[clang-tools-extra] Add #include <optional> (NFC)

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

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

206 files changed, 206 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp b/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
index b9e83ac..43ecfd8 100644
--- a/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
+++ b/clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp
@@ -29,6 +29,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang-tools-extra/clang-doc/HTMLGenerator.cpp b/clang-tools-extra/clang-doc/HTMLGenerator.cpp
index 37598c4..589a323 100644
--- a/clang-tools-extra/clang-doc/HTMLGenerator.cpp
+++ b/clang-tools-extra/clang-doc/HTMLGenerator.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <string>
 
 using namespace llvm;
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
index f41d4782..2cee438 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.cpp
@@ -16,6 +16,7 @@
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/Token.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace find_all_symbols {
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
index 0a51ab1..99a7f5d 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllMacros.h
@@ -13,6 +13,7 @@
 #include "SymbolInfo.h"
 #include "SymbolReporter.h"
 #include "clang/Lex/PPCallbacks.h"
+#include <optional>
 
 namespace clang {
 class MacroInfo;
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
index ccfdb93..8608ba7 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp
@@ -18,6 +18,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/FileSystem.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-query/Query.cpp b/clang-tools-extra/clang-query/Query.cpp
index 4d62f37..d1db851 100644
--- a/clang-tools-extra/clang-query/Query.cpp
+++ b/clang-tools-extra/clang-query/Query.cpp
@@ -14,6 +14,7 @@
 #include "clang/Frontend/TextDiagnostic.h"
 #include "clang/Tooling/NodeIntrospection.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::dynamic;
diff --git a/clang-tools-extra/clang-query/QueryParser.cpp b/clang-tools-extra/clang-query/QueryParser.cpp
index b80ad04..77621d2 100644
--- a/clang-tools-extra/clang-query/QueryParser.cpp
+++ b/clang-tools-extra/clang-query/QueryParser.cpp
@@ -14,6 +14,7 @@
 #include "clang/Tooling/NodeIntrospection.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 #include <set>
 
 using namespace llvm;
diff --git a/clang-tools-extra/clang-query/tool/ClangQuery.cpp b/clang-tools-extra/clang-query/tool/ClangQuery.cpp
index 2bdb361..6ba2b1a 100644
--- a/clang-tools-extra/clang-query/tool/ClangQuery.cpp
+++ b/clang-tools-extra/clang-query/tool/ClangQuery.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/WithColor.h"
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
index fedf3aa..8f90bec 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/YAMLParser.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/ClangTidyCheck.h b/clang-tools-extra/clang-tidy/ClangTidyCheck.h
index e5d98b0..f2486ea 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <type_traits>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
index e6b9070..05ca257 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
@@ -36,6 +36,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Regex.h"
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
index 261e4f7..475f38d 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
@@ -17,6 +17,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Regex.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
index 9df2641..0cfdda3 100644
--- a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
+++ b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
@@ -12,6 +12,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Serialization/ASTReader.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
index 08d837c..7a822cd 100644
--- a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
+++ b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
@@ -28,6 +28,7 @@
 #include <cassert>
 #include <cstddef>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <type_traits>
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
index 60047096..585b7c1 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
index a6e12dd..39c7ba4 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
index d3007d7..3a83e67 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
index 4b0ef1b..0951234 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
index ba7dc70..b33f1e3 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
index 43f8ed7..c2325c1 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <cmath>
+#include <optional>
 
 #include "DurationRewriter.h"
 #include "clang/Tooling/FixIt.h"
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
index d8b0acf..a23dfaf 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
+++ b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.h
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include <cinttypes>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
index 3221714..4d12fd3 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
index b73b100..36e670e 100644
--- a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
index 391f38f..ddbde75 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
index 58ce1f4..9f2fba4 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
index f1bfcc8..2676540 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
index 6276179..3a5919d 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_BADSIGNALTOKILLTHREADCHECK_H
 
 #include "../ClangTidyCheck.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
index f1b7888..23244dc 100644
--- a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
@@ -16,6 +16,7 @@
 
 #define DEBUG_TYPE "EasilySwappableParametersCheck"
 #include "llvm/Support/Debug.h"
+#include <optional>
 
 namespace optutils = clang::tidy::utils::options;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
index fbf3438..601949b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -9,6 +9,7 @@
 #include "ImplicitWideningOfMultiplicationResultCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
index 19c364d..74152ef 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "../utils/IncludeInserter.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
index 17537f1d1..ce58f1e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -13,6 +13,7 @@
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
index 71c7daa..560e9a1 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
@@ -14,6 +14,7 @@
 #include "clang/Lex/Token.h"
 #include <algorithm>
 #include <cctype>
+#include <optional>
 
 // FixItHint
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
index 0769fce..99c1dbe 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.h
@@ -11,6 +11,7 @@
 
 #include "../utils/RenamerClangTidyCheck.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
index cd9aa00..1778827 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
@@ -9,6 +9,7 @@
 #include "SuspiciousIncludeCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
index d731d7d..a1d04dc 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
@@ -9,6 +9,7 @@
 #include "SuspiciousMemoryComparisonCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
index ccf9365..89d39d2 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Error.h"
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
index ae583fd..052d6c6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h
@@ -12,6 +12,7 @@
 #include "../ClangTidyCheck.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
index d2a0dd6..6c4fa9c 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/STLExtras.h"
 
