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go.tools/go/types: handle p.x with p of type P *S

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R=adonovan
CC=golang-dev
https://golang.org/cl/10459044
This commit is contained in:
Robert Griesemer 2013-06-24 09:58:27 -07:00
parent cf8ec1591f
commit bd55eef6ec
2 changed files with 59 additions and 0 deletions
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42
go/types/lookup.go
View File

@ -32,6 +32,48 @@ import "go/ast"
// index sequence points to an ambiguous entry if it exists, or it is nil.
//
func LookupFieldOrMethod(typ Type, pkg *Package, name string) (obj Object, index []int, indirect bool) {
obj, index, indirect = lookupFieldOrMethod(typ, pkg, name)
if obj != nil {
return
}
// TODO(gri) The code below is not needed if we are looking for methods only,
// and it can be done always if we look for fields only. Consider
// providing LookupField and LookupMethod as well.
// If we didn't find anything, we still might have a field p.x as in:
//
// type S struct{ x int }
// func (*S) m() {}
// type P *S
// var p P
//
// which requires that we start the search with the underlying type
// of P (i.e., *S). We cannot do this always because we might find
// methods that don't exist for P but for S (e.g., m). Thus, if the
// result is a method we need to discard it.
//
// TODO(gri) WTF? There isn't a more direct way? Perhaps we should
// outlaw named types to pointer types - they are almost
// never what one wants, anyway.
if t, _ := typ.(*Named); t != nil {
u := t.underlying
if _, ok := u.(*Pointer); ok {
// typ is a named type with an underlying type of the form *T,
// start the search with the underlying type *T
if obj2, index2, indirect2 := lookupFieldOrMethod(u, pkg, name); obj2 != nil {
// only if the result is a field can we keep it
if _, ok := obj2.(*Field); ok {
return obj2, index2, indirect2
}
}
}
}
return
}
func lookupFieldOrMethod(typ Type, pkg *Package, name string) (obj Object, index []int, indirect bool) {
if name == "_" {
return // empty fields/methods are never found
}

17
go/types/testdata/decls3.src vendored
View File

@ -104,6 +104,23 @@ func _() {
}
}
// Named types that are pointers.
type S struct{ x int }
func (*S) m() {}
type P *S
func _() {
var s *S
_ = s.x
_ = s.m
var p P
_ = p.x
_ = p /* ERROR "no field or method" */ .m
_ = P /* ERROR "no field or method" */ .m
}
// Borrowed from the FieldByName test cases in reflect/all_test.go.
type D1 struct {