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go/types: support type parameters in NewMethodSet

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Add handling for TypeParams in NewMethodSet, to bring it in sync with
lookupFieldOrMethod. Also add a test, since we had none. I wanted this
fix to get gopls completion working with type params, but due to the
subtlety of lookupFieldOrMethod, I left a TODO to confirm that there are
no behavioral differences between the APIs.

Updates #45639

Change-Id: I16723e16d4d944ca4ecb4d87fc196815abb6fcff
Reviewed-on: https://go-review.googlesource.com/c/go/+/311455
Trust: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley 2021-04-19 17:18:54 -04:00 committed by Robert Findley
parent af8a176e91
commit 4ce49b4a15
4 changed files with 129 additions and 4 deletions
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7
src/go/types/api_test.go
View File

@ -21,6 +21,11 @@ import (
. "go/types"
)
// pkgFor parses and type checks the package specified by path and source,
// populating info if provided.
//
// If source begins with "package generic_" and type parameters are enabled,
// generic code is permitted.
func pkgFor(path, source string, info *Info) (*Package, error) {
fset := token.NewFileSet()
mode := modeForSource(source)
@ -1213,6 +1218,8 @@ func TestLookupFieldOrMethod(t *testing.T) {
// Test cases assume a lookup of the form a.f or x.f, where a stands for an
// addressable value, and x for a non-addressable value (even though a variable
// for ease of test case writing).
//
// Should be kept in sync with TestMethodSet.
var tests = []struct {
src string
found bool

2
src/go/types/lookup.go
View File

@ -142,6 +142,8 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
// continue with underlying type, but only if it's not a type parameter
// TODO(gri) is this what we want to do for type parameters? (spec question)
// TODO(#45639) the error message produced as a result of skipping an
// underlying type parameter should be improved.
typ = named.under()
if asTypeParam(typ) != nil {
continue

15
src/go/types/methodset.go
View File

@ -63,7 +63,7 @@ func (s *MethodSet) Lookup(pkg *Package, name string) *Selection {
var emptyMethodSet MethodSet
// Note: NewMethodSet is intended for external use only as it
// requires interfaces to be complete. If may be used
// requires interfaces to be complete. It may be used
// internally if LookupFieldOrMethod completed the same
// interfaces beforehand.
@ -73,8 +73,8 @@ func NewMethodSet(T Type) *MethodSet {
// WARNING: The code in this function is extremely subtle - do not modify casually!
// This function and lookupFieldOrMethod should be kept in sync.
// TODO(gri) This code is out-of-sync with the lookup code at this point.
// Need to update.
// TODO(rfindley) confirm that this code is in sync with lookupFieldOrMethod
// with respect to type params.
// method set up to the current depth, allocated lazily
var base methodSet
@ -127,8 +127,12 @@ func NewMethodSet(T Type) *MethodSet {
mset = mset.add(named.methods, e.index, e.indirect, e.multiples)
// continue with underlying type
// continue with underlying type, but only if it's not a type parameter
// TODO(rFindley): should this use named.under()? Can there be a difference?
typ = named.underlying
if _, ok := typ.(*_TypeParam); ok {
continue
}
}
switch t := typ.(type) {
@ -154,6 +158,9 @@ func NewMethodSet(T Type) *MethodSet {
case *Interface:
mset = mset.add(t.allMethods, e.index, true, e.multiples)
case *_TypeParam:
mset = mset.add(t.Bound().allMethods, e.index, true, e.multiples)
}
}

109
src/go/types/methodset_test.go Normal file
View File

@ -0,0 +1,109 @@
// Copyright 2021 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 types_test
import (
"testing"
"go/internal/typeparams"
. "go/types"
)
func TestNewMethodSet(t *testing.T) {
type method struct {
name string
index []int
indirect bool
}
// Tests are expressed src -> methods, for simplifying the composite literal.
// Should be kept in sync with TestLookupFieldOrMethod.
tests := map[string][]method{
// Named types
"var a T; type T struct{}; func (T) f() {}": {{"f", []int{0}, false}},
"var a *T; type T struct{}; func (T) f() {}": {{"f", []int{0}, true}},
"var a T; type T struct{}; func (*T) f() {}": {},
"var a *T; type T struct{}; func (*T) f() {}": {{"f", []int{0}, true}},
// Interfaces
"var a T; type T interface{ f() }": {{"f", []int{0}, true}},
"var a T1; type ( T1 T2; T2 interface{ f() } )": {{"f", []int{0}, true}},
"var a T1; type ( T1 interface{ T2 }; T2 interface{ f() } )": {{"f", []int{0}, true}},
// Embedding
"var a struct{ E }; type E interface{ f() }": {{"f", []int{0, 0}, true}},
"var a *struct{ E }; type E interface{ f() }": {{"f", []int{0, 0}, true}},
"var a struct{ E }; type E struct{}; func (E) f() {}": {{"f", []int{0, 0}, false}},
"var a struct{ *E }; type E struct{}; func (E) f() {}": {{"f", []int{0, 0}, true}},
"var a struct{ E }; type E struct{}; func (*E) f() {}": {},
"var a struct{ *E }; type E struct{}; func (*E) f() {}": {{"f", []int{0, 0}, true}},
// collisions
"var a struct{ E1; *E2 }; type ( E1 interface{ f() }; E2 struct{ f int })": {},
"var a struct{ E1; *E2 }; type ( E1 struct{ f int }; E2 struct{} ); func (E2) f() {}": {},
}
genericTests := map[string][]method{
// By convention, look up a in the scope of "g"
"type C interface{ f() }; func g[T C](a T){}": {{"f", []int{0}, true}},
"type C interface{ f() }; func g[T C]() { var a T; _ = a }": {{"f", []int{0}, true}},
"type C interface{ f() }; func g[T C]() { var a struct{T}; _ = a }": {{"f", []int{0, 0}, true}},
// Issue #45639.
"type C interface{ f() }; func g[T C]() { type Y T; var a Y; _ = a }": {},
}
check := func(src string, methods []method, generic bool) {
pkgName := "p"
if generic {
// The generic_ prefix causes pkgFor to allow generic code.
pkgName = "generic_p"
}
pkg, err := pkgFor("test", "package "+pkgName+";"+src, nil)
if err != nil {
t.Errorf("%s: incorrect test case: %s", src, err)
return
}
scope := pkg.Scope()
if generic {
fn := pkg.Scope().Lookup("g").(*Func)
scope = fn.Scope()
}
obj := scope.Lookup("a")
if obj == nil {
t.Errorf("%s: incorrect test case - no object a", src)
return
}
ms := NewMethodSet(obj.Type())
if got, want := ms.Len(), len(methods); got != want {
t.Errorf("%s: got %d methods, want %d", src, got, want)
return
}
for i, m := range methods {
sel := ms.At(i)
if got, want := sel.Obj().Name(), m.name; got != want {
t.Errorf("%s [method %d]: got name = %q at, want %q", src, i, got, want)
}
if got, want := sel.Index(), m.index; !sameSlice(got, want) {
t.Errorf("%s [method %d]: got index = %v, want %v", src, i, got, want)
}
if got, want := sel.Indirect(), m.indirect; got != want {
t.Errorf("%s [method %d]: got indirect = %v, want %v", src, i, got, want)
}
}
}
for src, methods := range tests {
check(src, methods, false)
}
if typeparams.Enabled {
for src, methods := range genericTests {
check(src, methods, true)
}
}
}