fix: skip DuckDB build on 32-bit targets and suppress GCC 16 SFINAE warning

[drrtuy]

PR Description

Fix one CI build issue with the DuckDB storage engine plugin.

Skip DuckDB on 32-bit builds

The existing CMAKE_SYSTEM_PROCESSOR guard in storage/duckdb/CMakeLists.txt does not protect against -m32 multilib builds running inside an x86_64 CI container — the processor is still reported as x86_64 while the actual target is 32-bit. This causes a link failure because DuckDB's jemalloc extension is 64-bit only and is not produced for 32-bit targets:

No rule to make target '.../jemalloc/libjemalloc_extension.a', needed by 'ha_duckdb.so'

Add a CMAKE_SIZEOF_VOID_P EQUAL 8 guard (the standard CMake way to detect pointer size, derived from the compiler's actual target) to skip DuckDB entirely on any 32-bit build.

Suppress -Wsfinae-incomplete on GCC 16+

GCC 16 introduces -Wsfinae-incomplete which fires on DuckDB's CompressionInfo class (upstream issue). Suppress it with -Wno-sfinae-incomplete for DuckDB plugin targets only (PRIVATE scope), gated by MY_CHECK_CXX_COMPILER_FLAG so older compilers are unaffected.

Changes

• storage/duckdb/CMakeLists.txt — add CMAKE_SIZEOF_VOID_P guard
• storage/duckdb/cmake/duckdb_target_setup.cmake — add conditional -Wno-sfinae-incomplete

[gemini-code-assist]

Code Review

This pull request adds a 64-bit build check to skip DuckDB on 32-bit architectures and silences GCC 16+ -Wsfinae-incomplete warnings. The reviewer recommends moving the compiler flag check for -Wsfinae-incomplete from the per-target setup macro to the directory-level CMakeLists.txt to avoid redundant evaluations and keep compiler checks centralized.

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[gemini-code-assist]

Calling MY_CHECK_CXX_COMPILER_FLAG inside a target setup macro (duckdb_setup_target) means the compiler flag check is evaluated repeatedly for every target that uses this macro. Although CMake caches the result, it is cleaner and more efficient to perform compiler capability checks once at the directory level (e.g., in storage/duckdb/CMakeLists.txt) and only reference the resulting variable here.

  IF(have_CXX__Wsfinae_incomplete)
    TARGET_COMPILE_OPTIONS(${_target} PRIVATE -Wno-sfinae-incomplete)
  ENDIF()

[gemini-code-assist]

Perform the compiler flag check for -Wsfinae-incomplete here at the directory level, rather than inside the per-target setup macro, to avoid redundant evaluations and keep compiler checks centralized.

IF(NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
  MESSAGE_ONCE(duckdb "DuckDB: not a 64-bit build, skipping")
  return()
ENDIF()

MY_CHECK_CXX_COMPILER_FLAG("-Wsfinae-incomplete")