| // Copyright 2014 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" |
| "go/constant" |
| ) |
| |
| func (err *error_) recordAltDecl(obj Object) { |
| if pos := obj.Pos(); pos.IsKnown() { |
| // We use "other" rather than "previous" here because |
| // the first declaration seen may not be textually |
| // earlier in the source. |
| err.errorf(pos, "other declaration of %s", obj.Name()) |
| } |
| } |
| |
| func (check *Checker) declare(scope *Scope, id *syntax.Name, obj Object, pos syntax.Pos) { |
| // spec: "The blank identifier, represented by the underscore |
| // character _, may be used in a declaration like any other |
| // identifier but the declaration does not introduce a new |
| // binding." |
| if obj.Name() != "_" { |
| if alt := scope.Insert(obj); alt != nil { |
| var err error_ |
| err.errorf(obj, "%s redeclared in this block", obj.Name()) |
| err.recordAltDecl(alt) |
| check.report(&err) |
| return |
| } |
| obj.setScopePos(pos) |
| } |
| if id != nil { |
| check.recordDef(id, obj) |
| } |
| } |
| |
| // pathString returns a string of the form a->b-> ... ->g for a path [a, b, ... g]. |
| func pathString(path []Object) string { |
| var s string |
| for i, p := range path { |
| if i > 0 { |
| s += "->" |
| } |
| s += p.Name() |
| } |
| return s |
| } |
| |
| // objDecl type-checks the declaration of obj in its respective (file) context. |
| // For the meaning of def, see Checker.definedType, in typexpr.go. |
| func (check *Checker) objDecl(obj Object, def *Named) { |
| if check.conf.Trace && obj.Type() == nil { |
| if check.indent == 0 { |
| fmt.Println() // empty line between top-level objects for readability |
| } |
| check.trace(obj.Pos(), "-- checking %s (%s, objPath = %s)", obj, obj.color(), pathString(check.objPath)) |
| check.indent++ |
| defer func() { |
| check.indent-- |
| check.trace(obj.Pos(), "=> %s (%s)", obj, obj.color()) |
| }() |
| } |
| |
| // Checking the declaration of obj means inferring its type |
| // (and possibly its value, for constants). |
| // An object's type (and thus the object) may be in one of |
| // three states which are expressed by colors: |
| // |
| // - an object whose type is not yet known is painted white (initial color) |
| // - an object whose type is in the process of being inferred is painted grey |
| // - an object whose type is fully inferred is painted black |
| // |
| // During type inference, an object's color changes from white to grey |
| // to black (pre-declared objects are painted black from the start). |
| // A black object (i.e., its type) can only depend on (refer to) other black |
| // ones. White and grey objects may depend on white and black objects. |
| // A dependency on a grey object indicates a cycle which may or may not be |
| // valid. |
| // |
| // When objects turn grey, they are pushed on the object path (a stack); |
| // they are popped again when they turn black. Thus, if a grey object (a |
| // cycle) is encountered, it is on the object path, and all the objects |
| // it depends on are the remaining objects on that path. Color encoding |
| // is such that the color value of a grey object indicates the index of |
| // that object in the object path. |
| |
| // During type-checking, white objects may be assigned a type without |
| // traversing through objDecl; e.g., when initializing constants and |
| // variables. Update the colors of those objects here (rather than |
| // everywhere where we set the type) to satisfy the color invariants. |
| if obj.color() == white && obj.Type() != nil { |
| obj.setColor(black) |
| return |
| } |
| |
| switch obj.color() { |
| case white: |
| assert(obj.Type() == nil) |
| // All color values other than white and black are considered grey. |
| // Because black and white are < grey, all values >= grey are grey. |
| // Use those values to encode the object's index into the object path. |
| obj.setColor(grey + color(check.push(obj))) |
| defer func() { |
| check.pop().setColor(black) |
| }() |
| |
| case black: |
| assert(obj.Type() != nil) |
