[lucasfang]

Purpose

Closes #529.

The default Debug build crashes GCC 13.3 while instantiating FieldsComparatorTest::CheckFloatingPointOrder<float>: the negated local constant is passed directly into the variant-backed row generator. Materialize the negated NaN as T before that conversion to avoid the compiler ICE.

The existing float/double ordering assertions continue to cover infinities, signed zero, NaNs, and sign-flipped NaN equality. A scan of 2,195 repository-owned C++ files and review of the other negated floating/template-constant candidates found no additional confirmed instance of this conversion pattern.

Tests

• Reproduced the original GCC 13.3 ICE in the project translation unit and a standalone standard-library example.
• Full default-feature Debug builds completed with GCC 13.3.0 and Clang 18.1.3; final incremental checks used cmake --build build --parallel 96 and cmake --build build-clang --parallel 96.
• build/debug/paimon-common-test --gtest_filter='FieldsComparatorTest.*': 6/6 passed with GCC 13.3.0.
• build-clang/debug/paimon-common-test --gtest_filter='FieldsComparatorTest.*': 6/6 passed with Clang 18.1.3.
• ctest --test-dir build -L unittest --output-on-failure --parallel 96: 32/32 test executables passed, 201.32 seconds.
• All configured pre-commit hooks passed with pre-commit run --all-files --show-diff-on-failure in an isolated validation checkout at the same base commit plus this patch.
• git diff --check passed.

API and Format

Unchanged: this only adjusts one test initialization.

Documentation

No user-facing documentation changes are needed for this test-only compiler workaround.

Generative AI tooling

Generated-by: OpenAI Codex 26.1029.70936

[SteNicholas]

LGTM.