From 32e62f9a643aed367063325581922233e34e9304 Mon Sep 17 00:00:00 2001
From: Kefu Chai <kchai@redhat.com>
Date: Sun, 27 Jun 2021 11:48:24 +0800
Subject: [PATCH] common/config: s/boost::variant/std::variant/

we should use standard library for more well defined behavior, and
less dependencies on 3rd party libraries.

Signed-off-by: Kefu Chai <kchai@redhat.com>
---
 src/common/config.cc | 25 +++++++++++--------------
 src/common/config.h  | 20 ++++++++++----------
 2 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/src/common/config.cc b/src/common/config.cc
index ca9f194a125b7..a58d9d9e1f2d2 100644
--- a/src/common/config.cc
+++ b/src/common/config.cc
@@ -13,8 +13,6 @@
  */
 
 #include <filesystem>
-#include <boost/type_traits.hpp>
-
 #include "common/ceph_argparse.h"
 #include "common/common_init.h"
 #include "common/config.h"
@@ -1455,7 +1453,7 @@ int md_config_t::_rm_val(ConfigValues& values,
 
 namespace {
 template<typename Size>
-struct get_size_visitor : public boost::static_visitor<Size>
+struct get_size_visitor
 {
   get_size_visitor() {}
 
@@ -1474,34 +1472,33 @@ struct get_size_visitor : public boost::static_visitor<Size>
 /**
  * Handles assigning from a variant-of-types to a variant-of-pointers-to-types
  */
-template<class Config>
-class assign_visitor : public boost::static_visitor<>
+class assign_visitor
 {
-  Config *conf;
+  ConfigValues *conf;
   Option::value_t val;
   public:
 
-  assign_visitor(Config *conf_, Option::value_t val_)
+  assign_visitor(ConfigValues *conf_, Option::value_t val_)
     : conf(conf_), val(val_)
   {}
 
   template <typename T>
-  void operator()(T Config::* ptr) const
+  void operator()(T ConfigValues::* ptr) const
   {
-    T *member = const_cast<T *>(&(conf->*(boost::get<const T Config::*>(ptr))));
+    T *member = const_cast<T *>(&(conf->*(ptr)));
 
     *member = std::get<T>(val);
   }
-  void operator()(uint64_t Config::* ptr) const
+  void operator()(uint64_t ConfigValues::* ptr) const
   {
     using T = uint64_t;
-    auto member = const_cast<T*>(&(conf->*(boost::get<const T Config::*>(ptr))));
+    auto member = const_cast<T*>(&(conf->*(ptr)));
     *member = std::visit(get_size_visitor<T>{}, val);
   }
-  void operator()(int64_t Config::* ptr) const
+  void operator()(int64_t ConfigValues::* ptr) const
   {
     using T = int64_t;
-    auto member = const_cast<T*>(&(conf->*(boost::get<const T Config::*>(ptr))));
+    auto member = const_cast<T*>(&(conf->*(ptr)));
     *member = std::visit(get_size_visitor<T>{}, val);
   }
 };
@@ -1522,7 +1519,7 @@ void md_config_t::update_legacy_val(ConfigValues& values,
                                     md_config_t::member_ptr_t member_ptr)
 {
   Option::value_t v = _get_val(values, opt);
-  boost::apply_visitor(assign_visitor(&values, v), member_ptr);
+  std::visit(assign_visitor(&values, v), member_ptr);
 }
 
 static void dump(Formatter *f, int level, Option::value_t in)
diff --git a/src/common/config.h b/src/common/config.h
index 8b5402b1095b7..ce5f9277796f8 100644
--- a/src/common/config.h
+++ b/src/common/config.h
@@ -16,8 +16,8 @@
 #define CEPH_CONFIG_H
 
 #include <map>
+#include <variant>
 #include <boost/container/small_vector.hpp>
-#include <boost/variant.hpp>
 #include "common/ConfUtils.h"
 #include "common/code_environment.h"
 #include "log/SubsystemMap.h"
@@ -70,14 +70,14 @@ extern const char *ceph_conf_level_name(int level);
  */
 struct md_config_t {
 public:
-  typedef boost::variant<int64_t ConfigValues::*,
-                         uint64_t ConfigValues::*,
-                         std::string ConfigValues::*,
-                         double ConfigValues::*,
-                         bool ConfigValues::*,
-                         entity_addr_t ConfigValues::*,
-			 entity_addrvec_t ConfigValues::*,
-                         uuid_d ConfigValues::*> member_ptr_t;
+  typedef std::variant<int64_t ConfigValues::*,
+                       uint64_t ConfigValues::*,
+                       std::string ConfigValues::*,
+                       double ConfigValues::*,
+                       bool ConfigValues::*,
+                       entity_addr_t ConfigValues::*,
+                       entity_addrvec_t ConfigValues::*,
+                       uuid_d ConfigValues::*> member_ptr_t;
 
   // For use when intercepting configuration updates
   typedef std::function<bool(
@@ -361,7 +361,7 @@ const T md_config_t::get_val(const ConfigValues& values,
   return std::get<T>(this->get_val_generic(values, key));
 }
 
-inline std::ostream& operator<<(std::ostream& o, const boost::blank& ) {
+inline std::ostream& operator<<(std::ostream& o, const std::monostate&) {
       return o << "INVALID_CONFIG_VALUE";
 }
 
-- 
2.39.5