build: silence -Wextra warnings across the library, tests and examples

[harshavardhana]

-Wall -Wextra -Wconversion are unconditional in CMakeLists.txt, and the tree currently emits 15 warnings (7 in the library, 8 in the tests). This clears all of them.

Changes

• src/client.cc — the four best-effort AbortMultipartUpload(amu_args) cleanup calls on failure paths now discard their [[nodiscard]] Result explicitly with (void), matching existing precedent in http.cc:71 and response.cc:615.
• tests/tests.cc — same treatment for the 8 client_.RemoveBucket(args) cleanup calls.
• src/client.cc — the two error-carrying ListObjectsResult / RemoveObjectsResult constructors take [[maybe_unused]] error::Error err.
• src/baseclient.cc — GetErrorResponse's unused resource parameter takes [[maybe_unused]]. The signature is left intact: BaseClient::GetErrorResponse is public and reachable from downstream C glue.

Touched files were run through clang-format.

Verification

Warning counts with -Wall -Wextra -Wconversion, GCC 14.2.0 on Linux/x86_64:

Configuration	Warnings
C++17 Release — library + tests + examples	0
C++20 Release (MINIO_CPP_STD=20) — all targets	0
MINIO_CPP_ENABLE_RDMA=ON Release — all targets, incl. src/c_api.cc	0
Debug	0 across 63 translation units (linking not completed locally — out of disk, unrelated to these changes)

Follow-up, not addressed here

[[maybe_unused]] on the two result constructors silences the warning but does not restore the dropped error. 3d21189 removed the lines that carried it:

• ListObjectsResult: resp_->contents.push_back(Item(std::move(err)))
• RemoveObjectsResult: resp_.errors.push_back(DeleteError(err))

So ListObjects with an invalid argument is now indistinguishable from an empty bucket. This is not only the validate path — StartPrefetch catches every exception and returns an empty ListObjectsResponse, and Populate sets failed_ = true either way, so a 403 or a network failure looks identical too.

That means a simple GetError() accessor fed only from the validate constructor would be worse than none — it would authoritatively report "no error" for a 403. A real fix needs an error channel out of the prefetch future, which changes the type at client.h:44-45. Left for a separate PR.

Summary by CodeRabbit

• Chores
  • Improved handling of intentionally unused results and parameters.
  • No user-visible behavior or error-handling changes.

[coderabbitai]

📝 Walkthrough

Walkthrough

The changes make intentionally unused parameters and ignored Result values explicit in client implementation and test cleanup code. Runtime behavior and error handling remain unchanged.

Changes

Compiler warning cleanup

Layer / File(s)	Summary
Explicit unused values src/baseclient.cc, src/client.cc, tests/tests.cc	Unused parameters use [[maybe_unused]]. Ignored multipart-abort and bucket-removal results use explicit (void) casts.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• minio/minio-cpp#242: Modifies the same unused parameters and ignored cleanup results to address build warnings.

Suggested reviewers: jiuker

Poem

A rabbit checks each result with care,
Marks unused values sitting there.
Cleanup hops through every test,
While warnings take a quiet rest.
No behavior changes in the burrow bright.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: silencing compiler warnings across the library, tests, and examples.

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