| return |
| |
| default: |
| // Color values other than white or black are considered grey. |
| fallthrough |
| |
| case grey: |
| // We have a cycle. |
| // In the existing code, this is marked by a non-nil type |
| // for the object except for constants and variables whose |
| // type may be non-nil (known), or nil if it depends on the |
| // not-yet known initialization value. |
| // In the former case, set the type to Typ[Invalid] because |
| // we have an initialization cycle. The cycle error will be |
| // reported later, when determining initialization order. |
| // TODO(gri) Report cycle here and simplify initialization |
| // order code. |
| switch obj := obj.(type) { |
| case *Const: |
| if check.cycle(obj) || obj.typ == nil { |
| obj.typ = Typ[Invalid] |
| } |
| |
| case *Var: |
| if check.cycle(obj) || obj.typ == nil { |
| obj.typ = Typ[Invalid] |
| } |
| |
| case *TypeName: |
| if check.cycle(obj) { |
| // break cycle |
| // (without this, calling underlying() |
| // below may lead to an endless loop |
| // if we have a cycle for a defined |
| // (*Named) type) |
| obj.typ = Typ[Invalid] |
| } |
| |
| case *Func: |
| if check.cycle(obj) { |
| // Don't set obj.typ to Typ[Invalid] here |
| // because plenty of code type-asserts that |
| // functions have a *Signature type. Grey |
| // functions have their type set to an empty |
| // signature which makes it impossible to |
| // initialize a variable with the function. |
| } |
| |
| default: |
| unreachable() |
| } |
| assert(obj.Type() != nil) |
| return |
| } |
| |
| d := check.objMap[obj] |
| if d == nil { |
| check.dump("%v: %s should have been declared", obj.Pos(), obj) |
| unreachable() |
| } |
| |
| // save/restore current context and setup object context |
| defer func(ctxt context) { |
| check.context = ctxt |
| }(check.context) |
| check.context = context{ |
| scope: d.file, |
| } |
| |
| // Const and var declarations must not have initialization |
| // cycles. We track them by remembering the current declaration |
| // in check.decl. Initialization expressions depending on other |
| // consts, vars, or functions, add dependencies to the current |
| // check.decl. |
| switch obj := obj.(type) { |
| case *Const: |
| check.decl = d // new package-level const decl |
| check.constDecl(obj, d.vtyp, d.init, d.inherited) |
| case *Var: |
| check.decl = d // new package-level var decl |
| check.varDecl(obj, d.lhs, d.vtyp, d.init) |
| case *TypeName: |
| // invalid recursive types are detected via path |
| check.typeDecl(obj, d.tdecl, def) |
| check.collectMethods(obj) // methods can only be added to top-level types |
| case *Func: |
| // functions may be recursive - no need to track dependencies |
| check.funcDecl(obj, d) |
| default: |
| unreachable() |
| } |
| } |
| |
| // cycle checks if the cycle starting with obj is valid and |
| // reports an error if it is not. |
| func (check *Checker) cycle(obj Object) (isCycle bool) { |
| // The object map contains the package scope objects and the non-interface methods. |
| if debug { |
| info := check.objMap[obj] |
| inObjMap := info != nil && (info.fdecl == nil || info.fdecl.Recv == nil) // exclude methods |
| isPkgObj := obj.Parent() == check.pkg.scope |
| if isPkgObj != inObjMap { |
| check.dump("%v: inconsistent object map for %s (isPkgObj = %v, inObjMap = %v)", obj.Pos(), obj, isPkgObj, inObjMap) |
| unreachable() |
| } |
| } |
| |
| // Count cycle objects. |
| assert(obj.color() >= grey) |
| start := obj.color() - grey // index of obj in objPath |
| cycle := check.objPath[start:] |
| nval := 0 // number of (constant or variable) values in the cycle |
| ndef := 0 // number of type definitions in the cycle |
| for _, obj := range cycle { |
| switch obj := obj.(type) { |
| case *Const, *Var: |
| nval++ |
| case *TypeName: |
| // Determine if the type name is an alias or not. For |
| // package-level objects, use the object map which |
| // provides syntactic information (which doesn't rely |
| // on the order in which the objects are set up). For |
