7: constant -3 overflows uint
 
 =========== fixedbugs/bug027.go
 hi
@@ -177,7 +173,7 @@ fixedbugs/bug039.go:6: variable x redeclared in this block
 fixedbugs/bug041.go:5: export of incomplete type t
 
 =========== fixedbugs/bug049.go
-fixedbugs/bug049.go:6: illegal conversion of nil to string
+fixedbugs/bug049.go:6: cannot convert nil constant to string
 
 =========== fixedbugs/bug050.go
 fixedbugs/bug050.go:3: package statement must be first
@@ -187,7 +183,7 @@ sys.6:1 fixedbugs/bug050.go:3: syntax error near package
 fixedbugs/bug051.go:10: expression must be a constant
 
 =========== fixedbugs/bug062.go
-fixedbugs/bug062.go:6: illegal conversion of nil to string
+fixedbugs/bug062.go:6: cannot convert nil constant to string
 fixedbugs/bug062.go:6: illegal types for operand: AS
 	string
 
@@ -210,9 +206,13 @@ fixedbugs/bug072.go:6: bug: undefined
 fixedbugs/bug073.go:8: illegal types for operand: LSH
 	int
 	int
+fixedbugs/bug073.go:8: illegal types for operand: AS
+	int
 fixedbugs/bug073.go:9: illegal types for operand: RSH
 	int
 	int
+fixedbugs/bug073.go:9: illegal types for operand: AS
+	int
 
 =========== fixedbugs/bug074.go
 fixedbugs/bug074.go:6: invalid type for composite literal: string
@@ -227,18 +227,6 @@ fixedbugs/bug083.dir/bug1.go:9: syntax error near t0
 =========== fixedbugs/bug086.go
 fixedbugs/bug086.go:5: function ends without a return statement
 
-=========== fixedbugs/bug090.go
-fixedbugs/bug090.go:32: cannot convert non-integer constant to int
-fixedbugs/bug090.go:32: illegal types for operand: AS
-	int
-fixedbugs/bug090.go:34: cannot convert non-integer constant to int
-fixedbugs/bug090.go:34: illegal types for operand: CALL
-	bool
-fixedbugs/bug090.go:40: cannot convert non-integer constant to int
-fixedbugs/bug090.go:40: illegal types for operand: AS
-	int
-	float64
-
 =========== fixedbugs/bug091.go
 fixedbugs/bug091.go:15: c: undefined
 fixedbugs/bug091.go:15: illegal types for operand: AS