cmd/gc: unnamed struct types can have methods

Fixes #3143.

R=ken2
CC=golang-dev
https://golang.org/cl/5752070

src/cmd/gc/dcl.c

@@ -1168,21 +1168,22 @@ methodsym(Sym *nsym, Type *t0, int iface)
 	char *p;
 	Type *t;
 	char *suffix;
+	Pkg *spkg;
+	static Pkg *toppkg;
 
 	t = t0;
 	if(t == T)
 		goto bad;
 	s = t->sym;
-	if(s == S) {
-		if(!isptr[t->etype])
-			goto bad;
+	if(s == S && isptr[t->etype]) {
 		t = t->type;
 		if(t == T)
 			goto bad;
 		s = t->sym;
-		if(s == S)
-			goto bad;
 	}
+	spkg = nil;
+	if(s != S)
+		spkg = s->pkg;
 
 	// if t0 == *t and t0 has a sym,
 	// we want to see *t, not t0, in the method name.
@@ -1195,7 +1196,7 @@ methodsym(Sym *nsym, Type *t0, int iface)
 		if(t0->width < types[tptr]->width)
 			suffix = "·i";
 	}
-	if(nsym->pkg != s->pkg && !exportname(nsym->name)) {
+	if((spkg == nil || nsym->pkg != spkg) && !exportname(nsym->name)) {
 		if(t0->sym == S && isptr[t0->etype])
 			p = smprint("(%-hT).%s.%s%s", t0, nsym->pkg->prefix, nsym->name, suffix);
 		else
@@ -1206,7 +1207,12 @@ methodsym(Sym *nsym, Type *t0, int iface)
 		else
 			p = smprint("%-hT.%s%s", t0, nsym->name, suffix);
 	}
-	s = pkglookup(p, s->pkg);
+	if(spkg == nil) {
+		if(toppkg == nil)
+			toppkg = mkpkg(strlit("go"));
+		spkg = toppkg;
+	}
+	s = pkglookup(p, spkg);
 	free(p);
 	return s;
 
@@ -1275,7 +1281,7 @@ addmethod(Sym *sf, Type *t, int local)
 	}
 
 	pa = pa->type;
-	f = methtype(pa);
+	f = methtype(pa, 1);
 	if(f == T) {
 		t = pa;
 		if(t != T) {

src/cmd/gc/go.h

@@ -1154,7 +1154,7 @@ int	cplxsubtype(int et);
 int	eqtype(Type *t1, Type *t2);
 int	eqtypenoname(Type *t1, Type *t2);
 void	errorexit(void);
-void	expandmeth(Sym *s, Type *t);
+void	expandmeth(Type *t);
 void	fatal(char *fmt, ...);
 void	flusherrors(void);
 void	frame(int context);
@@ -1192,7 +1192,7 @@ NodeList*	listtreecopy(NodeList *l);
 Sym*	lookup(char *name);
 void*	mal(int32 n);
 Type*	maptype(Type *key, Type *val);
-Type*	methtype(Type *t);
+Type*	methtype(Type *t, int mustname);
 Pkg*	mkpkg(Strlit *path);
 Sym*	ngotype(Node *n);
 int	noconv(Type *t1, Type *t2);

src/cmd/gc/reflect.c

@@ -144,11 +144,11 @@ methods(Type *t)
 	Sig *a, *b;
 	Sym *method;
 
-	// named method type
-	mt = methtype(t);
+	// method type
+	mt = methtype(t, 0);
 	if(mt == T)
 		return nil;
-	expandmeth(mt->sym, mt);
+	expandmeth(mt);
 
 	// type stored in interface word
 	it = t;

src/cmd/gc/subr.c

@@ -944,7 +944,7 @@ isideal(Type *t)
  * return type to hang methods off (r).
  */
 Type*
-methtype(Type *t)
+methtype(Type *t, int mustname)
 {
 	if(t == T)
 		return T;
@@ -959,7 +959,7 @@ methtype(Type *t)
 	}
 
