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Go: Do not panic when extracting an object without a parent scope #16865

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Go: Do not panic when extracting an object without a parent scope #16865

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43 changes: 23 additions & 20 deletions go/extractor/trap/labels.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package trap
import (
"fmt"
"go/types"
"log"

"github.com/github/codeql-go/extractor/util"
)
Expand Down Expand Up @@ -119,15 +120,12 @@ func (l *Labeler) ScopeID(scope *types.Scope, pkg *types.Package) Label {
func (l *Labeler) LookupObjectID(object types.Object, typelbl Label) (Label, bool) {
label, exists := l.objectLabels[object]
if !exists {
if object.Parent() == nil {
// blank identifiers and the pseudo-package `.` (from `import . "..."` imports) can only be referenced
// once, so we can use a fresh label for them
if object.Name() == "_" || object.Name() == "." {
label = l.FreshID()
l.objectLabels[object] = label
return label, false
}
label = InvalidLabel
// blank identifiers and the pseudo-package `.` (from `import . "..."` imports) do not have
// a parent scope, so we have to deal with them separately. They can only be referenced
// once, so we can use a fresh label for them.
if object.Parent() == nil && (object.Name() == "_" || object.Name() == ".") {
label = l.FreshID()
l.objectLabels[object] = label
} else {
label, exists = l.ScopedObjectID(object, func() Label { return typelbl })
}
Expand All @@ -147,20 +145,25 @@ func (l *Labeler) LookupObjectID(object types.Object, typelbl Label) (Label, boo
func (l *Labeler) ScopedObjectID(object types.Object, getTypeLabel func() Label) (Label, bool) {
label, exists := l.objectLabels[object]
if !exists {
scope := object.Parent()
if scope == nil {
panic(fmt.Sprintf("Object has no scope: %v :: %v.\n", object,
l.tw.Package.Fset.Position(object.Pos())))
if meth := findMethodWithGivenReceiver(object); meth != nil {
// associate method receiver objects to special keys, because those can be
// referenced from other files via their method
methlbl, _ := l.MethodID(meth, getTypeLabel())
label, _ = l.ReceiverObjectID(object, methlbl)
} else {
if meth := findMethodWithGivenReceiver(object); meth != nil {
// associate method receiver objects to special keys, because those can be
// referenced from other files via their method
methlbl, _ := l.MethodID(meth, getTypeLabel())
label, _ = l.ReceiverObjectID(object, methlbl)
scope := object.Parent()
var scopeLbl Label
if scope == nil {
// Something has gone wrong if we get here, but we can't panic because
// we want extraction to be deterministic, to avoid alerts appearing and
// disappearing.
log.Printf("Error: Object has no scope: %v :: %v.\n", object,
l.tw.Package.Fset.Position(object.Pos()))
scopeLbl = l.FreshID()
} else {
scopeLbl := l.ScopeID(scope, object.Pkg())
label = l.GlobalID(fmt.Sprintf("{%v},%s;object", scopeLbl, object.Name()))
scopeLbl = l.ScopeID(scope, object.Pkg())
}
label = l.GlobalID(fmt.Sprintf("{%v},%s;object", scopeLbl, object.Name()))
}
l.objectLabels[object] = label
}
Expand Down
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