go/types: change {Type,Object,Selection}String to accept a Qualifier function

automerge: 997b354

* commit '997b3545fd86c3a2d8e5fe6366174d7786e71278':
  go/types: change {Type,Object,Selection}String to accept a Qualifier function

19 files changed, 186 insertions, 123 deletions

diff --git a/go/callgraph/rta/rta_test.go b/go/callgraph/rta/rta_test.go
index aef788d..26eec49 100644
--- a/go/callgraph/rta/rta_test.go
+++ b/go/callgraph/rta/rta_test.go
@@ -126,7 +126,7 @@ func printResult(res *rta.Result, from *types.Package) string {
 	var rtypes []string
 	res.RuntimeTypes.Iterate(func(key types.Type, value interface{}) {
 		if value == false { // accessible to reflection
-			rtypes = append(rtypes, types.TypeString(from, key))
+			rtypes = append(rtypes, types.TypeString(key, types.RelativeTo(from)))
 		}
 	})
 	writeSorted(rtypes)
diff --git a/go/gccgoimporter/importer_test.go b/go/gccgoimporter/importer_test.go
index c7adb45..ee47425 100644
--- a/go/gccgoimporter/importer_test.go
+++ b/go/gccgoimporter/importer_test.go
@@ -34,7 +34,7 @@ func runImporterTest(t *testing.T, imp types.Importer, initmap map[*types.Packag
 			return
 		}
 
-		got := types.ObjectString(pkg, obj)
+		got := types.ObjectString(obj, types.RelativeTo(pkg))
 		if got != test.want {
 			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
 		}
diff --git a/go/gcimporter/gcimporter_test.go b/go/gcimporter/gcimporter_test.go
index e72c30f..73a4747 100644
--- a/go/gcimporter/gcimporter_test.go
+++ b/go/gcimporter/gcimporter_test.go
@@ -177,7 +177,7 @@ func TestImportedTypes(t *testing.T) {
 			continue
 		}
 
-		got := types.ObjectString(pkg, obj)
+		got := types.ObjectString(obj, types.RelativeTo(pkg))
 		if got != test.want {
 			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
 		}
diff --git a/go/loader/stdlib_test.go b/go/loader/stdlib_test.go
index d14928a..f5c45ab 100644
--- a/go/loader/stdlib_test.go
+++ b/go/loader/stdlib_test.go
@@ -62,9 +62,10 @@ func TestStdlib(t *testing.T) {
 		for pkg := range prog.AllPackages {
 			fmt.Printf("Package %s:\n", pkg.Path())
 			scope := pkg.Scope()
+			qualifier := types.RelativeTo(pkg)
 			for _, name := range scope.Names() {
 				if ast.IsExported(name) {
-					fmt.Printf("\t%s\n", types.ObjectString(pkg, scope.Lookup(name)))
+					fmt.Printf("\t%s\n", types.ObjectString(scope.Lookup(name), qualifier))
 				}
 			}
 			fmt.Println()
diff --git a/go/ssa/func.go b/go/ssa/func.go
index fec527b..a9c0f75 100644
--- a/go/ssa/func.go
+++ b/go/ssa/func.go
@@ -522,11 +522,11 @@ func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *ty
 			buf.WriteString(n)
 			buf.WriteString(" ")
 		}
-		types.WriteType(buf, from, params[0].Type())
+		types.WriteType(buf, params[0].Type(), types.RelativeTo(from))
 		buf.WriteString(") ")
 	}
 	buf.WriteString(name)
-	types.WriteSignature(buf, from, sig)
+	types.WriteSignature(buf, sig, types.RelativeTo(from))
 }
 
 func (f *Function) pkgobj() *types.Package {
diff --git a/go/ssa/print.go b/go/ssa/print.go
index 9fda3a4..88c31f6 100644
--- a/go/ssa/print.go
+++ b/go/ssa/print.go
@@ -39,7 +39,7 @@ func relName(v Value, i Instruction) string {
 }
 
 func relType(t types.Type, from *types.Package) string {
-	return types.TypeString(from, t)
+	return types.TypeString(t, types.RelativeTo(from))
 }
 
 func relString(m Member, from *types.Package) string {
@@ -407,7 +407,7 @@ func WritePackage(buf *bytes.Buffer, p *Package) {
 			fmt.Fprintf(buf, "  type  %-*s %s\n",
 				maxname, name, relType(mem.Type().Underlying(), from))
 			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
-				fmt.Fprintf(buf, "    %s\n", types.SelectionString(from, meth))
+				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
 			}
 
 		case *Global:
diff --git a/go/types/errors.go b/go/types/errors.go
index 0a9dd0e..0c0049b 100644
--- a/go/types/errors.go
+++ b/go/types/errors.go
@@ -23,6 +23,13 @@ func unreachable() {
 	panic("unreachable")
 }
 
