Retain empty optional import selection evidence

internal/engine/records.go

@@ -192,11 +192,21 @@ type SourceInfo struct {
 	UnderlayIndex         int
 	ImportedFrom          *Location
 	VersionCheck          *SourceVersionCheck
+	importSelections      []importSelectionEvidence
 	namespace             *namespaceToken
 	placementMode         placementMode
 	destinationUnresolved bool
 }
 
+// importSelectionEvidence records one completed optional declaration whose
+// selected candidates produced no admitted source.
+type importSelectionEvidence struct {
+	path     Path
+	location Location
+	selector importSelector
+	outcome  importSelectionOutcome
+}
+
 // SourceInfoPlacementModeForFacade converts private placement evidence to its
 // root-owned numeric representation.
 func SourceInfoPlacementModeForFacade(source SourceInfo) uint8 {
@@ -293,6 +303,14 @@ func cloneSourceInfo(source SourceInfo) SourceInfo {
 	source.ImportedFrom = cloneLocation(source.ImportedFrom)
 	source.Destination = source.Destination.clone()
 	source.VersionCheck = cloneSourceVersionCheck(source.VersionCheck)
+	if source.importSelections != nil {
+		selections := make([]importSelectionEvidence, len(source.importSelections))
+		for index, selection := range source.importSelections {
+			selection.path = selection.path.clone()
+			selections[index] = selection
+		}
+		source.importSelections = selections
+	}
 	return source
 }