From af2d9f2b78d68e2fa8f7d5f120da3127e954ec05 Mon Sep 17 00:00:00 2001
From: AMAN UPADHYAY <upadhyayaman512@gmail.com>
Date: Sun, 12 Jul 2026 21:51:55 +0530
Subject: [PATCH] Fix FMT_COMPILE failure with format_as mapped types  (Issue
 #4794) (#4836)

---
 include/fmt/compile.h |  4 ++++
 test/compile-test.cc  | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index 1a987cb0..2a0be049 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -178,6 +178,10 @@ template <typename Char, typename V, int N> struct field {
     if constexpr (std::is_convertible<V, basic_string_view<Char>>::value) {
       auto s = basic_string_view<Char>(arg);
       return copy<Char>(s.begin(), s.end(), out);
+    } else if constexpr (use_format_as<V>::value) {
+      return write<Char>(out, format_as(arg));
+    } else if constexpr (use_format_as_member<V>::value) {
+      return write<Char>(out, formatter<V>::format_as(arg));
     } else {
       return write<Char>(out, arg);
     }
diff --git a/test/compile-test.cc b/test/compile-test.cc
index 5a944612..73e86f35 100644
--- a/test/compile-test.cc
+++ b/test/compile-test.cc
@@ -479,3 +479,13 @@ TEST(compile_test, constexpr_string_format) {
   EXPECT_TRUE(big);
 }
 #endif  // FMT_USE_CONSTEXPR_STRING
+
+namespace {
+struct compile_format_as_type {
+  int value;
+};
+int format_as(compile_format_as_type f) { return f.value; }
+} 
+TEST(compile_test, format_as) {
+  EXPECT_EQ("42", fmt::format(FMT_COMPILE("{}"), compile_format_as_type{42}));
+}
\ No newline at end of file