diff --git a/bundled_typeparams.go b/bundled_typeparams.go new file mode 100644 index 0000000..696bb01 --- /dev/null +++ b/bundled_typeparams.go @@ -0,0 +1,354 @@ +// Originally bundled from golang.org/x/tools/internal/typeparams@v0.29.0, +// as it is used by x/tools/go/types/typeutil and is an internal package. + +package main + +import ( + "bytes" + "errors" + "fmt" + "go/types" +) + +var errEmptyTypeSet = errors.New("empty type set") + +// InterfaceTermSet computes the normalized terms for a constraint interface, +// returning an error if the term set cannot be computed or is empty. In the +// latter case, the error will be ErrEmptyTypeSet. +// +// See the documentation of StructuralTerms for more information on +// normalization. +func typeparams_InterfaceTermSet(iface *types.Interface) ([]*types.Term, error) { + return typeparams_computeTermSet(iface) +} + +// UnionTermSet computes the normalized terms for a union, returning an error +// if the term set cannot be computed or is empty. In the latter case, the +// error will be ErrEmptyTypeSet. +// +// See the documentation of StructuralTerms for more information on +// normalization. +func typeparams_UnionTermSet(union *types.Union) ([]*types.Term, error) { + return typeparams_computeTermSet(union) +} + +func typeparams_computeTermSet(typ types.Type) ([]*types.Term, error) { + tset, err := typeparams_computeTermSetInternal(typ, make(map[types.Type]*typeparams_termSet), 0) + if err != nil { + return nil, err + } + if tset.terms.isEmpty() { + return nil, errEmptyTypeSet + } + if tset.terms.isAll() { + return nil, nil + } + var terms []*types.Term + for _, term := range tset.terms { + terms = append(terms, types.NewTerm(term.tilde, term.typ)) + } + return terms, nil +} + +// A termSet holds the normalized set of terms for a given type. +// +// The name termSet is intentionally distinct from 'type set': a type set is +// all types that implement a type (and includes method restrictions), whereas +// a term set just represents the structural restrictions on a type. +type typeparams_termSet struct { + complete bool + terms typeparams_termlist +} + +func typeparams_computeTermSetInternal(t types.Type, seen map[types.Type]*typeparams_termSet, depth int) (res *typeparams_termSet, err error) { + if t == nil { + panic("nil type") + } + + const maxTermCount = 100 + if tset, ok := seen[t]; ok { + if !tset.complete { + return nil, fmt.Errorf("cycle detected in the declaration of %s", t) + } + return tset, nil + } + + // Mark the current type as seen to avoid infinite recursion. + tset := new(typeparams_termSet) + defer func() { + tset.complete = true + }() + seen[t] = tset + + switch u := t.Underlying().(type) { + case *types.Interface: + // The term set of an interface is the intersection of the term sets of its + // embedded types. + tset.terms = typeparams_allTermlist + for i := 0; i < u.NumEmbeddeds(); i++ { + embedded := u.EmbeddedType(i) + if _, ok := embedded.Underlying().(*types.TypeParam); ok { + return nil, fmt.Errorf("invalid embedded type %T", embedded) + } + tset2, err := typeparams_computeTermSetInternal(embedded, seen, depth+1) + if err != nil { + return nil, err + } + tset.terms = tset.terms.intersect(tset2.terms) + } + case *types.Union: + // The term set of a union is the union of term sets of its terms. + tset.terms = nil + for i := 0; i < u.Len(); i++ { + t := u.Term(i) + var terms typeparams_termlist + switch t.Type().Underlying().