second pass on interface fixes and tests.

R=ken
OCL=22370
CL=22372

src/cmd/gc/dcl.c

@@ -257,7 +257,7 @@ void
 addmethod(Node *n, Type *t, int local)
 {
 	Type *f, *d, *pa;
-	Sym *st, *sf;
+	Sym *sf;
 
 	pa = nil;
 	sf = nil;
@@ -282,19 +282,17 @@ addmethod(Node *n, Type *t, int local)
 	if(pa == T)
 		goto bad;
 
-	// and finally the receiver sym
-	f = ismethod(pa);
+	f = dclmethod(pa);
 	if(f == T)
 		goto bad;
-	pa = f;
-	st = pa->sym;
-	if(st == S)
-		goto bad;
+
 	if(local && !f->local) {
-		yyerror("method receiver type must be locally defined: %T", f);
+		yyerror("cannot define methods on non-local type %T", t);
 		return;
 	}
 
+	pa = f;
+
 	n = nod(ODCLFIELD, newname(sf), N);
 	n->type = t;
 
@@ -308,7 +306,7 @@ addmethod(Node *n, Type *t, int local)
 			continue;
 		}
 		if(!eqtype(t, f->type, 0)) {
-			yyerror("method redeclared: %S of type %S", sf, st);
+			yyerror("method redeclared: %T.%S", pa, sf);
 			print("\t%T\n\t%T\n", f->type, t);
 		}
 		return;
@@ -324,7 +322,7 @@ addmethod(Node *n, Type *t, int local)
 	return;
 
 bad:
-	yyerror("unknown method pointer: %T %S", pa, sf);
+	yyerror("invalid receiver type %T", pa);
 }
 
 /*

src/cmd/gc/go.h

@@ -633,9 +633,9 @@ int	isdarray(Type*);
 int	isinter(Type*);
 int	isnilinter(Type*);
 int	isddd(Type*);
-Type*	ismethod(Type*);
+Type*	dclmethod(Type*);
 Type*	methtype(Type*);
-int	needaddr(Type*);
+int	methconv(Type*);
 Sym*	signame(Type*);
 int	bytearraysz(Type*);
 int	eqtype(Type*, Type*, int);
@@ -682,6 +682,7 @@ int	Wconv(Fmt*);
 int	Zconv(Fmt*);
 
 int	lookdot0(Sym*, Type*, Type**);
+Type*	lookdot1(Sym*, Type*, Type*);
 int	adddot1(Sym*, Type*, int, Type**);
 Node*	adddot(Node*);
 void	expand0(Type*);
@@ -798,7 +799,9 @@ Type*	fixchan(Type*);
 Node*	chanop(Node*, int);
 Node*	arrayop(Node*, int);
 Node*	ifaceop(Type*, Node*, int);
-int	isandss(Type*, Node*);
+int	ifaceas(Type*, Type*);
+void	ifacecheck(Type*, Type*, int);
+void	runifacechecks(void);
 Node*	convas(Node*);
 void	arrayconv(Type*, Node*);
 Node*	colas(Node*, Node*);

src/cmd/gc/go.y

@@ -1252,14 +1252,10 @@ fndcl:
 	}
 |	'(' oarg_type_list ')' new_name '(' oarg_type_list ')' fnres
 	{
-		Type *t;
-
 		b0stack = dclstack;	// mark base for fn literals
 		$$ = nod(ODCLFUNC, N, N);
 		if(listcount($2) == 1) {
-			t = ismethod($2->type);
 			$$->nname = $4;
-			if(t != T)
 			$$->nname = methodname($4, $2->type);
 			$$->type = functype($2, $6, $8);
 			funchdr($$);

src/cmd/gc/lex.c

@@ -90,6 +90,7 @@ mainlex(int argc, char *argv[])
 
 	nerrors = 0;
 	yyparse();
+	runifacechecks();
 
 	linehist(nil, 0);
 	if(curio.bin != nil)

src/cmd/gc/subr.c

@@ -1525,60 +1525,50 @@ isddd(Type *t)
 	return 0;
 }
 
+/*
+ * given receiver of type t (t == r or t == *r)
+ * return type to hang methods off (r).
+ */
 Type*
-ismethod(Type *t)
+dclmethod(Type *t)
 {
-	int a;
-	Sym *s;
+	int ptr;
 
 	if(t == T)
 		return T;
 