 #include "../utils/ExprSequence.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils;
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
index e54a4f3..d759908 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
index c80be3d..6692bac 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
index 2eb6e40..234ddd4 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 #include <string>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
index f5ab332f..1055d26 100644
--- a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
index e7c7933..7c3811c 100644
--- a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -25,6 +25,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
index 93df491..eaa7022 100644
--- a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
+#include <optional>
 #include <string>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
index 5e3e05e..900077e 100644
--- a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
@@ -9,6 +9,7 @@
 #include "DeprecatedIosBaseAliasesCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
index 3033fcb..2db958c 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstring>
+#include <optional>
 #include <utility>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
index fc3dfbd..7253b1d 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
@@ -21,6 +21,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
index 438fd48..fd96cb2 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
index a545fae..adf07086 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
index 9dc9093..6023fdd 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/StringExtras.h"
 
 #include <cctype>
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
index c2d8310..fa9dd40 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "clang/Lex/Token.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
index a8da911..676654c 100644
--- a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
+++ b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "clang/StaticAnalyzer/Checkers/MPIFunctionClassifier.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
index da7b7c2..261fec4 100644
--- a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
+++ b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.h
@@ -12,6 +12,7 @@
 #include "../ClangTidyCheck.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/StaticAnalyzer/Checkers/MPIFunctionClassifier.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
index 1650563..5127eaa 100644
--- a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
@@ -25,6 +25,7 @@
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
index e16be63..1905247 100644
--- a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
index 8046301..d2899852 100644
--- a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
@@ -14,6 +14,7 @@
 #include "../utils/TypeTraits.h"
 #include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 #include "clang/Basic/Diagnostic.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
index b76f4bb..249c002 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -14,6 +14,7 @@
 #include "../utils/OptionsUtils.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/Diagnostic.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
index a8ca761..c3f742e 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -16,6 +16,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
index 0c9bda7..e1ad21a 100644
--- a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
@@ -13,6 +13,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
index ba9e3d8..416952c 100644
--- a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <array>
 #include <cassert>
+#include <optional>
 #include <stack>
 #include <tuple>
 #include <type_traits>
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
index 524cd90..6aaa46d1 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/YAMLParser.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
index 2739d18..a3ff2d5 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
@@ -11,6 +11,7 @@
 
 #include "../utils/RenamerClangTidyCheck.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 namespace clang {
 namespace tidy {
 namespace readability {
diff --git a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
index 45f3ea6..bc3d40d 100644
--- a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
@@ -9,6 +9,7 @@
 #include "IsolateDeclarationCheck.h"
 #include "../utils/LexerUtils.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils::lexer;
diff --git a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
index 7ee4838..c53565c2 100644
--- a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
@@ -14,6 +14,7 @@
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/StringExtras.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
index e25d147..c2ec931 100644
--- a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
index d1537eb..de250bbc 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
@@ -10,6 +10,7 @@
 #include "../utils/Matchers.h"
 #include "../utils/OptionsUtils.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include <optional>
 
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
diff --git a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
index 1f1d605..5e96a49 100644
--- a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/SaveAndRestore.h"
 
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
index 2a5e614..8272a55 100644
--- a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 #include <sstream>
 
 using namespace clang::ast_matchers;
diff --git a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
index dce1924..698d9cf 100644
--- a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.h
@@ -11,6 +11,7 @@
 
 #include "../ClangTidyCheck.h"
 #include "llvm/ADT/StringSet.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
index ee760f7..e6fe757 100644
--- a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallString.h"
 #include <cctype>
+#include <optional>
 
 using namespace clang::ast_matchers;
 
diff --git a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
index 1d7c11f..3ca854d 100644
--- a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
@@ -8,6 +8,7 @@
 
 #include "ExprSequence.h"
 #include "clang/AST/ParentMapContext.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
index 07c9eb0..6b1fe06 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
@@ -9,6 +9,7 @@
 #include "FileExtensionsUtils.h"
 #include "clang/Basic/CharInfo.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
index 26184a5..a79cf9a 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
index 546efd5..2e96f29 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
@@ -10,6 +10,7 @@
 #include "LexerUtils.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
index 2f5a741..ec2ed50 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.h
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
 #include "clang/Sema/DeclSpec.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
index f4ca2d9..ced2a73 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
@@ -10,6 +10,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/Token.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeInserter.h b/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
index 8e7c5f7..0f4ba11 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
+++ b/clang-tools-extra/clang-tidy/utils/IncludeInserter.h
@@ -13,6 +13,7 @@
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/StringSet.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 class Preprocessor;
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
index fc26d96..5b25d10 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/IncludeSorter.h b/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
index ac76fcd..21fe5e4 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
+++ b/clang-tools-extra/clang-tidy/utils/IncludeSorter.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_INCLUDESORTER_H
 
 #include "../ClangTidyCheck.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
index 6ab48af..8bdbc1d 100644
--- a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
@@ -9,6 +9,7 @@
 #include "LexerUtils.h"
 #include "clang/AST/AST.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/LexerUtils.h b/clang-tools-extra/clang-tidy/utils/LexerUtils.h
index b8e0f6a..f67e0cb 100644
--- a/clang-tools-extra/clang-tidy/utils/LexerUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/LexerUtils.h
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang-tools-extra/clang-tidy/utils/Matchers.h b/clang-tools-extra/clang-tidy/utils/Matchers.h
index ad9e25f..5a0e459 100644
--- a/clang-tools-extra/clang-tidy/utils/Matchers.h
+++ b/clang-tools-extra/clang-tidy/utils/Matchers.h
@@ -11,6 +11,7 @@
 
