Hotfix -DREFLECTCPP_USE_STD_EXPECTED=ON

[danielmohansahu]

Minor change required to locally build with -DREFLECTCPP_USE_STD_EXPECTED=ON.

Addresses #570 .

[gemini-code-assist]

Summary of Changes

Hello @danielmohansahu, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request provides a hotfix to address a compilation error that occurs when building with the -DREFLECTCPP_USE_STD_EXPECTED=ON flag. The change involves a minor syntax adjustment in a template function signature to ensure broader C++ standard compatibility, allowing the project to build successfully under the specified configuration.

Highlights

• C++ Standard Compatibility: Removed the C++23 explicit object parameter this from the error method signature in rfl::Result.hpp to ensure compatibility with older C++ standards when REFLECTCPP_USE_STD_EXPECTED is enabled, resolving a local build issue.

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[gemini-code-assist]

Code Review

The pull request aims to resolve a build issue when REFLECTCPP_USE_STD_EXPECTED=ON is enabled. However, the proposed change to the error method in std::bad_expected_access is incorrect. Removing the this keyword from the C++23 deducing this syntax without providing a valid alternative results in an invalid function signature, which will likely lead to a compilation error. If the compiler does not support C++23's deducing this feature, a more comprehensive fix involving explicit const&, &, and && overloads for the error() method would be required.

[gemini-code-assist]

The removal of the this keyword from the error method's signature on this line fundamentally changes its meaning. In C++23, this Self&& self is used for deducing this, where self refers to the object itself. By removing this, Self&& self becomes a regular parameter. This makes the function signature incorrect for a member function intended to return the err_ member of the std::bad_expected_access instance, as Self cannot be deduced from a non-existent parameter, and self.err_ would attempt to access a member of the parameter self, not the class's err_. This will lead to a compilation error. If the compiler does not support C++23's deducing this, the correct approach is to provide explicit const&, &, and && overloads for the error() method, which would also require removing the template <typename Self> line.

auto error(this Self&& self) noexcept {

[danielmohansahu]

Hmm, perhaps this indicates I'm just not using a sufficiently new version of GCC?

[liuzicheng1987]

@danielmohansahu I think so.

However, I think we don't have to use this feature here. I will take a closer look tomorrow.

[danielmohansahu]

Thanks! I'll leave this PR open for continuity, but please close it as appropriate.

[liuzicheng1987]

@danielmohansahu , I am replacing this with #572