gc: fix reflect table method receiver

Fixes issue 451.
Fixes issue 770.

R=ken2
CC=golang-dev
http://codereview.appspot.com/2207045

3 files changed, 133 insertions, 35 deletions

diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 06bc57373..acbfde4ff 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -1010,7 +1010,7 @@ void	walkrange(Node *n);
  *	reflect.c
  */
 void	dumptypestructs(void);
-Type*	methodfunc(Type *f, int use_receiver);
+Type*	methodfunc(Type *f, Type*);
 Node*	typename(Type *t);
 Sym*	typesym(Type *t);
 
diff --git a/src/cmd/gc/reflect.c b/src/cmd/gc/reflect.c
index 87b9b04ba..18b2a4fc6 100644
--- a/src/cmd/gc/reflect.c
+++ b/src/cmd/gc/reflect.c
@@ -100,16 +100,16 @@ lsort(Sig *l, int(*f)(Sig*, Sig*))
  * return function type, receiver as first argument (or not).
  */
 Type*
-methodfunc(Type *f, int use_receiver)
+methodfunc(Type *f, Type *receiver)
 {
 	NodeList *in, *out;
 	Node *d;
 	Type *t;
 
 	in = nil;
-	if(use_receiver) {
+	if(receiver) {
 		d = nod(ODCLFIELD, N, N);
-		d->type = getthisx(f)->type->type;
+		d->type = receiver;
 		in = list(in, d);
 	}
 	for(t=getinargx(f)->type; t; t=t->down) {
@@ -185,8 +185,8 @@ methods(Type *t)
 		a->name = method->name;
 		a->isym = methodsym(method, it, 1);
 		a->tsym = methodsym(method, t, 0);
-		a->type = methodfunc(f->type, 1);
-		a->mtype = methodfunc(f->type, 0);
+		a->type = methodfunc(f->type, t);
+		a->mtype = methodfunc(f->type, nil);
 
 		if(!(a->isym->flags & SymSiggen)) {
 			a->isym->flags |= SymSiggen;
@@ -241,22 +241,27 @@ imethods(Type *t)
 	Sig *a, *all, *last;
 	int o;
 	Type *f;
+	Sym *method, *isym;
+	Prog *oldlist;
 
 	all = nil;
 	last = nil;
 	o = 0;
+	oldlist = nil;
 	for(f=t->type; f; f=f->down) {
 		if(f->etype != TFIELD)
 			fatal("imethods: not field");
 		if(f->type->etype != TFUNC || f->sym == nil)
 			continue;
+		method = f->sym;
 		a = mal(sizeof(*a));
-		a->name = f->sym->name;
-		if(!exportname(f->sym->name))
-			a->pkg = f->sym->pkg;
+		a->name = method->name;
+		if(!exportname(method->name))
+			a->pkg = method->pkg;
 		a->mtype = f->type;
 		a->offset = 0;
-		a->type = methodfunc(f->type, 0);
+		a->type = methodfunc(f->type, nil);
+
 		if(last && sigcmp(last, a) >= 0)
 			fatal("sigcmp vs sortinter %s %s", last->name, a->name);
 		if(last == nil)
@@ -264,7 +269,43 @@ imethods(Type *t)
 		else
 			last->link = a;
 		last = a;
+		
+		// Compiler can only refer to wrappers for
+		// named interface types.
+		if(t->sym == S)
+			continue;
+		
+		// NOTE(rsc): Perhaps an oversight that
+		// IfaceType.Method is not in the reflect data.
+		// Generate the method body, so that compiled
+		// code can refer to it.
+		isym = methodsym(method, t, 0);
+		if(!(isym->flags & SymSiggen)) {
+			isym->flags |= SymSiggen;
+			if(oldlist == nil)
+				oldlist = pc;
+			genwrapper(t, f, isym, 0);
+		}
+		
+		// Generate wrapper for pointer to interface type.
+		isym = methodsym(method, ptrto(t), 0);
+		if(!(isym->flags & SymSiggen)) {
+			isym->flags |= SymSiggen;
+			if(oldlist == nil)
+				oldlist = pc;
+			genwrapper(ptrto(t), f, isym, 0);
+		}
 	}
+
+	if(oldlist) {
+		// old list ended with AEND; change to ANOP
+		// so that the trampolines that follow can be found.
+		nopout(oldlist);
+
+		// start new data list
+		newplist();
+	}
+
 	return all;
 }
 