+func (check *Checker) qualifier(pkg *Package) string {
+	if pkg != check.pkg {
+		return pkg.path
+	}
+	return ""
+}
+
 func (check *Checker) sprintf(format string, args ...interface{}) string {
 	for i, arg := range args {
 		switch a := arg.(type) {
@@ -31,15 +38,15 @@ func (check *Checker) sprintf(format string, args ...interface{}) string {
 		case operand:
 			panic("internal error: should always pass *operand")
 		case *operand:
-			arg = operandString(check.pkg, a)
+			arg = operandString(a, check.qualifier)
 		case token.Pos:
 			arg = check.fset.Position(a).String()
 		case ast.Expr:
 			arg = ExprString(a)
 		case Object:
-			arg = ObjectString(check.pkg, a)
+			arg = ObjectString(a, check.qualifier)
 		case Type:
-			arg = TypeString(check.pkg, a)
+			arg = TypeString(a, check.qualifier)
 		}
 		args[i] = arg
 	}
diff --git a/go/types/object.go b/go/types/object.go
index 0b44804..a9b6c43 100644
--- a/go/types/object.go
+++ b/go/types/object.go
@@ -208,7 +208,7 @@ func NewFunc(pos token.Pos, pkg *Package, name string, sig *Signature) *Func {
 // function or method obj.
 func (obj *Func) FullName() string {
 	var buf bytes.Buffer
-	writeFuncName(&buf, nil, obj)
+	writeFuncName(&buf, obj, nil)
 	return buf.String()
 }
 
@@ -242,7 +242,7 @@ type Nil struct {
 	object
 }
 
-func writeObject(buf *bytes.Buffer, this *Package, obj Object) {
+func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 	typ := obj.Type()
 	switch obj := obj.(type) {
 	case *PkgName:
@@ -268,9 +268,9 @@ func writeObject(buf *bytes.Buffer, this *Package, obj Object) {
 
 	case *Func:
 		buf.WriteString("func ")
-		writeFuncName(buf, this, obj)
+		writeFuncName(buf, obj, qf)
 		if typ != nil {
-			WriteSignature(buf, this, typ.(*Signature))
+			WriteSignature(buf, typ.(*Signature), qf)
 		}
 		return
 
@@ -292,39 +292,52 @@ func writeObject(buf *bytes.Buffer, this *Package, obj Object) {
 
 	buf.WriteByte(' ')
 
-	// For package-level objects, package-qualify the name,
-	// except for intra-package references (this != nil).
-	if pkg := obj.Pkg(); pkg != nil && this != pkg && pkg.scope.Lookup(obj.Name()) == obj {
-		buf.WriteString(pkg.path)
-		buf.WriteByte('.')
+	// For package-level objects, qualify the name.
+	if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
+		writePackage(buf, obj.Pkg(), qf)
 	}
 	buf.WriteString(obj.Name())
 	if typ != nil {
 		buf.WriteByte(' ')
-		WriteType(buf, this, typ)
+		WriteType(buf, typ, qf)
+	}
+}
+
+func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
+	if pkg == nil {
+		return
+	}
+	var s string
+	if qf != nil {
+		s = qf(pkg)
+	} else {
+		s = pkg.Path()
+	}
+	if s != "" {
+		buf.WriteString(s)
+		buf.WriteByte('.')
 	}
 }
 
 // ObjectString returns the string form of obj.
-// Object and type names are printed package-qualified
-// only if they do not belong to this package.
-//
-func ObjectString(this *Package, obj Object) string {
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func ObjectString(obj Object, qf Qualifier) string {
 	var buf bytes.Buffer
-	writeObject(&buf, this, obj)
+	writeObject(&buf, obj, qf)
 	return buf.String()
 }
 
-func (obj *PkgName) String() string  { return ObjectString(nil, obj) }
-func (obj *Const) String() string    { return ObjectString(nil, obj) }
-func (obj *TypeName) String() string { return ObjectString(nil, obj) }
-func (obj *Var) String() string      { return ObjectString(nil, obj) }
-func (obj *Func) String() string     { return ObjectString(nil, obj) }
-func (obj *Label) String() string    { return ObjectString(nil, obj) }
-func (obj *Builtin) String() string  { return ObjectString(nil, obj) }
-func (obj *Nil) String() string      { return ObjectString(nil, obj) }
+func (obj *PkgName) String() string  { return ObjectString(obj, nil) }
+func (obj *Const) String() string    { return ObjectString(obj, nil) }
+func (obj *TypeName) String() string { return ObjectString(obj, nil) }
+func (obj *Var) String() string      { return ObjectString(obj, nil) }
+func (obj *Func) String() string     { return ObjectString(obj, nil) }
+func (obj *Label) String() string    { return ObjectString(obj, nil) }
+func (obj *Builtin) String() string  { return ObjectString(obj, nil) }
+func (obj *Nil) String() string      { return ObjectString(obj, nil) }
 
