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compiler: prohibit to compile type assertion with two return values

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Close #2692.
This commit is contained in:
Anna Shaleva 2022-09-28 09:58:59 +03:00
parent 3dbd36ef70
commit b98848bf49
3 changed files with 117 additions and 8 deletions
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27
pkg/compiler/codegen.go
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@ -161,6 +161,9 @@ const (
varArgument
)
// ErrUnsupportedTypeAssertion is returned when type assertion statement is not supported by the compiler.
var ErrUnsupportedTypeAssertion = errors.New("type assertion with two return values is not supported")
// newLabel creates a new label to jump to.
func (c *codegen) newLabel() (l uint16) {
li := len(c.l)
@ -584,6 +587,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
for _, spec := range n.Specs {
switch t := spec.(type) {
case *ast.ValueSpec:
// Filter out type assertion with two return values: var i, ok = v.(int)
if len(t.Names) == 2 && len(t.Values) == 1 && n.Tok == token.VAR {
err := checkTypeAssertWithOK(t.Values[0])
if err != nil {
c.prog.Err = err
return nil
}
}
multiRet := n.Tok == token.VAR && len(t.Values) != 0 && len(t.Names) != len(t.Values)
for _, id := range t.Names {
if id.Name != "_" {
@ -630,6 +641,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
return nil
case *ast.AssignStmt:
// Filter out type assertion with two return values: i, ok = v.(int)
if len(n.Lhs) == 2 && len(n.Rhs) == 1 && (n.Tok == token.DEFINE || n.Tok == token.ASSIGN) {
err := checkTypeAssertWithOK(n.Rhs[0])
if err != nil {
c.prog.Err = err
return nil
}
}
multiRet := len(n.Rhs) != len(n.Lhs)
c.saveSequencePoint(n)
// Assign operations are grouped https://github.com/golang/go/blob/master/src/go/types/stmt.go#L160
@ -1346,6 +1365,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
return c
}
func checkTypeAssertWithOK(n ast.Node) error {
if t, ok := n.(*ast.TypeAssertExpr); ok &&
t.Type != nil { // not a type switch
return ErrUnsupportedTypeAssertion
}
return nil
}
// packVarArgs packs variadic arguments into an array
// and returns the amount of arguments packed.
func (c *codegen) packVarArgs(n *ast.CallExpr, typ *types.Signature) int {