From 243076da64d251853ed7a69ce770e9fa71b5bf0d Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Thu, 20 May 2021 14:53:21 -0700 Subject: [dev.typeparams] cmd/compile/internal/types2: move signature checking into separate file This only moves functionality from one file into another. Except for import adjustments there are no changes to the code. Change-Id: Id0d20a7537f20abe3a257ad3f550b0cb4499598c Reviewed-on: https://go-review.googlesource.com/c/go/+/321590 Trust: Robert Griesemer Run-TryBot: Robert Griesemer TryBot-Result: Go Bot Reviewed-by: Robert Findley --- src/cmd/compile/internal/types2/signature.go | 314 +++++++++++++++++++++++++++ 1 file changed, 314 insertions(+) create mode 100644 src/cmd/compile/internal/types2/signature.go (limited to 'src/cmd/compile/internal/types2/signature.go') diff --git a/src/cmd/compile/internal/types2/signature.go b/src/cmd/compile/internal/types2/signature.go new file mode 100644 index 0000000000..c8c4cca0a7 --- /dev/null +++ b/src/cmd/compile/internal/types2/signature.go @@ -0,0 +1,314 @@ +// Copyright 2021 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 types2 + +import ( + "cmd/compile/internal/syntax" + "fmt" +) + +// Disabled by default, but enabled when running tests (via types_test.go). +var acceptMethodTypeParams bool + +// funcType type-checks a function or method type. +func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) { + check.openScope(ftyp, "function") + check.scope.isFunc = true + check.recordScope(ftyp, check.scope) + sig.scope = check.scope + defer check.closeScope() + + var recvTyp syntax.Expr // rewritten receiver type; valid if != nil + if recvPar != nil { + // collect generic receiver type parameters, if any + // - a receiver type parameter is like any other type parameter, except that it is declared implicitly + // - the receiver specification acts as local declaration for its type parameters, which may be blank + _, rname, rparams := check.unpackRecv(recvPar.Type, true) + if len(rparams) > 0 { + // Blank identifiers don't get declared and regular type-checking of the instantiated + // parameterized receiver type expression fails in Checker.collectParams of receiver. + // Identify blank type parameters and substitute each with a unique new identifier named + // "n_" (where n is the parameter index) and which cannot conflict with any user-defined + // name. + var smap map[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers + for i, p := range rparams { + if p.Value == "_" { + new := *p + new.Value = fmt.Sprintf("%d_", i) + rparams[i] = &new // use n_ identifier instead of _ so it can be looked up + if smap == nil { + smap = make(map[*syntax.Name]*syntax.Name) + } + smap[p] = &new + } + } + if smap != nil { + // blank identifiers were found => use rewritten receiver type + recvTyp = isubst(recvPar.Type, smap) + } + // TODO(gri) rework declareTypeParams + sig.rparams = nil + for _, rparam := range rparams { + sig.rparams = check.declareTypeParam(sig.rparams, rparam) + } + // determine receiver type to get its type parameters + // and the respective type parameter bounds + var recvTParams []*TypeName + if rname != nil { + // recv should be a Named type (otherwise an error is reported elsewhere) + // Also: Don't report an error via genericType since it will be reported + // again when we type-check the signature. + // TODO(gri) maybe the receiver should be marked as invalid instead? + if recv := asNamed(check.genericType(rname, false)); recv != nil { + recvTParams = recv.tparams + } + } + // provide type parameter bounds + // - only do this if we have the right number (otherwise an error is reported elsewhere) + if len(sig.rparams) == len(recvTParams) { + // We have a list of *TypeNames but we need a list of Types. + list := make([]Type, len(sig.rparams)) + for i, t := range sig.rparams { + list[i] = t.typ + } + smap := makeSubstMap(recvTParams, list) + for i, tname := range sig.rparams { + bound := recvTParams[i].typ.(*TypeParam).bound + // bound is (possibly) parameterized in the context of the + // receiver type declaration. Substitute parameters for the + // current context. + // TODO(gri) should we assume now that bounds always exist? + // (no bound == empty interface) + if bound != nil { + bound = check.subst(tname.pos, bound, smap) + tname.typ.(*TypeParam).bound = bound + } + } + } + } + } + + if tparams != nil { + sig.tparams = check.collectTypeParams(tparams) + // Always type-check method type parameters but complain if they are not enabled. + // (A separate check is needed when type-checking interface method signatures because + // they don't have a receiver specification.) + if recvPar != nil && !acceptMethodTypeParams { + check.error(ftyp, "methods cannot have type parameters") + } + } + + // Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their + // declarations and then squash that scope into the parent scope (and report any redeclarations at + // that time). + scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)") + var recvList []*Var // TODO(gri) remove the need for making a list here + if recvPar != nil { + recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any + } + params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true) + results, _ := check.collectParams(scope, ftyp.ResultList, nil, false) + scope.Squash(func(obj, alt Object) { + var err error_ + err.errorf(obj, "%s redeclared in this block", obj.Name()) + err.recordAltDecl(alt) + check.report(&err) + }) + + if