 #include "TypeTraits.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
index fcefdc3..71a06f8 100644
--- a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 namespace clang {
 namespace tidy {
 namespace utils {
diff --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
index 177b098..934ce13 100644
--- a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
@@ -16,6 +16,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
 #include <map>
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
index 449b056..80a5005 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
@@ -16,6 +16,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/PointerIntPair.h"
+#include <optional>
 
 #define DEBUG_TYPE "clang-tidy"
 
diff --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
index 327d98f..2f3b79e 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
index 136b616..b5e4b2b 100644
--- a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/DiagnosticIDs.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
index c52fce5..8ba1529 100644
--- a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
+++ b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.h
@@ -14,6 +14,7 @@
 #include "IncludeSorter.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/Transformer/Transformer.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
index ef897da..70a6ca1 100644
--- a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/TypeTraits.h b/clang-tools-extra/clang-tidy/utils/TypeTraits.h
index 7e6b795..37db6ef 100644
--- a/clang-tools-extra/clang-tidy/utils/TypeTraits.h
+++ b/clang-tools-extra/clang-tidy/utils/TypeTraits.h
@@ -11,6 +11,7 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Type.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
index 480612c..2a10d99 100644
--- a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
@@ -12,6 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/clang-tidy/utils/UsingInserter.h b/clang-tools-extra/clang-tidy/utils/UsingInserter.h
index dfdf5ed..b23025b 100644
--- a/clang-tools-extra/clang-tidy/utils/UsingInserter.h
+++ b/clang-tools-extra/clang-tidy/utils/UsingInserter.h
@@ -13,6 +13,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 #include <set>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/AST.cpp b/clang-tools-extra/clangd/AST.cpp
index b9c7607..d33960a 100644
--- a/clang-tools-extra/clangd/AST.cpp
+++ b/clang-tools-extra/clangd/AST.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 #include <iterator>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/AST.h b/clang-tools-extra/clangd/AST.h
index 738d1b3..fbbee89 100644
--- a/clang-tools-extra/clangd/AST.h
+++ b/clang-tools-extra/clangd/AST.h
@@ -21,6 +21,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/MacroInfo.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp b/clang-tools-extra/clangd/ClangdLSPServer.cpp
index 8f5c8fa..7d75176 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -44,6 +44,7 @@
 #include <functional>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.h b/clang-tools-extra/clangd/ClangdLSPServer.h
index 43b5e74..1b1f4ad 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.h
+++ b/clang-tools-extra/clangd/ClangdLSPServer.h
@@ -23,6 +23,7 @@
 #include <chrono>
 #include <cstddef>
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
index 2bde2a9..5a9b2ed 100644
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -50,6 +50,7 @@
 #include <future>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <type_traits>
 
diff --git a/clang-tools-extra/clangd/ClangdServer.h b/clang-tools-extra/clangd/ClangdServer.h
index 98c67b8..097fed1 100644
--- a/clang-tools-extra/clangd/ClangdServer.h
+++ b/clang-tools-extra/clangd/ClangdServer.h
@@ -35,6 +35,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <functional>
 #include <memory>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index 9015be6..42e6ef2 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -70,6 +70,7 @@
 #include <algorithm>
 #include <iterator>
 #include <limits>
+#include <optional>
 #include <utility>
 
 // We log detailed candidate here if you run with -debug-only=codecomplete.
diff --git a/clang-tools-extra/clangd/CodeComplete.h b/clang-tools-extra/clangd/CodeComplete.h
index b661eac..e88e9b3 100644
--- a/clang-tools-extra/clangd/CodeComplete.h
+++ b/clang-tools-extra/clangd/CodeComplete.h
@@ -31,6 +31,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <functional>
 #include <future>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/CompileCommands.h b/clang-tools-extra/clangd/CompileCommands.h
index 3cf41af..561d9ea 100644
--- a/clang-tools-extra/clangd/CompileCommands.h
+++ b/clang-tools-extra/clangd/CompileCommands.h
@@ -13,6 +13,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <deque>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
index 2291e5fd..e1a511d 100644
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -45,6 +45,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Diagnostics.cpp b/clang-tools-extra/clangd/Diagnostics.cpp
index a6a0204..6c8cf5c 100644
--- a/clang-tools-extra/clangd/Diagnostics.cpp
+++ b/clang-tools-extra/clangd/Diagnostics.cpp
@@ -33,6 +33,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Diagnostics.h b/clang-tools-extra/clangd/Diagnostics.h
index 6004bb1..b1a1f01 100644
--- a/clang-tools-extra/clangd/Diagnostics.h
+++ b/clang-tools-extra/clangd/Diagnostics.h
@@ -23,6 +23,7 @@
 #include <cassert>
 #include <functional>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/DraftStore.cpp b/clang-tools-extra/clangd/DraftStore.cpp
index 8f5b54b..7df70e6 100644
--- a/clang-tools-extra/clangd/DraftStore.cpp
+++ b/clang-tools-extra/clangd/DraftStore.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/DraftStore.h b/clang-tools-extra/clangd/DraftStore.h
index 9a46926..a19fe55 100644
--- a/clang-tools-extra/clangd/DraftStore.h
+++ b/clang-tools-extra/clangd/DraftStore.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <mutex>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/DumpAST.cpp b/clang-tools-extra/clangd/DumpAST.cpp
index 1cf5e4e..438733d 100644
--- a/clang-tools-extra/clangd/DumpAST.cpp
+++ b/clang-tools-extra/clangd/DumpAST.cpp
@@ -23,6 +23,7 @@
 #include "clang/Tooling/Syntax/Tokens.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/ExpectedTypes.cpp b/clang-tools-extra/clangd/ExpectedTypes.cpp
index c45fa59..563612a 100644
--- a/clang-tools-extra/clangd/ExpectedTypes.cpp
+++ b/clang-tools-extra/clangd/ExpectedTypes.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Index/USRGeneration.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/ExpectedTypes.h b/clang-tools-extra/clangd/ExpectedTypes.h
index 873b106..6cfd093 100644
--- a/clang-tools-extra/clangd/ExpectedTypes.h
+++ b/clang-tools-extra/clangd/ExpectedTypes.h
@@ -20,6 +20,7 @@
 