(type) { + case *types.Interface: + tset2, err := typeparams_computeTermSetInternal(t.Type(), seen, depth+1) + if err != nil { + return nil, err + } + terms = tset2.terms + case *types.TypeParam, *types.Union: + // A stand-alone type parameter or union is not permitted as union + // term. + return nil, fmt.Errorf("invalid union term %T", t) + default: + if t.Type() == types.Typ[types.Invalid] { + continue + } + terms = typeparams_termlist{{t.Tilde(), t.Type()}} + } + tset.terms = tset.terms.union(terms) + if len(tset.terms) > maxTermCount { + return nil, fmt.Errorf("exceeded max term count %d", maxTermCount) + } + } + case *types.TypeParam: + panic("unreachable") + default: + // For all other types, the term set is just a single non-tilde term + // holding the type itself. + if u != types.Typ[types.Invalid] { + tset.terms = typeparams_termlist{{false, t}} + } + } + return tset, nil +} + +// under is a facade for the go/types internal function of the same name. It is +// used by typeterm.go. +func typeparams_under(t types.Type) types.Type { + return t.Underlying() +} + +// A termlist represents the type set represented by the union +// t1 βˆͺ y2 βˆͺ ... tn of the type sets of the terms t1 to tn. +// A termlist is in normal form if all terms are disjoint. +// termlist operations don't require the operands to be in +// normal form. +type typeparams_termlist []*typeparams_term + +// allTermlist represents the set of all types. +// It is in normal form. + +// allTermlist represents the set of all types. +// It is in normal form. +var typeparams_allTermlist = typeparams_termlist{new(typeparams_term)} + +// String prints the termlist exactly (without normalization). +func (xl typeparams_termlist) String() string { + if len(xl) == 0 { + return "βˆ…" + } + var buf bytes.Buffer + for i, x := range xl { + if i > 0 { + buf.WriteString(" | ") + } + buf.WriteString(x.String()) + } + return buf.String() +} + +// isEmpty reports whether the termlist xl represents the empty set of types. +func (xl typeparams_termlist) isEmpty() bool { + // If there's a non-nil term, the entire list is not empty. + // If the termlist is in normal form, this requires at most + // one iteration. + for _, x := range xl { + if x != nil { + return false + } + } + return true +} + +// isAll reports whether the termlist xl represents the set of all types. +func (xl typeparams_termlist) isAll() bool { + // If there's a 𝓀 term, the entire list is 𝓀. + // If the termlist is in normal form, this requires at most + // one iteration. + for _, x := range xl { + if x != nil && x.typ == nil { + return true + } + } + return false +} + +// norm returns the normal form of xl. +func (xl typeparams_termlist) norm() typeparams_termlist { + // Quadratic algorithm, but good enough for now. + // TODO(gri) fix asymptotic performance + used := make([]bool, len(xl)) + var rl typeparams_termlist + for i, xi := range xl { + if xi == nil || used[i] { + continue + } + for j := i + 1; j < len(xl); j++ { + xj := xl[j] + if xj == nil || used[j] { + continue + } + if u1, u2 := xi.union(xj); u2 == nil { + // If we encounter a 𝓀 term, the entire list is 𝓀. + // Exit early. + // (Note that this is not just an optimization; + // if we continue, we may end up with a 𝓀 term + // and other terms and the result would not be + // in normal form.) + if u1.typ == nil { + return typeparams_allTermlist + } + xi = u1 + used[j] = true // xj is now unioned into xi - ignore it in future iterations + } + } + rl = append(rl, xi) + } + return rl +} + +// union returns the union xl βˆͺ yl. +func (xl typeparams_termlist) union(yl typeparams_termlist) typeparams_termlist { + return append(xl, yl...).norm() +} + +// intersect returns the intersection xl ∩ yl. +func (xl typeparams_termlist) intersect(yl typeparams_termlist) typeparams_termlist { + if xl.isEmpty() || yl.isEmpty() { + return