Replace BOOST_FOREACH with range-based for in example/graph-thingie.cpp

[reach2sayan]

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

Replaces the single BOOST_FOREACH loop in example/graph-thingie.cpp (over vertices(graph)) with range-based for.
vertices() returns a std::pair of iterators, so the range is wrapped in boost::make_iterator_range(...).
#include <boost/foreach.hpp> becomes
#include <boost/range/iterator_range.hpp>.

The loop variable keeps its explicit type (graph_t::vertex_descriptor) and the loop body is unchanged. Example only; no library code is touched.

Motivation

Refs #593 (task 1.3, "BOOST_FOREACH to range-based for"), item
example/graph-thingie.cpp. Same approach as #603 and #604.

Testing

• b2 graph-thingie, b2 cxxstd=20 graph-thingie (gcc 13) and b2 toolset=clang cxxstd=17 graph-thingie (clang 18) from libs/graph/example on Linux: all
  passed.
• Standalone builds with -Wall -Wextra at C++14/17/20/23 on gcc 13 and clang 18:
  zero warnings.
• Program output is byte-for-byte identical to the develop version at every standard
  on both compilers, including the vertex a (NODE_A) / vertex b (NODE_B) / vertex c () lines printed by the converted loop.

Checklist

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

[github-actions]

Boost dependency footprint vs develop (auto-generated).
PR run 36272627641 vs develop run 36267169530 (192743b0b6).

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

No header-inclusion-weight changes.

Transitive Boost modules: 47 → 47 (0)

[github-actions]

Compiler-warning counts vs develop (auto-generated).
PR run 36272627653 vs develop run 36267169535 (192743b0b6).

Job	Baseline	After	Delta
macos (clang, 14)	392	392	0
macos (clang, 17)	391	391	0
macos (clang, 20)	391	391	0
ubuntu (clang-19, 14)	392	392	0
ubuntu (clang-19, 17)	391	391	0
ubuntu (clang-19, 20)	391	391	0
ubuntu (clang-19, 23)	391	391	0
ubuntu (gcc-14, 14)	345	345	0
ubuntu (gcc-14, 17)	341	341	0
ubuntu (gcc-14, 20)	341	341	0
ubuntu (gcc-14, 23)	341	341	0
windows_msvc_14_3 (msvc-14.3)	931	931	0

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Becheler]

Thanks again @reach2sayan !

One minor remark is to reduce the verbosity of such future PRs.

The git diff is very small/straightforward but the PR description makes it look like a serious change where reviewers must pay attention and read all the PR description :)

AI is pretty verbose and loves to generate text, so finding the right level of verbosity can be tricky!

Thanks again!

[reach2sayan]

Thanks again @reach2sayan !

One minor remark is to reduce the verbosity of such future PRs.

The git diff is very small/straightforward but the PR description makes it look like a serious change where reviewers must pay attention and read all the PR description :)

AI is pretty verbose and loves to generate text, so finding the right level of verbosity can be tricky!

Thanks again!

This is funny. This was the one bit that was totally me :p (painstakingly marking the x's) 😂. I thought that was a bgl standard. I was getting tired of that NGL 😂
I'll gladly right more succinct desc.

[Becheler]

Ahaha we do scan the crossed boxes ! It helps knowing what the expectations are (if there is a behavior change when the x shows refactor, then we can assume it's a mistake and flag it).

I was mostly speaking about this part, that can be much lighter as CI and bots will show us the required information!

b2 graph-thingie, b2 cxxstd=20 graph-thingie (gcc 13) and b2 toolset=clang cxxstd=17 graph-thingie (clang 18) from libs/graph/example on Linux: all
passed.
Standalone builds with -Wall -Wextra at C++14/17/20/23 on gcc 13 and clang 18:
zero warnings.
Program output is byte-for-byte identical to the develop version at every standard
on both compilers, including the vertex a (NODE_A) / vertex b (NODE_B) / vertex c () lines printed by the converted loop.

For short PRs, the "change summary" section may end up more verbose than the actual file diff, so no worries we will be happy with a "refactor BOOST_FOREACH in file xxx" 🤗

It's useful for more complex PRs with many changes when reviewers may need a high level vision on how the changes are related and why 🙃 or to show local benchmarks results