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go.tools/go/types: declare typeswitch local variable in correct scope

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R=adonovan
CC=golang-dev
https://golang.org/cl/11534044
This commit is contained in:
Robert Griesemer 2013-07-23 14:18:38 -07:00
parent 7bc647b29a
commit 09d04edfcf
2 changed files with 25 additions and 12 deletions
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23
go/types/stmt.go
View File

@ -381,12 +381,6 @@ func (check *checker) stmt(s ast.Stmt) {
return
}
var obj Object
if lhs != nil {
obj = NewVar(lhs.Pos(), check.pkg, lhs.Name, x.typ)
check.declare(check.topScope, lhs, obj)
}
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
@ -411,14 +405,19 @@ func (check *checker) stmt(s ast.Stmt) {
}
}
check.openScope(clause)
// If lhs exists, declare a corresponding object in the case-local scope if necessary.
// If lhs exists, declare a corresponding variable in the case-local scope if necessary.
if lhs != nil {
// A single-type case clause implicitly declares a new variable shadowing lhs.
if len(clause.List) == 1 && typ != nil {
obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, typ)
check.declare(check.topScope, nil, obj)
check.recordImplicit(clause, obj)
// spec: "The TypeSwitchGuard may include a short variable declaration.
// When that form is used, the variable is declared at the beginning of
// the implicit block in each clause. In clauses with a case listing
// exactly one type, the variable has that type; otherwise, the variable
// has the type of the expression in the TypeSwitchGuard."
if len(clause.List) != 1 || typ == nil {
typ = x.typ
}
obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, typ)
check.declare(check.topScope, nil, obj)
check.recordImplicit(clause, obj)
}
check.stmtList(clause.Body)
check.closeScope()

14
go/types/testdata/stmt0.src vendored
View File

@ -229,6 +229,20 @@ func typeswitch0() {
}
}
// Test correct scope setup.
// (no redeclaration errors expected in the type switch)
func typeswitch1() {
var t I
switch t := t; t := t.(type) {
case nil:
var _ I = t
case T:
var _ T = t
default:
var _ I = t
}
}
func rangeloops() {
var (
x int