From d6660cf718e798b9439fdb9ccb8a9b0a9582312a Mon Sep 17 00:00:00 2001 From: Niels Lohmann Date: Wed, 9 Sep 2026 09:48:18 +0200 Subject: [PATCH] Route hand-rolled diagnostic pragmas through Hedley (#5485) * Route hand-rolled diagnostic pragmas through Hedley Several places in the library hand-roll compiler diagnostic suppression with raw `#pragma`/`#ifdef __GNUC__`/`#ifdef __clang__` guards instead of using the Hedley primitives already bundled and used elsewhere (JSON_HEDLEY_DIAGNOSTIC_PUSH/POP, JSON_HEDLEY_PRAGMA, ...). Converted six of the seven listed push/pop pairs to use those primitives instead of raw `#pragma GCC diagnostic`/`#pragma clang diagnostic` text: - include/nlohmann/json.hpp (~3770, ~3863): -Wfloat-equal - include/nlohmann/detail/conversions/to_chars.hpp (~1078): -Wfloat-equal - include/nlohmann/detail/output/binary_writer.hpp (~1844): -Wfloat-equal - include/nlohmann/detail/iterators/iteration_proxy.hpp (~211): -Wmismatched-tags - include/nlohmann/detail/exceptions.hpp (~36): -Wweak-vtables iteration_proxy.hpp did not previously include macro_scope.hpp itself (it only compiled because some other header included earlier in json.hpp happened to pull macro_scope.hpp in first); it now includes it directly like the other detail headers that use Hedley macros, so it is self-contained. Each push/pop pair now uses JSON_HEDLEY_DIAGNOSTIC_PUSH/POP unconditionally (a no-op on compilers that don't need it) and wraps the actual `#pragma ... diagnostic ignored` text in JSON_HEDLEY_PRAGMA so it goes through Hedley's _Pragma()-based emission instead of a raw #pragma line, while keeping the original `#ifdef __GNUC__` / `#if defined(__clang__)` guard around the ignored-pragma itself. Deviation from the issue's suggested transformation: the issue's example replaces the `#ifdef __GNUC__` guard with `#if JSON_HEDLEY_HAS_WARNING("-Wfloat-equal")`. JSON_HEDLEY_HAS_WARNING is implemented purely via Clang's `__has_warning` builtin and evaluates to 0 on real GCC (`#define JSON_HEDLEY_HAS_WARNING(warning) (0)` when `__has_warning` is not defined), so adopting it verbatim would silently stop suppressing -Wfloat-equal on GCC -- a real regression, not just a style change. The existing `#ifdef __GNUC__` / `#if defined(__clang__)` guards were kept for the ignored-pragma to stay behavior-preserving, and only the push/pop/pragma-emission mechanism was routed through Hedley. Two of the seven locations from the issue (the -Wignored-attributes push at the very top of json.hpp and its matching pop after `#include `) were intentionally left unconverted: - The push, at the very top of json.hpp, runs before `detail/macro_scope.hpp` (and therefore hedley.hpp) has been included anywhere in the translation unit, so JSON_HEDLEY_DIAGNOSTIC_PUSH is not yet defined at that point. - The pop runs after `macro_unscope.hpp`, which -- via hedley_undef.hpp -- has already #undef'd every JSON_HEDLEY_* macro (by design, see #5408) precisely so they don't leak to users, so JSON_HEDLEY_DIAGNOSTIC_POP is no longer defined by the time the pop is reached either. Making this one pair work would require either hoisting the ~2000 line vendored hedley.hpp to the very top of the amalgamated single header (a much bigger structural change to single_include than a pure mechanism swap) or special-casing this one pop ahead of the general macro cleanup. Both are riskier than the mechanical, behavior-preserving change requested, so this pair was left as-is. ## Validation - Compiled include/nlohmann/json.hpp and single_include/nlohmann/json.hpp with `-Wall -Wextra -Wfloat-equal -Wmismatched-tags -Wweak-vtables` (clang, which self-identifies as __GNUC__ too): no warnings, same as before the change. - Compiled and ran tests/src/unit-to_chars.cpp, unit-conversions.cpp, unit-iterators1.cpp, unit-iterators2.cpp, and unit-class_parser.cpp against the fixed include/: all pass. - Compiled unit-msgpack.cpp, unit-bjdata.cpp, and unit-ubjson.cpp (which exercise binary_writer.hpp's write_compact_float extensively): all compile cleanly; the vast majority of assertions pass (the only failures are pre-existing environment issues unrelated to this change -- missing generated test-data files, not code correctness). - Ran `make amalgamate`; the single_include diff is limited to exactly the lines touched in include/, with no unrelated reordering. - No real (non-Apple) GCC was available in this environment to test directly; the `_Pragma("GCC diagnostic ...")