diff options
Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/apidiff.go | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/apidiff.go b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/apidiff.go new file mode 100644 index 0000000..76669d8 --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/apidiff/apidiff.go @@ -0,0 +1,220 @@ +// 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" +) + +// 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 { + 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(), "", v.Type())) + } + return types.NewTuple(vars...) + } + + return types.NewSignature(sig.Recv(), dename(sig.Params()), dename(sig.Results()), sig.Variadic()) +} |