 #include "clang/AST/Type.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 
 namespace clang {
 class CodeCompletionResult;
diff --git a/clang-tools-extra/clangd/FS.cpp b/clang-tools-extra/clangd/FS.cpp
index 089fbac..587b921 100644
--- a/clang-tools-extra/clangd/FS.cpp
+++ b/clang-tools-extra/clangd/FS.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/LLVM.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/FS.h b/clang-tools-extra/clangd/FS.h
index 5994bdf..96b04dc 100644
--- a/clang-tools-extra/clangd/FS.h
+++ b/clang-tools-extra/clangd/FS.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/FeatureModule.h b/clang-tools-extra/clangd/FeatureModule.h
index 43007a2..eb4232f 100644
--- a/clang-tools-extra/clangd/FeatureModule.h
+++ b/clang-tools-extra/clangd/FeatureModule.h
@@ -16,6 +16,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/JSON.h"
 #include <memory>
+#include <optional>
 #include <type_traits>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/FindSymbols.cpp b/clang-tools-extra/clangd/FindSymbols.cpp
index 0a18d5b..682ca79 100644
--- a/clang-tools-extra/clangd/FindSymbols.cpp
+++ b/clang-tools-extra/clangd/FindSymbols.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include <limits>
+#include <optional>
 #include <tuple>
 
 #define DEBUG_TYPE "FindSymbols"
diff --git a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
index 086315f..37f6173 100644
--- a/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
+++ b/clang-tools-extra/clangd/GlobalCompilationDatabase.cpp
@@ -30,6 +30,7 @@
 #include <chrono>
 #include <condition_variable>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <vector>
diff --git a/clang-tools-extra/clangd/GlobalCompilationDatabase.h b/clang-tools-extra/clangd/GlobalCompilationDatabase.h
index 511fa6c..04481fa 100644
--- a/clang-tools-extra/clangd/GlobalCompilationDatabase.h
+++ b/clang-tools-extra/clangd/GlobalCompilationDatabase.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/StringMap.h"
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/HeaderSourceSwitch.cpp b/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
index 9221fad..ded7a43 100644
--- a/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
+++ b/clang-tools-extra/clangd/HeaderSourceSwitch.cpp
@@ -13,6 +13,7 @@
 #include "support/Logger.h"
 #include "support/Path.h"
 #include "clang/AST/Decl.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/HeaderSourceSwitch.h b/clang-tools-extra/clangd/HeaderSourceSwitch.h
index 092b413..1cf9da9 100644
--- a/clang-tools-extra/clangd/HeaderSourceSwitch.h
+++ b/clang-tools-extra/clangd/HeaderSourceSwitch.h
@@ -11,6 +11,7 @@
 
 #include "ParsedAST.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Headers.cpp b/clang-tools-extra/clangd/Headers.cpp
index b22589a..fd058e8 100644
--- a/clang-tools-extra/clangd/Headers.cpp
+++ b/clang-tools-extra/clangd/Headers.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Path.h"
 #include <cstring>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Headers.h b/clang-tools-extra/clangd/Headers.h
index fd73984..68ccf93 100644
--- a/clang-tools-extra/clangd/Headers.h
+++ b/clang-tools-extra/clangd/Headers.h
@@ -27,6 +27,7 @@
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem/UniqueID.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Hover.cpp b/clang-tools-extra/clangd/Hover.cpp
index 72c0841..ca63019 100644
--- a/clang-tools-extra/clangd/Hover.cpp
+++ b/clang-tools-extra/clangd/Hover.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Support/Format.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/Hover.h b/clang-tools-extra/clangd/Hover.h
index 4565e64..a2c4e60 100644
--- a/clang-tools-extra/clangd/Hover.h
+++ b/clang-tools-extra/clangd/Hover.h
@@ -13,6 +13,7 @@
 #include "Protocol.h"
 #include "support/Markup.h"
 #include "clang/Index/IndexSymbol.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/IncludeCleaner.cpp b/clang-tools-extra/clangd/IncludeCleaner.cpp
index 3cfa52b..daac976 100644
--- a/clang-tools-extra/clangd/IncludeCleaner.cpp
+++ b/clang-tools-extra/clangd/IncludeCleaner.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/IncludeCleaner.h b/clang-tools-extra/clangd/IncludeCleaner.h
index 4ce31ba..fc3d04d 100644
--- a/clang-tools-extra/clangd/IncludeCleaner.h
+++ b/clang-tools-extra/clangd/IncludeCleaner.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/StringSet.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/IncludeFixer.cpp b/clang-tools-extra/clangd/IncludeFixer.cpp
index d48d593..5ab9932 100644
--- a/clang-tools-extra/clangd/IncludeFixer.cpp
+++ b/clang-tools-extra/clangd/IncludeFixer.cpp
@@ -41,6 +41,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
 #include <algorithm>
+#include <optional>
 #include <set>
 #include <string>
 #include <vector>
diff --git a/clang-tools-extra/clangd/IncludeFixer.h b/clang-tools-extra/clangd/IncludeFixer.h
index 50237dd..2a74c23 100644
--- a/clang-tools-extra/clangd/IncludeFixer.h
+++ b/clang-tools-extra/clangd/IncludeFixer.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
index 7af3965..20a8adc 100644
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -18,6 +18,7 @@
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/ScopeExit.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/JSONTransport.cpp b/clang-tools-extra/clangd/JSONTransport.cpp
index 254e54a..50b1833 100644
--- a/clang-tools-extra/clangd/JSONTransport.cpp
+++ b/clang-tools-extra/clangd/JSONTransport.cpp
@@ -13,6 +13,7 @@
 #include "support/ThreadCrashReporter.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <system_error>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/ParsedAST.cpp b/clang-tools-extra/clangd/ParsedAST.cpp
index aa84ce3..c2846749 100644
--- a/clang-tools-extra/clangd/ParsedAST.cpp
+++ b/clang-tools-extra/clangd/ParsedAST.cpp
@@ -50,6 +50,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <vector>
 