` text emitted by JSON_HEDLEY_PRAGMA is byte-identical to the prior `#pragma GCC diagnostic ...` text, and the `#ifdef __GNUC__` guard is unchanged, so GCC's behavior is expected to be identical. CI covers the GCC matrix. This PR is stacked on top of #5475 (issue-5408-hedley-undef-leak) since both touch the same files; only the last commit here is new. Fixes #5409. Signed-off-by: Niels Lohmann * Guard JSON_HEDLEY_DIAGNOSTIC_PUSH/POP with the same compiler check as the pragma they bracket Addresses review feedback from @gregmarr on PR #5485: the push/pop calls were unconditional, so compilers other than the one the ignored-pragma targets (e.g. MSVC, or GCC where the pair only applies under __clang__) now did a needless push/pop with nothing suppressed in between. Move the existing #ifdef __GNUC__ / #if defined(__clang__) guard to also cover the push/pop, restoring the original zero-overhead behavior on other compilers while still emitting the pragma itself through Hedley. Signed-off-by: Niels Lohmann --------- Signed-off-by: Niels Lohmann --- .../nlohmann/detail/conversions/to_chars.hpp | 6 +-- include/nlohmann/detail/exceptions.hpp | 6 +-- .../detail/iterators/iteration_proxy.hpp | 9 +++-- .../nlohmann/detail/output/binary_writer.hpp | 6 +-- include/nlohmann/json.hpp | 12 +++--- single_include/nlohmann/json.hpp | 40 ++++++++++--------- 6 files changed, 41 insertions(+), 38 deletions(-) diff --git a/include/nlohmann/detail/conversions/to_chars.hpp b/include/nlohmann/detail/conversions/to_chars.hpp index 70fb9b933..c0945ab9e 100644 --- a/include/nlohmann/detail/conversions/to_chars.hpp +++ b/include/nlohmann/detail/conversions/to_chars.hpp @@ -1075,8 +1075,8 @@ char* to_chars(char* first, const char* last, FloatType value) } #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif if (value == 0) // +-0 { @@ -1087,7 +1087,7 @@ char* to_chars(char* first, const char* last, FloatType value) return first; } #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif JSON_ASSERT(last - first >= std::numeric_limits::max_digits10); diff --git a/include/nlohmann/detail/exceptions.hpp b/include/nlohmann/detail/exceptions.hpp index cb87bb93e..3e5b45101 100644 --- a/include/nlohmann/detail/exceptions.hpp +++ b/include/nlohmann/detail/exceptions.hpp @@ -33,8 +33,8 @@ // code stumbling over this. See https://github.com/nlohmann/json/issues/4087 // for a discussion. #if defined(__clang__) - #pragma clang diagnostic push - #pragma clang diagnostic ignored "-Wweak-vtables" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wweak-vtables") #endif NLOHMANN_JSON_NAMESPACE_BEGIN @@ -287,5 +287,5 @@ class other_error : public exception NLOHMANN_JSON_NAMESPACE_END #if defined(__clang__) - #pragma clang diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif diff --git a/include/nlohmann/detail/iterators/iteration_proxy.hpp b/include/nlohmann/detail/iterators/iteration_proxy.hpp index 99246d120..c8aa50dd2 100644 --- a/include/nlohmann/detail/iterators/iteration_proxy.hpp +++ b/include/nlohmann/detail/iterators/iteration_proxy.hpp @@ -18,6 +18,7 @@ #endif #include +#include #include #include #include @@ -206,10 +207,10 @@ NLOHMANN_JSON_NAMESPACE_END namespace std { +// Fix: https://github.com/nlohmann/json/issues/1401 #if defined(__clang__) - // Fix: https://github.com/nlohmann/json/issues/1401 - #pragma clang diagnostic push - #pragma clang diagnostic ignored "-Wmismatched-tags" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wmismatched-tags") #endif template class tuple_size<::nlohmann::detail::iteration_proxy_value> // NOLINT(cert-dcl58-cpp) @@ -224,7 +225,7 @@ class tuple_element> ::nlohmann::detail::iteration_proxy_value> ())); }; #if defined(__clang__) - #pragma clang diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } // namespace std diff --git a/include/nlohmann/detail/output/binary_writer.hpp b/include/nlohmann/detail/output/binary_writer.hpp index b8e9efa45..496c733d1 100644 --- a/include/nlohmann/detail/output/binary_writer.hpp +++ b/include/nlohmann/detail/output/binary_writer.hpp @@ -1850,8 +1850,8 @@ class binary_writer void write_compact_float(const number_float_t n, detail::input_format_t format) { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif if (!std::isfinite(n) || ((static_cast(n) >= static_cast(std::numeric_limits::lowest()) && static_cast(n) <= static_cast((std::numeric_limits::max)()) && @@ -1870,7 +1870,7 @@ class binary_writer write_number(n); } #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp index 6f9876478..feafd9e20 100644 --- a/include/nlohmann/json.hpp +++ b/include/nlohmann/json.hpp @@ -3771,13 +3771,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec bool operator==(const_reference rhs) const noexcept { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif const_reference lhs = *this; JSON_IMPLEMENT_OPERATOR( ==, true, false, false) #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } @@ -3864,12 +3864,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec friend bool operator==(const_reference lhs, const_reference rhs) noexcept { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif JSON_IMPLEMENT_OPERATOR( ==, true, false, false) #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp index 68691769c..605bf8364 100644 --- a/single_include/nlohmann/json.hpp +++ b/single_include/nlohmann/json.hpp @@ -4945,8 +4945,8 @@ NLOHMANN_JSON_NAMESPACE_END // code stumbling over this. See https://github.com/nlohmann/json/issues/4087 // for a discussion. #if defined(__clang__) - #pragma clang diagnostic push - #pragma clang diagnostic ignored "-Wweak-vtables" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wweak-vtables") #endif NLOHMANN_JSON_NAMESPACE_BEGIN @@ -5199,7 +5199,7 @@ class other_error : public exception NLOHMANN_JSON_NAMESPACE_END #if defined(__clang__) - #pragma clang diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif // #include @@ -5975,6 +5975,8 @@ NLOHMANN_JSON_NAMESPACE_END // #include +// #include + // #include // #include @@ -6204,10 +6206,10 @@ NLOHMANN_JSON_NAMESPACE_END namespace std { +// Fix: https://github.com/nlohmann/json/issues/1401 #if defined(__clang__) - // Fix: https://github.com/nlohmann/json/issues/1401 - #pragma clang diagnostic push - #pragma clang diagnostic ignored "-Wmismatched-tags" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wmismatched-tags") #endif template class tuple_size<::nlohmann::detail::iteration_proxy_value> // NOLINT(cert-dcl58-cpp) @@ -6222,7 +6224,7 @@ class tuple_element> ::nlohmann::detail::iteration_proxy_value> ())); }; #if defined(__clang__) - #pragma clang diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } // namespace std @@ -18982,8 +18984,8 @@ class binary_writer void write_compact_float(const number_float_t n, detail::input_format_t format) { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif if (!std::isfinite(n) || ((static_cast(n) >= static_cast(std::numeric_limits::lowest()) && static_cast(n) <= static_cast((std::numeric_limits::max)()) && @@ -19002,7 +19004,7 @@ class binary_writer write_number(n); } #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } @@ -20177,8 +20179,8 @@ char* to_chars(char* first, const char* last, FloatType value) } #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif if (value == 0) // +-0 { @@ -20189,7 +20191,7 @@ char* to_chars(char* first, const char* last, FloatType value) return first; } #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif JSON_ASSERT(last - first >= std::numeric_limits::max_digits10); @@ -25323,13 +25325,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec bool operator==(const_reference rhs) const noexcept { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif const_reference lhs = *this; JSON_IMPLEMENT_OPERATOR( ==, true, false, false) #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif } @@ -25416,12 +25418,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec friend bool operator==(const_reference lhs, const_reference rhs) noexcept { #ifdef __GNUC__ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wfloat-equal" + JSON_HEDLEY_DIAGNOSTIC_PUSH + JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal") #endif JSON_IMPLEMENT_OPERATOR( ==, true, false, false) #ifdef __GNUC__ -#pragma GCC diagnostic pop + JSON_HEDLEY_DIAGNOSTIC_POP #endif }