[EXPORTER] Convert uint64_t attribute values exceeding INT64_MAX to string per OTel spec by thc1006 · Pull Request #4090 · open-telemetry/opentelemetry-cpp

thc1006 · 2026-05-18T13:31:57Z

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`)

SetUint64OverflowAsStringPerSpec — INT64_MAX + 1 → string_value with decimal representation
SetUint64BoundaryAsIntPerSpec — INT64_MAX → int_value (encoding split is val > INT64_MAX)
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 · 2026-05-18T15:41:36Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.00%. Comparing base (8fbe81e) to head (8792789).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4090      +/-   ##
==========================================
+ Coverage   82.00%   82.00%   +0.01%     
==========================================
  Files         385      385              
  Lines       16030    16031       +1     
==========================================
+ Hits        13143    13144       +1     
  Misses       2887     2887

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

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Eliminate the 29 misc-unused-alias-decls warnings flagged by clang-tidy across 27 files in examples, exporters, sdk, and tests. The most common pattern was a file-scope `namespace nostd = opentelemetry::nostd;` declaration that was never referenced via the file-scope alias path (uses of `nostd::` resolved through the surrounding OPENTELEMETRY_BEGIN_NAMESPACE namespace nesting instead). No behavior change. Removed declarations were genuinely dead per clang-tidy. Where removing an alias affected sibling-line alignment (e.g. `using M = ...` next to the removed alias), clang-format auto-collapsed the alignment. Ratchet: * abiv1-preview warning_limit lowered from 418 to 389 * abiv2-preview warning_limit lowered from 424 to 395 A 30th misc-unused-alias-decls site at exporters/otlp/src/otlp_populate_attribute_utils.cc:30 is intentionally not touched in this PR to avoid conflicting with the in-flight open-telemetry#4090. It can be cleaned up in a follow-up after open-telemetry#4090 lands. Part of open-telemetry#2053 Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

Eliminate 29 misc-unused-alias-decls warnings flagged by clang-tidy v22 across 27 files in examples, exporters, sdk, and tests. The dominant pattern was a file-scope `namespace nostd = opentelemetry::nostd;` declaration never referenced via the file-scope alias path (uses of `nostd::` resolved through OPENTELEMETRY_BEGIN_NAMESPACE namespace nesting instead). Also remove 4 unused type-alias `using M = std::map<std::string, std::string>;` declarations in storage tests, observed by Copilot review. clang-tidy does not flag these (misc-unused-alias-decls targets only namespace aliases, not type aliases), but they are genuinely dead code in the same spirit and the same files this PR already touches. No behavior change. Removed declarations were genuinely unused. clang-format auto-collapsed adjacent orphan alignment whitespace where removing a line left aligned siblings. Ratchet: * abiv1-preview warning_limit lowered from 418 to 389 * abiv2-preview warning_limit lowered from 424 to 395 A 30th misc-unused-alias-decls site at exporters/otlp/src/otlp_populate_attribute_utils.cc:30 is intentionally not touched in this PR to avoid conflicting with the in-flight open-telemetry#4090. It can be cleaned up in a trivial follow-up after open-telemetry#4090 lands. Part of open-telemetry#2053 Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

Eliminate 29 misc-unused-alias-decls warnings flagged by clang-tidy v22 across 27 files in examples, exporters, sdk, and tests. The dominant pattern was a file-scope `namespace nostd = opentelemetry::nostd;` declaration never referenced via the file-scope alias path (uses of `nostd::` resolved through OPENTELEMETRY_BEGIN_NAMESPACE namespace nesting instead). Also remove 4 unused type-alias `using M = std::map<std::string, std::string>;` declarations in storage tests, observed by Copilot review. clang-tidy does not flag these (misc-unused-alias-decls targets only namespace aliases, not type aliases), but they are genuinely dead code in the same spirit and the same files this PR already touches. Also remove 9 now-unused #include directives that IWYU flagged as a consequence of the alias removals: when an alias like `namespace http_client = opentelemetry::ext::http::client;` is removed, the include that brought the namespace into scope is no longer needed. Same logic for several `opentelemetry/common/attribute_value.h` includes that supported `namespace common = opentelemetry::common;` aliases, and `<map>` after removing the unused `using M = ...` from async_metric_storage_test.cc. No behavior change. Removed declarations were genuinely unused. clang-format auto-collapsed adjacent orphan alignment whitespace where removing a line left aligned siblings. Ratchet: * abiv1-preview warning_limit lowered from 418 to 389 * abiv2-preview warning_limit lowered from 424 to 395 A 30th misc-unused-alias-decls site at exporters/otlp/src/otlp_populate_attribute_utils.cc:30 is intentionally not touched in this PR to avoid conflicting with the in-flight open-telemetry#4090. It can be cleaned up in a trivial follow-up after open-telemetry#4090 lands. Part of open-telemetry#2053 Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

