Invert build.rs version detection flags and update CI

[joshlf]

Inverts version detection flags to default to enabled on modern compilers. Renames zerocopy-foo to no-zerocopy-foo in Cargo.toml, build.rs, source code, and .github/workflows/ci.yml. Ensures check_all_toolchains_tested.sh passes by syncing CI config. Verified unit tests on all affected toolchains.

Closes #2259

[gemini-code-assist]

Summary of Changes

Hello @joshlf, 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 refactors the version detection mechanism within the zerocopy crate. Instead of explicitly enabling features for newer compiler versions, the system now defaults to enabling features and uses no- prefixed flags to disable them for older, less capable toolchains. This change simplifies the configuration for modern compilers and ensures compatibility across various Rust toolchains, with corresponding updates to the CI pipeline.

Highlights

• Inverted Feature Flag Logic: The build.rs script now emits no-zerocopy-foo flags when the Rust toolchain version is lower than a specified version, effectively enabling features by default on modern compilers and using the no- flags to disable them for older toolchains.
• Renamed Configuration Flags: All zerocopy-foo flags in Cargo.toml, build.rs, and the source code have been systematically renamed to no-zerocopy-foo to align with the new inverted logic.
• CI Configuration Update: The Continuous Integration (CI) pipeline, specifically the check_all_toolchains_tested.sh script and .github/workflows/ci.yml, has been updated to reflect these changes, ensuring continued compatibility and testing across various Rust toolchains.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/ci.yml

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[gemini-code-assist]

Code Review

This pull request correctly inverts the version detection flags, which is a good improvement for maintainability. The changes are applied consistently across Cargo.toml, build.rs, and all affected source files. The logic for conditional compilation has been preserved correctly with the new inverted flags. I've reviewed the changes thoroughly and found no issues. Great work on this large-scale refactoring!

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.14%. Comparing base (f65c938) to head (94f4d2f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2804   +/-   ##
=======================================
  Coverage   88.14%   88.14%           
=======================================
  Files          20       20           
  Lines        5450     5450           
=======================================
  Hits         4804     4804           
  Misses        646      646           

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[jswrenn]

What's the motivation here?

[joshlf]

What's the motivation here?

See #2259