-func writeFuncName(buf *bytes.Buffer, this *Package, f *Func) {
+func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
 	if f.typ != nil {
 		sig := f.typ.(*Signature)
 		if recv := sig.Recv(); recv != nil {
@@ -336,13 +349,12 @@ func writeFuncName(buf *bytes.Buffer, this *Package, f *Func) {
 				// Don't print it in full.
 				buf.WriteString("interface")
 			} else {
-				WriteType(buf, this, recv.Type())
+				WriteType(buf, recv.Type(), qf)
 			}
 			buf.WriteByte(')')
 			buf.WriteByte('.')
-		} else if f.pkg != nil && f.pkg != this {
-			buf.WriteString(f.pkg.path)
-			buf.WriteByte('.')
+		} else if f.pkg != nil {
+			writePackage(buf, f.pkg, qf)
 		}
 	}
 	buf.WriteString(f.name)
diff --git a/go/types/operand.go b/go/types/operand.go
index 7418eef..0ac6767 100644
--- a/go/types/operand.go
+++ b/go/types/operand.go
@@ -94,7 +94,7 @@ func (x *operand) pos() token.Pos {
 // commaok    <expr> (<untyped kind> <mode>                    )
 // commaok    <expr> (               <mode>       of type <typ>)
 //
-func operandString(this *Package, x *operand) string {
+func operandString(x *operand, qf Qualifier) string {
 	var buf bytes.Buffer
 
 	var expr string
@@ -105,7 +105,7 @@ func operandString(this *Package, x *operand) string {
 		case builtin:
 			expr = predeclaredFuncs[x.id].name
 		case typexpr:
-			expr = TypeString(this, x.typ)
+			expr = TypeString(x.typ, qf)
 		case constant:
 			expr = x.val.String()
 		}
@@ -147,7 +147,7 @@ func operandString(this *Package, x *operand) string {
 	if hasType {
 		if x.typ != Typ[Invalid] {
 			buf.WriteString(" of type ")
-			WriteType(&buf, this, x.typ)
+			WriteType(&buf, x.typ, qf)
 		} else {
 			buf.WriteString(" with invalid type")
 		}
@@ -162,7 +162,7 @@ func operandString(this *Package, x *operand) string {
 }
 
 func (x *operand) String() string {
-	return operandString(nil, x)
+	return operandString(x, nil)
 }
 
 // setConst sets x to the untyped constant for literal lit.
diff --git a/go/types/selection.go b/go/types/selection.go
index 1c70165..124e0d3 100644
--- a/go/types/selection.go
+++ b/go/types/selection.go
@@ -105,18 +105,18 @@ func (s *Selection) Index() []int { return s.index }
 // x to f in x.f.
 func (s *Selection) Indirect() bool { return s.indirect }
 
-func (s *Selection) String() string { return SelectionString(nil, s) }
+func (s *Selection) String() string { return SelectionString(s, nil) }
 
 // SelectionString returns the string form of s.
-// Type names are printed package-qualified
-// only if they do not belong to this package.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
 //
 // Examples:
 //	"field (T) f int"
 //	"method (T) f(X) Y"
 //	"method expr (T) f(X) Y"
 //
-func SelectionString(this *Package, s *Selection) string {
+func SelectionString(s *Selection, qf Qualifier) string {
 	var k string
 	switch s.kind {
 	case FieldVal:
@@ -131,13 +131,13 @@ func SelectionString(this *Package, s *Selection) string {
 	var buf bytes.Buffer
 	buf.WriteString(k)
 	buf.WriteByte('(')
-	WriteType(&buf, this, s.Recv())
+	WriteType(&buf, s.Recv(), qf)
 	fmt.Fprintf(&buf, ") %s", s.obj.Name())
 	if T := s.Type(); s.kind == FieldVal {
 		buf.WriteByte(' ')
-		WriteType(&buf, this, T)
+		WriteType(&buf, T, qf)
 	} else {
-		WriteSignature(&buf, this, T.(*Signature))
+		WriteSignature(&buf, T.(*Signature), qf)
 	}
 	return buf.String()
 }
diff --git a/go/types/type.go b/go/types/type.go
index 3d1af20..1df8b45 100644
--- a/go/types/type.go
+++ b/go/types/type.go
@@ -441,14 +441,14 @@ func (t *Map) Underlying() Type       { return t }
 func (t *Chan) Underlying() Type      { return t }
 func (t *Named) Underlying() Type     { return t.underlying }
 
