go decl 源码
golang decl 代码
文件路径：/src/go/types/decl.go
// 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 types
import (
"bytes"
"fmt"
"go/ast"
"go/constant"
"go/token"
)
func (check *Checker) reportAltDecl(obj Object) {
if pos := obj.Pos(); pos.IsValid() {
// We use "other" rather than "previous" here because
// the first declaration seen may not be textually
// earlier in the source.
check.errorf(obj, _DuplicateDecl, "\tother declaration of %s", obj.Name()) // secondary error, \t indented
}
}
func (check *Checker) declare(scope *Scope, id *ast.Ident, obj Object, pos token.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 {
check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
check.reportAltDecl(alt)
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) environment.
// For the meaning of def, see Checker.definedType, in typexpr.go.
func (check *Checker) objDecl(obj Object, def *Named) {
if 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 (possibly invalid) 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.validCycle(obj) || obj.typ == nil {
obj.typ = Typ[Invalid]
}
case *Var:
if !check.validCycle(obj) || obj.typ == nil {
obj.typ = Typ[Invalid]
}
case *TypeName:
if !check.validCycle(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.validCycle(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 environment and set up object environment
defer func(env environment) {
check.environment = env
}(check.environment)
check.environment = environment{
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()
}
}
// validCycle checks if the cycle starting with obj is valid and
// reports an error if it is not.
func (check *Checker) validCycle(obj Object) (valid 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:]
tparCycle := false // if set, the cycle is through a type parameter list
nval := 0 // number of (constant or variable) values in the cycle; valid if !generic
ndef := 0 // number of type definitions in the cycle; valid if !generic
loop:
for _, obj := range cycle {
switch obj := obj.(type) {
case *Const, *Var:
nval++
case *TypeName:
// If we reach a generic type that is part of a cycle
// and we are in a type parameter list, we have a cycle
// through a type parameter list, which is invalid.
if check.inTParamList && isGeneric(obj.typ) {
tparCycle = true
break loop
}
// 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.Assign.IsValid() // package-level object
} else {
alias = obj.IsAlias() // function local object
}
if !alias {
ndef++
}
case *Func:
// ignored for now
default:
unreachable()
}
}
if trace {
check.trace(obj.Pos(), "## cycle detected: objPath = %s->%s (len = %d)", pathString(cycle), obj.Name(), len(cycle))
if tparCycle {
check.trace(obj.Pos(), "## cycle contains: generic type in a type parameter list")
} else {
check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef)
}
defer func() {
if valid {
check.trace(obj.Pos(), "=> cycle is valid")
} else {
check.trace(obj.Pos(), "=> error: cycle is invalid")
}
}()
}
if !tparCycle {
// 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 true
}
// 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 true
}
}
check.cycleError(cycle)
return false
}
// cycleError reports a declaration cycle starting with
// the object in cycle that is "first" in the source.
func (check *Checker) cycleError(cycle []Object) {
// name returns the (possibly qualified) object name.
// This is needed because with generic types, cycles
// may refer to imported types. See issue #50788.
// TODO(gri) Thus functionality is used elsewhere. Factor it out.
name := func(obj Object) string {
var buf bytes.Buffer
writePackage(&buf, obj.Pkg(), check.qualifier)
buf.WriteString(obj.Name())
return buf.String()
}
// 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]
objName := name(obj)
// If obj is a type alias, mark it as valid (not broken) in order to avoid follow-on errors.
