[EXPORTER] Convert uint64_t attribute values exceeding INT64_MAX to string per OTel spec

[thc1006]

Summary

Per OpenTelemetry attribute type-mapping spec:

Integer values which are within the range of 64 bit signed numbers [-2^63..2^63-1] SHOULD be converted to AnyValue's int_value field.
Integer values which are outside the range of 64 bit signed numbers SHOULD be converted to AnyValue's string_value field using decimal representation.

Pre-PR behavior at the four uint64_t conversion sites in exporters/otlp/src/otlp_populate_attribute_utils.cc implicitly narrowed via // NOLINT(cppcoreguidelines-narrowing-conversions). For uint64_t values exceeding INT64_MAX, this produced negative int_value on the wire — a long-standing spec violation that predates this PR.

This PR replaces the four narrowing call sites with a file-local helper that dispatches per spec:

inline void SetUint64Value(opentelemetry::proto::common::v1::AnyValue *proto_value, uint64_t val)
{
  if (val <= static_cast<uint64_t>(std::numeric_limits<int64_t>::max()))
    proto_value->set_int_value(static_cast<int64_t>(val));
  else
    proto_value->set_string_value(std::to_string(val));
}

Both PopulateAnyValue overloads (for AttributeValue and OwnedAttributeValue) and both shapes (scalar and array element) route through the same helper. Spec-link comment is attached to the helper for future readers.

Scope of fix (4 sites, 1 file)

Site	Variant
otlp_populate_attribute_utils.cc:~94	uint64_t scalar in AttributeValue overload
otlp_populate_attribute_utils.cc:~187	nostd::span<const uint64_t> array
otlp_populate_attribute_utils.cc:~254	uint64_t scalar in OwnedAttributeValue overload
otlp_populate_attribute_utils.cc:~331	std::vector<uint64_t> array

Other integer conversions (int, int64_t, unsigned int, uint32_t) always fit in int64_t and were not affected by the spec rule. No other files in exporters/ or sdk/ call set_int_value with uint64_t source (verified via grep).

Tests (new, in otlp_recordable_test.cc)

1. SetUint64OverflowAsStringPerSpec — INT64_MAX + 1 → string_value with decimal representation
2. SetUint64BoundaryAsIntPerSpec — INT64_MAX → int_value (encoding split is val > INT64_MAX)
3. SetUint64ArrayOverflowAsStringPerSpec — mixed-value array dispatches per element (int + string in same array)

Ratchet

Helper's explicit static_cast is now in a value-guarded branch, so the bugprone-narrowing-conversions diagnostics on these four sites are still silenced.

• all-options-abiv1-preview warning_limit lowered from 389 to 385
• all-options-abiv2-preview warning_limit lowered from 395 to 391

Behavior change disclosure

For uint64_t attribute values exceeding INT64_MAX (~9.2e18):

• Before: wrapped to negative int_value on the wire (non-spec-conformant)
• After: decimal string in string_value (spec-conformant)

Callers relying on the wrap-to-negative behavior would see breakage. This behavior was never spec-conformant; the new behavior aligns OTLP output with the protocol specification.

Review history

Originally opened as a [CODE HEALTH] PR to fix bugprone-narrowing-conversions warnings via static_cast. @dbarker pointed out in review that the static_cast preserves the spec-violating wrap behavior and asked for spec-compliant string fallback. This PR was then upgraded in scope to the present spec fix.

Test plan

• CI clang-tidy job passes both abiv1-preview and abiv2-preview at the new limits
• CI Format job passes (verified locally via clang-format --dry-run --Werror)
• CI build matrices pass — new tests build and run as part of the OTLP test suite
• No behavior change for int, int64_t, unsigned int, uint32_t paths

Part of #2053

[Copilot]

Pull request overview

Updates OTLP exporter code to align existing clang-tidy suppression comments with the clang-tidy v22 check name, and adjusts CI warning limits accordingly. This is a code health/CI maintenance change intended to keep the clang-tidy ratchet stable after the LLVM/clang-tidy 22 upgrade.

Changes:

• Renames four NOLINT suppressions in otlp_populate_attribute_utils.cc from the old alias to bugprone-narrowing-conversions.
• Lowers clang-tidy workflow warning limits for all-options-abiv1-preview and all-options-abiv2-preview.
• Adds a corresponding CHANGELOG.md entry.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
exporters/otlp/src/otlp_populate_attribute_utils.cc	Updates four narrowing-conversion NOLINT suppressions to match clang-tidy v22’s check name.
CHANGELOG.md	Adds an Unreleased entry for the code health change.
.github/workflows/clang-tidy.yaml	Lowers the warning limits to reflect the reduced warning count.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.01%. Comparing base (0ac79fe) to head (0779513).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4090      +/-   ##
==========================================
+ Coverage   82.01%   82.01%   +0.01%     
==========================================
  Files         385      385              
  Lines       16030    16031       +1     
==========================================
+ Hits        13145    13146       +1     
  Misses       2885     2885              

Files with missing lines	Coverage Δ
...xporters/otlp/src/otlp_populate_attribute_utils.cc	92.96% <100.00%> (+0.05%)	⬆️

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[dbarker]

Thanks for the PR. Looks reasonable.