-func (t *Basic) String() string     { return TypeString(nil, t) }
-func (t *Array) String() string     { return TypeString(nil, t) }
-func (t *Slice) String() string     { return TypeString(nil, t) }
-func (t *Struct) String() string    { return TypeString(nil, t) }
-func (t *Pointer) String() string   { return TypeString(nil, t) }
-func (t *Tuple) String() string     { return TypeString(nil, t) }
-func (t *Signature) String() string { return TypeString(nil, t) }
-func (t *Interface) String() string { return TypeString(nil, t) }
-func (t *Map) String() string       { return TypeString(nil, t) }
-func (t *Chan) String() string      { return TypeString(nil, t) }
-func (t *Named) String() string     { return TypeString(nil, t) }
+func (t *Basic) String() string     { return TypeString(t, nil) }
+func (t *Array) String() string     { return TypeString(t, nil) }
+func (t *Slice) String() string     { return TypeString(t, nil) }
+func (t *Struct) String() string    { return TypeString(t, nil) }
+func (t *Pointer) String() string   { return TypeString(t, nil) }
+func (t *Tuple) String() string     { return TypeString(t, nil) }
+func (t *Signature) String() string { return TypeString(t, nil) }
+func (t *Interface) String() string { return TypeString(t, nil) }
+func (t *Map) String() string       { return TypeString(t, nil) }
+func (t *Chan) String() string      { return TypeString(t, nil) }
+func (t *Named) String() string     { return TypeString(t, nil) }
diff --git a/go/types/typestring.go b/go/types/typestring.go
index 9a537e8..abee8ab 100644
--- a/go/types/typestring.go
+++ b/go/types/typestring.go
@@ -11,6 +11,33 @@ import (
 	"fmt"
 )
 
+// A Qualifier controls how named package-level objects are printed in
+// calls to TypeString, ObjectString, and SelectionString.
+//
+// These three formatting routines call the Qualifier for each
+// package-level object O, and if the Qualifier returns a non-empty
+// string p, the object is printed in the form p.O.
+// If it returns an empty string, only the object name O is printed.
+//
+// Using a nil Qualifier is equivalent to using (*Package).Path: the
+// object is qualified by the import path, e.g., "encoding/json.Marshal".
+//
+type Qualifier func(*Package) string
+
+// RelativeTo(pkg) returns a Qualifier that fully qualifies members of
+// all packages other than pkg.
+func RelativeTo(pkg *Package) Qualifier {
+	if pkg == nil {
+		return nil
+	}
+	return func(other *Package) string {
+		if pkg == other {
+			return "" // same package; unqualified
+		}
+		return other.Path()
+	}
+}
+
 // If GcCompatibilityMode is set, printing of types is modified
 // to match the representation of some types in the gc compiler:
 //
@@ -28,22 +55,22 @@ import (
 var GcCompatibilityMode bool
 
 // TypeString returns the string representation of typ.
-// Named types are printed package-qualified if they
-// do not belong to this package.
-func TypeString(this *Package, typ Type) string {
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func TypeString(typ Type, qf Qualifier) string {
 	var buf bytes.Buffer
-	WriteType(&buf, this, typ)
+	WriteType(&buf, typ, qf)
 	return buf.String()
 }
 
 // WriteType writes the string representation of typ to buf.
-// Named types are printed package-qualified if they
-// do not belong to this package.
-func WriteType(buf *bytes.Buffer, this *Package, typ Type) {
-	writeType(buf, this, typ, make([]Type, 8))
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func WriteType(buf *bytes.Buffer, typ Type, qf Qualifier) {
+	writeType(buf, typ, qf, make([]Type, 8))
 }
 