-	// no interfaces
-	if(t->etype == TINTER || (t->etype == tptr && t->type->etype == TINTER))
-		return T;
-
-	a = algtype(t);
-
-	// direct receiver
-	s = t->sym;
-	if(s != S) {
-		if(t->methptr == 2)
-			goto both;
-		t->methptr |= 1;
-		goto out;
-	}
-
-	// pointer receiver
-	if(!isptr[t->etype])
+	// strip away pointer if it's there
+	ptr = 0;
+	if(isptr[t->etype]) {
+		if(t->sym != S)
 			return T;
-
+		ptr = 1;
 		t = t->type;
 		if(t == T)
 			return T;
-
-	s = t->sym;
-	if(s != S) {
-		if(t->methptr == 1)
-			goto both;
-		t->methptr |= 2;
-		goto out;
 	}
 
+	// need a type name
+	if(t->sym == S)
 		return T;
 
-both:
-	yyerror("type %T used as both direct and indirect method", t);
+	// check that all method receivers are consistent
+	if(t->methptr != 0 && t->methptr != (1<<ptr)) {
+		if(t->methptr != 3) {
 			t->methptr = 3;
+			yyerror("methods on both %T and *%T", t, t);
+		}
+	}
+	t->methptr |= 1<<ptr;
 
-out:
-	switch(a) {
+	// check types
+	// TODO(rsc): map, chan etc are not quite right
+	if(!issimple[t->etype])
+	switch(t->etype) {
 	default:
-		yyerror("type %T cannot be used as a method", t);
-	case ASIMP:
-	case APTR:
-	case ASTRING:
-	case ASLICE:
+		return T;
+	case TSTRUCT:
+	case TARRAY:
 		break;
 	}
 
@@ -1586,47 +1576,46 @@ out:
 }
 
 /*
- * this is ismethod() without side effects
+ * this is dclmethod() without side effects.
  */
 Type*
 methtype(Type *t)
 {
-	Sym *s;
-
 	if(t == T)
 		return T;
-	if(t->etype == TINTER || (t->etype == tptr && t->type->etype == TINTER))
-		return T;
-	s = t->sym;
-	if(s != S)
-		return t;
-	if(!isptr[t->etype])
+	if(isptr[t->etype]) {
+		if(t->sym != S)
 			return T;
 		t = t->type;
-	if(t == T)
+	}
+	if(t == T || t->etype == TINTER || t->sym == S)
 		return T;
-	s = t->sym;
-	if(s != S)
 	return t;
-	return T;
 }
 
 /*
- * this is another ismethod()
- * returns 1 if t=T and method wants *T
+ * given type t in a method call, returns op
+ * to convert t into appropriate receiver.
+ * returns OADDR if t==x and method takes *x
+ * returns OIND if t==*x and method takes x
  */
 int
-needaddr(Type *t)
+methconv(Type *t)
 {
-	Sym *s;
+	Type *m;
 
-	if(t == T)
+	m = methtype(t);
+	if(m == T)
 		return 0;
-	if(t->etype == TINTER || (t->etype == tptr && t->type->etype == TINTER))
+	if(m->methptr&2) {
+		// want pointer
+		if(t == m)
+			return OADDR;
 		return 0;
-	s = t->sym;
-	if(s != S && t->methptr == 2)
-		return 1;
+	}
+	// want non-pointer
+	if(t != m)
+		return OIND;
 	return 0;
 }
 
