From 085aae0e497872c9bbcd63c25a6bd32c74ab5710 Mon Sep 17 00:00:00 2001
From: Yuqian Yang <crupest@crupest.life>
Date: Fri, 12 Sep 2025 23:27:09 +0800
Subject: Fix ImplementFormatterByToUtf8String.

---
 include/cru/base/Format.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/cru/base/Format.h b/include/cru/base/Format.h
index 83fda3f1..2d95b2fd 100644
--- a/include/cru/base/Format.h
+++ b/include/cru/base/Format.h
@@ -5,6 +5,7 @@
 
 #include <cassert>
 #include <cstdio>
+#include <format>
 #include <type_traits>
 #include <vector>
 
@@ -156,7 +157,12 @@ template <typename T>
 struct ImplementFormatterByToUtf8String {
   template <class ParseContext>
   constexpr ParseContext::iterator parse(ParseContext& ctx) const {
-    return ctx.end();
+    auto iter = ctx.begin();
+    if (*iter != '}') {
+      throw std::format_error(
+          "ImplementFormatterByToUtf8String does not accept format args.");
+    }
+    return iter;
   }
 
   template <class FmtContext>
-- 
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