-func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
+func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 	// Theoretically, this is a quadratic lookup algorithm, but in
 	// practice deeply nested composite types with unnamed component
 	// types are uncommon. This code is likely more efficient than
@@ -77,11 +104,11 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 
 	case *Array:
 		fmt.Fprintf(buf, "[%d]", t.len)
-		writeType(buf, this, t.elem, visited)
+		writeType(buf, t.elem, qf, visited)
 
 	case *Slice:
 		buf.WriteString("[]")
-		writeType(buf, this, t.elem, visited)
+		writeType(buf, t.elem, qf, visited)
 
 	case *Struct:
 		buf.WriteString("struct{")
@@ -93,7 +120,7 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 				buf.WriteString(f.name)
 				buf.WriteByte(' ')
 			}
-			writeType(buf, this, f.typ, visited)
+			writeType(buf, f.typ, qf, visited)
 			if tag := t.Tag(i); tag != "" {
 				fmt.Fprintf(buf, " %q", tag)
 			}
@@ -102,14 +129,14 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 
 	case *Pointer:
 		buf.WriteByte('*')
-		writeType(buf, this, t.base, visited)
+		writeType(buf, t.base, qf, visited)
 
 	case *Tuple:
-		writeTuple(buf, this, t, false, visited)
+		writeTuple(buf, t, false, qf, visited)
 
 	case *Signature:
 		buf.WriteString("func")
-		writeSignature(buf, this, t, visited)
+		writeSignature(buf, t, qf, visited)
 
 	case *Interface:
 		// We write the source-level methods and embedded types rather
@@ -132,7 +159,7 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 					buf.WriteString("; ")
 				}
 				buf.WriteString(m.name)
-				writeSignature(buf, this, m.typ.(*Signature), visited)
+				writeSignature(buf, m.typ.(*Signature), qf, visited)
 			}
 		} else {
 			// print explicit interface methods and embedded types
@@ -141,22 +168,22 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 					buf.WriteString("; ")
 				}
 				buf.WriteString(m.name)
-				writeSignature(buf, this, m.typ.(*Signature), visited)
+				writeSignature(buf, m.typ.(*Signature), qf, visited)
 			}
 			for i, typ := range t.embeddeds {
 				if i > 0 || len(t.methods) > 0 {
 					buf.WriteString("; ")
 				}
-				writeType(buf, this, typ, visited)
+				writeType(buf, typ, qf, visited)
 			}
 		}
 		buf.WriteByte('}')
 
 	case *Map:
 		buf.WriteString("map[")
-		writeType(buf, this, t.key, visited)
+		writeType(buf, t.key, qf, visited)
 		buf.WriteByte(']')
-		writeType(buf, this, t.elem, visited)
+		writeType(buf, t.elem, qf, visited)
 
 	case *Chan:
 		var s string
@@ -179,7 +206,7 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 		if parens {
 			buf.WriteByte('(')
 		}
-		writeType(buf, this, t.elem, visited)
+		writeType(buf, t.elem, qf, visited)
 		if parens {
 			buf.WriteByte(')')
 		}
@@ -187,9 +214,8 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 	case *Named:
 		s := "<Named w/o object>"
 		if obj := t.obj; obj != nil {
-			if pkg := obj.pkg; pkg != nil && pkg != this {
-				buf.WriteString(pkg.path)
-				buf.WriteByte('.')
+			if obj.pkg != nil {
+				writePackage(buf, obj.pkg, qf)
 			}
 			// TODO(gri): function-local named types should be displayed
 			// differently from named types at package level to avoid
@@ -204,7 +230,7 @@ func writeType(buf *bytes.Buffer, this *Package, typ Type, visited []Type) {
 	}
 }
 
-func writeTuple(buf *bytes.Buffer, this *Package, tup *Tuple, variadic bool, visited []Type) {
+func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
 	buf.WriteByte('(')
 	if tup != nil {
 		for i, v := range tup.vars {
@@ -226,12 +252,12 @@ func writeTuple(buf *bytes.Buffer, this *Package, tup *Tuple, variadic bool, vis
 					if t, ok := typ.Underlying().(*Basic); !ok || t.kind != String {
 						panic("internal error: string type expected")
 					}
-					writeType(buf, this, typ, visited)
+					writeType(buf, typ, qf, visited)
 					buf.WriteString("...")
 					continue
 				}
 			}
-			writeType(buf, this, typ, visited)
+			writeType(buf, typ, qf, visited)
 		}
 	}
 	buf.WriteByte(')')
@@ -239,14 +265,14 @@ func writeTuple(buf *bytes.Buffer, this *Package, tup *Tuple, variadic bool, vis
 
 // WriteSignature writes the representation of the signature sig to buf,
 // without a leading "func" keyword.
-// Named types are printed package-qualified if they
-// do not belong to this package.
-func WriteSignature(buf *bytes.Buffer, this *Package, sig *Signature) {
-	writeSignature(buf, this, sig, make([]Type, 8))
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier) {
+	writeSignature(buf, sig, qf, make([]Type, 8))
 }
 