@@ -2735,3 +2724,111 @@ genptrtramp(Sym *method, Sym *oldname, Type *oldthis, Type *oldtype, Sym *newnam
 	funcbody(fn);
 }
 
+/*
+ * delayed interface type check.
+ * remember that there is an interface conversion
+ * on the given line.  once the file is completely read
+ * and all methods are known, we can check that
+ * the conversions are valid.
+ */
+
+typedef struct Icheck Icheck;
+struct Icheck
+{
+	Icheck *next;
+	Type *dst;
+	Type *src;
+	int lineno;
+};
+Icheck *icheck;
+Icheck *ichecktail;
+
+void
+ifacecheck(Type *dst, Type *src, int lineno)
+{
+	Icheck *p;
+
+	p = mal(sizeof *p);
+	if(ichecktail)
+		ichecktail->next = p;
+	else
+		icheck = p;
+	p->dst = dst;
+	p->src = src;
+	p->lineno = lineno;
+	ichecktail = p;
+}
+
+Type*
+ifacelookdot(Sym *s, Type *t)
+{
+	int c, d;
+	Type *m;
+
+	for(d=0; d<nelem(dotlist); d++) {
+		c = adddot1(s, t, d, &m);
+		if(c > 1) {
+			yyerror("%T.%S is ambiguous", t, s);
+			return T;
+		}
+		if(c == 1)
+			return m;
+	}
+	return T;
+}
+
+int
+hasiface(Type *t, Type *iface, Type **m)
+{
+	Type *im, *tm;
+	int imhash;
+
+	t = methtype(t);
+	if(t == T)
+		return 0;
+
+	// if this is too slow,
+	// could sort these first
+	// and then do one loop.
+
+	// could also do full type compare
+	// instead of using hash, but have to
+	// avoid checking receivers, and
+	// typehash already does that for us.
+	// also, it's what the runtime will do,
+	// so we can both be wrong together.
+
+	for(im=iface->type; im; im=im->down) {
+		imhash = typehash(im, 0);
+		tm = ifacelookdot(im->sym, t);
+		if(tm == T || typehash(tm, 0) != imhash) {
+			*m = im;
+			return 0;
+		}
+	}
+	return 1;
+}
+
+void
+runifacechecks(void)
+{
+	Icheck *p;
+	int lno;
+	Type *m, *l, *r;
+
+	lno = lineno;
+	for(p=icheck; p; p=p->next) {
+		lineno = p->lineno;
+		if(isinter(p->dst)) {
+			l = p->src;
+			r = p->dst;
+		} else {
+			l = p->dst;
+			r = p->src;
+		}
+		if(!hasiface(l, r, &m))
+			yyerror("%T is not %T - missing %S%hT",
+				l, r, m->sym, m->type);
+	}
+	lineno = lno;
+}

src/cmd/gc/walk.c

@@ -471,7 +471,7 @@ loop:
 				walktype(r->left, Erv);
 				if(r->left == N)
 					break;
-				et = isandss(r->type, r->left);
+				et = ifaceas(r->type, r->left->type);
 				switch(et) {
 				case I2T:
 					et = I2T2;
@@ -604,8 +604,8 @@ loop:
 			}
 		}
 
-		// interface and structure
-		et = isandss(n->type, l);
+		// interface assignment
+		et = ifaceas(n->type, l->type);
 		if(et != Inone) {
 			indir(n, ifaceop(n->type, l, et));
 			goto ret;
@@ -1542,14 +1542,11 @@ walkselect(Node *sel)
 }
 