| // local objects, we can rely on the order, so use |
| // the object's predicate. |
| // TODO(gri) It would be less fragile to always access |
| // the syntactic information. We should consider storing |
| // this information explicitly in the object. |
| var alias bool |
| if d := check.objMap[obj]; d != nil { |
| alias = d.tdecl.Alias // package-level object |
| } else { |
| alias = obj.IsAlias() // function local object |
| } |
| if !alias { |
| ndef++ |
| } |
| case *Func: |
| // ignored for now |
| default: |
| unreachable() |
| } |
| } |
| |
| if check.conf.Trace { |
| check.trace(obj.Pos(), "## cycle detected: objPath = %s->%s (len = %d)", pathString(cycle), obj.Name(), len(cycle)) |
| check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef) |
| defer func() { |
| if isCycle { |
| check.trace(obj.Pos(), "=> error: cycle is invalid") |
| } |
| }() |
| } |
| |
| // A cycle involving only constants and variables is invalid but we |
| // ignore them here because they are reported via the initialization |
| // cycle check. |
| if nval == len(cycle) { |
| return false |
| } |
| |
| // A cycle involving only types (and possibly functions) must have at least |
| // one type definition to be permitted: If there is no type definition, we |
| // have a sequence of alias type names which will expand ad infinitum. |
| if nval == 0 && ndef > 0 { |
| return false // cycle is permitted |
| } |
| |
| check.cycleError(cycle) |
| |
| return true |
| } |
| |
| type typeInfo uint |
| |
| // validType verifies that the given type does not "expand" infinitely |
| // producing a cycle in the type graph. Cycles are detected by marking |
| // defined types. |
| // (Cycles involving alias types, as in "type A = [10]A" are detected |
| // earlier, via the objDecl cycle detection mechanism.) |
| func (check *Checker) validType(typ Type, path []Object) typeInfo { |
| const ( |
| unknown typeInfo = iota |
| marked |
| valid |
| invalid |
| ) |
| |
| switch t := typ.(type) { |
| case *Array: |
| return check.validType(t.elem, path) |
| |
| case *Struct: |
| for _, f := range t.fields { |
| if check.validType(f.typ, path) == invalid { |
| return invalid |
| } |
| } |
| |
| case *Interface: |
| for _, etyp := range t.embeddeds { |
| if check.validType(etyp, path) == invalid { |
| return invalid |
| } |
| } |
| |
| case *Named: |
| t.expand(check.typMap) |
| |
| // 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 { |
| return valid |
| } |
| |
| // don't report a 2nd error if we already know the type is invalid |
| // (e.g., if a cycle was detected earlier, via under). |
| if t.underlying == Typ[Invalid] { |
| t.info = invalid |
| return invalid |
| } |
| |
| switch t.info { |
| case unknown: |
| t.info = marked |
| t.info = check.validType(t.fromRHS, append(path, t.obj)) // only types of current package added to path |
| case marked: |
| // cycle detected |
| for i, tn := range path { |
| if t.obj.pkg != check.pkg { |
| panic("type cycle via package-external type") |
| } |
| if tn == t.obj { |
| check.cycleError(path[i:]) |
| t.info = invalid |
| return t.info |
| } |
| } |
| panic("cycle start not found") |
| } |
| return t.info |
| } |
| |
| return valid |
| } |
| |
| // cycleError reports a declaration cycle starting with |
| // the object in cycle that is "first" in the source. |
| func (check *Checker) cycleError(cycle []Object) { |
| // TODO(gri) Should we start with the last (rather than the first) object in the cycle |
| // since that is the earliest point in the source where we start seeing the |
| // cycle? That would be more consistent with other error messages. |
| i := firstInSrc(cycle) |
| obj := cycle[i] |
| var err error_ |
| if check.conf.CompilerErrorMessages { |
| err.errorf(obj, "invalid recursive type %s", obj.Name()) |
| } else { |
| err.errorf(obj, "illegal cycle in declaration of %s", obj.Name()) |
| } |
| for range cycle { |
| err.errorf(obj, "%s refers to", obj.Name()) |
| i++ |
| if i >= len(cycle) { |
| i = 0 |
| } |
| obj = cycle[i] |
| } |
| err.errorf(obj, "%s", obj.Name()) |