 	// need a type name
-	if(t->sym == S)
+	if(t->sym == S && (mustname || t->etype != TSTRUCT))
 		return T;
 
 	// check types
@@ -2101,7 +2101,7 @@ lookdot0(Sym *s, Type *t, Type **save, int ignorecase)
 				c++;
 			}
 	}
-	u = methtype(t);
+	u = methtype(t, 0);
 	if(u != T) {
 		for(f=u->method; f!=T; f=f->down)
 			if(f->embedded == 0 && (f->sym == s || (ignorecase && ucistrcmp(f->sym->name, s->name) == 0))) {
@@ -2251,7 +2251,7 @@ expand0(Type *t, int followptr)
 		return;
 	}
 
-	u = methtype(t);
+	u = methtype(t, 0);
 	if(u != T) {
 		for(f=u->method; f!=T; f=f->down) {
 			if(f->sym->flags & SymUniq)
@@ -2301,14 +2301,12 @@ out:
 }
 
 void
-expandmeth(Sym *s, Type *t)
+expandmeth(Type *t)
 {
 	Symlink *sl;
 	Type *f;
 	int c, d;
 
-	if(s == S)
-		return;
 	if(t == T || t->xmethod != nil)
 		return;
 
@@ -3021,9 +3019,9 @@ implements(Type *t, Type *iface, Type **m, Type **samename, int *ptr)
 		return 1;
 	}
 
-	t = methtype(t);
+	t = methtype(t, 0);
 	if(t != T)
-		expandmeth(t->sym, t);
+		expandmeth(t);
 	for(im=iface->type; im; im=im->down) {
 		imtype = methodfunc(im->type, 0);
 		tm = ifacelookdot(im->sym, t, &followptr, 0);

src/cmd/gc/typecheck.c

@@ -1664,11 +1664,11 @@ looktypedot(Node *n, Type *t, int dostrcmp)
 	if(t->sym == S && isptr[t->etype])
 		tt = t->type;
 
-	f2 = methtype(tt);
+	f2 = methtype(tt, 0);
 	if(f2 == T)
 		return 0;
 
-	expandmeth(f2->sym, f2);
+	expandmeth(f2);
 	f2 = lookdot1(n, s, f2, f2->xmethod, dostrcmp);
 	if(f2 == T)
 		return 0;
@@ -1712,7 +1712,7 @@ lookdot(Node *n, Type *t, int dostrcmp)
 
 	f2 = T;
 	if(n->left->type == t || n->left->type->sym == S) {
-		f2 = methtype(t);
+		f2 = methtype(t, 0);
 		if(f2 != T) {
 			// Use f2->method, not f2->xmethod: adddot has
 			// already inserted all the necessary embedded dots.

test/fixedbugs/bug424.go

@@ -72,4 +72,28 @@ func main() {
 		}
 		println("BUG: myT3:", i.m(), "called")
 	}
+	
+	var t4 struct {
+		localT
+		lib.T
+	}
+	if t4.m() != "main.localT.m" {
+		println("BUG: t4:", t4.m(), "called")
+	}
+	i = &t4
+	if i.m() != "main.localT.m" {
+		println("BUG: myT4:", i.m(), "called")
+	}
+	
+	var t5 struct {
+		lib.T
+		localT
+	}
+	if t5.m() != "main.localT.m" {
+		println("BUG: t5:", t5.m(), "called")
+	}
+	i = &t5
+	if i.m() != "main.localT.m" {
+		println("BUG: myT5:", i.m(), "called")
+	}
 }

test/method.go

@@ -94,27 +94,27 @@ func main() {
 	}
 
 	if val(s) != 1 {
-		println("s.val:", val(s))
+		println("val(s):", val(s))
 		panic("fail")
 	}
 	if val(ps) != 2 {
-		println("ps.val:", val(ps))
+		println("val(ps):", val(ps))
 		panic("fail")
 	}
 	if val(i) != 3 {
-		println("i.val:", val(i))
+		println("val(i):", val(i))
 		panic("fail")
 	}
 	if val(pi) != 4 {
-		println("pi.val:", val(pi))
+		println("val(pi):", val(pi))
 		panic("fail")
 	}
 	if val(t) != 7 {
-		println("t.val:", val(t))
+		println("val(t):", val(t))
 		panic("fail")
 	}
 	if val(pt) != 8 {
-		println("pt.val:", val(pt))
+		println("val(pt):", val(pt))
 		panic("fail")
 	}
 