nil + } + + // Quadratic algorithm, but good enough for now. + // TODO(gri) fix asymptotic performance + var rl typeparams_termlist + for _, x := range xl { + for _, y := range yl { + if r := x.intersect(y); r != nil { + rl = append(rl, r) + } + } + } + return rl.norm() +} + +// A term describes elementary type sets: +// +// βˆ…: (*term)(nil) == βˆ… // set of no types (empty set) +// 𝓀: &term{} == 𝓀 // set of all types (𝓀niverse) +// T: &term{false, T} == {T} // set of type T +// ~t: &term{true, t} == {t' | under(t') == t} // set of types with underlying type t +type typeparams_term struct { + tilde bool // valid if typ != nil + typ types.Type +} + +func (x *typeparams_term) String() string { + switch { + case x == nil: + return "βˆ…" + case x.typ == nil: + return "𝓀" + case x.tilde: + return "~" + x.typ.String() + default: + return x.typ.String() + } +} + +// union returns the union x βˆͺ y: zero, one, or two non-nil terms. +func (x *typeparams_term) union(y *typeparams_term) (_, _ *typeparams_term) { + // easy cases + switch { + case x == nil && y == nil: + return nil, nil // βˆ… βˆͺ βˆ… == βˆ… + case x == nil: + return y, nil // βˆ… βˆͺ y == y + case y == nil: + return x, nil // x βˆͺ βˆ… == x + case x.typ == nil: + return x, nil // 𝓀 βˆͺ y == 𝓀 + case y.typ == nil: + return y, nil // x βˆͺ 𝓀 == 𝓀 + } + // βˆ… βŠ‚ x, y βŠ‚ 𝓀 + + if x.disjoint(y) { + return x, y // x βˆͺ y == (x, y) if x ∩ y == βˆ… + } + // x.typ == y.typ + + // ~t βˆͺ ~t == ~t + // ~t βˆͺ T == ~t + // T βˆͺ ~t == ~t + // T βˆͺ T == T + if x.tilde || !y.tilde { + return x, nil + } + return y, nil +} + +// intersect returns the intersection x ∩ y. +func (x *typeparams_term) intersect(y *typeparams_term) *typeparams_term { + // easy cases + switch { + case x == nil || y == nil: + return nil // βˆ… ∩ y == βˆ… and ∩ βˆ… == βˆ… + case x.typ == nil: + return y // 𝓀 ∩ y == y + case y.typ == nil: + return x // x ∩ 𝓀 == x + } + // βˆ… βŠ‚ x, y βŠ‚ 𝓀 + + if x.disjoint(y) { + return nil // x ∩ y == βˆ… if x ∩ y == βˆ… + } + // x.typ == y.typ + + // ~t ∩ ~t == ~t + // ~t ∩ T == T + // T ∩ ~t == T + // T ∩ T == T + if !x.tilde || y.tilde { + return x + } + return y +} + +// disjoint reports whether x ∩ y == βˆ…. +// x.typ and y.typ must not be nil. +func (x *typeparams_term) disjoint(y *typeparams_term) bool { + ux := x.typ + if y.tilde { + ux = typeparams_under(ux) + } + uy := y.typ + if x.tilde { + uy = typeparams_under(uy) + } + return !types.Identical(ux, uy) +} diff --git a/bundled_typeutil.go b/bundled_typeutil.go new file mode 100644 index 0000000..4433f7c --- /dev/null +++ b/bundled_typeutil.go @@ -0,0 +1,295 @@ +// Originally bundled from golang.org/x/tools/go/types/typeutil@v0.29.0. +// Edited to just keep the hasher API in place, removing the use of internal/typeparams, +// and removed the inclusion of struct field tags in the hasher. + +package main + +import ( + "fmt" + "go/types" +) + +// -- Hasher -- + +// hash returns the hash of type t. +// TODO(adonovan): replace by types.Hash when Go proposal #69420 is accepted. +func typeutil_hash(t types.Type) uint32 { + return typeutil_theHasher.Hash(t) +} + +// A Hasher provides a [Hasher.Hash] method to map a type to its hash value. +// Hashers are stateless, and all are equivalent. +type typeutil_Hasher struct{} + +var typeutil_theHasher typeutil_Hasher + +// Hash computes a hash value for the given type t such that +// Identical(t, t') => Hash(t) == Hash(t'). +func (h typeutil_Hasher) Hash(t types.Type) uint32 { + return typeutil_hasher{inGenericSig: false}.hash(t) +} + +// hasher holds the state of a single Hash traversal: whether we are +// inside the signature of a generic function; this is used to +// optimize [hasher.hashTypeParam]. +type typeutil_hasher struct{ inGenericSig bool } + +// hashString computes the Fowler–Noll–Vo hash of s. +func typeutil_hashString(s string) uint32 { + var h uint32 + for i := 0; i < len(s); i++ { + h ^= uint32(s[i]) + h *= 16777619 + } + return h +} + +// hash computes the hash of t. +func (h typeutil_hasher) hash(t types.Type) uint32 { + // See Identical for rationale. + switch t := t.