| check.report(&err) |
| } |
| |
| // firstInSrc reports the index of the object with the "smallest" |
| // source position in path. path must not be empty. |
| func firstInSrc(path []Object) int { |
| fst, pos := 0, path[0].Pos() |
| for i, t := range path[1:] { |
| if t.Pos().Cmp(pos) < 0 { |
| fst, pos = i+1, t.Pos() |
| } |
| } |
| return fst |
| } |
| |
| func (check *Checker) constDecl(obj *Const, typ, init syntax.Expr, inherited bool) { |
| assert(obj.typ == nil) |
| |
| // use the correct value of iota and errpos |
| defer func(iota constant.Value, errpos syntax.Pos) { |
| check.iota = iota |
| check.errpos = errpos |
| }(check.iota, check.errpos) |
| check.iota = obj.val |
| check.errpos = nopos |
| |
| // provide valid constant value under all circumstances |
| obj.val = constant.MakeUnknown() |
| |
| // determine type, if any |
| if typ != nil { |
| t := check.typ(typ) |
| if !isConstType(t) { |
| // don't report an error if the type is an invalid C (defined) type |
| // (issue #22090) |
| if under(t) != Typ[Invalid] { |
| check.errorf(typ, "invalid constant type %s", t) |
| } |
| obj.typ = Typ[Invalid] |
| return |
| } |
| obj.typ = t |
| } |
| |
| // check initialization |
| var x operand |
| if init != nil { |
| if inherited { |
| // The initialization expression is inherited from a previous |
| // constant declaration, and (error) positions refer to that |
| // expression and not the current constant declaration. Use |
| // the constant identifier position for any errors during |
| // init expression evaluation since that is all we have |
| // (see issues #42991, #42992). |
| check.errpos = obj.pos |
| } |
| check.expr(&x, init) |
| } |
| check.initConst(obj, &x) |
| } |
| |
| func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init syntax.Expr) { |
| assert(obj.typ == nil) |
| |
| // If we have undefined variable types due to errors, |
| // mark variables as used to avoid follow-on errors. |
| // Matches compiler behavior. |
| defer func() { |
| if obj.typ == Typ[Invalid] { |
| obj.used = true |
| } |
| for _, lhs := range lhs { |
| if lhs.typ == Typ[Invalid] { |
| lhs.used = true |
| } |
| } |
| }() |
| |
| // determine type, if any |
| if typ != nil { |
| obj.typ = check.varType(typ) |
| // We cannot spread the type to all lhs variables if there |
| // are more than one since that would mark them as checked |
| // (see Checker.objDecl) and the assignment of init exprs, |
| // if any, would not be checked. |
| // |
| // TODO(gri) If we have no init expr, we should distribute |
| // a given type otherwise we need to re-evalate the type |
| // expr for each lhs variable, leading to duplicate work. |
| } |
| |
| // check initialization |
| if init == nil { |
| if typ == nil { |
| // error reported before by arityMatch |
| obj.typ = Typ[Invalid] |
| } |
| return |
| } |
| |
| if lhs == nil || len(lhs) == 1 { |
| assert(lhs == nil || lhs[0] == obj) |
| var x operand |
| check.expr(&x, init) |
| check.initVar(obj, &x, "variable declaration") |
| return |
| } |
| |
| if debug { |
| // obj must be one of lhs |
| found := false |
| for _, lhs := range lhs { |
| if obj == lhs { |
| found = true |
| break |
| } |
| } |
| if !found { |
| panic("inconsistent lhs") |
| } |
| } |
| |
| // We have multiple variables on the lhs and one init expr. |
| // Make sure all variables have been given the same type if |
| // one was specified, otherwise they assume the type of the |
| // init expression values (was issue #15755). |
| if typ != nil { |
| for _, lhs := range lhs { |
| lhs.typ = obj.typ |
| } |
| } |
| |
| check.initVars(lhs, []syntax.Expr{init}, nopos) |
| } |
| |
| // isImportedConstraint reports whether typ is an imported type constraint. |
| func (check *Checker) isImportedConstraint(typ Type) bool { |
| named, _ := typ.(*Named) |
| if named == nil || named.obj.pkg == check.pkg || named.obj.pkg == nil { |
| return false |
| } |
| u, _ := named.under().(*Interface) |
| return u != nil && u.IsConstraint() |
| } |
| |