-func writeSignature(buf *bytes.Buffer, this *Package, sig *Signature, visited []Type) {
-	writeTuple(buf, this, sig.params, sig.variadic, visited)
+func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
+	writeTuple(buf, sig.params, sig.variadic, qf, visited)
 
 	n := sig.results.Len()
 	if n == 0 {
@@ -257,10 +283,10 @@ func writeSignature(buf *bytes.Buffer, this *Package, sig *Signature, visited []
 	buf.WriteByte(' ')
 	if n == 1 && sig.results.vars[0].name == "" {
 		// single unnamed result
-		writeType(buf, this, sig.results.vars[0].typ, visited)
+		writeType(buf, sig.results.vars[0].typ, qf, visited)
 		return
 	}
 
 	// multiple or named result(s)
-	writeTuple(buf, this, sig.results, false, visited)
+	writeTuple(buf, sig.results, false, qf, visited)
 }
diff --git a/go/types/typestring_test.go b/go/types/typestring_test.go
index 8693687..975b623 100644
--- a/go/types/typestring_test.go
+++ b/go/types/typestring_test.go
@@ -152,7 +152,13 @@ func TestQualifiedTypeString(t *testing.T) {
 		{NewPointer(pT), p, "*T"},
 		{NewPointer(pT), q, "*p.T"},
 	} {
-		if got := TypeString(test.this, test.typ); got != test.want {
+		qualifier := func(pkg *Package) string {
+			if pkg != test.this {
+				return pkg.Name()
+			}
+			return ""
+		}
+		if got := TypeString(test.typ, qualifier); got != test.want {
 			t.Errorf("TypeString(%s, %s) = %s, want %s",
 				test.this, test.typ, got, test.want)
 		}
diff --git a/godoc/analysis/callgraph.go b/godoc/analysis/callgraph.go
index 149b60c..a98d294 100644
--- a/godoc/analysis/callgraph.go
+++ b/godoc/analysis/callgraph.go
@@ -237,7 +237,7 @@ func funcToken(fn *ssa.Function) token.Pos {
 func prettyFunc(this *types.Package, fn *ssa.Function) string {
 	if fn.Parent() != nil {
 		return fmt.Sprintf("%s in %s",
-			types.TypeString(this, fn.Signature),
+			types.TypeString(fn.Signature, types.RelativeTo(this)),
 			prettyFunc(this, fn.Parent()))
 	}
 	if fn.Synthetic != "" && fn.Name() == "init" {
diff --git a/godoc/analysis/typeinfo.go b/godoc/analysis/typeinfo.go
index bd1b0c1..83e19c1 100644
--- a/godoc/analysis/typeinfo.go
+++ b/godoc/analysis/typeinfo.go
@@ -69,6 +69,7 @@ func (a *analysis) doTypeInfo(info *loader.PackageInfo, implements map[*types.Na
 	}
 
 	// RESOLUTION
+	qualifier := types.RelativeTo(info.Pkg)
 	for id, obj := range info.Uses {
 		// Position of the object definition.
 		pos := obj.Pos()
@@ -92,7 +93,7 @@ func (a *analysis) doTypeInfo(info *loader.PackageInfo, implements map[*types.Na
 		fi.addLink(aLink{
 			start: offset,
 			end:   offset + len(id.Name),
-			title: types.ObjectString(info.Pkg, obj),
+			title: types.ObjectString(obj, qualifier),
 			href:  a.posURL(pos, Len),
 		})
 	}
@@ -106,7 +107,7 @@ func (a *analysis) doTypeInfo(info *loader.PackageInfo, implements map[*types.Na
 }
 
 func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]implementsFacts) {
-	this := obj.Pkg()
+	qualifier := types.RelativeTo(obj.Pkg())
 	T := obj.Type().(*types.Named)
 	v := &TypeInfoJSON{
 		Name:    obj.Name(),
@@ -130,7 +131,7 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 			ByKind: byKind,
 			Other: anchorJSON{
 				Href: a.posURL(Tobj.Pos(), len(Tobj.Name())),
-				Text: types.TypeString(this, T),
+				Text: types.TypeString(T, qualifier),
 			},
 		})
 	}
@@ -142,7 +143,7 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 			// "T is implemented by <iface>"...
 			// "T implements        <iface>"...
 			group := implGroupJSON{
-				Descr: types.TypeString(this, T),
+				Descr: types.TypeString(T, qualifier),
 			}
 			// Show concrete types first; use two passes.
 			for _, sub := range r.to {
@@ -164,7 +165,7 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 			if r.from != nil {
 				// "T implements <iface>"...
 				group := implGroupJSON{
-					Descr: types.TypeString(this, T),
+					Descr: types.TypeString(T, qualifier),
 				}
 				for _, super := range r.from {
 					addFact(&group, super, false)
@@ -174,7 +175,7 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 			if r.fromPtr != nil {
 				// "*C implements <iface>"...
 				group := implGroupJSON{
-					Descr: "*" + types.TypeString(this, T),
+					Descr: "*" + types.TypeString(T, qualifier),
 				}
 				for _, psuper := range r.fromPtr {
 					addFact(&group, psuper, false)
@@ -190,7 +191,7 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 		pos := meth.Pos() // may be 0 for error.Error
 		v.Methods = append(v.Methods, anchorJSON{
 			Href: a.posURL(pos, len(meth.Name())),
-			Text: types.SelectionString(this, sel),
+			Text: types.SelectionString(sel, qualifier),
 		})
 	}
 
