Fix WARN_CFLAGS sed filtering

[rgerhards]

Summary

• ensure sed only drops -Wdeclaration-after-statement and converts -Wno-error= flags to -W

Testing

• autoreconf -fi
• make

---

https://chatgpt.com/codex/tasks/task_e_68bb02b2d2508332bf27d7ae94273134

[gemini-code-assist]

Summary of Changes

Hello @rgerhards, 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 refines the build configuration by improving how compiler warning flags are processed. The changes ensure that specific problematic flags are correctly removed or transformed, leading to a more robust and predictable build environment. The primary goal is to enhance the accuracy and efficiency of the flag filtering mechanism.

Highlights

• Sed Command Refactoring: The sed command used to filter WARN_CFLAGS in configure.ac has been refactored to use a single sed invocation with multiple -e expressions, improving efficiency and readability.
• Improved Flag Filtering Precision: The regular expression for removing the -Wdeclaration-after-statement flag has been made more precise by requiring a leading space, preventing unintended matches within other compiler flags.
• Warning Flag Conversion: The logic for converting -Wno-error= flags to -W remains, ensuring proper handling of compiler warnings.

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[gemini-code-assist]

Code Review

This pull request fixes a bug in how WARN_CFLAGS is filtered by sed, specifically preventing a greedy match from removing too many compiler flags. The change is an improvement, but it could be made more robust. I've added a suggestion to handle an edge case where the flag to be removed is at the beginning of the string.

[gemini-code-assist]

This change correctly fixes the greedy .* in the previous sed command. However, by adding a leading space to the pattern (s/ -Wdeclaration-after-statement//), it will fail to remove the -Wdeclaration-after-statement flag if it happens to be the first flag in the $WARN_CFLAGS string.

The other substitution, s/-Wno-error=/-W/g, does not have a leading space, which implies that flags can indeed appear at the beginning of the string.

To make this more robust, I suggest also handling the case where the flag is at the start of the string. This will ensure the flag is removed regardless of its position.

                        WARN_CFLAGS="$(echo "$WARN_CFLAGS" | sed -e 's/-Wno-error=/-W/g' -e 's/ -Wdeclaration-after-statement//g' -e 's/^-Wdeclaration-after-statement//g')"