[DWARF] Use std::optional in DWARFFormValue.cpp (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
index 1fecd5e..bd8c9d6 100644 (file)
--- a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -25,6 +25,7 @@
 #include <cinttypes>
 #include <cstdint>
 #include <limits>
+#include <optional>
 
 using namespace llvm;
 using namespace dwarf;
@@ -635,7 +636,7 @@ Expected<const char *> DWARFFormValue::getAsCString() const {
     return make_error<StringError>("Unsupported form for string attribute",
                                    inconvertibleErrorCode());
   uint64_t Offset = Value.uval;
-  Optional<uint32_t> Index;
+  std::optional<uint32_t> Index;
   if (Form == DW_FORM_GNU_str_index || Form == DW_FORM_strx ||
       Form == DW_FORM_strx1 || Form == DW_FORM_strx2 || Form == DW_FORM_strx3 ||
       Form == DW_FORM_strx4) {