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go/types: remove visited flag for constants and variables (cleanup)

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Now that we have a color marking scheme for all objects, the
pre-existing 'visited' flag for constants and variables is
redundant: visited is the same as marking an object non-white.

Refactor the respective 'visited' flag logic from constDecl and
varDecl into the color switch in objDecl and remove the 'visited'
flag.

Follow-up on https://go-review.googlesource.com/c/go/+/114517 .

Change-Id: Ie20de65e3b26a5a6ff7b0eddc3d089f56be204e8
Reviewed-on: https://go-review.googlesource.com/115619
Reviewed-by: Alan Donovan <adonovan@google.com>
This commit is contained in:
Robert Griesemer 2018-05-31 15:18:21 -07:00
parent 3d6e4ec0a8
commit 6cfeedb229
2 changed files with 18 additions and 37 deletions
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49
src/go/types/decl.go
View File

@ -113,27 +113,29 @@ func (check *Checker) objDecl(obj Object, def *Named, path []*TypeName) {
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, which
// have their own "visited" flag (the new marking approach
// will allow us to remove that flag eventually). Their type
// may be nil because they haven't determined their init
// values yet (from which to deduce the type). But in that
// case, they must have been marked as visited.
// For now, handle constants and variables specially.
visited := false
// 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:
visited = obj.visited
if obj.typ == nil {
obj.typ = Typ[Invalid]
}
case *Var:
visited = obj.visited
if obj.typ == nil {
obj.typ = Typ[Invalid]
}
case *TypeName:
assert(obj.Type() != nil)
if useCycleMarking {
check.typeCycle(obj)
}
return
case *Func:
// Cycles involving functions require variables in
@ -142,19 +144,12 @@ func (check *Checker) objDecl(obj Object, def *Named, path []*TypeName) {
// function type is set to an empty signature which
// makes it impossible to initialize a variable with
// the function).
assert(obj.Type() != nil)
return
default:
unreachable()
}
// we have a *Const or *Var
if obj.Type() != nil {
return
}
assert(visited)
assert(obj.Type() != nil)
return
}
if trace {
@ -260,12 +255,6 @@ func (check *Checker) typeCycle(obj *TypeName) {
func (check *Checker) constDecl(obj *Const, typ, init ast.Expr) {
assert(obj.typ == nil)
if obj.visited {
obj.typ = Typ[Invalid]
return
}
obj.visited = true
// use the correct value of iota
check.iota = obj.val
defer func() { check.iota = nil }()
@ -299,12 +288,6 @@ func (check *Checker) constDecl(obj *Const, typ, init ast.Expr) {
func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
assert(obj.typ == nil)
if obj.visited {
obj.typ = Typ[Invalid]
return
}
obj.visited = true
// determine type, if any
if typ != nil {
obj.typ = check.typ(typ)

6
src/go/types/object.go
View File

@ -197,14 +197,13 @@ func (obj *PkgName) Imported() *Package { return obj.imported }
// A Const represents a declared constant.
type Const struct {
object
val constant.Value
visited bool // for initialization cycle detection
val constant.Value
}
// NewConst returns a new constant with value val.
// The remaining arguments set the attributes found with all Objects.
func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const {
return &Const{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, val, false}
return &Const{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, val}
}
// Val returns the constant's value.
@ -256,7 +255,6 @@ func (obj *TypeName) IsAlias() bool {
type Var struct {
object
embedded bool // if set, the variable is an embedded struct field, and name is the type name
visited bool // for initialization cycle detection
isField bool // var is struct field
used bool // set if the variable was used
}