@@ -207,9 +208,9 @@ func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]im
 
 	// Add info for exported package-level types to the package info.
 	if obj.Exported() && isPackageLevel(obj) {
-		// TODO(adonovan): this.Path() is not unique!
+		// TODO(adonovan): Path is not unique!
 		// It is possible to declare a non-test package called x_test.
-		a.result.pkgInfo(this.Path()).addType(v)
+		a.result.pkgInfo(obj.Pkg().Path()).addType(v)
 	}
 }
 
diff --git a/oracle/describe.go b/oracle/describe.go
index 00c0525..ea1c5ec 100644
--- a/oracle/describe.go
+++ b/oracle/describe.go
@@ -590,20 +590,21 @@ func (r *describePackageResult) display(printf printfFunc) {
 	for _, mem := range r.members {
 		printf(mem.obj, "\t%s", formatMember(mem.obj, maxname))
 		for _, meth := range mem.methods {
-			printf(meth.Obj(), "\t\t%s", types.SelectionString(r.pkg, meth))
+			printf(meth.Obj(), "\t\t%s", types.SelectionString(meth, types.RelativeTo(r.pkg)))
 		}
 	}
 }
 
 func formatMember(obj types.Object, maxname int) string {
+	qualifier := types.RelativeTo(obj.Pkg())
 	var buf bytes.Buffer
 	fmt.Fprintf(&buf, "%-5s %-*s", tokenOf(obj), maxname, obj.Name())
 	switch obj := obj.(type) {
 	case *types.Const:
-		fmt.Fprintf(&buf, " %s = %s", types.TypeString(obj.Pkg(), obj.Type()), obj.Val().String())
+		fmt.Fprintf(&buf, " %s = %s", types.TypeString(obj.Type(), qualifier), obj.Val().String())
 
 	case *types.Func:
-		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type()))
+		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Type(), qualifier))
 
 	case *types.TypeName:
 		// Abbreviate long aggregate type names.
@@ -619,13 +620,13 @@ func formatMember(obj types.Object, maxname int) string {
 			}
 		}
 		if abbrev == "" {
-			fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type().Underlying()))
+			fmt.Fprintf(&buf, " %s", types.TypeString(obj.Type().Underlying(), qualifier))
 		} else {
 			fmt.Fprintf(&buf, " %s", abbrev)
 		}
 
 	case *types.Var:
-		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type()))
+		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Type(), qualifier))
 	}
 	return buf.String()
 }
@@ -746,12 +747,13 @@ func isAccessibleFrom(obj types.Object, pkg *types.Package) bool {
 }
 
 func methodsToSerial(this *types.Package, methods []*types.Selection, fset *token.FileSet) []serial.DescribeMethod {
+	qualifier := types.RelativeTo(this)
 	var jmethods []serial.DescribeMethod
 	for _, meth := range methods {
 		var ser serial.DescribeMethod
 		if meth != nil { // may contain nils when called by implements (on a method)
 			ser = serial.DescribeMethod{
-				Name: types.SelectionString(this, meth),
+				Name: types.SelectionString(meth, qualifier),
 				Pos:  fset.Position(meth.Obj().Pos()).String(),
 			}
 		}
diff --git a/oracle/freevars.go b/oracle/freevars.go
index 580c97b..400a118 100644
--- a/oracle/freevars.go
+++ b/oracle/freevars.go
@@ -180,11 +180,12 @@ func (r *freevarsResult) display(printf printfFunc) {
 		printf(r.qpos, "No free identifiers.")
 	} else {
 		printf(r.qpos, "Free identifiers:")
+		qualifier := types.RelativeTo(r.qpos.info.Pkg)
 		for _, ref := range r.refs {
 			// Avoid printing "type T T".
 			var typstr string
 			if ref.kind != "type" {
-				typstr = " " + types.TypeString(r.qpos.info.Pkg, ref.typ)
+				typstr = " " + types.TypeString(ref.typ, qualifier)
 			}
 			printf(ref.obj, "%s %s%s", ref.kind, ref.ref, typstr)
 		}
diff --git a/oracle/oracle.go b/oracle/oracle.go
index 65ac9ed..544cfa4 100644
--- a/oracle/oracle.go
+++ b/oracle/oracle.go
@@ -58,17 +58,17 @@ type queryPos struct {
 
