Fix RAFT_LOG_TRACE_VEC after the rapids-logger migration

[Wint3rNight]

Closes #2622.

Building with LIBRAFT_LOGGING_LEVEL=TRACE fails to compile. The issue reports one broken symbol; there are actually three, all left behind by #2566 when the logger moved to rapids-logger:

raft::detail::format was removed in that PR — replaced with direct stream insertion, which is all it was doing here
print_vector is unqualified so it doesn't resolve — now raft::print_vector
log() is passed RAPIDS_LOGGER_LOG_LEVEL_TRACE where it wants rapids_logger::level_enum::trace, which is what the sibling RAFT_LOG_TRACE already uses
Added cpp/tests/core/logger.cu covering the host and device pointer paths. The existing ext_headers test only does a bare #include <raft/core/logger.hpp> at the default log level, so the macro body expands to void(0) and is never compiled — which is why this went unnoticed since the migration. The new test raises the level for that translation unit only; reverting the fix makes it fail to build.

Callers still need raft/util/cudart_utils.hpp for print_vector. The macro only expands at the call site, so core/ doesn't take a dependency on util/.

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📝 Summary

Summary by CodeRabbit

• Bug Fixes

  • Improved trace-level vector logging with more reliable formatting.
  • Enhanced support for logging data from both host and device memory.
  • Reduced unexpected failures when logging vector contents.

• Tests

  • Added coverage for trace logging with host and device pointers.
  • Verified logging during device memory allocation, transfer, synchronization, and cleanup workflows.

Walkthrough

Changes

The trace vector logging macro now uses typed trace logging and qualified vector formatting. CUDA tests cover host and device pointer logging, and the test source is included in the core test target.

Trace Vector Logging

Layer / File(s)	Summary
Trace macro implementation cpp/include/raft/core/logger.hpp	RAFT_LOG_TRACE_VEC builds the source prefix with std::stringstream, calls raft::print_vector, and logs the resulting string at trace level.
Host and device logger tests cpp/tests/core/logger.cu, cpp/tests/CMakeLists.txt	The core test target includes the CUDA test. The test exercises host and device pointer logging, including device allocation, copying, synchronization, logging, and cleanup.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: achirkin

Merge Risk: ⚪ Minimal · up to 80b52

The trace logging change has registered host and device coverage, with no concrete merge-blocking issue identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the primary change: fixing RAFT_LOG_TRACE_VEC after the rapids-logger migration.
Description check	✅ Passed	The description directly explains the compilation failures, the three fixes, and the added host and device pointer tests.
Linked Issues check	✅ Passed	The change satisfies issue #2622. RAFT_LOG_TRACE_VEC no longer calls removed raft::detail::format. It builds the file and line prefix with stream insertion, calls raft::print_vector, and passes …
Out of Scope Changes check	✅ Passed	The changed files are within issue #2622 scope. The logger macro change fixes the reported TRACE compilation failure. The CMake update and host/device tests provide automated coverage for that macro. …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…

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Actionable comments posted: 1

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Verify each finding against current code. Fix only still-valid issues, skip the
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Inline comments:
In `@cpp/tests/core/logger.cu`:
- Around line 42-49: Replace the raw device_data allocation and manual cudaFree
with the project-standard RAII device container, preserving the existing size
and host-to-device copy behavior. Update the cudaMemcpy destination and
RAFT_LOG_TRACE_VEC call to use the container’s data() pointer, ensuring
ownership remains automatic if either operation fails.

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Fix all unresolved CodeRabbit comments on this PR:

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📒 Files selected for processing (3)

• cpp/include/raft/core/logger.hpp
• cpp/tests/CMakeLists.txt
• cpp/tests/core/logger.cu