From 2994bcd9e242eb065ee43e074a26714996084b83 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Fri, 25 Sep 2026 17:55:03 +0200
Subject: [PATCH] Select the BON8 float prefix by type

get_bon8_float_prefix only depends on the type of its argument, so make
the type a template parameter instead of passing an unused value.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 include/nlohmann/detail/output/binary_writer.hpp | 15 ++++++---------
 single_include/nlohmann/json.hpp                 | 15 ++++++---------
 2 files changed, 12 insertions(+), 18 deletions(-)

diff --git a/include/nlohmann/detail/output/binary_writer.hpp b/include/nlohmann/detail/output/binary_writer.hpp
index db6c90394..9f6d0167f 100644
--- a/include/nlohmann/detail/output/binary_writer.hpp
+++ b/include/nlohmann/detail/output/binary_writer.hpp
@@ -1447,14 +1447,11 @@ class binary_writer
         return to_char_type(0xCB);  // float 64
     }
 
-    static constexpr CharType get_bon8_float_prefix(float /*unused*/)
+    /// @return the BON8 type marker for binary32 (float) or binary64 (double)
+    template<typename FloatType>
+    static constexpr CharType get_bon8_float_prefix()
     {
-        return to_char_type(0x8E);  // binary32
-    }
-
-    static constexpr CharType get_bon8_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0x8F);  // binary64
+        return to_char_type(std::is_same<FloatType, float>::value ? 0x8E : 0x8F);
     }
 
     ////////////
@@ -2511,7 +2508,7 @@ class binary_writer
             oa.write_character(format == detail::input_format_t::cbor
                                ? get_cbor_float_prefix(static_cast<float>(n))
                                : format == detail::input_format_t::bon8
-                               ? get_bon8_float_prefix(static_cast<float>(n))
+                               ? get_bon8_float_prefix<float>()
                                : get_msgpack_float_prefix(static_cast<float>(n)));
             write_number(static_cast<float>(n));
         }
@@ -2520,7 +2517,7 @@ class binary_writer
             oa.write_character(format == detail::input_format_t::cbor
                                ? get_cbor_float_prefix(n)
                                : format == detail::input_format_t::bon8
-                               ? get_bon8_float_prefix(n)
+                               ? get_bon8_float_prefix<number_float_t>()
                                : get_msgpack_float_prefix(n));
             write_number(n);
         }
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index dadda405c..dd5804f4e 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -21000,14 +21000,11 @@ class binary_writer
         return to_char_type(0xCB);  // float 64
     }
 
-    static constexpr CharType get_bon8_float_prefix(float /*unused*/)
+    /// @return the BON8 type marker for binary32 (float) or binary64 (double)
+    template<typename FloatType>
+    static constexpr CharType get_bon8_float_prefix()
     {
-        return to_char_type(0x8E);  // binary32
-    }
-
-    static constexpr CharType get_bon8_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0x8F);  // binary64
+        return to_char_type(std::is_same<FloatType, float>::value ? 0x8E : 0x8F);
     }
 
     ////////////
@@ -22064,7 +22061,7 @@ class binary_writer
             oa.write_character(format == detail::input_format_t::cbor
                                ? get_cbor_float_prefix(static_cast<float>(n))
                                : format == detail::input_format_t::bon8
-                               ? get_bon8_float_prefix(static_cast<float>(n))
+                               ? get_bon8_float_prefix<float>()
                                : get_msgpack_float_prefix(static_cast<float>(n)));
             write_number(static_cast<float>(n));
         }
@@ -22073,7 +22070,7 @@ class binary_writer
             oa.write_character(format == detail::input_format_t::cbor
                                ? get_cbor_float_prefix(n)
                                : format == detail::input_format_t::bon8
-                               ? get_bon8_float_prefix(n)
+                               ? get_bon8_float_prefix<number_float_t>()
                                : get_msgpack_float_prefix(n));
             write_number(n);
         }