| // Copyright 2019 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. |
| |
| // TODO: test swap corresponding types (e.g. u1 <-> u2 and u2 <-> u1) |
| // TODO: test exported alias refers to something in another package -- does correspondence work then? |
| // TODO: CODE COVERAGE |
| // TODO: note that we may miss correspondences because we bail early when we compare a signature (e.g. when lengths differ; we could do up to the shorter) |
| // TODO: if you add an unexported method to an exposed interface, you have to check that |
| // every exposed type that previously implemented the interface still does. Otherwise |
| // an external assignment of the exposed type to the interface type could fail. |
| // TODO: check constant values: large values aren't representable by some types. |
| // TODO: Document all the incompatibilities we don't check for. |
| |
| package apidiff |
| |
| import ( |
| "fmt" |
| "go/constant" |
| "go/token" |
| "go/types" |
| |
| "golang.org/x/tools/internal/aliases" |
| ) |
| |
| // Changes reports on the differences between the APIs of the old and new packages. |
| // It classifies each difference as either compatible or incompatible (breaking.) For |
| // a detailed discussion of what constitutes an incompatible change, see the package |
| // documentation. |
| func Changes(old, new *types.Package) Report { |
| d := newDiffer(old, new) |
| d.checkPackage() |
| r := Report{} |
| for _, m := range d.incompatibles.collect() { |
| r.Changes = append(r.Changes, Change{Message: m, Compatible: false}) |
| } |
| for _, m := range d.compatibles.collect() { |
| r.Changes = append(r.Changes, Change{Message: m, Compatible: true}) |
| } |
| return r |
| } |
| |
| type differ struct { |
| old, new *types.Package |
| // Correspondences between named types. |
| // Even though it is the named types (*types.Named) that correspond, we use |
| // *types.TypeName as a map key because they are canonical. |
| // The values can be either named types or basic types. |
| correspondMap map[*types.TypeName]types.Type |
| |
| // Messages. |
| incompatibles messageSet |
| compatibles messageSet |
| } |
| |
| func newDiffer(old, new *types.Package) *differ { |
| return &differ{ |
| old: old, |
| new: new, |
| correspondMap: map[*types.TypeName]types.Type{}, |
| incompatibles: messageSet{}, |
| compatibles: messageSet{}, |
| } |
| } |
| |
| func (d *differ) incompatible(obj types.Object, part, format string, args ...interface{}) { |
| addMessage(d.incompatibles, obj, part, format, args) |
| } |
| |
| func (d *differ) compatible(obj types.Object, part, format string, args ...interface{}) { |
| addMessage(d.compatibles, obj, part, format, args) |
| } |
| |
| func addMessage(ms messageSet, obj types.Object, part, format string, args []interface{}) { |
| ms.add(obj, part, fmt.Sprintf(format, args...)) |
| } |
| |
| func (d *differ) checkPackage() { |
| // Old changes. |
| for _, name := range d.old.Scope().Names() { |
| oldobj := d.old.Scope().Lookup(name) |
| if !oldobj.Exported() { |
| continue |
| } |
| newobj := d.new.Scope().Lookup(name) |
| if newobj == nil { |
| d.incompatible(oldobj, "", "removed") |
| continue |
| } |
| d.checkObjects(oldobj, newobj) |
| } |
| // New additions. |
| for _, name := range d.new.Scope().Names() { |
| newobj := d.new.Scope().Lookup(name) |
| if newobj.Exported() && d.old.Scope().Lookup(name) == nil { |
| d.compatible(newobj, "", "added") |
| } |
| } |
| |
| // Whole-package satisfaction. |
| // For every old exposed interface oIface and its corresponding new interface nIface... |
| for otn1, nt1 := range d.correspondMap { |
| oIface, ok := otn1.Type().Underlying().(*types.Interface) |
| if !ok { |
| continue |
| } |
