nc_perf does not build with MSVC (NETCDF_ENABLE_BENCHMARKS=ON fails on Windows)

[hyoklee]

Environment Information

• What platform are you using?
  • Windows (GitHub Actions windows-2025, MSVC 14.51.36231)
• 32 and/or 64 bit?
  • 64-bit
• What build system are you using?
  • cmake
• Can you provide a sample netCDF file or C code to recreate the issue?
  • Not at this time (the existing nc_perf sources reproduce it)

Summary of Issue

nc_perf does not compile with MSVC, so -DNETCDF_ENABLE_BENCHMARKS=ON cannot
be used on Windows. The sources are POSIX-only by construction: none of the 23
.c files in nc_perf/ contains a single _WIN32 guard, and nearly all of
them use gettimeofday, getrusage, or <unistd.h> directly.

Two specific things block tst_chunks3, which is otherwise a useful portable
benchmark (it exercises contiguous / chunked / compressed access at a
configurable shape):

1. nc_perf/tst_chunks3.c — the TIMING_DECLS / TIMING_START / TIMING_END
   macros are built on struct rusage and getrusage(RUSAGE_SELF, ...).
   MSVC provides neither, and the <sys/resource.h> include is already behind
   HAVE_SYS_RESOURCE_H, so the macros are left without a definition.

2. nc_perf/tst_utils.c — includes <sys/time.h> unconditionally (for
   struct timeval, used by nc4_timeval_subtract). tst_chunks3 links this
   file, so it fails even if (1) is addressed:

   nc_perf\tst_utils.c(18,10): error C1083: Cannot open include file:
   'sys/time.h': No such file or directory
   

The rest of the directory fails the same way, e.g.:

nc_perf\bm_many_atts.c(17,10): error C1083: Cannot open include file: 'sys/time.h'
nc_perf\tst_mem.c(15,10):      error C1083: Cannot open include file: 'unistd.h'
nc_perf\bm_file.c(19,10):      error C1083: Cannot open include file: 'sys/time.h'
nc_perf\tst_wrf_reads.c(17,10):error C1083: Cannot open include file: 'sys/time.h'

Steps to reproduce the behavior

cmake -S netcdf-c -B build -A x64 -DNETCDF_ENABLE_BENCHMARKS=ON -DENABLE_HDF5=ON
cmake --build build --config Release

Note

I have a PR that addresses (1) and (2) only, which is enough to build and run
tst_chunks3 on Windows; the other nc_perf programs are untouched and remain
POSIX-only. Happy to extend it if you would rather see the whole directory
ported, or to close it if nc_perf is intentionally POSIX-only — in which case
it may be worth skipping add_subdirectory(nc_perf) on WIN32 so that
NETCDF_ENABLE_BENCHMARKS=ON fails early with a clear message instead of
partway through the build.