recvPar != nil { + // recv parameter list present (may be empty) + // spec: "The receiver is specified via an extra parameter section preceding the + // method name. That parameter section must declare a single parameter, the receiver." + var recv *Var + switch len(recvList) { + case 0: + // error reported by resolver + recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below + default: + // more than one receiver + check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver") + fallthrough // continue with first receiver + case 1: + recv = recvList[0] + } + + // TODO(gri) We should delay rtyp expansion to when we actually need the + // receiver; thus all checks here should be delayed to later. + rtyp, _ := deref(recv.typ) + rtyp = expand(rtyp) + + // spec: "The receiver type must be of the form T or *T where T is a type name." + // (ignore invalid types - error was reported before) + if t := rtyp; t != Typ[Invalid] { + var err string + if T := asNamed(t); T != nil { + // spec: "The type denoted by T is called the receiver base type; it must not + // be a pointer or interface type and it must be declared in the same package + // as the method." + if T.obj.pkg != check.pkg { + err = "type not defined in this package" + if check.conf.CompilerErrorMessages { + check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ) + err = "" + } + } else { + switch u := optype(T).(type) { + case *Basic: + // unsafe.Pointer is treated like a regular pointer + if u.kind == UnsafePointer { + err = "unsafe.Pointer" + } + case *Pointer, *Interface: + err = "pointer or interface type" + } + } + } else if T := asBasic(t); T != nil { + err = "basic or unnamed type" + if check.conf.CompilerErrorMessages { + check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ) + err = "" + } + } else { + check.errorf(recv.pos, "invalid receiver type %s", recv.typ) + } + if err != "" { + check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err) + // ok to continue + } + } + sig.recv = recv + } + + sig.params = NewTuple(params...) + sig.results = NewTuple(results...) + sig.variadic = variadic +} + +// collectParams declares the parameters of list in scope and returns the corresponding +// variable list. If type0 != nil, it is used instead of the first type in list. +func (check *Checker) collectParams(scope *Scope, list []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) { + if list == nil { + return + } + + var named, anonymous bool + + var typ Type + var prev syntax.Expr + for i, field := range list { + ftype := field.Type + // type-check type of grouped fields only once + if ftype != prev { + prev = ftype + if i == 0 && type0 != nil { + ftype = type0 + } + if t, _ := ftype.(*syntax.DotsType); t != nil { + ftype = t.Elem + if variadicOk && i == len(list)-1 { + variadic = true + } else { + check.softErrorf(t, "can only use ... with final parameter in list") + // ignore ... and continue + } + } + typ = check.varType(ftype) + } + // The parser ensures that f.Tag is nil and we don't + // care if a constructed AST contains a non-nil tag. + if field.Name != nil { + // named parameter + name := field.Name.Value + if name == "" { + check.error(field.Name, invalidAST+"anonymous parameter") + // ok to continue + } + par := NewParam(field.Name.Pos(), check.pkg, name, typ) + check.declare(scope, field.Name, par, scope.pos) + params = append(params, par) + named = true + } else { + // anonymous parameter + par := NewParam(field.Pos(), check.pkg, "", typ) + check.recordImplicit(field, par) + params = append(params, par) + anonymous = true + } + } + + if named && anonymous { + check.error(list[0], invalidAST+"list contains both named and anonymous parameters") + // ok to continue + } + + // For a variadic function, change the last parameter's type from T to []T. + // Since we type-checked T rather than ...T, we also need to retro-actively + // record the type for ...T. + if variadic { + last := params[len(params)-1] + last.typ = &Slice{elem: last.typ} + check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil) + } + + return +} + +// isubst returns an x with identifiers substituted per the substitution map smap. +// isubst only handles the case of (valid) method receiver type expressions correctly. +func isubst(x syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr { + switch n := x.(type) { + case *syntax.Name: + if alt := smap[n]; alt != nil { + return alt + } + // case *syntax.StarExpr: + // X := isubst(n.X, smap) + // if X != n.X { + // new := *n + // new.X = X + // return &new + // } + case *syntax.Operation: + if n.Op == syntax.Mul && n.Y == nil { + X := isubst(n.X, smap) + if X != n.X { + new := *n + new.X = X + return &new + } + } + case *syntax.IndexExpr: + Index := isubst(n.Index, smap) + if Index != n.Index { + new := *n + new.Index = Index + return &new + } + case *syntax.ListExpr: + var elems []syntax.Expr + for i, elem := range n.ElemList { + new := isubst(elem, smap) + if new != elem { + if elems == nil { + elems = make([]syntax.Expr, len(n.ElemList)) + copy(elems, n.ElemList) + } + elems[i] = new + } + } + if elems != nil { + new := *n + new.ElemList = elems + return &new + } + case *syntax.ParenExpr: + return isubst(n.X, smap) // no need to keep parentheses + default: + // Other receiver type expressions are invalid. + // It's fine to ignore those here as they will + // be checked elsewhere. + } + return x +} -- cgit v1.2.3-54-g00ecf