 // TypeString prints type T relative to the query position.
 func (qpos *queryPos) typeString(T types.Type) string {
-	return types.TypeString(qpos.info.Pkg, T)
+	return types.TypeString(T, types.RelativeTo(qpos.info.Pkg))
 }
 
 // ObjectString prints object obj relative to the query position.
 func (qpos *queryPos) objectString(obj types.Object) string {
-	return types.ObjectString(qpos.info.Pkg, obj)
+	return types.ObjectString(obj, types.RelativeTo(qpos.info.Pkg))
 }
 
 // SelectionString prints selection sel relative to the query position.
 func (qpos *queryPos) selectionString(sel *types.Selection) string {
-	return types.SelectionString(qpos.info.Pkg, sel)
+	return types.SelectionString(sel, types.RelativeTo(qpos.info.Pkg))
 }
 
 // A Query specifies a single oracle query.
diff --git a/refactor/lexical/lexical.go b/refactor/lexical/lexical.go
index 55ec391..c6567e4 100644
--- a/refactor/lexical/lexical.go
+++ b/refactor/lexical/lexical.go
@@ -189,6 +189,13 @@ func (r *resolver) setBlock(kind string, syntax ast.Node) *Block {
 	return b
 }
 
+func (r *resolver) qualifier(pkg *types.Package) string {
+	if pkg == r.pkg {
+		return "" // unqualified intra-package reference
+	}
+	return pkg.Path()
+}
+
 func (r *resolver) use(id *ast.Ident, env Environment) {
 	if id.Name == "_" {
 		return // an error
@@ -199,12 +206,12 @@ func (r *resolver) use(id *ast.Ident, env Environment) {
 	} else if want := r.info.Uses[id]; obj != want {
 		// sanity check against go/types resolver
 		logf("%s: internal error: lookup of %s yielded wrong object: got %v (%s), want %v\n",
-			r.fset.Position(id.Pos()), id.Name, types.ObjectString(r.pkg, obj),
+			r.fset.Position(id.Pos()), id.Name, types.ObjectString(obj, r.qualifier),
 			r.fset.Position(obj.Pos()),
 			want)
 	}
 	if trace {
-		logf("use %s = %v in %s\n", id.Name, types.ObjectString(r.pkg, obj), env)
+		logf("use %s = %v in %s\n", id.Name, types.ObjectString(obj, r.qualifier), env)
 	}
 
 	r.result.Refs[obj] = append(r.result.Refs[obj], Reference{id, env})
@@ -248,7 +255,7 @@ func (r *resolver) defineObject(b *Block, name string, obj types.Object) {
 	b.bindings = append(b.bindings, obj)
 	b.index[name] = i
 	if trace {
-		logf("def %s = %s in %s\n", name, types.ObjectString(r.pkg, obj), b)
+		logf("def %s = %s in %s\n", name, types.ObjectString(obj, r.qualifier), b)
 	}
 	r.result.Defs[obj] = b
 }
@@ -323,7 +330,7 @@ func (r *resolver) expr(n ast.Expr) {
 					//  id := kv.Key.(*ast.Ident)
 					//  obj := r.info.Uses[id]
 					//  logf("use %s = %v (field)\n",
-					// 	id.Name, types.ObjectString(r.pkg, obj))
+					// 	id.Name, types.ObjectString(obj, r.qualifier))
 					// TODO make a fake FieldVal selection?
 				} else {
 					r.expr(elt)
@@ -344,10 +351,10 @@ func (r *resolver) expr(n ast.Expr) {
 		// 	switch sel.Kind() {
 		// 	case types.FieldVal:
 		// 		logf("use %s = %v (field)\n",
-		// 			n.Sel.Name, types.ObjectString(r.pkg, sel.Obj()))
+		// 			n.Sel.Name, types.ObjectString(sel.Obj(), r.qualifier))
 		// 	case types.MethodExpr, types.MethodVal:
 		// 		logf("use %s = %v (method)\n",
-		// 			n.Sel.Name, types.ObjectString(r.pkg, sel.Obj()))
+		// 			n.Sel.Name, types.ObjectString(sel.Obj(), r.qualifier))
 		// 	}
 		// } else { // qualified identifier
 		// 	obj := r.info.Uses[n.Sel]