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 1c736d432..821d540fa 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -17,6 +17,7 @@ static void	implicitstar(Node**);
 static int	onearg(Node*, char*, ...);
 static int	twoarg(Node*);
 static int	lookdot(Node*, Type*, int);
+static int	looktypedot(Node*, Type*, int);
 static void	typecheckaste(int, int, Type*, NodeList*, char*);
 static Type*	lookdot1(Sym *s, Type *t, Type *f, int);
 static int	nokeys(NodeList*);
@@ -497,41 +498,42 @@ reswitch:
 			yyerror("rhs of . must be a name");	// impossible
 			goto error;
 		}
-		if(isptr[t->etype]) {
-			t = t->type;
-			if(t == T)
-				goto error;
-			n->op = ODOTPTR;
-			checkwidth(t);
-		}
 		sym = n->right->sym;
-		if(!lookdot(n, t, 0)) {
-			if(lookdot(n, t, 1))
-				yyerror("%#N undefined (cannot refer to unexported field %S)", n, n->right->sym);
-			else
-				yyerror("%#N undefined (type %T has no field %S)", n, t, n->right->sym);
-			goto error;
-		}
 		if(l->op == OTYPE) {
-			if(n->type->etype != TFUNC || n->type->thistuple != 1) {
-				yyerror("type %T has no method %hS", n->left->type, sym);
-				n->type = T;
+			if(!looktypedot(n, t, 0)) {
+				if(looktypedot(n, t, 1))
+					yyerror("%#N undefined (cannot refer to unexported method %S)", n, n->right->sym);
+				else
+					yyerror("%#N undefined (type %T has no method %S)", n, t, n->right->sym);
 				goto error;
 			}
-			if(t->etype == TINTER) {
-				yyerror("method expression on interface not implemented");
+			if(n->type->etype != TFUNC || n->type->thistuple != 1) {
+				yyerror("type %T has no method %hS", n->left->type, sym);
 				n->type = T;
 				goto error;
 			}
 			n->op = ONAME;
 			n->sym = methodsym(sym, l->type, 0);
-			n->type = methodfunc(n->type, 1);
+			n->type = methodfunc(n->type, l->type);
 			n->xoffset = 0;
-			getinargx(n->type)->type->type = l->type;	// fix up receiver
 			n->class = PFUNC;
 			ok = Erv;
 			goto ret;
 		}
+		if(isptr[t->etype]) {
+			t = t->type;
+			if(t == T)
+				goto error;
+			n->op = ODOTPTR;
+			checkwidth(t);
+		}
+		if(!lookdot(n, t, 0)) {
+			if(lookdot(n, t, 1))
+				yyerror("%#N undefined (cannot refer to unexported field or method %S)", n, n->right->sym);
+			else
+				yyerror("%#N undefined (type %T has no field or method %S)", n, t, n->right->sym);
+			goto error;
+		}
 		switch(n->op) {
 		case ODOTINTER:
 		case ODOTMETH:
@@ -1382,6 +1384,55 @@ lookdot1(Sym *s, Type *t, Type *f, int dostrcmp)
 }
 
 static int
+looktypedot(Node *n, Type *t, int dostrcmp)
+{
+	Type *f1, *f2, *tt;
+	Sym *s;
+	
+	s = n->right->sym;
+
+	if(t->etype == TINTER) {
+		f1 = lookdot1(s, t, t->type, dostrcmp);
+		if(f1 == T)
+			return 0;
+
+		if(f1->width == BADWIDTH)
+			fatal("lookdot badwidth %T %p", f1, f1);
+		n->right = methodname(n->right, t);
+		n->xoffset = f1->width;
+		n->type = f1->type;
+		n->op = ODOTINTER;
+		return 1;
+	}
+
+	tt = t;
+	if(t->sym == S && isptr[t->etype])
+		tt = t->type;
+
+	f2 = methtype(tt);
+	if(f2 == T)
+		return 0;
+
+	expandmeth(f2->sym, f2);
+	f2 = lookdot1(s, f2, f2->xmethod, dostrcmp);
+
+	// disallow T.m if m requires *T receiver
+	if(isptr[getthisx(f2->type)->type->type->etype]
+	&& !isptr[t->etype]
+	&& f2->embedded != 2
+	&& !isifacemethod(f2->type)) {
+		yyerror("invalid method expression %#N (needs pointer receiver: (*%T).%s)", n, t, f2->sym->name);
+		return 0;
+	}
+
+	n->right = methodname(n->right, t);
+	n->xoffset = f2->width;
+	n->type = f2->type;
+	n->op = ODOTMETH;
+	return 1;
+}
+
+static int
 lookdot(Node *n, Type *t, int dostrcmp)
 {
 	Type *f1, *f2, *tt, *rcvr;
@@ -1394,9 +1445,15 @@ lookdot(Node *n, Type *t, int dostrcmp)
 	if(t->etype == TSTRUCT || t->etype == TINTER)
 		f1 = lookdot1(s, t, t->type, dostrcmp);
 
-	f2 = methtype(n->left->type);
-	if(f2 != T)
-		f2 = lookdot1(s, f2, f2->method, dostrcmp);
+	f2 = T;
+	if(n->left->type == t || n->left->type->sym == S) {
+		f2 = methtype(t);
+		if(f2 != T) {
+			// Use f2->method, not f2->xmethod: adddot has
+			// already inserted all the necessary embedded dots.
+			f2 = lookdot1(s, f2, f2->method, dostrcmp);
+		}
+	}
 
 	if(f1 != T) {
 		if(f2 != T)
@@ -1420,7 +1477,7 @@ lookdot(Node *n, Type *t, int dostrcmp)
 		tt = n->left->type;
 		dowidth(tt);
 		rcvr = getthisx(f2->type)->type->type;
-		if(n->left->op != OTYPE && !eqtype(rcvr, tt)) {
+		if(!eqtype(rcvr, tt)) {
 			if(rcvr->etype == tptr && eqtype(rcvr->type, tt)) {
 				checklvalue(n->left, "call pointer method on");
 				addrescapes(n->left);