fix: replace blanket -Wno-maybe-uninitialized with targeted pragmas (#979)

[alandefreitas]

Remove the blanket -Wno-maybe-uninitialized suppression from all GCC builds and add a scoped pragma around the one site in our code that triggers the false positive (parse_sequence in tuple_rule.hpp). Also removes the unused BOOST_URL_NO_INLINE macro.

The remaining false positives originate inside variant2 and optional headers and need to be fixed upstream:

• fix: add missing -Wmaybe-uninitialized pragma to recursive variant_storage_impl variant2#57
• fix: add -Wmaybe-uninitialized pragma to union storage constructors optional#145

The third commit is a temporary CI patch that copies fixed versions of those headers to prove the full fix works across GCC 7–15. It will be dropped once the upstream PRs are merged.

[cppalliance-bot]

An automated preview of the documentation is available at https://981.url.prtest2.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-02-24 21:55:26 UTC

[cppalliance-bot]

GCOVR code coverage report https://981.url.prtest2.cppalliance.org/gcovr/index.html
LCOV code coverage report https://981.url.prtest2.cppalliance.org/genhtml/index.html
Coverage Diff Report https://981.url.prtest2.cppalliance.org/diff-report/index.html

Build time: 2026-02-24 17:19:12 UTC

[cppalliance-bot]

GCOVR code coverage report https://981.url.prtest2.cppalliance.org/gcovr/index.html
LCOV code coverage report https://981.url.prtest2.cppalliance.org/genhtml/index.html
Coverage Diff Report https://981.url.prtest2.cppalliance.org/diff-report/index.html

Build time: 2026-02-24 22:02:59 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.15%. Comparing base (fdb3ca4) to head (d0f686e).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #981   +/-   ##
========================================
  Coverage    99.15%   99.15%           
========================================
  Files          155      155           
  Lines        10045    10045           
========================================
  Hits          9960     9960           
  Misses          85       85           

Files with missing lines	Coverage Δ
include/boost/url/grammar/impl/tuple_rule.hpp	100.00% <100.00%> (ø)

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