| func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named) { |
| assert(obj.typ == nil) |
| |
| var rhs Type |
| check.later(func() { |
| check.validType(obj.typ, nil) |
| // If typ is local, an error was already reported where typ is specified/defined. |
| if check.isImportedConstraint(rhs) && !check.allowVersion(check.pkg, 1, 18) { |
| check.errorf(tdecl.Type.Pos(), "using type constraint %s requires go1.18 or later", rhs) |
| } |
| }) |
| |
| alias := tdecl.Alias |
| if alias && tdecl.TParamList != nil { |
| // The parser will ensure this but we may still get an invalid AST. |
| // Complain and continue as regular type definition. |
| check.error(tdecl, "generic type cannot be alias") |
| alias = false |
| } |
| |
| // alias declaration |
| if alias { |
| if !check.allowVersion(check.pkg, 1, 9) { |
| if check.conf.CompilerErrorMessages { |
| check.error(tdecl, "type aliases only supported as of -lang=go1.9") |
| } else { |
| check.error(tdecl, "type aliases requires go1.9 or later") |
| } |
| } |
| |
| obj.typ = Typ[Invalid] |
| rhs = check.anyType(tdecl.Type) |
| obj.typ = rhs |
| return |
| } |
| |
| // type definition or generic type declaration |
| named := check.newNamed(obj, nil, nil, nil, nil) |
| def.setUnderlying(named) |
| |
| if tdecl.TParamList != nil { |
| check.openScope(tdecl, "type parameters") |
| defer check.closeScope() |
| named.tparams = check.collectTypeParams(tdecl.TParamList) |
| } |
| |
| // determine underlying type of named |
| rhs = check.definedType(tdecl.Type, named) |
| assert(rhs != nil) |
| named.fromRHS = rhs |
| // The underlying type of named may be itself a named type that is |
| // incomplete: |
| // |
| // type ( |
| // A B |
| // B *C |
| // C A |
| // ) |
| // |
| // The type of C is the (named) type of A which is incomplete, |
| // and which has as its underlying type the named type B. |
| // Determine the (final, unnamed) underlying type by resolving |
| // any forward chain. |
| // TODO(gri) Investigate if we can just use named.fromRHS here |
| // and rely on lazy computation of the underlying type. |
| named.underlying = under(named) |
| |
| // If the RHS is a type parameter, it must be from this type declaration. |
| if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.TParams().list(), tpar) < 0 { |
| check.errorf(tdecl.Type, "cannot use function type parameter %s as RHS in type declaration", tpar) |
| named.underlying = Typ[Invalid] |
| } |
| } |
| |
| func (check *Checker) collectTypeParams(list []*syntax.Field) *TParamList { |
| tparams := make([]*TypeParam, len(list)) |
| |
| // Declare type parameters up-front. |
| // The scope of type parameters starts at the beginning of the type parameter |
| // list (so we can have mutually recursive parameterized type bounds). |
| for i, f := range list { |
| tparams[i] = check.declareTypeParam(f.Name) |
| } |
| |
| var bound Type |
| for i, f := range list { |
| // Optimization: Re-use the previous type bound if it hasn't changed. |
| // This also preserves the grouped output of type parameter lists |
| // when printing type strings. |
| if i == 0 || f.Type != list[i-1].Type { |
| bound = check.boundType(f.Type) |
| } |
| tparams[i].bound = bound |
| } |
| |
| return bindTParams(tparams) |
| } |
| |
| func (check *Checker) declareTypeParam(name *syntax.Name) *TypeParam { |
| tname := NewTypeName(name.Pos(), check.pkg, name.Value, nil) |
| tpar := check.NewTypeParam(tname, nil) // assigns type to tname as a side-effect |
| check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position |
| return tpar |
| } |
| |
| // boundType type-checks the type expression e and returns its type, or Typ[Invalid]. |
| // The type must be an interface, including the predeclared type "any". |
| func (check *Checker) boundType(e syntax.Expr) Type { |
| // The predeclared identifier "any" is visible only as a type bound in a type parameter list. |
| // If we allow "any" for general use, this if-statement can be removed (issue #33232). |
| if name, _ := unparen(e).(*syntax.Name); name != nil && name.Value == "any" && check.lookup("any") == universeAny { |
