From e5c6ccbc9623a0c9a1a64ac2662ed0c27b2c0fe9 Mon Sep 17 00:00:00 2001
From: Sam McCall <sammccall@google.com>
Date: Mon, 13 Oct 2025 23:47:49 -0700
Subject: [PATCH] FlagStateInterface implementors need only support being
 restored once.

PiperOrigin-RevId: 819030565
Change-Id: I92ac8ce4318f8d2e575c13752e490326030ba583
---
 absl/flags/internal/commandlineflag.h | 2 +-
 absl/flags/internal/flag.cc           | 5 +++--
 absl/flags/reflection.cc              | 7 ++++---
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index daef4e35..e2c4c82f 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -58,7 +58,7 @@ class FlagStateInterface {
   virtual ~FlagStateInterface();
 
   // Restores the flag originated this object to the saved state.
-  virtual void Restore() const = 0;
+  virtual void Restore() && = 0;
 };
 
 }  // namespace flags_internal
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index b05e1bdc..8e894250 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -26,6 +26,7 @@
 #include <memory>
 #include <string>
 #include <typeinfo>
+#include <utility>
 #include <vector>
 
 #include "absl/base/attributes.h"
@@ -139,8 +140,8 @@ class FlagState : public flags_internal::FlagStateInterface {
   friend class FlagImpl;
 
   // Restores the flag to the saved state.
-  void Restore() const override {
-    if (!flag_impl_.RestoreState(*this)) return;
+  void Restore() && override {
+    if (!std::move(flag_impl_).RestoreState(*this)) return;
 
     ABSL_INTERNAL_LOG(INFO,
                       absl::StrCat("Restore saved value of ", flag_impl_.Name(),
diff --git a/absl/flags/reflection.cc b/absl/flags/reflection.cc
index 845099e2..fb64a653 100644
--- a/absl/flags/reflection.cc
+++ b/absl/flags/reflection.cc
@@ -19,6 +19,7 @@
 
 #include <atomic>
 #include <string>
+#include <utility>
 
 #include "absl/base/config.h"
 #include "absl/base/no_destructor.h"
@@ -320,9 +321,9 @@ class FlagSaverImpl {
   }
 
   // Restores the saved flag states into the flag registry.
-  void RestoreToRegistry() {
+  void RestoreToRegistry() && {
     for (const auto& flag_state : backup_registry_) {
-      flag_state->Restore();
+      std::move(*flag_state).Restore();
     }
   }
 
@@ -340,7 +341,7 @@ FlagSaver::FlagSaver() : impl_(new flags_internal::FlagSaverImpl) {
 FlagSaver::~FlagSaver() {
   if (!impl_) return;
 
-  impl_->RestoreToRegistry();
+  std::move(*impl_).RestoreToRegistry();
   delete impl_;
 }