tname, _ := obj.(*TypeName)
if tname != nil && tname.IsAlias() {
check.validAlias(tname, Typ[Invalid])
}
if tname != nil && compilerErrorMessages {
check.errorf(obj, _InvalidDeclCycle, "invalid recursive type %s", objName)
} else {
check.errorf(obj, _InvalidDeclCycle, "illegal cycle in declaration of %s", objName)
}
for range cycle {
check.errorf(obj, _InvalidDeclCycle, "\t%s refers to", objName) // secondary error, \t indented
i++
if i >= len(cycle) {
i = 0
}
obj = cycle[i]
objName = name(obj)
}
check.errorf(obj, _InvalidDeclCycle, "\t%s", objName)
}
// 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() < pos {
fst, pos = i+1, t.Pos()
}
}
return fst
}
type (
decl interface {
node() ast.Node
}
importDecl struct{ spec *ast.ImportSpec }
constDecl struct {
spec *ast.ValueSpec
iota int
typ ast.Expr
init []ast.Expr
inherited bool
}
varDecl struct{ spec *ast.ValueSpec }
typeDecl struct{ spec *ast.TypeSpec }
funcDecl struct{ decl *ast.FuncDecl }
)
func (d importDecl) node() ast.Node { return d.spec }
func (d constDecl) node() ast.Node { return d.spec }
func (d varDecl) node() ast.Node { return d.spec }
func (d typeDecl) node() ast.Node { return d.spec }
func (d funcDecl) node() ast.Node { return d.decl }
func (check *Checker) walkDecls(decls []ast.Decl, f func(decl)) {
for _, d := range decls {
check.walkDecl(d, f)
}
}
func (check *Checker) walkDecl(d ast.Decl, f func(decl)) {
switch d := d.(type) {
case *ast.BadDecl:
// ignore
case *ast.GenDecl:
var last *ast.ValueSpec // last ValueSpec with type or init exprs seen
for iota, s := range d.Specs {
switch s := s.(type) {
case *ast.ImportSpec:
f(importDecl{s})
case *ast.ValueSpec:
switch d.Tok {
case token.CONST:
// determine which initialization expressions to use
inherited := true
switch {
case s.Type != nil || len(s.Values) > 0:
last = s
inherited = false
case last == nil:
last = new(ast.ValueSpec) // make sure last exists
inherited = false
}
check.arityMatch(s, last)
f(constDecl{spec: s, iota: iota, typ: last.Type, init: last.Values, inherited: inherited})
case token.VAR:
check.arityMatch(s, nil)
f(varDecl{s})
default:
check.invalidAST(s, "invalid token %s", d.Tok)
}
case *ast.TypeSpec:
f(typeDecl{s})
default:
check.invalidAST(s, "unknown ast.Spec node %T", s)
}
}
case *ast.FuncDecl:
f(funcDecl{d})
default:
check.invalidAST(d, "unknown ast.Decl node %T", d)
}
}
func (check *Checker) constDecl(obj *Const, typ, init ast.Expr, inherited bool) {
assert(obj.typ == nil)
// use the correct value of iota
defer func(iota constant.Value, errpos positioner) {
check.iota = iota
check.errpos = errpos
}(check.iota, check.errpos)
check.iota = obj.val
check.errpos = nil
// 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, _InvalidConstType, "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 = atPos(obj.pos)
}
check.expr(&x, init)
}
check.initConst(obj, &x)
}
func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
assert(obj.typ == nil)
// 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, []ast.Expr{init}, nil)
}
// 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.IsMethodSet()
}
func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
assert(obj.typ == nil)
var rhs Type
check.later(func() {
if t, _ := obj.typ.(*Named); t != nil { // type may be invalid
check.validType(t)
}
// 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, _UnsupportedFeature, "using type constraint %s requires go1.18 or later", rhs)
}
}).describef(obj, "validType(%s)", obj.Name())
alias := tdecl.Assign.IsValid()
if alias && tdecl.TypeParams.NumFields() != 0 {
// The parser will ensure this but we may still get an invalid AST.