| return universeAny.Type() |
| } |
| |
| bound := check.typ(e) |
| check.later(func() { |
| u := under(bound) |
| if _, ok := u.(*Interface); !ok && u != Typ[Invalid] { |
| check.errorf(e, "%s is not an interface", bound) |
| } |
| }) |
| return bound |
| } |
| |
| func (check *Checker) collectMethods(obj *TypeName) { |
| // get associated methods |
| // (Checker.collectObjects only collects methods with non-blank names; |
| // Checker.resolveBaseTypeName ensures that obj is not an alias name |
| // if it has attached methods.) |
| methods := check.methods[obj] |
| if methods == nil { |
| return |
| } |
| delete(check.methods, obj) |
| assert(!check.objMap[obj].tdecl.Alias) // don't use TypeName.IsAlias (requires fully set up object) |
| |
| // use an objset to check for name conflicts |
| var mset objset |
| |
| // spec: "If the base type is a struct type, the non-blank method |
| // and field names must be distinct." |
| base := asNamed(obj.typ) // shouldn't fail but be conservative |
| if base != nil { |
| u := safeUnderlying(base) // base should be expanded, but use safeUnderlying to be conservative |
| if t, _ := u.(*Struct); t != nil { |
| for _, fld := range t.fields { |
| if fld.name != "_" { |
| assert(mset.insert(fld) == nil) |
| } |
| } |
| } |
| |
| // Checker.Files may be called multiple times; additional package files |
| // may add methods to already type-checked types. Add pre-existing methods |
| // so that we can detect redeclarations. |
| for _, m := range base.methods { |
| assert(m.name != "_") |
| assert(mset.insert(m) == nil) |
| } |
| } |
| |
| // add valid methods |
| for _, m := range methods { |
| // spec: "For a base type, the non-blank names of methods bound |
| // to it must be unique." |
| assert(m.name != "_") |
| if alt := mset.insert(m); alt != nil { |
| var err error_ |
| switch alt.(type) { |
| case *Var: |
| err.errorf(m.pos, "field and method with the same name %s", m.name) |
| case *Func: |
| if check.conf.CompilerErrorMessages { |
| err.errorf(m.pos, "%s.%s redeclared in this block", obj.Name(), m.name) |
| } else { |
| err.errorf(m.pos, "method %s already declared for %s", m.name, obj) |
| } |
| default: |
| unreachable() |
| } |
| err.recordAltDecl(alt) |
| check.report(&err) |
| continue |
| } |
| |
| if base != nil { |
| base.load() // TODO(mdempsky): Probably unnecessary. |
| base.methods = append(base.methods, m) |
| } |
| } |
| } |
| |
| func (check *Checker) funcDecl(obj *Func, decl *declInfo) { |
| assert(obj.typ == nil) |
| |
| // func declarations cannot use iota |
| assert(check.iota == nil) |
| |
| sig := new(Signature) |
| obj.typ = sig // guard against cycles |
| |
| // Avoid cycle error when referring to method while type-checking the signature. |
| // This avoids a nuisance in the best case (non-parameterized receiver type) and |
| // since the method is not a type, we get an error. If we have a parameterized |
| // receiver type, instantiating the receiver type leads to the instantiation of |
| // its methods, and we don't want a cycle error in that case. |
| // TODO(gri) review if this is correct and/or whether we still need this? |
| saved := obj.color_ |
| obj.color_ = black |
| fdecl := decl.fdecl |
| check.funcType(sig, fdecl.Recv, fdecl.TParamList, fdecl.Type) |
| obj.color_ = saved |
| |
| if len(fdecl.TParamList) > 0 && fdecl.Body == nil { |
| check.softErrorf(fdecl, "parameterized function is missing function body") |
| } |
| |
| // function body must be type-checked after global declarations |
| // (functions implemented elsewhere have no body) |
| if !check.conf.IgnoreFuncBodies && fdecl.Body != nil { |
| check.later(func() { |
| check.funcBody(decl, obj.name, sig, fdecl.Body, nil) |
| }) |
| } |
| } |
| |
| func (check *Checker) declStmt(list []syntax.Decl) { |
| pkg := check.pkg |
| |
| first := -1 // index of first ConstDecl in the current group, or -1 |
| var last *syntax.ConstDecl // last ConstDecl with init expressions, or nil |
| for index, decl := range list { |