| nIface, ok := nt1.Underlying().(*types.Interface) |
| if !ok { |
| // If nt1 isn't an interface but otn1 is, then that's an incompatibility that |
| // we've already noticed, so there's no need to do anything here. |
| continue |
| } |
| // For every old type that implements oIface, its corresponding new type must implement |
| // nIface. |
| for otn2, nt2 := range d.correspondMap { |
| if otn1 == otn2 { |
| continue |
| } |
| if types.Implements(otn2.Type(), oIface) && !types.Implements(nt2, nIface) { |
| d.incompatible(otn2, "", "no longer implements %s", objectString(otn1)) |
| } |
| } |
| } |
| } |
| |
| func (d *differ) checkObjects(old, new types.Object) { |
| switch old := old.(type) { |
| case *types.Const: |
| if new, ok := new.(*types.Const); ok { |
| d.constChanges(old, new) |
| return |
| } |
| case *types.Var: |
| if new, ok := new.(*types.Var); ok { |
| d.checkCorrespondence(old, "", old.Type(), new.Type()) |
| return |
| } |
| case *types.Func: |
| switch new := new.(type) { |
| case *types.Func: |
| d.checkCorrespondence(old, "", old.Type(), new.Type()) |
| return |
| case *types.Var: |
| d.compatible(old, "", "changed from func to var") |
| d.checkCorrespondence(old, "", old.Type(), new.Type()) |
| return |
| |
| } |
| case *types.TypeName: |
| if new, ok := new.(*types.TypeName); ok { |
| d.checkCorrespondence(old, "", old.Type(), new.Type()) |
| return |
| } |
| default: |
| panic("unexpected obj type") |
| } |
| // Here if kind of type changed. |
| d.incompatible(old, "", "changed from %s to %s", |
| objectKindString(old), objectKindString(new)) |
| } |
| |
| // Compare two constants. |
| func (d *differ) constChanges(old, new *types.Const) { |
| ot := old.Type() |
| nt := new.Type() |
| // Check for change of type. |
| if !d.correspond(ot, nt) { |
| d.typeChanged(old, "", ot, nt) |
| return |
| } |
| // Check for change of value. |
| // We know the types are the same, so constant.Compare shouldn't panic. |
| if !constant.Compare(old.Val(), token.EQL, new.Val()) { |
| d.incompatible(old, "", "value changed from %s to %s", old.Val(), new.Val()) |
| } |
| } |
| |
| func objectKindString(obj types.Object) string { |
| switch obj.(type) { |
| case *types.Const: |
| return "const" |
| case *types.Var: |
| return "var" |
| case *types.Func: |
| return "func" |
| case *types.TypeName: |
| return "type" |
| default: |
| return "???" |
| } |
| } |
| |
| func (d *differ) checkCorrespondence(obj types.Object, part string, old, new types.Type) { |
| if !d.correspond(old, new) { |
| d.typeChanged(obj, part, old, new) |
| } |
| } |
| |
| func (d *differ) typeChanged(obj types.Object, part string, old, new types.Type) { |
| old = removeNamesFromSignature(old) |
| new = removeNamesFromSignature(new) |
| olds := types.TypeString(old, types.RelativeTo(d.old)) |
| news := types.TypeString(new, types.RelativeTo(d.new)) |
| d.incompatible(obj, part, "changed from %s to %s", olds, news) |
| } |
| |
| // go/types always includes the argument and result names when formatting a signature. |
| // Since these can change without affecting compatibility, we don't want users to |
| // be distracted by them, so we remove them. |
| func removeNamesFromSignature(t types.Type) types.Type { |
| t = aliases.Unalias(t) |
| sig, ok := t.(*types.Signature) |
| if !ok { |
| return t |
| } |
| |
| dename := func(p *types.Tuple) *types.Tuple { |
| var vars []*types.Var |
| for i := 0; i < p.Len(); i++ { |
| v := p.At(i) |
| vars = append(vars, types.NewVar(v.Pos(), v.Pkg(), "", aliases.Unalias(v.Type()))) |
| } |
| return types.NewTuple(vars...) |
| } |
| |
| return types.NewSignature(sig.Recv(), dename(sig.Params()), dename(sig.Results()), sig.Variadic()) |
| } |