…tring per OTel spec Per OpenTelemetry attribute type-mapping spec (https://opentelemetry.io/ docs/specs/otel/common/attribute-type-mapping/#integer-values), integer values outside the 64-bit signed range MUST be encoded as AnyValue's string_value using decimal representation, not wrapped to a negative int64 via narrowing. Pre-PR behavior at the four uint64_t conversion sites in otlp_populate_attribute_utils.cc was to implicitly narrow (suppressed via NOLINT). 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 fixes the violation via a file-local helper SetUint64Value that dispatches to set_int_value or set_string_value based on the value's range. All four uint64_t sites in both PopulateAnyValue overloads now follow the spec. Spec-compliance verified by three new tests in otlp_recordable_test.cc: - UINT64_MAX-equivalent value -> string_value with decimal representation - INT64_MAX boundary value -> int_value (encoding split is val > INT64_MAX) - Mixed-value array -> per-element dispatch (int + string in same array) Side effect: the four bugprone-narrowing-conversions warnings clang-tidy v22 was reporting are eliminated (the static_cast is now in a guarded branch, suppressing the diagnostic). Ratchet drops accordingly: * abiv1-preview warning_limit lowered from 389 to 385 * abiv2-preview warning_limit lowered from 395 to 391 Behavior change: existing callers relying on the wrap-to-negative behavior for uint64 > INT64_MAX will now see string_value on the wire instead of negative int_value. This was never spec-conformant; the new behavior aligns OTLP output with the protocol specification. Part of open-telemetry#2053 Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

Copilot AI review requested due to automatic review settings May 18, 2026 13:31

thc1006 requested a review from a team as a code owner May 18, 2026 13:31

thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from b15a543 to e9fc36b Compare May 18, 2026 13:32

Copilot started reviewing on behalf of thc1006 May 18, 2026 13:32 View session

Copilot AI reviewed May 18, 2026

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Comment thread CHANGELOG.md Outdated

thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from e9fc36b to cc4c581 Compare May 18, 2026 14:16

thc1006 changed the title ~~[CODE HEALTH] Update bugprone-narrowing-conversions NOLINT suppressions in otlp_populate_attribute_utils~~ [CODE HEALTH] Fix clang-tidy narrowing-conversions warnings in otlp_populate_attribute_utils May 18, 2026

thc1006 requested a review from Copilot May 18, 2026 14:18

Copilot AI reviewed May 18, 2026

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thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from cc4c581 to 2c3d074 Compare May 18, 2026 14:32

Copilot started reviewing on behalf of thc1006 May 18, 2026 14:46 View session

thc1006 mentioned this pull request May 18, 2026

[CODE HEALTH] Remove unused alias declarations #4091

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3 tasks

thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from 2c3d074 to 785ec9a Compare May 19, 2026 16:35

thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from 785ec9a to c77b2ba Compare May 27, 2026 02:10

thc1006 changed the title ~~[CODE HEALTH] Fix clang-tidy narrowing-conversions warnings in otlp_populate_attribute_utils~~ [EXPORTER] Convert uint64_t attribute values exceeding INT64_MAX to string per OTel spec May 27, 2026

thc1006 force-pushed the codehealth/otlp-narrowing-nolint-alias branch from c77b2ba to 8792789 Compare May 27, 2026 03:01

thc1006 requested a review from dbarker May 27, 2026 03:50

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[EXPORTER] Convert uint64_t attribute values exceeding INT64_MAX to string per OTel spec#4090

[EXPORTER] Convert uint64_t attribute values exceeding INT64_MAX to string per OTel spec#4090
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thc1006 commented May 18, 2026 •

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thc1006 commented May 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Scope of fix (4 sites, 1 file)

Tests (new, in otlp_recordable_test.cc)

Ratchet

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thc1006 commented May 18, 2026 •

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Tests (new, in `otlp_recordable_test.cc`)

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