(type) { + case *types.Basic: + return uint32(t.Kind()) + + case *types.Alias: + return h.hash(types.Unalias(t)) + + case *types.Array: + return 9043 + 2*uint32(t.Len()) + 3*h.hash(t.Elem()) + + case *types.Slice: + return 9049 + 2*h.hash(t.Elem()) + + case *types.Struct: + var hash uint32 = 9059 + for i, n := 0, t.NumFields(); i < n; i++ { + f := t.Field(i) + if f.Anonymous() { + hash += 8861 + } + // NOTE: we must not hash struct field tags, as they do not affect type identity. + // hash += typeutil_hashString(t.Tag(i)) + hash += typeutil_hashString(f.Name()) // (ignore f.Pkg) + hash += h.hash(f.Type()) + } + return hash + + case *types.Pointer: + return 9067 + 2*h.hash(t.Elem()) + + case *types.Signature: + var hash uint32 = 9091 + if t.Variadic() { + hash *= 8863 + } + + tparams := t.TypeParams() + for i := range tparams.Len() { + h.inGenericSig = true + tparam := tparams.At(i) + hash += 7 * h.hash(tparam.Constraint()) + } + + return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results()) + + case *types.Union: + return h.hashUnion(t) + + case *types.Interface: + // Interfaces are identical if they have the same set of methods, with + // identical names and types, and they have the same set of type + // restrictions. See go/types.identical for more details. + var hash uint32 = 9103 + + // Hash methods. + for i, n := 0, t.NumMethods(); i < n; i++ { + // Method order is not significant. + // Ignore m.Pkg(). + m := t.Method(i) + // Use shallow hash on method signature to + // avoid anonymous interface cycles. + hash += 3*typeutil_hashString(m.Name()) + 5*h.shallowHash(m.Type()) + } + + // Hash type restrictions. + terms, err := typeparams_InterfaceTermSet(t) + // if err != nil t has invalid type restrictions. + if err == nil { + hash += h.hashTermSet(terms) + } + + return hash + + case *types.Map: + return 9109 + 2*h.hash(t.Key()) + 3*h.hash(t.Elem()) + + case *types.Chan: + return 9127 + 2*uint32(t.Dir()) + 3*h.hash(t.Elem()) + + case *types.Named: + hash := h.hashTypeName(t.Obj()) + targs := t.TypeArgs() + for i := 0; i < targs.Len(); i++ { + targ := targs.At(i) + hash += 2 * h.hash(targ) + } + return hash + + case *types.TypeParam: + return h.hashTypeParam(t) + + case *types.Tuple: + return h.hashTuple(t) + } + + panic(fmt.Sprintf("%T: %v", t, t)) +} + +func (h typeutil_hasher) hashTuple(tuple *types.Tuple) uint32 { + // See go/types.identicalTypes for rationale. + n := tuple.Len() + hash := 9137 + 2*uint32(n) + for i := range n { + hash += 3 * h.hash(tuple.At(i).Type()) + } + return hash +} + +func (h typeutil_hasher) hashUnion(t *types.Union) uint32 { + // Hash type restrictions. + terms, err := typeparams_UnionTermSet(t) + // if err != nil t has invalid type restrictions. Fall back on a non-zero + // hash. + if err != nil { + return 9151 + } + return h.hashTermSet(terms) +} + +func (h typeutil_hasher) hashTermSet(terms []*types.Term) uint32 { + hash := 9157 + 2*uint32(len(terms)) + for _, term := range terms { + // term order is not significant. + termHash := h.hash(term.Type()) + if term.Tilde() { + termHash *= 9161 + } + hash += 3 * termHash + } + return hash +} + +// hashTypeParam returns the hash of a type