fix get flag in module support

[waruqi]

#7230

[gemini-code-assist]

Summary of Changes

Hello @waruqi, 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 resolves an issue where the C++ module support in Xmake might incorrectly determine the C++ standard version due to a subtle bug in how compiler flags were parsed. By ensuring the predicate function used for flag detection explicitly returns a boolean value, the system can now reliably identify the specified C++ standard, preventing unintended fallbacks and improving build configuration accuracy.

Highlights

• Lua table.find_if Predicate Fix: Corrected the anonymous function passed to table.find_if in both GCC and MSVC C++ module support files to explicitly return the boolean result of string.startswith. This ensures proper detection of C++ standard flags.
• Improved C++ Standard Flag Detection: Addressed an issue where the get_cppversionflag function might not correctly identify the C++ standard flag from compiler flags, potentially defaulting to c++20 (for GCC) or c++latest (for MSVC) even when another standard was specified.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request correctly adds the return keyword for Lua 5.1 compatibility. However, the logic for finding the compiler flag is still flawed in both modified files. The predicate passed to table.find_if uses the wrong argument (array index instead of value), and the function itself returns a list of indices instead of the desired flag string. My review includes suggestions to correct this logic by using table.find_first_if and retrieving the flag value properly. I've also included a fix for a missing caching implementation in the MSVC support file.