From 61f69d2559a1177c23dea06343a4784514e8dd85 Mon Sep 17 00:00:00 2001 From: Rob Findley Date: Mon, 19 Jul 2021 13:11:50 -0400 Subject: [PATCH] [dev.typeparams] go/types: merge instance and Named to eliminate sanitization Storing temporary syntactic information using an *instance type forces us to be careful not to leak references to *instance in the checker output. This is complex and error prone, as types are written in many places during type checking. Instead, temporarily pin the necessary syntactic information directly to the Named type during the type checking pass. This allows us to avoid having to sanitize references. This includes a couple of small, unrelated changes that were made in the process of debugging: - eliminate the expandf indirection: it is no longer necessary - include type parameters when printing objects For #46151 Change-Id: I767e35b289f2fea512a168997af0f861cd242175 Reviewed-on: https://go-review.googlesource.com/c/go/+/335929 Trust: Robert Findley Trust: Robert Griesemer Run-TryBot: Robert Findley TryBot-Result: Go Bot Reviewed-by: Robert Griesemer --- src/go/types/check.go | 4 - src/go/types/decl.go | 8 +- src/go/types/infer.go | 3 - src/go/types/instance.go | 53 +++---- src/go/types/instantiate.go | 67 ++++---- src/go/types/named.go | 28 ++-- src/go/types/object.go | 3 + src/go/types/predicates.go | 6 +- src/go/types/sanitize.go | 206 ------------------------- src/go/types/sizeof_test.go | 1 - src/go/types/subst.go | 15 +- src/go/types/testdata/check/issues.go2 | 4 +- src/go/types/typeparam.go | 3 +- src/go/types/typestring.go | 7 - src/go/types/typexpr.go | 2 +- 15 files changed, 96 insertions(+), 314 deletions(-) delete mode 100644 src/go/types/sanitize.go diff --git a/src/go/types/check.go b/src/go/types/check.go index 4398475501..b2d076dc68 100644 --- a/src/go/types/check.go +++ b/src/go/types/check.go @@ -273,10 +273,6 @@ func (check *Checker) checkFiles(files []*ast.File) (err error) { check.recordUntyped() - if check.Info != nil { - sanitizeInfo(check.Info) - } - check.pkg.complete = true // no longer needed - release memory diff --git a/src/go/types/decl.go b/src/go/types/decl.go index e38124f077..1195104b59 100644 --- a/src/go/types/decl.go +++ b/src/go/types/decl.go @@ -317,6 +317,7 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo { } case *Named: + t.complete() // don't touch the type if it is from a different package or the Universe scope // (doing so would lead to a race condition - was issue #35049) if t.obj.pkg != check.pkg { @@ -349,9 +350,6 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo { panic("internal error: cycle start not found") } return t.info - - case *instance: - return check.validType(t.expand(), path) } return valid @@ -607,6 +605,7 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) { // determine underlying type of named named.fromRHS = check.definedType(tdecl.Type, named) + assert(named.fromRHS != nil) // The underlying type of named may be itself a named type that is // incomplete: @@ -685,7 +684,8 @@ func (check *Checker) boundType(e ast.Expr) Type { bound := check.typ(e) check.later(func() { - if _, ok := under(bound).(*Interface); !ok && bound != Typ[Invalid] { + u := under(bound) + if _, ok := u.(*Interface); !ok && u != Typ[Invalid] { check.errorf(e, _Todo, "%s is not an interface", bound) } }) diff --git a/src/go/types/infer.go b/src/go/types/infer.go index 9faf7b7520..774d2fd158 100644 --- a/src/go/types/infer.go +++ b/src/go/types/infer.go @@ -337,9 +337,6 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) { // t must be one of w.tparams return t.index < len(w.tparams) && w.tparams[t.index].typ == t - case *instance: - return w.isParameterizedList(t.targs) - default: unreachable() } diff --git a/src/go/types/instance.go b/src/go/types/instance.go index 25f1442881..205cb47046 100644 --- a/src/go/types/instance.go +++ b/src/go/types/instance.go @@ -4,56 +4,39 @@ package types +// TODO(rfindley): move this code to named.go. + import "go/token" -// An instance represents an instantiated generic type syntactically -// (without expanding the instantiation). Type instances appear only -// during type-checking and are replaced by their fully instantiated -// (expanded) types before the end of type-checking. +// instance holds a Checker along with syntactic information +// information, for use in lazy instantiation. type instance struct { - check *Checker // for lazy instantiation + check *Checker pos token.Pos // position of type instantiation; for error reporting only - base *Named // parameterized type to be instantiated - targs []Type // type arguments posList []token.Pos // position of each targ; for error reporting only verify bool // if set, constraint satisfaction is verified - value Type // base[targs...] after instantiation or Typ[Invalid]; nil if not yet set } -// expand returns the instantiated (= expanded) type of t. -// The result is either an instantiated *Named type, or -// Typ[Invalid] if there was an error. -func (t *instance) expand() Type { - v := t.value - if v == nil { - v = t.check.Instantiate(t.pos, t.base, t.targs, t.posList, t.verify) - if v == nil { - v = Typ[Invalid] - } - t.value = v +// complete ensures that the underlying type of n is instantiated. +// The underlying type will be Typ[Invalid] if there was an error. +// TODO(rfindley): expand would be a better name for this method, but conflicts +// with the existing concept of lazy expansion. Need to reconcile this. +func (n *Named) complete() { + if n.instance != nil && len(n.targs) > 0 && n.underlying == nil { + check := n.instance.check + inst := check.instantiate(n.instance.pos, n.orig.underlying, n.tparams, n.targs, n.instance.posList, n.instance.verify) + n.underlying = inst + n.fromRHS = inst + n.methods = n.orig.methods } - // After instantiation we must have an invalid or a *Named type. - if debug && v != Typ[Invalid] { - _ = v.(*Named) - } - return v } // expand expands a type instance into its instantiated // type and leaves all other types alone. expand does // not recurse. func expand(typ Type) Type { - if t, _ := typ.(*instance); t != nil { - return t.expand() + if t, _ := typ.(*Named); t != nil { + t.complete() } return typ } - -// expandf is set to expand. -// Call expandf when calling expand causes compile-time cycle error. -var expandf func(Type) Type - -func init() { expandf = expand } - -func (t *instance) Underlying() Type { return t } -func (t *instance) String() string { return TypeString(t, nil) } diff --git a/src/go/types/instantiate.go b/src/go/types/instantiate.go index 99ffb9e604..270652149f 100644 --- a/src/go/types/instantiate.go +++ b/src/go/types/instantiate.go @@ -25,29 +25,6 @@ import ( // Any methods attached to a *Named are simply copied; they are not // instantiated. func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList []token.Pos, verify bool) (res Type) { - if verify && check == nil { - panic("cannot have nil receiver if verify is set") - } - - if check != nil && trace { - check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs)) - check.indent++ - defer func() { - check.indent-- - var under Type - if res != nil { - // Calling under() here may lead to endless instantiations. - // Test case: type T[P any] T[P] - // TODO(gri) investigate if that's a bug or to be expected. - under = res.Underlying() - } - check.trace(pos, "=> %s (under = %s)", res, under) - }() - } - - assert(len(posList) <= len(targs)) - - // TODO(gri) What is better here: work with TypeParams, or work with TypeNames? var tparams []*TypeName switch t := typ.(type) { case *Named: @@ -77,6 +54,10 @@ func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ)) } + return check.instantiate(pos, typ, tparams, targs, posList, verify) +} + +func (check *Checker) instantiate(pos token.Pos, typ Type, tparams []*TypeName, targs []Type, posList []token.Pos, verify bool) (res Type) { // the number of supplied types must match the number of type parameters if len(targs) != len(tparams) { // TODO(gri) provide better error message @@ -86,6 +67,29 @@ func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList } panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams))) } + if verify && check == nil { + panic("cannot have nil receiver if verify is set") + } + + if check != nil && trace { + check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs)) + check.indent++ + defer func() { + check.indent-- + var under Type + if res != nil { + // Calling under() here may lead to endless instantiations. + // Test case: type T[P any] T[P] + // TODO(gri) investigate if that's a bug or to be expected. + under = res.Underlying() + } + check.trace(pos, "=> %s (under = %s)", res, under) + }() + } + + assert(len(posList) <= len(targs)) + + // TODO(gri) What is better here: work with TypeParams, or work with TypeNames? if len(tparams) == 0 { return typ // nothing to do (minor optimization) @@ -120,15 +124,26 @@ func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, pos if base == nil { panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ)) } + h := instantiatedHash(base, targs) + if check != nil { + if named := check.typMap[h]; named != nil { + return named + } + } - return &instance{ + tname := NewTypeName(pos, base.obj.pkg, base.obj.name, nil) + named := check.newNamed(tname, base, nil, base.tparams, base.methods) // methods are instantiated lazily + named.targs = targs + named.instance = &instance{ check: check, pos: pos, - base: base, - targs: targs, posList: posList, verify: verify, } + if check != nil { + check.typMap[h] = named + } + return named } // satisfies reports whether the type argument targ satisfies the constraint of type parameter diff --git a/src/go/types/named.go b/src/go/types/named.go index 4511f395e0..a500f5663b 100644 --- a/src/go/types/named.go +++ b/src/go/types/named.go @@ -10,7 +10,7 @@ import "sync" // A Named represents a named (defined) type. type Named struct { - check *Checker // for Named.under implementation; nilled once under has been called + instance *instance // syntactic information for lazy instantiation info typeInfo // for cycle detection obj *TypeName // corresponding declared object orig *Named // original, uninstantiated type @@ -65,7 +65,13 @@ func (t *Named) expand() *Named { // newNamed is like NewNamed but with a *Checker receiver and additional orig argument. func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named { - typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods} + var inst *instance + if check != nil { + inst = &instance{ + check: check, + } + } + typ := &Named{instance: inst, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods} if typ.orig == nil { typ.orig = typ } @@ -83,10 +89,10 @@ func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tpar if check != nil { check.later(func() { switch typ.under().(type) { - case *Named, *instance: + case *Named: panic("internal error: unexpanded underlying type") } - typ.check = nil + typ.instance = nil }) } return typ @@ -153,6 +159,8 @@ func (t *Named) String() string { return TypeString(t, nil) } // is detected, the result is Typ[Invalid]. If a cycle is detected and // n0.check != nil, the cycle is reported. func (n0 *Named) under() Type { + n0.complete() + u := n0.Underlying() if u == Typ[Invalid] { @@ -168,17 +176,17 @@ func (n0 *Named) under() Type { default: // common case return u - case *Named, *instance: + case *Named: // handled below } - if n0.check == nil { + if n0.instance == nil || n0.instance.check == nil { panic("internal error: Named.check == nil but type is incomplete") } // Invariant: after this point n0 as well as any named types in its // underlying chain should be set up when this function exits. - check := n0.check + check := n0.instance.check // If we can't expand u at this point, it is invalid. n := asNamed(u) @@ -199,12 +207,8 @@ func (n0 *Named) under() Type { var n1 *Named switch u1 := u.(type) { case *Named: + u1.complete() n1 = u1 - case *instance: - n1, _ = u1.expand().(*Named) - if n1 == nil { - u = Typ[Invalid] - } } if n1 == nil { break // end of chain diff --git a/src/go/types/object.go b/src/go/types/object.go index 7913008814..4ea2837ea7 100644 --- a/src/go/types/object.go +++ b/src/go/types/object.go @@ -429,6 +429,9 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) { if _, ok := typ.(*Basic); ok { return } + if named, _ := typ.(*Named); named != nil && len(named.tparams) > 0 { + writeTParamList(buf, named.tparams, qf, nil) + } if tname.IsAlias() { buf.WriteString(" =") } else { diff --git a/src/go/types/predicates.go b/src/go/types/predicates.go index ea2bed720a..ce350f4470 100644 --- a/src/go/types/predicates.go +++ b/src/go/types/predicates.go @@ -10,7 +10,7 @@ package types // isNamed may be called with types that are not fully set up. func isNamed(typ Type) bool { switch typ.