// Complain and continue as regular type definition.
check.error(atPos(tdecl.Assign), _BadDecl, "generic type cannot be alias")
alias = false
}
// alias declaration
if alias {
if !check.allowVersion(check.pkg, 1, 9) {
check.errorf(atPos(tdecl.Assign), _BadDecl, "type aliases requires go1.9 or later")
}
check.brokenAlias(obj)
rhs = check.typ(tdecl.Type)
check.validAlias(obj, rhs)
return
}
// type definition or generic type declaration
named := check.newNamed(obj, nil, nil)
def.setUnderlying(named)
if tdecl.TypeParams != nil {
check.openScope(tdecl, "type parameters")
defer check.closeScope()
check.collectTypeParams(&named.tparams, tdecl.TypeParams)
}
// determine underlying type of named
rhs = check.definedType(tdecl.Type, named)
assert(rhs != nil)
named.fromRHS = rhs
// If the underlying type was not set while type-checking the right-hand
// side, it is invalid and an error should have been reported elsewhere.
if named.underlying == nil {
named.underlying = Typ[Invalid]
}
// Disallow a lone type parameter as the RHS of a type declaration (issue #45639).
// We don't need this restriction anymore if we make the underlying type of a type
// parameter its constraint interface: if the RHS is a lone type parameter, we will
// use its underlying type (like we do for any RHS in a type declaration), and its
// underlying type is an interface and the type declaration is well defined.
if isTypeParam(rhs) {
check.error(tdecl.Type, _MisplacedTypeParam, "cannot use a type parameter as RHS in type declaration")
named.underlying = Typ[Invalid]
}
}
func (check *Checker) collectTypeParams(dst **TypeParamList, list *ast.FieldList) {
var tparams []*TypeParam
// Declare type parameters up-front, with empty interface as type bound.
// The scope of type parameters starts at the beginning of the type parameter
// list (so we can have mutually recursive parameterized interfaces).
for _, f := range list.List {
tparams = check.declareTypeParams(tparams, f.Names)
}
// Set the type parameters before collecting the type constraints because
// the parameterized type may be used by the constraints (issue #47887).
// Example: type T[P T[P]] interface{}
*dst = bindTParams(tparams)
// Signal to cycle detection that we are in a type parameter list.
// We can only be inside one type parameter list at any given time:
// function closures may appear inside a type parameter list but they
// cannot be generic, and their bodies are processed in delayed and
// sequential fashion. Note that with each new declaration, we save
// the existing environment and restore it when done; thus inTPList is
// true exactly only when we are in a specific type parameter list.
assert(!check.inTParamList)
check.inTParamList = true
defer func() {
check.inTParamList = false
}()
index := 0
for _, f := range list.List {
var bound Type
// NOTE: we may be able to assert that f.Type != nil here, but this is not
// an invariant of the AST, so we are cautious.
if f.Type != nil {
bound = check.bound(f.Type)
if isTypeParam(bound) {
// We may be able to allow this since it is now well-defined what
// the underlying type and thus type set of a type parameter is.
// But we may need some additional form of cycle detection within
// type parameter lists.
check.error(f.Type, _MisplacedTypeParam, "cannot use a type parameter as constraint")
bound = Typ[Invalid]
}
} else {
bound = Typ[Invalid]
}
for i := range f.Names {
tparams[index+i].bound = bound
}
index += len(f.Names)
}
}
func (check *Checker) bound(x ast.Expr) Type {
// A type set literal of the form ~T and A|B may only appear as constraint;
// embed it in an implicit interface so that only interface type-checking
// needs to take care of such type expressions.
wrap := false
switch op := x.(type) {
case *ast.UnaryExpr:
wrap = op.Op == token.TILDE
case *ast.BinaryExpr:
wrap = op.Op == token.OR
}
if wrap {
x = &ast.InterfaceType{Methods: &ast.FieldList{List: []*ast.Field{{Type: x}}}}
t := check.typ(x)
// mark t as implicit interface if all went well
if t, _ := t.(*Interface); t != nil {
t.implicit = true
}
return t
}
return check.typ(x)
}
func (check *Checker) declareTypeParams(tparams []*TypeParam, names []*ast.Ident) []*TypeParam {
// Use Typ[Invalid] for the type constraint to ensure that a type
// is present even if the actual constraint has not been assigned
// yet.
