Use constexpr for flags

[phst]

No description provided.

[gemini-code-assist]

Summary of Changes

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This pull request refactors the CopyFile utility by leveraging constexpr for file operation flags. This enhancement improves code clarity and ensures that critical flag values are determined at compile time, aligning with modern C++ best practices for constant expressions. Additionally, a routine copyright year update was included.

Highlights

• Refactoring to use constexpr: The from_flags and to_flags variables in the CopyFile function have been updated from const int to constexpr int. This change ensures that these flag values are evaluated at compile-time, potentially leading to minor performance improvements and stricter compile-time checks for their immutability.
• Copyright Year Update: The copyright year in elisp/private/tools/system.cc has been extended from 2025 to 2026.

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Changelog

• elisp/private/tools/system.cc
  • Updated copyright year from 2025 to 2026.
  • Changed from_flags variable to constexpr int.
  • Changed to_flags variable to constexpr int.

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[gemini-code-assist]

Code Review

This pull request correctly updates two local flag variables in the CopyFile function to use constexpr instead of const. Since these variables are initialized with compile-time constants, using constexpr is a good practice that makes the intent clear and allows the compiler to evaluate them at compile time. The changes are a good improvement to the code.