(type) { - case *Basic, *Named, *TypeParam, *instance: + case *Basic, *Named, *TypeParam: return true } return false @@ -159,8 +159,8 @@ func (p *ifacePair) identical(q *ifacePair) bool { // For changes to this code the corresponding changes should be made to unifier.nify. func identical(x, y Type, cmpTags bool, p *ifacePair) bool { // types must be expanded for comparison - x = expandf(x) - y = expandf(y) + x = expand(x) + y = expand(y) if x == y { return true diff --git a/src/go/types/sanitize.go b/src/go/types/sanitize.go deleted file mode 100644 index 62b91ef8c3..0000000000 --- a/src/go/types/sanitize.go +++ /dev/null @@ -1,206 +0,0 @@ -// Copyright 2020 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 - -// sanitizeInfo walks the types contained in info to ensure that all instances -// are expanded. -// -// This includes some objects that may be shared across concurrent -// type-checking passes (such as those in the universe scope), so we are -// careful here not to write types that are already sanitized. This avoids a -// data race as any shared types should already be sanitized. -func sanitizeInfo(info *Info) { - var s sanitizer = make(map[Type]Type) - - // Note: Some map entries are not references. - // If modified, they must be assigned back. - - for e, tv := range info.Types { - if typ := s.typ(tv.Type); typ != tv.Type { - tv.Type = typ - info.Types[e] = tv - } - } - - inferred := info.Inferred - for e, inf := range inferred { - changed := false - for i, targ := range inf.TArgs { - if typ := s.typ(targ); typ != targ { - inf.TArgs[i] = typ - changed = true - } - } - if typ := s.typ(inf.Sig); typ != inf.Sig { - inf.Sig = typ.(*Signature) - changed = true - } - if changed { - inferred[e] = inf - } - } - - for _, obj := range info.Defs { - if obj != nil { - if typ := s.typ(obj.Type()); typ != obj.Type() { - obj.setType(typ) - } - } - } - - for _, obj := range info.Uses { - if obj != nil { - if typ := s.typ(obj.Type()); typ != obj.Type() { - obj.setType(typ) - } - } - } - - // TODO(gri) sanitize as needed - // - info.Implicits - // - info.Selections - // - info.Scopes - // - info.InitOrder -} - -type sanitizer map[Type]Type - -func (s sanitizer) typ(typ Type) Type { - if typ == nil { - return nil - } - - if t, found := s[typ]; found { - return t - } - s[typ] = typ - - switch t := typ.(type) { - case *Basic, *top: - // nothing to do - - case *Array: - if elem := s.typ(t.elem); elem != t.elem { - t.elem = elem - } - - case *Slice: - if elem := s.typ(t.elem); elem != t.elem { - t.elem = elem - } - - case *Struct: - s.varList(t.fields) - - case *Pointer: - if base := s.typ(t.base); base != t.base { - t.base = base - } - - case *Tuple: - s.tuple(t) - - case *Signature: - s.var_(t.recv) - s.tuple(t.params) - s.tuple(t.results) - - case *Union: - s.typeList(t.types) - - case *Interface: - s.funcList(t.methods) - s.typeList(t.embeddeds) - // TODO(gri) do we need to sanitize type sets? - tset := t.typeSet() - s.funcList(tset.methods) - if types := s.typ(tset.types); types != tset.types { - tset.types = types - } - - case *Map: - if key := s.typ(t.key); key != t.key { - t.key = key - } - if elem := s.typ(t.elem); elem != t.elem { - t.elem = elem - } - - case *Chan: - if elem := s.typ(t.elem); elem != t.elem { - t.elem = elem - } - - case *Named: - if debug && t.check != nil { - panic("internal error: Named.check != nil") - } - t.expand() - if orig := s.typ(t.fromRHS); orig != t.fromRHS { - t.fromRHS = orig - } - if under := s.typ(t.underlying); under != t.underlying { - t.underlying = under - } - s.typeList(t.targs) - s.funcList(t.methods) - - case *TypeParam: - if bound := s.typ(t.bound); bound != t.bound { - t.bound = bound - } - - case *instance: - typ = t.expand() - s[t] = typ - - default: - panic("unimplemented") - } - - return typ -} - -func (s sanitizer) var_(v *Var) { - if v != nil { - if typ := s.typ(v.typ); typ != v.typ { - v.typ = typ - } - } -} - -func (s sanitizer) varList(list []*Var) { - for _, v := range list { - s.var_(v) - } -} - -func (s sanitizer) tuple(t *Tuple) { - if t != nil { - s.varList(t.vars) - } -} - -func (s sanitizer) func_(f *Func) { - if f != nil { - if typ := s.typ(f.typ); typ != f.typ { - f.typ = typ - } - } -} - -func (s sanitizer) funcList(list []*Func) { - for _, f := range list { - s.func_(f) - } -} - -func (s sanitizer) typeList(list []Type) { - for i, t := range list { - if typ := s.typ(t); typ != t { - list[i] = typ - } - } -} diff --git a/src/go/types/sizeof_test.go b/src/go/types/sizeof_test.go index 8c18de8675..fc548f7c58 100644 --- a/src/go/types/sizeof_test.go +++ b/src/go/types/sizeof_test.go @@ -32,7 +32,6 @@ func TestSizeof(t *testing.T) { {Chan{}, 12, 24}, {Named{}, 84, 160}, {TypeParam{}, 28, 48}, - {instance{}, 48, 96}, {top{}, 0, 0}, // Objects diff --git a/src/go/types/subst.go b/src/go/types/subst.go index ec85a6bfc4..42be508cd9 100644 --- a/src/go/types/subst.go +++ b/src/go/types/subst.go @@ -29,12 +29,7 @@ func makeSubstMap(tpars []*TypeName, targs []Type) *substMap { assert(len(tpars) == len(targs)) proj := make(map[*TypeParam]Type, len(tpars)) for i, tpar := range tpars { - // We must expand type arguments otherwise *instance - // types end up as components in composite types. - // TODO(gri) explain why this causes problems, if it does - targ := expand(targs[i]) // possibly nil - targs[i] = targ - proj[tpar.typ.(*TypeParam)] = targ + proj[tpar.typ.(*TypeParam)] = targs[i] } return &substMap{targs, proj} } @@ -86,6 +81,7 @@ func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap) Type { // for recursive types (example: type T[P any] *T[P]). subst.typMap = make(map[string]*Named) } + return subst.typ(typ) } @@ -248,10 +244,13 @@ func (subst *subster) typ(typ Type) Type { named := subst.check.newNamed(tname, t, t.Underlying(), t.TParams(), t.methods) // method signatures are updated lazily named.targs = newTargs subst.typMap[h] = named + t.complete() // must happen after typMap update to avoid infinite recursion // do the substitution dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTargs) named.underlying = subst.typOrNil(t.Underlying()) + dump(">>> underlying: %v", named.underlying) + assert(named.underlying != nil) named.fromRHS = named.underlying // for cycle detection (Checker.validType) return named @@ -259,10 +258,6 @@ func (subst *subster) typ(typ Type) Type { case *TypeParam: return subst.smap.lookup(t) - case *instance: - // TODO(gri) can we avoid the expansion here and just substitute the type parameters? - return subst.typ(t.expand()) - default: panic("unimplemented") } diff --git a/src/go/types/testdata/check/issues.go2 b/src/go/types/testdata/check/issues.go2 index c57f002303..ce0d608216 100644 --- a/src/go/types/testdata/check/issues.go2 +++ b/src/go/types/testdata/check/issues.go2 @@ -81,8 +81,10 @@ func (u T2[U]) Add1() U { return u.s + 1 } +// TODO(rfindley): we should probably report an error here as well, not +// just when the type is first instantiated. func NewT2[U any]() T2[U /* ERROR U has no type constraints */ ] { - return T2[U /* ERROR U has no type constraints */ ]{} + return T2[U]{} } func _() { diff --git a/src/go/types/typeparam.go b/src/go/types/typeparam.go index e42c24f8cb..bb5b28cdf8 100644 --- a/src/go/types/typeparam.go +++ b/src/go/types/typeparam.go @@ -24,7 +24,8 @@ type TypeParam struct { id uint64 // unique id, for debugging only obj *TypeName // corresponding type name index int // type parameter index in source order, starting at 0 - bound Type // *Named or *Interface; underlying type is always *Interface + // TODO(rfindley): this could also be Typ[Invalid]. Verify that this is handled correctly. + bound Type // *Named or *Interface; underlying type is always *Interface } // NewTypeParam returns a new TypeParam. bound can be nil (and set later). diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go index cba678588a..ef3808230a 100644 --- a/src/go/types/typestring.go +++ b/src/go/types/typestring.go @@ -295,13 +295,6 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) { } buf.WriteString(s + subscript(t.id)) - case *instance: - buf.WriteByte(instanceMarker) // indicate "non-evaluated" syntactic instance - writeTypeName(buf, t.base.obj, qf) - buf.WriteByte('[') - writeTypeList(buf, t.targs, qf, visited) - buf.WriteByte(']') - case *top: buf.WriteString("⊤") diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go index f2c4762a6b..a812ba6519 100644 --- a/src/go/types/typexpr.go +++ b/src/go/types/typexpr.go @@ -436,7 +436,7 @@ func (check *Checker) instantiatedType(x ast.Expr, targsx []ast.Expr, def *Named // make sure we check instantiation works at least once // and that the resulting type is valid check.later(func() { - t := typ.(*instance).expand() + t := expand(typ) check.validType(t, nil) })