// TODO(gri) Need to systematically review all uses of type parameter
// constraints to make sure we don't rely on them if they
// are not properly set yet.
for _, name := range names {
tname := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
tpar := check.newTypeParam(tname, Typ[Invalid]) // assigns type to tpar as a side-effect
check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position
tparams = append(tparams, tpar)
}
if trace && len(names) > 0 {
check.trace(names[0].Pos(), "type params = %v", tparams[len(tparams)-len(names):])
}
return tparams
}
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.Assign.IsValid()) // 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, _ := obj.typ.(*Named) // shouldn't fail but be conservative
if base != nil {
assert(base.TypeArgs().Len() == 0) // collectMethods should not be called on an instantiated type
// See issue #52529: we must delay the expansion of underlying here, as
// base may not be fully set-up.
check.later(func() {
check.checkFieldUniqueness(base)
}).describef(obj, "verifying field uniqueness for %v", base)
// 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 i := 0; i < base.NumMethods(); i++ {
m := base.Method(i)
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 {
check.errorf(m, _DuplicateMethod, "method %s already declared for %s", m.name, obj)
check.reportAltDecl(alt)
continue
}
if base != nil {
base.AddMethod(m)
}
}
}
func (check *Checker) checkFieldUniqueness(base *Named) {
if t, _ := base.under().(*Struct); t != nil {
var mset objset
for i := 0; i < base.NumMethods(); i++ {
m := base.Method(i)
assert(m.name != "_")
assert(mset.insert(m) == nil)
}
// Check that any non-blank field names of base are distinct from its
// method names.
for _, fld := range t.fields {
if fld.name != "_" {
if alt := mset.insert(fld); alt != nil {
// Struct fields should already be unique, so we should only
// encounter an alternate via collision with a method name.
_ = alt.(*Func)
// For historical consistency, we report the primary error on the
// method, and the alt decl on the field.
check.errorf(alt, _DuplicateFieldAndMethod, "field and method with the same name %s", fld.name)
check.reportAltDecl(fld)
}
}
}
}
}
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.Type)
obj.color_ = saved
if fdecl.Type.TypeParams.NumFields() > 0 && fdecl.Body == nil {
check.softErrorf(fdecl.Name, _BadDecl, "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)
}).describef(obj, "func %s", obj.name)
}
}
func (check *Checker) declStmt(d ast.Decl) {
pkg := check.pkg
check.walkDecl(d, func(d decl) {
switch d := d.(type) {
case constDecl:
top := len(check.delayed)
// declare all constants
lhs := make([]*Const, len(d.spec.Names))
for i, name := range d.spec.Names {
obj := NewConst(name.Pos(), pkg, name.Name, nil, constant.MakeInt64(int64(d.iota)))
lhs[i] = obj
var init ast.Expr
if i < len(d.init) {
init = d.init[i]
}
check.constDecl(obj, d.typ, init, d.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 := d.spec.End()
for i, name := range d.spec.Names {
check.declare(check.scope, name, lhs[i], scopePos)
}
case varDecl:
top := len(check.delayed)
lhs0 := make([]*Var, len(d.spec.Names))
for i, name := range d.spec.Names {
lhs0[i] = NewVar(name.Pos(), pkg, name.Name, nil)
}
// initialize all variables
for i, obj := range lhs0 {
var lhs []*Var
var init ast.Expr
switch len(d.spec.Values) {
case len(d.spec.Names):
// lhs and rhs match
init = d.spec.Values[i]
case 1:
// rhs is expected to be a multi-valued expression
lhs = lhs0
init = d.spec.Values[0]
default:
if i < len(d.spec.Values) {
init = d.spec.Values[i]
}
}
check.varDecl(obj, lhs, d.spec.Type, init)
if len(d.spec.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
}
}
// 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 := d.spec.End() // see constant declarations
for i, name := range d.spec.Names {
// see constant declarations
check.declare(check.scope, name, lhs0[i], scopePos)
}
case typeDecl:
obj := NewTypeName(d.spec.Name.Pos(), pkg, d.spec.Name.Name, 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 := d.spec.Name.Pos()
check.declare(check.scope, d.spec.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, d.spec, nil)
check.pop().setColor(black)
default:
check.invalidAST(d.node(), "unknown ast.Decl node %T", d.node())
}
})
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