From f257ac3373ed0f285153dd110b65e5b579953025 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Wed, 30 Sep 2026 17:58:51 +0200
Subject: [PATCH] Remove the GCC C++20 -Wignored-attributes pragma in json.hpp

The pragma (added in #5164) claimed to work around the C++ modules
redefinition errors of #5103, but #5103 is about hard errors (e.g.
"redefinition of std::__is_constant_evaluated()", conflicting
std::integral_constant) that ignoring a warning cannot suppress; they
are traced to GCC PR 124430 and reproduce with <map> or <string>
instead of json.hpp too. A GCC 16.2 -std=gnu++20 -fmodules build
following #5103's repro steps still fails with the pragma in place,
and a build of all test TUs with GCC_CXXFLAGS (which enable
-Wignored-attributes) and the pragma removed produces no such
warning. The block only hid a warning class from GCC C++20 users
while suggesting #5103 was handled.

Overlaps #5610, whose hunks touch the closing half of this pragma to
insert the json_literals.hpp include.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

#5725 item 9
---
 include/nlohmann/json.hpp        | 15 ---------------
 single_include/nlohmann/json.hpp | 15 ---------------
 2 files changed, 30 deletions(-)

diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 500fcddf2..0bf165748 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -18,16 +18,6 @@
 #ifndef INCLUDE_NLOHMANN_JSON_HPP_
 #define INCLUDE_NLOHMANN_JSON_HPP_
 
-// Workaround for GCC template redefinition errors in C++ modules
-// When nlohmann/json.hpp is included in a C++20 module preamble after
-// other module imports, GCC may report spurious redefinition errors for
-// STL templates. These pragmas suppress those false positives.
-// See: https://github.com/nlohmann/json/issues/5103
-#if defined(__GNUC__) && !defined(__clang__) && __cplusplus >= 202002L
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wignored-attributes"
-#endif
-
 #include <algorithm> // all_of, find, for_each, none_of
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
 #include <functional> // hash, less
@@ -6619,9 +6609,4 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
 
 #include <nlohmann/detail/macro_unscope.hpp>
 
-// End of GCC diagnostic pragmas for C++ modules support
-#if defined(__GNUC__) && !defined(__clang__) && __cplusplus >= 202002L
-    #pragma GCC diagnostic pop
-#endif
-
 #endif  // INCLUDE_NLOHMANN_JSON_HPP_
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index e9d09c478..a7b129cce 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -18,16 +18,6 @@
 #ifndef INCLUDE_NLOHMANN_JSON_HPP_
 #define INCLUDE_NLOHMANN_JSON_HPP_
 
-// Workaround for GCC template redefinition errors in C++ modules
-// When nlohmann/json.hpp is included in a C++20 module preamble after
-// other module imports, GCC may report spurious redefinition errors for
-// STL templates. These pragmas suppress those false positives.
-// See: https://github.com/nlohmann/json/issues/5103
-#if defined(__GNUC__) && !defined(__clang__) && __cplusplus >= 202002L
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wignored-attributes"
-#endif
-
 #include <algorithm> // all_of, find, for_each, none_of
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
 #include <functional> // hash, less
@@ -32919,9 +32909,4 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
 
 
 
-// End of GCC diagnostic pragmas for C++ modules support
-#if defined(__GNUC__) && !defined(__clang__) && __cplusplus >= 202002L
-    #pragma GCC diagnostic pop
-#endif
-
 #endif  // INCLUDE_NLOHMANN_JSON_HPP_