 Type*
-lookdot1(Node *n, Type *t, Type *f)
+lookdot1(Sym *s, Type *t, Type *f)
 {
 	Type *r;
-	Sym *s;
 
 	r = T;
-	s = n->sym;
-
 	for(; f!=T; f=f->down) {
 		if(f->sym == S)
 			continue;
@@ -1567,15 +1564,19 @@ lookdot1(Node *n, Type *t, Type *f)
 int
 lookdot(Node *n, Type *t)
 {
-	Type *f1, *f2;
+	Type *f1, *f2, *tt;
+	int op;
+	Sym *s;
+
+	s = n->right->sym;
 
 	f1 = T;
 	if(t->etype == TSTRUCT || t->etype == TINTER)
-		f1 = lookdot1(n->right, t, t->type);
+		f1 = lookdot1(s, t, t->type);
 
 	f2 = methtype(n->left->type);
 	if(f2 != T)
-		f2 = lookdot1(n->right, f2, f2->method);
+		f2 = lookdot1(s, f2, f2->method);
 
 	if(f1 != T) {
 		if(f2 != T)
@@ -1590,12 +1591,20 @@ lookdot(Node *n, Type *t)
 	}
 
 	if(f2 != T) {
-		if(needaddr(n->left->type)) {
+		tt = n->left->type;
+		if((op = methconv(tt)) != 0) {
+			switch(op) {
+			case OADDR:
 				walktype(n->left, Elv);
 				n->left = nod(OADDR, n->left, N);
-			n->left->type = ptrto(n->left->left->type);
+				n->left->type = ptrto(tt);
+				break;
+			case OIND:
+				n->left = nod(OIND, n->left, N);
+				n->left->type = tt->type;
+				break;
+			}
 		}
-		ismethod(n->left->type);
 		n->right = methodname(n->right, n->left->type);
 		n->xoffset = f2->width;
 		n->type = f2->type;
@@ -1903,36 +1912,27 @@ loop:
 }
 
 /*
- * can we assign var of type t2 to var of type t1
+ * can we assign var of type src to var of type dst
  */
 int
-ascompat(Type *t1, Type *t2)
+ascompat(Type *dst, Type *src)
 {
-	if(eqtype(t1, t2, 0))
+	if(eqtype(dst, src, 0))
 		return 1;
 
-//	if(eqtype(t1, nilptr, 0))
-//		return 1;
-//	if(eqtype(t2, nilptr, 0))
-//		return 1;
-
-	if(isnilinter(t1))
-		return 1;
-	if(isinter(t1)) {
-		if(isinter(t2))
+	if(isdarray(dst) && issarray(src))
 		return 1;
-		if(ismethod(t2))
+
+	if(isnilinter(dst) || isnilinter(src))
 		return 1;
-	}
 
-	if(isnilinter(t2))
+	if(isinter(dst) && isinter(src))
 		return 1;
-	if(isinter(t2))
-		if(ismethod(t1))
+
+	if(isinter(dst) && methtype(src))
 		return 1;
 
-	if(isdarray(t1))
-		if(issarray(t2))
+	if(isinter(src) && methtype(dst))
 		return 1;
 
 	return 0;
@@ -2817,33 +2817,33 @@ arrayop(Node *n, int top)
 	return r;
 }
 
+/*
+ * assigning src to dst involving interfaces?
+ * return op to use.
+ */
 int
-isandss(Type *lt, Node *r)
+ifaceas(Type *dst, Type *src)
 {
-	Type *rt;
+	if(src == T || dst == T)
+		return Inone;
 
-	rt = r->type;
-	if(isinter(lt)) {
-		if(isinter(rt)) {
-			if(isnilinter(lt) && isnilinter(rt))
+	if(isinter(dst)) {
+		if(isinter(src)) {
+			if(eqtype(dst, src, 0))
 				return Inone;
-			if(!eqtype(rt, lt, 0))
 			return I2I;
-			return Inone;
 		}
-		if(isnilinter(lt))
+		if(isnilinter(dst))
 			return T2I;
-		if(ismethod(rt) != T)
+		ifacecheck(dst, src, lineno);
 		return T2I;
-		return Inone;
 	}
-
-	if(isinter(rt)) {
-		if(isnilinter(rt) || ismethod(lt) != T)
+	if(isinter(src)) {
+		if(isnilinter(src))
+			return I2T;
+		ifacecheck(dst, src, lineno);
 		return I2T;
-		return Inone;
 	}
-
 	return Inone;
 }
 
