From e66a55066e0452cbf57226433cf294bf559629cb Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Fri, 21 Aug 2026 03:19:53 +0200
Subject: [PATCH] Include <span> where the split moved its only use

The #2546 test case guards itself with __has_include(<span>), but the
include itself sat in unit-regression2.cpp's preamble and stayed behind,
so the section compiled without a declaration wherever the guard passed -
which nvhpc reported and libc++ builds do not, as they skip the section
altogether.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 tests/src/unit-regression3.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/src/unit-regression3.cpp b/tests/src/unit-regression3.cpp
index e9ae61a6a..c65321c84 100644
--- a/tests/src/unit-regression3.cpp
+++ b/tests/src/unit-regression3.cpp
@@ -27,6 +27,7 @@ using json = nlohmann::json;
 using ordered_json = nlohmann::ordered_json;
 
 #include <cmath>
+#include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <string>
@@ -60,6 +61,12 @@ using ordered_json = nlohmann::ordered_json;
     >;
 #endif
 
+#ifdef JSON_HAS_CPP_20
+    #if __has_include(<span>)
+        #include <span>
+    #endif
+#endif
+
 #if JSON_HAS_RANGES == 1
     #include <ranges>
 #endif