 // Force the linker to link in Clang-tidy modules.
diff --git a/clang-tools-extra/clangd/ParsedAST.h b/clang-tools-extra/clangd/ParsedAST.h
index e9133f1..8f74c17 100644
--- a/clang-tools-extra/clangd/ParsedAST.h
+++ b/clang-tools-extra/clangd/ParsedAST.h
@@ -34,6 +34,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Protocol.h b/clang-tools-extra/clangd/Protocol.h
index d68efad..9cd1955 100644
--- a/clang-tools-extra/clangd/Protocol.h
+++ b/clang-tools-extra/clangd/Protocol.h
@@ -33,6 +33,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <bitset>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/Quality.cpp b/clang-tools-extra/clangd/Quality.cpp
index da8e60e..72e3154 100644
--- a/clang-tools-extra/clangd/Quality.cpp
+++ b/clang-tools-extra/clangd/Quality.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cmath>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/Quality.h b/clang-tools-extra/clangd/Quality.h
index 8823596..2a4efe9 100644
--- a/clang-tools-extra/clangd/Quality.h
+++ b/clang-tools-extra/clangd/Quality.h
@@ -33,6 +33,7 @@
 #include "llvm/ADT/StringSet.h"
 #include <algorithm>
 #include <functional>
+#include <optional>
 #include <vector>
 
 namespace llvm {
diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
index 754d31c..56836fd 100644
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
+#include <optional>
 #include <set>
 #include <string>
 
diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
index 1f9f851..eaed887 100644
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/SemanticSelection.cpp b/clang-tools-extra/clangd/SemanticSelection.cpp
index 3541ede..fe01c15 100644
--- a/clang-tools-extra/clangd/SemanticSelection.cpp
+++ b/clang-tools-extra/clangd/SemanticSelection.cpp
@@ -25,6 +25,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <queue>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/SourceCode.cpp b/clang-tools-extra/clangd/SourceCode.cpp
index 0ba98f3..90dd37f 100644
--- a/clang-tools-extra/clangd/SourceCode.cpp
+++ b/clang-tools-extra/clangd/SourceCode.cpp
@@ -40,6 +40,7 @@
 #include "llvm/Support/xxhash.h"
 #include <algorithm>
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/SourceCode.h b/clang-tools-extra/clangd/SourceCode.h
index fa4e03b..69626c2 100644
--- a/clang-tools-extra/clangd/SourceCode.h
+++ b/clang-tools-extra/clangd/SourceCode.h
@@ -28,6 +28,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
index b65902b..d78d56e 100644
--- a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
+++ b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
@@ -52,6 +52,7 @@
 #include <algorithm>
 #include <iterator>
 #include <map>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/TUScheduler.cpp b/clang-tools-extra/clangd/TUScheduler.cpp
index 44a0d4a..50802d2 100644
--- a/clang-tools-extra/clangd/TUScheduler.cpp
+++ b/clang-tools-extra/clangd/TUScheduler.cpp
@@ -85,6 +85,7 @@
 #include <functional>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <queue>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/TUScheduler.h b/clang-tools-extra/clangd/TUScheduler.h
index d616814..f9582a6 100644
--- a/clang-tools-extra/clangd/TUScheduler.h
+++ b/clang-tools-extra/clangd/TUScheduler.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <chrono>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/XRefs.cpp b/clang-tools-extra/clangd/XRefs.cpp
index 953f911..da33b72 100644
--- a/clang-tools-extra/clangd/XRefs.cpp
+++ b/clang-tools-extra/clangd/XRefs.cpp
@@ -61,6 +61,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/XRefs.h b/clang-tools-extra/clangd/XRefs.h
index 60e8e88..8af5106 100644
--- a/clang-tools-extra/clangd/XRefs.h
+++ b/clang-tools-extra/clangd/XRefs.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Background.cpp b/clang-tools-extra/clangd/index/Background.cpp
index 2b75b8b..f09fb5d 100644
--- a/clang-tools-extra/clangd/index/Background.cpp
+++ b/clang-tools-extra/clangd/index/Background.cpp
@@ -49,6 +49,7 @@
 #include <memory>
 #include <mutex>
 #include <numeric>
+#include <optional>
 #include <queue>
 #include <random>
 #include <string>
diff --git a/clang-tools-extra/clangd/index/Background.h b/clang-tools-extra/clangd/index/Background.h
index ac99a15..45f679a 100644
--- a/clang-tools-extra/clangd/index/Background.h
+++ b/clang-tools-extra/clangd/index/Background.h
@@ -27,6 +27,7 @@
 #include <condition_variable>
 #include <deque>
 #include <mutex>
+#include <optional>
 #include <queue>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp b/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
index 1de1189..c7bbd98 100644
--- a/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
+++ b/clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/BackgroundQueue.cpp b/clang-tools-extra/clangd/index/BackgroundQueue.cpp
index b0dc2ac..5fb1511 100644
--- a/clang-tools-extra/clangd/index/BackgroundQueue.cpp
+++ b/clang-tools-extra/clangd/index/BackgroundQueue.cpp
@@ -8,6 +8,7 @@
 