@@ -127,4 +127,124 @@ func main() {
 		println("Val.val(v):", Val.val(v))
 		panic("fail")
 	}
+
+	var zs struct { S }
+	var zps struct { *S1 }
+	var zi struct { I }
+	var zpi struct { *I1 }
+	var zpt struct { *T1 }
+	var zt struct { T }
+	var zv struct { Val }
+
+	if zs.val() != 1 {
+		println("zs.val:", zs.val())
+		panic("fail")
+	}
+	if zps.val() != 2 {
+		println("zps.val:", zps.val())
+		panic("fail")
+	}
+	if zi.val() != 3 {
+		println("zi.val:", zi.val())
+		panic("fail")
+	}
+	if zpi.val() != 4 {
+		println("zpi.val:", zpi.val())
+		panic("fail")
+	}
+	if zt.val() != 7 {
+		println("zt.val:", zt.val())
+		panic("fail")
+	}
+	if zpt.val() != 8 {
+		println("zpt.val:", zpt.val())
+		panic("fail")
+	}
+
+	if val(zs) != 1 {
+		println("val(zs):", val(zs))
+		panic("fail")
+	}
+	if val(zps) != 2 {
+		println("val(zps):", val(zps))
+		panic("fail")
+	}
+	if val(zi) != 3 {
+		println("val(zi):", val(zi))
+		panic("fail")
+	}
+	if val(zpi) != 4 {
+		println("val(zpi):", val(zpi))
+		panic("fail")
+	}
+	if val(zt) != 7 {
+		println("val(zt):", val(zt))
+		panic("fail")
+	}
+	if val(zpt) != 8 {
+		println("val(zpt):", val(zpt))
+		panic("fail")
+	}
+
+	zv.Val = zi
+	if zv.val() != 3 {
+		println("zv.val():", zv.val())
+		panic("fail")
+	}
+
+	if (&zs).val() != 1 {
+		println("(&zs).val:", (&zs).val())
+		panic("fail")
+	}
+	if (&zps).val() != 2 {
+		println("(&zps).val:", (&zps).val())
+		panic("fail")
+	}
+	if (&zi).val() != 3 {
+		println("(&zi).val:", (&zi).val())
+		panic("fail")
+	}
+	if (&zpi).val() != 4 {
+		println("(&zpi).val:", (&zpi).val())
+		panic("fail")
+	}
+	if (&zt).val() != 7 {
+		println("(&zt).val:", (&zt).val())
+		panic("fail")
+	}
+	if (&zpt).val() != 8 {
+		println("(&zpt).val:", (&zpt).val())
+		panic("fail")
+	}
+
+	if val(&zs) != 1 {
+		println("val(&zs):", val(&zs))
+		panic("fail")
+	}
+	if val(&zps) != 2 {
+		println("val(&zps):", val(&zps))
+		panic("fail")
+	}
+	if val(&zi) != 3 {
+		println("val(&zi):", val(&zi))
+		panic("fail")
+	}
+	if val(&zpi) != 4 {
+		println("val(&zpi):", val(&zpi))
+		panic("fail")
+	}
+	if val(&zt) != 7 {
+		println("val(&zt):", val(&zt))
+		panic("fail")
+	}
+	if val(&zpt) != 8 {
+		println("val(&zpt):", val(&zpt))
+		panic("fail")
+	}
+
+	zv.Val = &zi
+	if zv.val() != 3 {
+		println("zv.val():", zv.val())
+		panic("fail")
+	}
 }