From 2db638f20a6fbc327a58a26a3d0fbb58a2405417 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@meta.com>
Date: Sun, 31 Dec 2023 07:37:59 -0800
Subject: [PATCH] Cleanup error handling

---
 include/fmt/core.h   |  2 ++
 include/fmt/format.h | 42 +++++++++++++++---------------------------
 2 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index 1e0503db5739b..6fa22d3a2c1b1 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -644,6 +644,7 @@ enum {
   pointer_set = set(type::pointer_type)
 };
 
+// DEPRECATED!
 FMT_NORETURN FMT_API void throw_format_error(const char* message);
 
 struct error_handler {
@@ -1762,6 +1763,7 @@ template <typename OutputIt, typename Char> class basic_format_context {
   }
   auto args() const -> const format_args& { return args_; }
 
+  // DEPRECATED!
   FMT_CONSTEXPR auto error_handler() -> detail::error_handler { return {}; }
   void on_error(const char* message) { error_handler().on_error(message); }
 
diff --git a/include/fmt/format.h b/include/fmt/format.h
index ded5d51341e43..445c1d9a0ce88 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -3813,51 +3813,41 @@ template <typename Char> struct custom_formatter {
   template <typename T> void operator()(T) const {}
 };
 
-template <typename ErrorHandler> class width_checker {
- public:
-  explicit FMT_CONSTEXPR width_checker(ErrorHandler& eh) : handler_(eh) {}
-
+struct width_checker {
   template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
   FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
-    if (is_negative(value)) handler_.on_error("negative width");
+    if (is_negative(value)) throw_format_error("negative width");
     return static_cast<unsigned long long>(value);
   }
 
   template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
   FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
-    handler_.on_error("width is not integer");
+    throw_format_error("width is not integer");
     return 0;
   }
-
- private:
-  ErrorHandler& handler_;
 };
 
-template <typename ErrorHandler> class precision_checker {
- public:
-  explicit FMT_CONSTEXPR precision_checker(ErrorHandler& eh) : handler_(eh) {}
+struct precision_checker {
+  constexpr precision_checker() {}
 
   template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
   FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
-    if (is_negative(value)) handler_.on_error("negative precision");
+    if (is_negative(value)) throw_format_error("negative precision");
     return static_cast<unsigned long long>(value);
   }
 
   template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
   FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
-    handler_.on_error("precision is not integer");
+    throw_format_error("precision is not integer");
     return 0;
   }
-
- private:
-  ErrorHandler& handler_;
 };
 
-template <template <typename> class Handler, typename FormatArg,
-          typename ErrorHandler>
-FMT_CONSTEXPR auto get_dynamic_spec(FormatArg arg, ErrorHandler eh) -> int {
-  unsigned long long value = visit_format_arg(Handler<ErrorHandler>(eh), arg);
-  if (value > to_unsigned(max_value<int>())) eh.on_error("number is too big");
+template <typename Handler, typename FormatArg>
+FMT_CONSTEXPR auto get_dynamic_spec(FormatArg arg) -> int {
+  unsigned long long value = visit_format_arg(Handler(), arg);
+  if (value > to_unsigned(max_value<int>()))
+    throw_format_error("number is too big");
   return static_cast<int>(value);
 }
 
@@ -3868,7 +3858,7 @@ FMT_CONSTEXPR auto get_arg(Context& ctx, ID id) -> decltype(ctx.arg(id)) {
   return arg;
 }
 
-template <template <typename> class Handler, typename Context>
+template <typename Handler, typename Context>
 FMT_CONSTEXPR void handle_dynamic_spec(int& value,
                                        arg_ref<typename Context::char_type> ref,
                                        Context& ctx) {
@@ -3876,12 +3866,10 @@ FMT_CONSTEXPR void handle_dynamic_spec(int& value,
   case arg_id_kind::none:
     break;
   case arg_id_kind::index:
-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.index),
-                                              ctx.error_handler());
+    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.index));
     break;
   case arg_id_kind::name:
-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.name),
-                                              ctx.error_handler());
+    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.name));
     break;
   }
 }