 #include "index/Background.h"
 #include "support/Logger.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/FileIndex.cpp b/clang-tools-extra/clangd/index/FileIndex.cpp
index 1080cb0..95bda42 100644
--- a/clang-tools-extra/clangd/index/FileIndex.cpp
+++ b/clang-tools-extra/clangd/index/FileIndex.cpp
@@ -35,6 +35,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/index/FileIndex.h b/clang-tools-extra/clangd/index/FileIndex.h
index 24ffbc9..31757d1 100644
--- a/clang-tools-extra/clangd/index/FileIndex.h
+++ b/clang-tools-extra/clangd/index/FileIndex.h
@@ -31,6 +31,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
index 5406b95..e836d45 100644
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/JSON.h"
 #include <mutex>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/IndexAction.cpp b/clang-tools-extra/clangd/index/IndexAction.cpp
index a5f8f6b..d97dc40 100644
--- a/clang-tools-extra/clangd/index/IndexAction.cpp
+++ b/clang-tools-extra/clangd/index/IndexAction.cpp
@@ -22,6 +22,7 @@
 #include <cstddef>
 #include <functional>
 #include <memory>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/Serialization.h b/clang-tools-extra/clangd/index/Serialization.h
index 16b8096..fceaefe 100644
--- a/clang-tools-extra/clangd/index/Serialization.h
+++ b/clang-tools-extra/clangd/index/Serialization.h
@@ -29,6 +29,7 @@
 #include "index/Symbol.h"
 #include "clang/Tooling/CompilationDatabase.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/StdLib.cpp b/clang-tools-extra/clangd/index/StdLib.cpp
index ac7388c..ab9a8ed 100644
--- a/clang-tools-extra/clangd/index/StdLib.cpp
+++ b/clang-tools-extra/clangd/index/StdLib.cpp
@@ -8,6 +8,7 @@
 #include "StdLib.h"
 #include <fstream>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/index/StdLib.h b/clang-tools-extra/clangd/index/StdLib.h
index 6df30ace..6c170dc 100644
--- a/clang-tools-extra/clangd/index/StdLib.h
+++ b/clang-tools-extra/clangd/index/StdLib.h
@@ -26,6 +26,7 @@
 #include "index/Symbol.h"
 #include "support/ThreadsafeFS.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.cpp b/clang-tools-extra/clangd/index/SymbolCollector.cpp
index 4c865a4..5f9c8bb 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ b/clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.h b/clang-tools-extra/clangd/index/SymbolCollector.h
index f3d8d80..6acce1f 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.h
+++ b/clang-tools-extra/clangd/index/SymbolCollector.h
@@ -25,6 +25,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/YAMLSerialization.cpp b/clang-tools-extra/clangd/index/YAMLSerialization.cpp
index 593ce30..c51489f 100644
--- a/clang-tools-extra/clangd/index/YAMLSerialization.cpp
+++ b/clang-tools-extra/clangd/index/YAMLSerialization.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdint>
+#include <optional>
 
