From 814411ced376b5ecaf1078f0a71366d26ff7ce36 Mon Sep 17 00:00:00 2001
From: cpplearner <cpplearner@outlook.com>
Date: Wed, 27 Jul 2022 17:21:46 +0800
Subject: [PATCH 1/2] Check `make_format_args`'s preconditions

---
 stl/inc/format | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/stl/inc/format b/stl/inc/format
index cf26ca191f..9b6406b953 100644
--- a/stl/inc/format
+++ b/stl/inc/format
@@ -3397,11 +3397,15 @@ using wformat_args = basic_format_args<wformat_context>;
 
 template <class _Context = format_context, class... _Args>
 _NODISCARD auto make_format_args(_Args&&... _Vals) {
+    static_assert((_Has_formatter<_Args, _Context> && ...),
+        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization.");
     return _Format_arg_store<_Context, _Args...>{_Vals...};
 }
 
 template <class... _Args>
 _NODISCARD auto make_wformat_args(_Args&&... _Vals) {
+    static_assert((_Has_formatter<_Args, wformat_context> && ...),
+        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization.");
     return _Format_arg_store<wformat_context, _Args...>{_Vals...};
 }
 

From 1ab9067673c172e208537d628ca8baf720dbd1d7 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@nuwen.net>
Date: Thu, 22 Sep 2022 20:16:54 -0700
Subject: [PATCH 2/2] Add Standardese citations.

Co-authored-by: Sam Huang <samestimable2016@gmail.com>
---
 stl/inc/format | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/stl/inc/format b/stl/inc/format
index 9b6406b953..b0d8b02667 100644
--- a/stl/inc/format
+++ b/stl/inc/format
@@ -3398,14 +3398,16 @@ using wformat_args = basic_format_args<wformat_context>;
 template <class _Context = format_context, class... _Args>
 _NODISCARD auto make_format_args(_Args&&... _Vals) {
     static_assert((_Has_formatter<_Args, _Context> && ...),
-        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization.");
+        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization. "
+        "See N4917 [format.arg.store]/2 and [formatter.requirements].");
     return _Format_arg_store<_Context, _Args...>{_Vals...};
 }
 
 template <class... _Args>
 _NODISCARD auto make_wformat_args(_Args&&... _Vals) {
     static_assert((_Has_formatter<_Args, wformat_context> && ...),
-        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization.");
+        "Cannot format an argument. To make type T formattable, provide a formatter<T> specialization. "
+        "See N4917 [format.arg.store]/2 and [formatter.requirements].");
     return _Format_arg_store<wformat_context, _Args...>{_Vals...};
 }