[CODE HEALTH] Fix clang-tidy bugprone-exception-escape in ostream exporters

[jensecrest]

Fixes #2053

Changes

Fixes 3 bugprone-exception-escape clang-tidy warnings in the ostream exporters by wrapping the throwing portions of Export in try/catch, guarded by #if OPENTELEMETRY_HAVE_EXCEPTIONS.

• OStreamLogRecordExporter::Export in log_record_exporter.cc
• OStreamSpanExporter::Export in span_exporter.cc
• OStreamMetricExporter::Export in metric_exporter.cc

What the problem is

All three Export functions are marked noexcept (required by their base class interfaces), but contain operations that can throw:

• sout_ << ... — std::ostream::operator<< can throw std::ios_base::failure if exceptions are enabled on the stream
• std::string(char*, len) construction — can throw std::bad_alloc
• Helper functions like printAttributes, printEvents, printInstrumentationInfoMetricData — all use ostream internally

If any of these throw inside a noexcept function, the program calls std::terminate() — a crash.

Why try/catch is the minimal fix

• We cannot remove noexcept — it's on the pure virtual base class interfaces (LogRecordExporter, SpanExporter, PushMetricExporter). Changing it would be an API/ABI break.
• We cannot replace the throwing operations with non-throwing alternatives — there is no non-throwing version of operator<< or std::string construction. The entire purpose of these functions is to write to an ostream.
• try/catch is the established pattern in this codebase — see PeriodicExportingMetricReader::CollectAndExportOnce() in periodic_exporting_metric_reader.cc, which uses the same #if OPENTELEMETRY_HAVE_EXCEPTIONS / try / catch structure.

What the change does

Wraps the throwing portion of each Export function in try/catch, guarded by #if OPENTELEMETRY_HAVE_EXCEPTIONS (the project's standard guard for builds with exceptions disabled via -fno-exceptions). On exception, the error is logged via OTEL_INTERNAL_LOG_ERROR and kFailure is returned.

What the change does NOT do

• Does not change function signatures, return types, or the noexcept specifier
• Does not change behavior on the happy path — when no exception occurs, the functions execute identically and return kSuccess
• Does not change the error-path return for the shutdown check (still returns kFailure before the try block)
• On the exception path: changes behavior from std::terminate() (crash) to logging an error and returning kFailure (graceful degradation)

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

AI

Assisted-by: This contribution was prepared with the assistance of an AI development tool.

[codecov]

Codecov Report

❌ Patch coverage is 75.78947% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.89%. Comparing base (af27cc9) to head (6633f3e).

Files with missing lines	Patch %	Lines
exporters/ostream/src/log_record_exporter.cc	81.64%	9 Missing ⚠️
exporters/ostream/src/metric_exporter.cc	22.23%	7 Missing ⚠️
exporters/ostream/src/span_exporter.cc	81.09%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4137      +/-   ##
==========================================
- Coverage   82.02%   81.89%   -0.13%     
==========================================
  Files         385      385              
  Lines       16071    16095      +24     
==========================================
- Hits        13181    13179       -2     
- Misses       2890     2916      +26     

Files with missing lines	Coverage Δ
exporters/ostream/src/metric_exporter.cc	86.37% <22.23%> (-4.73%)	⬇️
exporters/ostream/src/span_exporter.cc	81.91% <81.09%> (-6.75%)	⬇️
exporters/ostream/src/log_record_exporter.cc	80.52% <81.64%> (-9.33%)	⬇️

... and 1 file with indirect coverage changes

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