 namespace {
 struct YIncludeHeaderWithReferences;
diff --git a/clang-tools-extra/clangd/index/dex/Dex.cpp b/clang-tools-extra/clangd/index/dex/Dex.cpp
index c66e7f0..0e94f59 100644
--- a/clang-tools-extra/clangd/index/dex/Dex.cpp
+++ b/clang-tools-extra/clangd/index/dex/Dex.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include <algorithm>
+#include <optional>
 #include <queue>
 #include <utility>
 #include <vector>
diff --git a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
index 7bbcba3..7633822 100644
--- a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
+++ b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
@@ -21,6 +21,7 @@
 #include "llvm/LineEditor/LineEditor.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Signals.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/index/remote/server/Server.cpp b/clang-tools-extra/clangd/index/remote/server/Server.cpp
index 016ae72..5d2c82e 100644
--- a/clang-tools-extra/clangd/index/remote/server/Server.cpp
+++ b/clang-tools-extra/clangd/index/remote/server/Server.cpp
@@ -36,6 +36,7 @@
 #include <grpc++/grpc++.h>
 #include <grpc++/health_check_service_interface.h>
 #include <memory>
+#include <optional>
 #include <string>
 #include <thread>
 #include <utility>
diff --git a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
index 3158863..ff17ddd 100644
--- a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
+++ b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
@@ -13,6 +13,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/Basic/SourceManager.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Rename.cpp b/clang-tools-extra/clangd/refactor/Rename.cpp
index 5145ba4..afddab0 100644
--- a/clang-tools-extra/clangd/refactor/Rename.cpp
+++ b/clang-tools-extra/clangd/refactor/Rename.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/JSON.h"
 #include <algorithm>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Rename.h b/clang-tools-extra/clangd/refactor/Rename.h
index c10aa5a..6b917d5 100644
--- a/clang-tools-extra/clangd/refactor/Rename.h
+++ b/clang-tools-extra/clangd/refactor/Rename.h
@@ -13,6 +13,7 @@
 #include "SourceCode.h"
 #include "clang/Basic/LangOptions.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/Tweak.h b/clang-tools-extra/clangd/refactor/Tweak.h
index 5e7b77f..f91faf2 100644
--- a/clang-tools-extra/clangd/refactor/Tweak.h
+++ b/clang-tools-extra/clangd/refactor/Tweak.h
@@ -28,6 +28,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
index 8c2bf9f..410dec0 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
@@ -39,6 +39,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstddef>
+#include <optional>
 #include <set>
 #include <string>
 #include <unordered_map>
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
index 87890b9..1e09da9 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include <cstddef>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp b/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
index f2ae97c..7a89ce7 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DumpAST.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp b/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
index 04f4a2c..aabaed0 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp
@@ -16,6 +16,7 @@
 #include <AST.h>
 #include <climits>
 #include <memory>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp b/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
index c645859..a259deb 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
@@ -72,6 +72,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_os_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp b/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
index 3fb9ac5..dbaf2a5 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ObjCMemberwiseInitializer.cpp
@@ -23,6 +23,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
index ec02beb..51d299e 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
@@ -16,6 +16,7 @@
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Tooling/Core/Replacement.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/tool/Check.cpp b/clang-tools-extra/clangd/tool/Check.cpp
index f2677d3..3250571 100644
--- a/clang-tools-extra/clangd/tool/Check.cpp
+++ b/clang-tools-extra/clangd/tool/Check.cpp
@@ -54,6 +54,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp b/clang-tools-extra/clangd/tool/ClangdMain.cpp
index 3975ae9..fa6bda1 100644
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -44,6 +44,7 @@
 #include <cstdlib>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <thread>
 #include <utility>
diff --git a/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp b/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
index c3ad1b8..a9a30ea 100644
--- a/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdLSPServerTests.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/ClangdTests.cpp b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
index 226fbad..0563062 100644
--- a/clang-tools-extra/clangd/unittests/ClangdTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
@@ -40,6 +40,7 @@
 #include <algorithm>
 #include <chrono>
 #include <iostream>
+#include <optional>
 #include <random>
 #include <string>
 #include <thread>
diff --git a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
index 1c87cea..8d434a2 100644
--- a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/ConfigTesting.h b/clang-tools-extra/clangd/unittests/ConfigTesting.h
index f31a9c0..c06a061 100644
--- a/clang-tools-extra/clangd/unittests/ConfigTesting.h
+++ b/clang-tools-extra/clangd/unittests/ConfigTesting.h
@@ -14,6 +14,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "gmock/gmock.h"
 #include <functional>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp b/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
index c52413a..839f4c8 100644
--- a/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
+++ b/clang-tools-extra/clangd/unittests/ExpectedTypeTest.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp b/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
index 2d4cdde..71bcb12 100644
--- a/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
+++ b/clang-tools-extra/clangd/unittests/GlobalCompilationDatabaseTests.cpp
@@ -24,6 +24,7 @@
 #include "gtest/gtest.h"
 #include <chrono>
 #include <fstream>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp b/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
index 4a61ada..f6bc9a6 100644
--- a/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HeaderSourceSwitchTests.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/HeadersTests.cpp b/clang-tools-extra/clangd/unittests/HeadersTests.cpp
index 66caa5e..b14a14f0 100644
--- a/clang-tools-extra/clangd/unittests/HeadersTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HeadersTests.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp b/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
index 97a4316..b23c00e 100644
--- a/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
+++ b/clang-tools-extra/clangd/unittests/LSPBinderTests.cpp
@@ -10,6 +10,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/LSPClient.cpp b/clang-tools-extra/clangd/unittests/LSPClient.cpp
index aaadc62..027bf57 100644
--- a/clang-tools-extra/clangd/unittests/LSPClient.cpp
+++ b/clang-tools-extra/clangd/unittests/LSPClient.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 #include <condition_variable>
+#include <optional>
 #include <queue>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/PreambleTests.cpp b/clang-tools-extra/clangd/unittests/PreambleTests.cpp
index f38e297..eb071e3 100644
--- a/clang-tools-extra/clangd/unittests/PreambleTests.cpp
+++ b/clang-tools-extra/clangd/unittests/PreambleTests.cpp
@@ -25,6 +25,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
index 459b4db..eb5f60c 100644
--- a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <tuple>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp b/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
index 2785400..08523ed 100644
--- a/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SymbolCollectorTests.cpp
@@ -26,6 +26,7 @@
 #include "gtest/gtest.h"
 
