From 34ffa4de405d053ef4b53d58e1437f2e82d152b1 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Mon, 13 Jul 2026 12:18:08 +0200
Subject: kstd: make error_code formattable

---
 kernel/kapi/system.cpp          |  4 ++--
 libs/kstd/kstd/format.hpp       |  1 +
 libs/kstd/kstd/system_error.hpp | 25 +++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/kernel/kapi/system.cpp b/kernel/kapi/system.cpp
index 23dadd3a..629e5990 100644
--- a/kernel/kapi/system.cpp
+++ b/kernel/kapi/system.cpp
@@ -22,8 +22,8 @@ namespace kapi::system
   [[gnu::weak]]
   auto panic(std::string_view message, kstd::error_code error, std::source_location location) -> void
   {
-    kstd::println(kstd::print_sink::stderr, "[PANIC] in {} : {} ({}:{}) @ {}:{}", location.function_name(), message,
-                  error.category().name(), error.message(), location.file_name(), location.line());
+    kstd::println(kstd::print_sink::stderr, "[PANIC] in {} : {} ({}) @ {}:{}", location.function_name(), message, error,
+                  location.file_name(), location.line());
     cpu::halt();
   }
 
diff --git a/libs/kstd/kstd/format.hpp b/libs/kstd/kstd/format.hpp
index 5ed798db..5d7f4ae6 100644
--- a/libs/kstd/kstd/format.hpp
+++ b/libs/kstd/kstd/format.hpp
@@ -5,6 +5,7 @@
 #include <kstd/bits/format/arg.hpp>
 #include <kstd/bits/format/args.hpp>
 #include <kstd/bits/format/context.hpp>
+#include <kstd/bits/format/error.hpp>
 #include <kstd/bits/format/formatter.hpp>
 #include <kstd/bits/format/formatter/bool.hpp>
 #include <kstd/bits/format/formatter/byte.hpp>
diff --git a/libs/kstd/kstd/system_error.hpp b/libs/kstd/kstd/system_error.hpp
index f971703b..08725609 100644
--- a/libs/kstd/kstd/system_error.hpp
+++ b/libs/kstd/kstd/system_error.hpp
@@ -1,6 +1,8 @@
 #ifndef KSTD_SYSTEM_ERROR_HPP
 #define KSTD_SYSTEM_ERROR_HPP
 
+#include <kstd/format.hpp>
+
 #include <compare>
 #include <cstdint>
 #include <functional>
@@ -472,6 +474,29 @@ namespace kstd
     return {static_cast<int>(value), generic_category()};
   }
 
+  template<>
+  struct formatter<error_code>
+  {
+    constexpr auto parse(format_parse_context & context) -> format_parse_context::iterator
+    {
+      auto it = context.begin();
+      if (it != context.end() && *it != '}')
+      {
+        bits::format::error("Invalid specifier for string_view.");
+      }
+      return it;
+    }
+
+    auto format(error_code const & error, format_context & context) const -> void
+    {
+      context.push(error.category().name());
+      context.push(':');
+      formatter<int>{}.format(error.value(), context);
+      context.push(':');
+      context.push(error.message());
+    }
+  };
+
 }  // namespace kstd
 
 #endif
-- 
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