std::atomic<T> Reflector bypasses domain validation present on bare T (#575 followup)

[RampantDespair]

Following up on #575, now that std::atomic<T> support has been implemented, I discovered a validation inconsistency between bare T and std::atomic<T> when going through the Reflector path.

Observed behavior

When deserializing a negative JSON number into a std::uint64_t field directly, reflect-cpp correctly rejects it. When the same field is wrapped in std::atomic<std::uint64_t>, the parse succeeds and the value silently wraps to UINT64_MAX.

Repro

#include <atomic>
#include <cstdint>

#include <gtest/gtest.h>
#include <rfl.hpp>
#include <rfl/json.hpp>

struct TestObject {
    std::uint64_t number{0};
};

struct AtomicTestObject {
    std::atomic<std::uint64_t> number{0};
};

TEST(
    ReflectCppUint,
    NegativeIntoUint64
) {
    auto req = rfl::json::read<TestObject>(R"({"number": -1})");
    EXPECT_FALSE(req.has_value());
}

TEST(
    ReflectCppUint,
    NegativeIntoAtomicUint64
) {
    auto req = rfl::json::read<rfl::Ref<AtomicTestObject>>(R"({"number": -1})");
    EXPECT_FALSE(req.has_value());
}

Test output

[17:18:37.340] [info] [tid 31448] [==========] Running 2 test(s) from 1 test suite(s).
[17:18:37.340] [info] [tid 31448] [----------] Global test environment set-up.
[17:18:37.340] [info] [tid 31448] [----------] 2 test(s) from ReflectCppUint
[17:18:37.340] [info] [tid 31448] [RUN] ReflectCppUint.NegativeIntoUint64
[17:18:37.341] [info] [tid 31448] [OK] ReflectCppUint.NegativeIntoUint64 (0 ms)
[17:18:37.341] [info] [tid 31448] [RUN] ReflectCppUint.NegativeIntoAtomicUint64
[17:18:37.341] [error] [tid 31448] ASSERT FAILED at [REDACTED]: Value of: req.has_value()
  Actual: true
Expected: false

[17:18:37.341] [info] [tid 31448] [FAILED] ReflectCppUint.NegativeIntoAtomicUint64 (0 ms)
[17:18:37.341] [info] [tid 31448] [----------] 2 test(s) from ReflectCppUint (0 ms total)
[17:18:37.341] [info] [tid 31448] [----------] Global test environment tear-down.
[17:18:37.341] [info] [tid 31448] [==========] 77 test(s) from 19 test suite(s) ran. (0 ms total)
[17:18:37.341] [info] [tid 31448] [PASSED] 1 test(s).
[17:18:37.341] [error] [tid 31448] [FAILED] 1 test(s).

Root cause (hypothesis)

The domain validation that reflect-cpp applies to bare uint64_t fields during normal struct parsing does not appear to be applied when the value is parsed through the std::atomic<T> path. The negative number passes through and the unsigned integer silently wraps.

[liuzicheng1987]

OK, I'll take a look