diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index c9d56e09..79ca1814 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -15,21 +15,16 @@ jobs:
         # https://github.com/actions/virtual-environments.
         os: [windows-2019]
         platform: [Win32, x64]
-        toolset: [v140, v141, v142]
+        toolset: [v141, v142]
         standard: [14, 17, 20]
         shared: ["", -DBUILD_SHARED_LIBS=ON]
         build_type: [Debug, Release]
         exclude:
-          - { toolset: v140, standard: 17 }
-          - { toolset: v140, standard: 20 }
-          - { toolset: v141, standard: 14 }
           - { toolset: v141, standard: 20 }
           - { toolset: v142, standard: 14 }
-          - { platform: Win32, toolset: v140 }
           - { platform: Win32, toolset: v141 }
           - { platform: Win32, standard: 14 }
           - { platform: Win32, standard: 20 }
-          - { platform: x64, toolset: v140, shared: -DBUILD_SHARED_LIBS=ON }
           - { platform: x64, toolset: v141, shared: -DBUILD_SHARED_LIBS=ON }
           - { platform: x64, standard: 14, shared: -DBUILD_SHARED_LIBS=ON }
           - { platform: x64, standard: 20, shared: -DBUILD_SHARED_LIBS=ON }
diff --git a/include/fmt/base.h b/include/fmt/base.h
index 72cac7c4..cb2a36a4 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -2238,8 +2238,19 @@ template <typename Context> class value {
   }
   FMT_ALWAYS_INLINE value(const void* val) : pointer(val) {}
 
-  template <typename T>
-  FMT_CONSTEXPR20 FMT_ALWAYS_INLINE value(T&& val, custom_tag = {}) {
+  template <typename T,
+            FMT_ENABLE_IF(
+                !std::is_same<T, decltype(detail::arg_mapper<char_type>::map(
+                                     std::declval<T&>()))>::value)>
+  FMT_CONSTEXPR20 FMT_ALWAYS_INLINE value(T&& val) {
+    *this = arg_mapper<typename Context::char_type>::map(val);
+  }
+
+  template <
+      typename T,
+      FMT_ENABLE_IF(std::is_same<T, decltype(detail::arg_mapper<char_type>::map(
+                                        std::declval<T&>()))>::value)>
+  FMT_CONSTEXPR20 FMT_ALWAYS_INLINE value(T&& val) {
     // Use enum instead of constexpr because the latter may generate code.
     enum { formattable_char = !std::is_same<T, unformattable_char>::value };
     static_assert(formattable_char, "mixing character types is disallowed");
@@ -2374,8 +2385,7 @@ struct named_arg_store {
 
   template <typename... T>
   FMT_CONSTEXPR FMT_ALWAYS_INLINE named_arg_store(T&... values)
-      : args{{named_args, NUM_NAMED_ARGS},
-             arg_mapper<typename Context::char_type>::map(values)...} {
+      : args{{named_args, NUM_NAMED_ARGS}, values...} {
     int arg_index = 0, named_arg_index = 0;
     FMT_APPLY_VARIADIC(
         init_named_arg(named_args, arg_index, named_arg_index, values));
@@ -2636,6 +2646,10 @@ template <typename Context> class basic_format_args {
     return static_cast<detail::type>((desc_ >> shift) & mask);
   }
 
+  template <size_t NUM_ARGS, size_t NUM_NAMED_ARGS, unsigned long long DESC>
+  using store =
+      detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>;
+
  public:
   using format_arg = basic_format_arg<Context>;
 
@@ -2646,33 +2660,26 @@ template <typename Context> class basic_format_args {
             FMT_ENABLE_IF(NUM_ARGS <= detail::max_packed_args &&
                           NUM_NAMED_ARGS == 0)>
   constexpr FMT_ALWAYS_INLINE basic_format_args(
-      const detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>&
-          store)
-      : desc_(DESC), values_(store.args) {}
+      const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
+      : desc_(DESC), values_(s.args) {}
 
   template <size_t NUM_ARGS, size_t NUM_NAMED_ARGS, unsigned long long DESC,
             FMT_ENABLE_IF(NUM_ARGS <= detail::max_packed_args &&
                           NUM_NAMED_ARGS != 0)>
-  constexpr FMT_ALWAYS_INLINE basic_format_args(
-      const detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>&
-          store)
-      : desc_(DESC), values_(store.args.args + 1) {}
+  constexpr basic_format_args(const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
+      : desc_(DESC | detail::has_named_args_bit), values_(s.args.args + 1) {}
 
   template <size_t NUM_ARGS, size_t NUM_NAMED_ARGS, unsigned long long DESC,
             FMT_ENABLE_IF(NUM_ARGS > detail::max_packed_args &&
                           NUM_NAMED_ARGS == 0)>
-  constexpr basic_format_args(
-      const detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>&
-          store)
-      : desc_(DESC), args_(store.args + (NUM_NAMED_ARGS != 0 ? 1 : 0)) {}
+  constexpr basic_format_args(const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
+      : desc_(DESC), args_(s.args) {}
 
   template <size_t NUM_ARGS, size_t NUM_NAMED_ARGS, unsigned long long DESC,
             FMT_ENABLE_IF(NUM_ARGS > detail::max_packed_args &&
                           NUM_NAMED_ARGS != 0)>
-  constexpr basic_format_args(
-      const detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>&
-          store)
-      : desc_(DESC), args_(store.args.args + 1) {}
+  constexpr basic_format_args(const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
+      : desc_(DESC | detail::has_named_args_bit), args_(s.args.args + 1) {}
 
   /// Constructs a `basic_format_args` object from a dynamic list of arguments.
   constexpr basic_format_args(const format_arg* args, int count,
@@ -2870,6 +2877,8 @@ struct formatter<T, Char,
 #  define FMT_CUSTOM , detail::custom_tag()
 #endif
 
+template <typename T> constexpr T& identity(T& x) { return x; }
+
 /**
  * Constructs an object that stores references to arguments and can be
  * implicitly converted to `format_args`. `Context` can be omitted in which case
@@ -2901,6 +2910,12 @@ constexpr auto make_format_args(T&... args)
 }
 #endif
 
+template <typename... T>
+using vargs =
+    detail::format_arg_store<context, sizeof...(T),
+                             detail::count_named_args<T...>(),
+                             detail::make_descriptor<context, T...>()>;
+
 /**
  * Returns a named argument to be used in a formatting function.
  * It should only be used in a call to a formatting function.