 #include <memory>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp b/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
index f68f87f..ad76d7d 100644
--- a/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SymbolInfoTests.cpp
@@ -11,6 +11,7 @@
 #include "XRefs.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/SyncAPI.cpp b/clang-tools-extra/clangd/unittests/SyncAPI.cpp
index 52f47b0..2c4fde7 100644
--- a/clang-tools-extra/clangd/unittests/SyncAPI.cpp
+++ b/clang-tools-extra/clangd/unittests/SyncAPI.cpp
@@ -9,6 +9,7 @@
 #include "SyncAPI.h"
 #include "Protocol.h"
 #include "index/Index.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/SyncAPI.h b/clang-tools-extra/clangd/unittests/SyncAPI.h
index 4620223..6b4e3fc 100644
--- a/clang-tools-extra/clangd/unittests/SyncAPI.h
+++ b/clang-tools-extra/clangd/unittests/SyncAPI.h
@@ -18,6 +18,7 @@
 #include "ClangdServer.h"
 #include "Protocol.h"
 #include "index/Index.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp b/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
index 67d6fd2c..c7e28a0 100644
--- a/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
@@ -36,6 +36,7 @@
 #include <chrono>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang-tools-extra/clangd/unittests/TestFS.cpp b/clang-tools-extra/clangd/unittests/TestFS.cpp
index b820bc7..be26a6c 100644
--- a/clang-tools-extra/clangd/unittests/TestFS.cpp
+++ b/clang-tools-extra/clangd/unittests/TestFS.cpp
@@ -13,6 +13,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestFS.h b/clang-tools-extra/clangd/unittests/TestFS.h
index 7d3d4d3..3e4ac3b 100644
--- a/clang-tools-extra/clangd/unittests/TestFS.h
+++ b/clang-tools-extra/clangd/unittests/TestFS.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestWorkspace.cpp b/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
index bca24fc..662eef6 100644
--- a/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
+++ b/clang-tools-extra/clangd/unittests/TestWorkspace.cpp
@@ -9,6 +9,7 @@
 #include "TestWorkspace.h"
 #include "index/FileIndex.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/TestWorkspace.h b/clang-tools-extra/clangd/unittests/TestWorkspace.h
index 4467c7e..bc6aee1 100644
--- a/clang-tools-extra/clangd/unittests/TestWorkspace.h
+++ b/clang-tools-extra/clangd/unittests/TestWorkspace.h
@@ -19,6 +19,7 @@
 #include "TestTU.h"
 #include "index/Index.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/XRefsTests.cpp b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
index 1a25b5d..ae19656 100644
--- a/clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/ScopedPrinter.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp b/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
index 8d2bc4d..133b83b 100644
--- a/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
+++ b/clang-tools-extra/clangd/unittests/support/FileCacheTests.cpp
@@ -13,6 +13,7 @@
 #include "gtest/gtest.h"
 #include <atomic>
 #include <chrono>
+#include <optional>
 
 namespace clang {
 namespace clangd {
diff --git a/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp b/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
index 59885ce..12836d0 100644
--- a/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
+++ b/clang-tools-extra/clangd/unittests/tweaks/TweakTesting.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang-tools-extra/clangd/xpc/XPCTransport.cpp b/clang-tools-extra/clangd/xpc/XPCTransport.cpp
index 9c43647..dac8e29 100644
--- a/clang-tools-extra/clangd/xpc/XPCTransport.cpp
+++ b/clang-tools-extra/clangd/xpc/XPCTransport.cpp
@@ -11,6 +11,7 @@
 #include "support/Logger.h"
 #include "llvm/Support/Errno.h"
 
+#include <optional>
 #include <xpc/xpc.h>
 
 using namespace llvm;
diff --git a/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h b/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
index e9af9a5..e8f4240 100644
--- a/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
+++ b/clang-tools-extra/pseudo/include/clang-pseudo/DirectiveTree.h
@@ -30,6 +30,7 @@
 
 #include "clang-pseudo/Token.h"
 #include "clang/Basic/TokenKinds.h"
+#include <optional>
 #include <variant>
 #include <vector>
 
diff --git a/clang-tools-extra/pseudo/lib/DirectiveTree.cpp b/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
index 4835fc2..4e86681 100644
--- a/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
+++ b/clang-tools-extra/pseudo/lib/DirectiveTree.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/TokenKinds.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 #include <variant>
 
 namespace clang {
diff --git a/clang-tools-extra/pseudo/lib/Forest.cpp b/clang-tools-extra/pseudo/lib/Forest.cpp
index 78e7983..e6b2d2e 100644
--- a/clang-tools-extra/pseudo/lib/Forest.cpp
+++ b/clang-tools-extra/pseudo/lib/Forest.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <optional>
 
 namespace clang {
 namespace pseudo {
diff --git a/clang-tools-extra/pseudo/lib/GLR.cpp b/clang-tools-extra/pseudo/lib/GLR.cpp
index e49cbc4..a4169dd 100644
--- a/clang-tools-extra/pseudo/lib/GLR.cpp
+++ b/clang-tools-extra/pseudo/lib/GLR.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <queue>
 
 #define DEBUG_TYPE "GLR.cpp"
diff --git a/clang-tools-extra/pseudo/tool/ClangPseudo.cpp b/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
index c6d0673..c22ea17 100644
--- a/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
+++ b/clang-tools-extra/pseudo/tool/ClangPseudo.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
+#include <optional>
 
 using clang::pseudo::ForestNode;
 using clang::pseudo::Token;
diff --git a/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp b/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
index 31a444f..437d9b4 100644
--- a/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/AddConstTest.cpp
@@ -5,6 +5,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Tooling/Tooling.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp b/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
index 5dcec03..d861e86 100644
--- a/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp
@@ -6,6 +6,7 @@
 #include "llvm/Testing/Support/Annotations.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {
diff --git a/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp b/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
index 5394e75..964f5f7 100644
--- a/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp
@@ -5,6 +5,7 @@
 #include "llvm/HeaderGuardCheck.h"
 #include "llvm/IncludeOrderCheck.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang::tidy::llvm_check;
 
diff --git a/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp b/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
index e1ebad7..87325941 100644
--- a/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/TransformerClangTidyCheckTest.cpp
@@ -15,6 +15,7 @@
 #include "clang/Tooling/Transformer/Transformer.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tidy {