+++ /dev/null
-package apidiff
-
-import (
- "go/types"
- "sort"
-)
-
-// Two types are correspond if they are identical except for defined types,
-// which must correspond.
-//
-// Two defined types correspond if they can be interchanged in the old and new APIs,
-// possibly after a renaming.
-//
-// This is not a pure function. If we come across named types while traversing,
-// we establish correspondence.
-func (d *differ) correspond(old, new types.Type) bool {
- return d.corr(old, new, nil)
-}
-
-// corr determines whether old and new correspond. The argument p is a list of
-// known interface identities, to avoid infinite recursion.
-//
-// corr calls itself recursively as much as possible, to establish more
-// correspondences and so check more of the API. E.g. if the new function has more
-// parameters than the old, compare all the old ones before returning false.
-//
-// Compare this to the implementation of go/types.Identical.
-func (d *differ) corr(old, new types.Type, p *ifacePair) bool {
- // Structure copied from types.Identical.
- switch old := old.(type) {
- case *types.Basic:
- return types.Identical(old, new)
-
- case *types.Array:
- if new, ok := new.(*types.Array); ok {
- return d.corr(old.Elem(), new.Elem(), p) && old.Len() == new.Len()
- }
-
- case *types.Slice:
- if new, ok := new.(*types.Slice); ok {
- return d.corr(old.Elem(), new.Elem(), p)
- }
-
- case *types.Map:
- if new, ok := new.(*types.Map); ok {
- return d.corr(old.Key(), new.Key(), p) && d.corr(old.Elem(), new.Elem(), p)
- }
-
- case *types.Chan:
- if new, ok := new.(*types.Chan); ok {
- return d.corr(old.Elem(), new.Elem(), p) && old.Dir() == new.Dir()
- }
-
- case *types.Pointer:
- if new, ok := new.(*types.Pointer); ok {
- return d.corr(old.Elem(), new.Elem(), p)
- }
-
- case *types.Signature:
- if new, ok := new.(*types.Signature); ok {
- pe := d.corr(old.Params(), new.Params(), p)
- re := d.corr(old.Results(), new.Results(), p)
- return old.Variadic() == new.Variadic() && pe && re
- }
-
- case *types.Tuple:
- if new, ok := new.(*types.Tuple); ok {
- for i := 0; i < old.Len(); i++ {
- if i >= new.Len() || !d.corr(old.At(i).Type(), new.At(i).Type(), p) {
- return false
- }
- }
- return old.Len() == new.Len()
- }
-
- case *types.Struct:
- if new, ok := new.(*types.Struct); ok {
- for i := 0; i < old.NumFields(); i++ {
- if i >= new.NumFields() {
- return false
- }
- of := old.Field(i)
- nf := new.Field(i)
- if of.Anonymous() != nf.Anonymous() ||
- old.Tag(i) != new.Tag(i) ||
- !d.corr(of.Type(), nf.Type(), p) ||
- !d.corrFieldNames(of, nf) {
- return false
- }
- }
- return old.NumFields() == new.NumFields()
- }
-
- case *types.Interface:
- if new, ok := new.(*types.Interface); ok {
- // Deal with circularity. See the comment in types.Identical.
- q := &ifacePair{old, new, p}
- for p != nil {
- if p.identical(q) {
- return true // same pair was compared before
- }
- p = p.prev
- }
- oldms := d.sortedMethods(old)
- newms := d.sortedMethods(new)
- for i, om := range oldms {
- if i >= len(newms) {
- return false
- }
- nm := newms[i]
- if d.methodID(om) != d.methodID(nm) || !d.corr(om.Type(), nm.Type(), q) {
- return false
- }
- }
- return old.NumMethods() == new.NumMethods()
- }
-
- case *types.Named:
- if new, ok := new.(*types.Named); ok {
- return d.establishCorrespondence(old, new)
- }
- if new, ok := new.(*types.Basic); ok {
- // Basic types are defined types, too, so we have to support them.
-
- return d.establishCorrespondence(old, new)
- }
-
- default:
- panic("unknown type kind")
- }
- return false
-}
-
-// Compare old and new field names. We are determining correspondence across packages,
-// so just compare names, not packages. For an unexported, embedded field of named
-// type (non-named embedded fields are possible with aliases), we check that the type
-// names correspond. We check the types for correspondence before this is called, so
-// we've established correspondence.
-func (d *differ) corrFieldNames(of, nf *types.Var) bool {
- if of.Anonymous() && nf.Anonymous() && !of.Exported() && !nf.Exported() {
- if on, ok := of.Type().(*types.Named); ok {
- nn := nf.Type().(*types.Named)
- return d.establishCorrespondence(on, nn)
- }
- }
- return of.Name() == nf.Name()
-}
-
-// Establish that old corresponds with new if it does not already
-// correspond to something else.
-func (d *differ) establishCorrespondence(old *types.Named, new types.Type) bool {
- oldname := old.Obj()
- oldc := d.correspondMap[oldname]
- if oldc == nil {
- // For now, assume the types don't correspond unless they are from the old
- // and new packages, respectively.
- //
- // This is too conservative. For instance,
- // [old] type A = q.B; [new] type A q.C
- // could be OK if in package q, B is an alias for C.
- // Or, using p as the name of the current old/new packages:
- // [old] type A = q.B; [new] type A int
- // could be OK if in q,
- // [old] type B int; [new] type B = p.A
- // In this case, p.A and q.B name the same type in both old and new worlds.
- // Note that this case doesn't imply circular package imports: it's possible
- // that in the old world, p imports q, but in the new, q imports p.
- //
- // However, if we didn't do something here, then we'd incorrectly allow cases
- // like the first one above in which q.B is not an alias for q.C
- //
- // What we should do is check that the old type, in the new world's package
- // of the same path, doesn't correspond to something other than the new type.
- // That is a bit hard, because there is no easy way to find a new package
- // matching an old one.
- if newn, ok := new.(*types.Named); ok {
- if old.Obj().Pkg() != d.old || newn.Obj().Pkg() != d.new {
- return old.Obj().Id() == newn.Obj().Id()
- }
- }
- // If there is no correspondence, create one.
- d.correspondMap[oldname] = new
- // Check that the corresponding types are compatible.
- d.checkCompatibleDefined(oldname, old, new)
- return true
- }
- return types.Identical(oldc, new)
-}
-
-func (d *differ) sortedMethods(iface *types.Interface) []*types.Func {
- ms := make([]*types.Func, iface.NumMethods())
- for i := 0; i < iface.NumMethods(); i++ {
- ms[i] = iface.Method(i)
- }
- sort.Slice(ms, func(i, j int) bool { return d.methodID(ms[i]) < d.methodID(ms[j]) })
- return ms
-}
-
-func (d *differ) methodID(m *types.Func) string {
- // If the method belongs to one of the two packages being compared, use
- // just its name even if it's unexported. That lets us treat unexported names
- // from the old and new packages as equal.
- if m.Pkg() == d.old || m.Pkg() == d.new {
- return m.Name()
- }
- return m.Id()
-}
-
-// Copied from the go/types package:
-
-// An ifacePair is a node in a stack of interface type pairs compared for identity.
-type ifacePair struct {
- x, y *types.Interface
- prev *ifacePair
-}
-
-func (p *ifacePair) identical(q *ifacePair) bool {
- return p.x == q.x && p.y == q.y || p.x == q.y && p.y == q.x
-}
projects / dotfiles / .git / blobdiff