Cleanup dead cxx11 guards from /include/boost/pending/container_traits.hpp

[samkelemen]

Before submitting

• This PR targets the develop branch.
• I searched for an existing PR or issue covering the same change.
• My contribution is licensed under the Boost Software License 1.0.

Type of change

• Bug fix
• New feature or API addition
• Refactor (no behavior change)
• Documentation
• Build, CI, or tooling
• Other (specify below)

Does this PR introduce a breaking change?

• Yes (describe migration impact below)
• No

What this PR does

This PR removes the following guards from include/boost/pending/container_traits.hpp:

• #ifndef BOOST_NO_CXX11_HDR_UNORDERED_SET
• #ifndef BOOST_NO_CXX11_HDR_UNORDERED_MAP
• #ifdef BOOST_NO_CXX11_RVALUE_REFERENCES

Motivation

Fixes #587

Checklist

• Existing tests pass (b2 in the test/ directory).
• New behavior is covered by a test, or this is a docs / build / refactor change. -- N/A
• Documentation was updated if user-facing behavior changed. -- N/A
• No new compiler warnings on the platforms I built against.

[github-actions]

Boost dependency footprint vs develop (auto-generated).
PR run 33710957429 vs develop run 33632978542 (d497a08b8a).

Header-inclusion weights (graph files pulling each direct dependency in):

No header-inclusion-weight changes.

Transitive Boost modules: 66 → 66 (0)

[github-actions]

Compiler-warning counts vs develop (auto-generated).
PR run 33710957426 vs develop run 33632978502 (d497a08b8a).

Job	Baseline	After	Delta
macos (clang, 14)	648	648	0
macos (clang, 17)	611	611	0
macos (clang, 20)	611	611	0
ubuntu (clang-19, 14)	648	648	0
ubuntu (clang-19, 17)	611	611	0
ubuntu (clang-19, 20)	611	611	0
ubuntu (clang-19, 23)	611	611	0
ubuntu (gcc-14, 14)	801	801	0
ubuntu (gcc-14, 17)	937	937	0
ubuntu (gcc-14, 20)	937	937	0
ubuntu (gcc-14, 23)	937	937	0
windows_msvc_14_3 (msvc-14.3)	961	961	0

[codecov]

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✅ All modified and coverable lines are covered by tests.

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[jeremy-murphy]

Looks great, thank you! Just some minor quibble about unnecessary changes.

[Becheler]

Thank you so much for this first PR !
It revealed a consequent gap in the unit test coverage: I guess because historically the CI was running on old compilers, the modern paths you accidentally deleted were never tested ! So the PR breaks users but CI is green, what a wonderful world ! 😆
The solution is relatively straightforwards (delete the question #ifndef BOOST_NO_CXX11_HDR_UNORDERED_MAP but keep the overload it guards), I indicated it in comment, just let me know if you have questions 🤗

[samkelemen]

Hi @Becheler. I updated the PR, but I just noticed you assigned this PR to yourself. Are you wanting to take this one, perhaps to add test coverage?

[samkelemen]

Also the CI run failed for Linux g++-10 20, but the error looks unrelated to the actual code changes:

Cloning into '/drone/boost-root/tools/build'...
fatal: could not read Username for 'https://github.com': terminal prompts disabled
fatal: the remote end hung up unexpectedly
fatal: clone of 'https://github.com/boostorg/build.git' into submodule path '/drone/boost-root/tools/build' failed
Failed to clone 'tools/build'. Retry scheduled
Cloning into '/drone/boost-root/tools/build'...
fatal: could not read Username for 'https://github.com': terminal prompts disabled
fatal: the remote end hung up unexpectedly
fatal: clone of 'https://github.com/boostorg/build.git' into submodule path '/drone/boost-root/tools/build' failed
Failed to clone 'tools/build' a second time, aborting