parameter. +func (h typeutil_hasher) hashTypeParam(t *types.TypeParam) uint32 { + // Within the signature of a generic function, TypeParams are + // identical if they have the same index and constraint, so we + // hash them based on index. + // + // When we are outside a generic function, free TypeParams are + // identical iff they are the same object, so we can use a + // more discriminating hash consistent with object identity. + // This optimization saves [Map] about 4% when hashing all the + // types.Info.Types in the forward closure of net/http. + if !h.inGenericSig { + // Optimization: outside a generic function signature, + // use a more discrimating hash consistent with object identity. + return h.hashTypeName(t.Obj()) + } + return 9173 + 3*uint32(t.Index()) +} + +// hashTypeName hashes the pointer of tname. +func (typeutil_hasher) hashTypeName(tname *types.TypeName) uint32 { + // NOTE: we must not hash any pointers, as garble is a toolexec tool + // so by nature it uses multiple processes. + return typeutil_hashString(tname.Name()) + // Since types.Identical uses == to compare TypeNames, + // the Hash function uses maphash.Comparable. + // TODO(adonovan): or will, when it becomes available in go1.24. + // In the meantime we use the pointer's numeric value. + // + // hash := maphash.Comparable(theSeed, tname) + // + // (Another approach would be to hash the name and package + // path, and whether or not it is a package-level typename. It + // is rare for a package to define multiple local types with + // the same name.) + // hash := uintptr(unsafe.Pointer(tname)) + // return uint32(hash ^ (hash >> 32)) +} + +// shallowHash computes a hash of t without looking at any of its +// element Types, to avoid potential anonymous cycles in the types of +// interface methods. +// +// When an unnamed non-empty interface type appears anywhere among the +// arguments or results of an interface method, there is a potential +// for endless recursion. Consider: +// +// type X interface { m() []*interface { X } } +// +// The problem is that the Methods of the interface in m's result type +// include m itself; there is no mention of the named type X that +// might help us break the cycle. +// (See comment in go/types.identical, case *Interface, for more.) +func (h typeutil_hasher) shallowHash(t types.Type) uint32 { + // t is the type of an interface method (Signature), + // its params or results (Tuples), or their immediate + // elements (mostly Slice, Pointer, Basic, Named), + // so there's no need to optimize anything else. + switch t := t.(type) { + case *types.Alias: + return h.shallowHash(types.Unalias(t)) + + case *types.Signature: + var hash uint32 = 604171 + if t.Variadic() { + hash *= 971767 + } + // The Signature/Tuple recursion is always finite + // and invariably shallow. + return hash + 1062599*h.shallowHash(t.Params()) + 1282529*h.shallowHash(t.Results()) + + case *types.Tuple: + n := t.Len() + hash := 9137 + 2*uint32(n) + for i := range n { + hash += 53471161 * h.shallowHash(t.At(i).Type()) + } + return hash + + case *types.Basic: + return 45212177 * uint32(t.Kind()) + + case *types.Array: + return 1524181 + 2*uint32(t.Len()) + + case *types.Slice: + return 2690201 + + case *types.Struct: + return 3326489 + + case *types.Pointer: + return 4393139 + + case *types.Union: + return 562448657 + + case *types.Interface: + return 2124679 // no recursion here + + case *types.Map: + return 9109 + + case *types.Chan: + return 9127 + + case *types.Named: + return h.hashTypeName(t.Obj()) + + case *types.TypeParam: + return h.hashTypeParam(t) + } + panic(fmt.Sprintf("shallowHash: %T: %v", t, t)) +}