Update cppcheck to 1.5.2 (Cppcheck 2.20) and fix its new findings

Cppcheck 2.20 rejects invocations of unknown function-like macros in #if
conditions instead of evaluating them as 0. default_defines.hpp expands
the Hedley macros to the compiler's feature-test operators (__has_attribute
etc.), so define them as 0 in a generated include file.

It also reports a false bufferAccessOutOfBounds in the float overload of
float_from_bits, sizing the parameter as the double overload's; use the
size of the source instead (equal by the static_assert).

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

cmake/ci.cmake

@@ -485,6 +485,13 @@ add_custom_target(ci_clang_analyze
 # Check code with Cppcheck.
 ###############################################################################
 
+# default_defines.hpp expands the Hedley macros to the compiler's feature-test operators, which Cppcheck does not know.
+# Since Cppcheck 2.20, it rejects their invocations in #if conditions instead of evaluating them as 0.
+file(WRITE ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "")
+foreach(OPERATOR __has_attribute __has_builtin __has_cpp_attribute __has_declspec_attribute __has_extension __has_feature __has_include __has_warning)
+    file(APPEND ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "#define ${OPERATOR}(x) 0\n")
+endforeach()
+
 add_custom_target(ci_cppcheck
     COMMAND mkdir -p cppcheck
     COMMAND clang -dM -E -x c++ -std=c++11 ${CMAKE_SOURCE_DIR}/include/nlohmann/thirdparty/hedley/hedley.hpp > default_defines.hpp 2> /dev/null
@@ -493,7 +500,7 @@ add_custom_target(ci_cppcheck
     COMMAND venv_cppcheck/bin/cppcheck --enable=warning --check-level=exhaustive --inline-suppr --inconclusive --force
             --std=c++11 ${PROJECT_SOURCE_DIR}/include/nlohmann/json.hpp -I ${CMAKE_SOURCE_DIR}/include
             --error-exitcode=1 --relative-paths=${PROJECT_SOURCE_DIR} -j ${N} --include=default_defines.hpp
-            --cppcheck-build-dir=cppcheck
+            --include=${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp --cppcheck-build-dir=cppcheck
             -UJSON_CATCH_USER -UJSON_TRY_USER -UJSON_ASSERT -UJSON_INTERNAL_CATCH -UJSON_THROW
             -DJSON_HAS_CPP_11 -UJSON_HAS_CPP_14 -UJSON_HAS_CPP_17 -UJSON_HAS_CPP_20 -UJSON_HAS_THREE_WAY_COMPARISON
     COMMENT "Check code with Cppcheck"

cmake/requirements/requirements-cppcheck.txt

@@ -1 +1 @@
-cppcheck==1.5.1
+cppcheck==1.5.2

include/nlohmann/detail/input/number_parse.hpp

@@ -704,7 +704,7 @@ inline void float_from_bits(std::uint64_t bits, float& value) noexcept
 {
     static_assert(sizeof(float) == sizeof(std::uint32_t), "float must have 32 bits");
     const auto bits32 = static_cast<std::uint32_t>(bits);
-    std::memcpy(&value, &bits32, sizeof(value));
+    std::memcpy(&value, &bits32, sizeof(bits32));
 }
 
 /// the powers of ten that are exact in binary64 (up to 10^22)

single_include/nlohmann/json.hpp

@@ -10151,7 +10151,7 @@ inline void float_from_bits(std::uint64_t bits, float& value) noexcept
 {
     static_assert(sizeof(float) == sizeof(std::uint32_t), "float must have 32 bits");
     const auto bits32 = static_cast<std::uint32_t>(bits);
-    std::memcpy(&value, &bits32, sizeof(value));
+    std::memcpy(&value, &bits32, sizeof(bits32));
 }
 
 /// the powers of ten that are exact in binary64 (up to 10^22)