gc, spec, tests: no auto-indirect of pointer to interface value

Implies no embedding of pointer to interface value either.

R=gri, iant, ken2, r, r2
CC=golang-dev
https://golang.org/cl/2289041

diff --git a/doc/go_spec.html b/doc/go_spec.html
index 8e1b45ab966ceb0b58d2c4e53c948687652cd548..2373490c249c44208e0a09d8b5ce7d002799c51d 100644 (file)
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -879,9 +879,10 @@ struct {
 </pre>
 
 <p>
-A field declared with a type but no explicit field name is an <i>anonymous field</i>.
+A field declared with a type but no explicit field name is an <i>anonymous field</i>
+(colloquially called an embedded field).
 Such a field type must be specified as
-a type name <code>T</code> or as a pointer to a type name <code>*T</code>,
+a type name <code>T</code> or as a pointer to a non-interface type name <code>*T</code>,
 and <code>T</code> itself may not be
 a pointer type. The unqualified type name acts as the field name.
 </p>
@@ -2214,8 +2215,7 @@ x.f
 
 <p>
 denotes the field or method <code>f</code> of the value denoted by <code>x</code>
-(or of <code>*x</code> if
-<code>x</code> is of pointer type). The identifier <code>f</code>
+(or sometimes <code>*x</code>; see below). The identifier <code>f</code>
 is called the (field or method)
 <i>selector</i>; it must not be the <a href="#Blank_identifier">blank identifier</a>.
 The type of the expression is the type of <code>f</code>.
@@ -2258,16 +2258,13 @@ In all other cases, <code>x.f</code> is illegal.
 </li>
 </ol>
 <p>
-Selectors automatically dereference pointers.
-If <code>x</code> is of pointer type, <code>x.y</code>
-is shorthand for <code>(*x).y</code>; if <code>y</code>
-is also of pointer type, <code>x.y.z</code> is shorthand
+Selectors automatically dereference pointers to structs.
+If <code>x</code> is a pointer to a struct, <code>x.y</code>
+is shorthand for <code>(*x).y</code>; if the field <code>y</code>
+is also a pointer to a struct, <code>x.y.z</code> is shorthand
 for <code>(*(*x).y).z</code>, and so on.
-If <code>*x</code> is of pointer type, dereferencing
-must be explicit;
-only one level of automatic dereferencing is provided.
-For an <code>x</code> of type <code>T</code> containing an
-anonymous field declared as <code>*A</code>,
+If <code>x</code> contains an anonymous field of type <code>*A</code>,
+where <code>A</code> is also a struct type,
 <code>x.f</code> is a shortcut for <code>(*x.A).f</code>.
 </p>
 <p>

diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index 05eff966f7ab1f79db7c462f88e2015b04f75c08..a9a17b236d6ed6223f97a65b770331e5cb508364 100644 (file)
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -729,8 +729,11 @@ stotype(NodeList *l, int et, Type **t)
                                n->right = N;
                                if(n->embedded && n->type != T) {
                                        t1 = n->type;
-                                       if(t1->sym == S && isptr[t1->etype])
+                                       if(t1->sym == S && isptr[t1->etype]) {
                                                t1 = t1->type;
+                                               if(t1->etype == TINTER)
+                                                       yyerror("embedded type cannot be a pointer to interface");
+                                       }
                                        if(isptr[t1->etype])
                                                yyerror("embedded type cannot be a pointer");
                                        else if(t1->etype == TFORW && t1->embedlineno == 0)

diff --git a/src/cmd/gc/reflect.c b/src/cmd/gc/reflect.c
index 18b2a4fc65bcc038c711a2cf32f721ede90d40b3..9a24e7b2a0a423fb066bc8f76f84e692b09886e8 100644 (file)
--- a/src/cmd/gc/reflect.c
+++ b/src/cmd/gc/reflect.c
@@ -286,15 +286,6 @@ imethods(Type *t)
                                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) {

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 821d540fa1fafe665a9dbe6241dd511fa3010e72..83c5ff72b9f1bc38ad6257377a271a67ddb1fb3d 100644 (file)
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -520,7 +520,7 @@ reswitch:
                        ok = Erv;
                        goto ret;
                }
-               if(isptr[t->etype]) {
+               if(isptr[t->etype] && t->type->etype != TINTER) {
                        t = t->type;
                        if(t == T)
                                goto error;

diff --git a/test/hashmap.go b/test/hashmap.go
index 096ece0a5309d263d172626376348e6a875ff9e7..0a4d7ab61eeb137b498c9c13f177d675a240547f 100755 (executable)
--- a/test/hashmap.go
+++ b/test/hashmap.go
@@ -21,7 +21,7 @@ func ASSERT(p bool) {
 
 type KeyType interface {
        Hash() uint32
-       Match(other *KeyType) bool
+       Match(other KeyType) bool
 }
 
 
@@ -31,8 +31,8 @@ type ValueType interface {
 
 
 type Entry struct {
-       key *KeyType
-       value *ValueType
+       key KeyType
+       value ValueType
 }
 
 
@@ -68,7 +68,7 @@ func (m *HashMap) Initialize (initial_log2_capacity uint32) {
 }
 
 
-func (m *HashMap) Probe (key *KeyType) *Entry {
+func (m *HashMap) Probe (key KeyType) *Entry {
        ASSERT(key != nil)
 
        var i uint32 = key.Hash() % m.capacity()
@@ -86,7 +86,7 @@ func (m *HashMap) Probe (key *KeyType) *Entry {
 }
 