@@ -2988,7 +2988,7 @@ convas(Node *n)
 	if(eqtype(lt, rt, 0))
 		goto out;
 
-	et = isandss(lt, r);
+	et = ifaceas(lt, rt);
 	if(et != Inone) {
 		n->right = ifaceop(lt, r, et);
 		goto out;

test/bugs/bug046.go

@@ -8,7 +8,7 @@ package main
 
 type T *struct {}
 
-func (x T) M () {}  // ERROR "pointer"
+func (x T) M () {}  // ERROR "pointer|receiver"
 
 /*
 bug046.go:7: illegal <this> pointer

test/interface2.go

@@ -15,7 +15,9 @@ type I interface {
 func main() {
 	var s *S;
 	var i I;
-	i = s;
+	var e interface {};
+	e = s;
+	i = e;
 }
 
 // hide S down here to avoid static warning

test/interface4.go

+// $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.
+
+// check that big vs small, pointer vs not
+// interface methods work.
+
+package main
+
+type I interface { M() int64 }
+
+type BigPtr struct { a, b, c, d int64 }
+func (z *BigPtr) M() int64 { return z.a+z.b+z.c+z.d }
+
+type SmallPtr struct { a int32 }
+func (z *SmallPtr) M() int64 { return int64(z.a) }
+
+type IntPtr int32
+func (z *IntPtr) M() int64 { return int64(*z) }
+
+var bad bool
+
+func test(name string, i I) {
+	m := i.M();
+	if m != 12345 {
+		println(name, m);
+		bad = true;
+	}
+}
+
+func ptrs() {
+	var bigptr BigPtr = BigPtr{ 10000, 2000, 300, 45 };
+	var smallptr SmallPtr = SmallPtr{ 12345 };
+	var intptr IntPtr = 12345;
+
+	test("bigptr", bigptr);
+	test("&bigptr", &bigptr);
+	test("smallptr", smallptr);
+	test("&smallptr", &smallptr);
+	test("intptr", intptr);
+	test("&intptr", &intptr);
+}
+
+type Big struct { a, b, c, d int64 }
+func (z Big) M() int64 { return z.a+z.b+z.c+z.d }
+
+type Small struct { a int32 }
+func (z Small) M() int64 { return int64(z.a) }
+
+type Int int32
+func (z Int) M() int64 { return int64(z) }
+
+func nonptrs() {
+	var big Big = Big{ 10000, 2000, 300, 45 };
+	var small Small = Small{ 12345 };
+	var int Int = 12345;
+
+	test("big", big);
+	test("&big", &big);
+	test("small", small);
+	test("&small", &small);
+	test("int", int);
+	test("&int", &int);
+}
+
+func main() {
+	ptrs();
+	nonptrs();
+
+	if bad {
+		sys.exit(1)
+	}
+}

test/interface5.go

+// 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
+
+type T struct { a int }
+var t *T
+
+type I interface { M() }
+var i I
+
+func main() {
+	// neither of these can work,
+	// because i has an extra method
+	// that t does not, so i cannot contain a t.
+	i = t;	// ERROR "missing"
+	t = i;	// ERROR "missing"
+}

test/method3.go

+// $G $D/$F.go && $L $F.$A && ./$A.out || echo BUG method3
+
+// 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.
+
+// test that methods on slices work
+
+package main
+
+type T [] int
+func (t T) Len() int { return len(t) }
+
+type I interface {
+	Len() int
+}
+
+func main() {
+	var t T = T{0,1,2,3,4};
+	var i I;
+	i = t;
+	if i.Len() != 5 {
+		panicln("length", i.Len());
+	}
+}