| if _, ok := decl.(*syntax.ConstDecl); !ok { |
| first = -1 // we're not in a constant declaration |
| } |
| |
| switch s := decl.(type) { |
| case *syntax.ConstDecl: |
| top := len(check.delayed) |
| |
| // iota is the index of the current constDecl within the group |
| if first < 0 || list[index-1].(*syntax.ConstDecl).Group != s.Group { |
| first = index |
| last = nil |
| } |
| iota := constant.MakeInt64(int64(index - first)) |
| |
| // determine which initialization expressions to use |
| inherited := true |
| switch { |
| case s.Type != nil || s.Values != nil: |
| last = s |
| inherited = false |
| case last == nil: |
| last = new(syntax.ConstDecl) // make sure last exists |
| inherited = false |
| } |
| |
| // declare all constants |
| lhs := make([]*Const, len(s.NameList)) |
| values := unpackExpr(last.Values) |
| for i, name := range s.NameList { |
| obj := NewConst(name.Pos(), pkg, name.Value, nil, iota) |
| lhs[i] = obj |
| |
| var init syntax.Expr |
| if i < len(values) { |
| init = values[i] |
| } |
| |
| check.constDecl(obj, last.Type, init, inherited) |
| } |
| |
| // Constants must always have init values. |
| check.arity(s.Pos(), s.NameList, values, true, inherited) |
| |
| // process function literals in init expressions before scope changes |
| check.processDelayed(top) |
| |
| // spec: "The scope of a constant or variable identifier declared |
| // inside a function begins at the end of the ConstSpec or VarSpec |
| // (ShortVarDecl for short variable declarations) and ends at the |
| // end of the innermost containing block." |
| scopePos := syntax.EndPos(s) |
| for i, name := range s.NameList { |
| check.declare(check.scope, name, lhs[i], scopePos) |
| } |
| |
| case *syntax.VarDecl: |
| top := len(check.delayed) |
| |
| lhs0 := make([]*Var, len(s.NameList)) |
| for i, name := range s.NameList { |
| lhs0[i] = NewVar(name.Pos(), pkg, name.Value, nil) |
| } |
| |
| // initialize all variables |
| values := unpackExpr(s.Values) |
| for i, obj := range lhs0 { |
| var lhs []*Var |
| var init syntax.Expr |
| switch len(values) { |
| case len(s.NameList): |
| // lhs and rhs match |
| init = values[i] |
| case 1: |
| // rhs is expected to be a multi-valued expression |
| lhs = lhs0 |
| init = values[0] |
| default: |
| if i < len(values) { |
| init = values[i] |
| } |
| } |
| check.varDecl(obj, lhs, s.Type, init) |
| if len(values) == 1 { |
| // If we have a single lhs variable we are done either way. |
| // If we have a single rhs expression, it must be a multi- |
| // valued expression, in which case handling the first lhs |
| // variable will cause all lhs variables to have a type |
| // assigned, and we are done as well. |
| if debug { |
| for _, obj := range lhs0 { |
| assert(obj.typ != nil) |
| } |
| } |
| break |
| } |
| } |
| |
| // If we have no type, we must have values. |
| if s.Type == nil || values != nil { |
| check.arity(s.Pos(), s.NameList, values, false, false) |
| } |
| |
| // process function literals in init expressions before scope changes |
| check.processDelayed(top) |
| |
| // declare all variables |
| // (only at this point are the variable scopes (parents) set) |
| scopePos := syntax.EndPos(s) // see constant declarations |
| for i, name := range s.NameList { |
| // see constant declarations |
| check.declare(check.scope, name, lhs0[i], scopePos) |
| } |
| |
| case *syntax.TypeDecl: |
| obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Value, nil) |
| // spec: "The scope of a type identifier declared inside a function |
| // begins at the identifier in the TypeSpec and ends at the end of |
| // the innermost containing block." |
| scopePos := s.Name.Pos() |
| check.declare(check.scope, s.Name, obj, scopePos) |
| // mark and unmark type before calling typeDecl; its type is still nil (see Checker.objDecl) |
| obj.setColor(grey + color(check.push(obj))) |
| check.typeDecl(obj, s, nil) |
| check.pop().setColor(black) |
| |
| default: |
| check.errorf(s, invalidAST+"unknown syntax.Decl node %T", s) |
| } |
| } |
| } |