 
-func (m *HashMap) Lookup (key *KeyType, insert bool) *Entry {
+func (m *HashMap) Lookup (key KeyType, insert bool) *Entry {
        // Find a matching entry.
        var p *Entry = m.Probe(key)
                if p.key != nil {
@@ -145,7 +145,7 @@ func (n *Number) Hash() uint32 {
 }
 
 
-func (n *Number) Match(other *KeyType) bool {
+func (n *Number) Match(other KeyType) bool {
        // var y *Number = other
        // return n.x == y.x
        return false

diff --git a/test/interface/embed.go b/test/interface/embed.go
index 4a702398c67d76b06852d11643fe45e7605b6989..2fddee1905a06394dfa1be4a2c702649923fb907 100644 (file)
--- a/test/interface/embed.go
+++ b/test/interface/embed.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check methods derived from embedded interface and *interface values.
+// Check methods derived from embedded interface values.
 
 package main
 
@@ -19,18 +19,12 @@ func (t T) M() int64 { return int64(t) }
 var t = T(Value)
 var pt = &t
 var ti Inter = t
-var pti = &ti
 
 type S struct { Inter }
 var s = S{ ti }
 var ps = &s
 
-type SP struct { *Inter }
-var sp = SP{ &ti }
-var psp = &sp
-
 var i Inter
-var pi = &i
 
 var ok = true
 
@@ -45,35 +39,20 @@ func main() {
        check("t.M()", t.M())
        check("pt.M()", pt.M())
        check("ti.M()", ti.M())
-       check("pti.M()", pti.M())
        check("s.M()", s.M())
        check("ps.M()", ps.M())
-       check("sp.M()", sp.M())
-       check("psp.M()", psp.M())
 
        i = t
        check("i = t; i.M()", i.M())
-       check("i = t; pi.M()", pi.M())
 
        i = pt
        check("i = pt; i.M()", i.M())
-       check("i = pt; pi.M()", pi.M())
 
        i = s
        check("i = s; i.M()", i.M())
-       check("i = s; pi.M()", pi.M())
 
        i = ps
        check("i = ps; i.M()", i.M())
-       check("i = ps; pi.M()", pi.M())
-
-       i = sp
-       check("i = sp; i.M()", i.M())
-       check("i = sp; pi.M()", pi.M())
-
-       i = psp
-       check("i = psp; i.M()", i.M())
-       check("i = psp; pi.M()", pi.M())
 
        if !ok {
                println("BUG: interface10")

diff --git a/test/interface/embed2.go b/test/interface/embed2.go
new file mode 100644 (file)
index 0000000..c18a1fe
--- /dev/null
+++ b/test/interface/embed2.go
@@ -0,0 +1,70 @@
+// errchk $G -e $D/$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.
+
+// Check methods derived from embedded interface and *interface values.
+
+package main
+
+import "os"
+
+const Value = 1e12
+
+type Inter interface { M() int64 }
+
+type T int64
+func (t T) M() int64 { return int64(t) }
+var t = T(Value)
+var pt = &t
+var ti Inter = t
+var pti = &ti
+
+type S struct { Inter }
+var s = S{ ti }
+var ps = &s
+
+type SP struct { *Inter }      // ERROR "interface"
+
+var i Inter
+var pi = &i
+
+var ok = true
+
+func check(s string, v int64) {
+       if v != Value {
+               println(s, v)
+               ok = false
+       }
+}
+
+func main() {
+       check("t.M()", t.M())
+       check("pt.M()", pt.M())
+       check("ti.M()", ti.M())
+       check("pti.M()", pti.M())       // ERROR "method"
+       check("s.M()", s.M())
+       check("ps.M()", ps.M())
+
+       i = t
+       check("i = t; i.M()", i.M())
+       check("i = t; pi.M()", pi.M())  // ERROR "method"
+
+       i = pt
+       check("i = pt; i.M()", i.M())
+       check("i = pt; pi.M()", pi.M()) // ERROR "method"
+
+       i = s
+       check("i = s; i.M()", i.M())
+       check("i = s; pi.M()", pi.M())  // ERROR "method"
+
+       i = ps
+       check("i = ps; i.M()", i.M())
+       check("i = ps; pi.M()", pi.M()) // ERROR "method"
+
+       if !ok {
+               println("BUG: interface10")
+               os.Exit(1)
+       }
+}

diff --git a/test/method.go b/test/method.go
index b52d97894cc182680af2776408021bb5c908eb48..b5a02c6873ebca877c9a264f4aedf272f8910017 100644 (file)
--- a/test/method.go
+++ b/test/method.go
@@ -124,9 +124,4 @@ func main() {
                println("Val.val(v):", Val.val(v))
                panic("fail")
        }
-       pv := &v
-       if pv.val() != 3 {
-               println("pv.val():", pv.val())
-               panic("fail")
-       }
 }

diff --git a/test/method2.go b/test/method2.go
index cda6d9aadf76f4753ecc67a0e7252da9e89c0e40..a72536e7b33da791d64ac328f778ada44d46fc31 100644 (file)
--- a/test/method2.go
+++ b/test/method2.go
@@ -20,3 +20,8 @@ type Val interface {
 }
 
 var _ = (*Val).val // ERROR "method"
+
+var v Val
+var pv = &v
+
+var _ = pv.val()       // ERROR "method"