[gdal-dev] float16 woes on solaris

[Greg Troxel]

The pkgsrc package isn't building on SmartOS (which is illumos, which is
OpenSolaris, more or less).

Full build at the last link:

  https://reports.pkgci.org/SmartOS/upstream/trunk/20250518.2249/meta/report.html
  https://reports.pkgci.org/SmartOS/upstream/trunk/20250518.2249/gdal-lib-3.11.0/configure.log
  https://reports.pkgci.org/SmartOS/upstream/trunk/20250518.2249/gdal-lib-3.11.0/build.log

but the key points are:

  configure:
    -- Performing Test HAVE_STD_FLOAT16_T
    -- Performing Test HAVE_STD_FLOAT16_T - Failed

  build:
    [ 94%] Linking CXX shared library libgdal.so
    Undefined			first referenced
     symbol  			    in file
    __extendhfsf2                       port/CMakeFiles/cpl.dir/cpl_json_streaming_writer.cpp.o
    __extendhfxf2                       /home/pbulk/build/geography/gdal-lib/work/.buildlink/lib/libhdf5.so.310
    __extendhfdf2                       port/CMakeFiles/cpl.dir/cpl_json_streaming_writer.cpp.o
    __truncdfhf2                        alg/CMakeFiles/alg.dir/gdalrasterize.cpp.o
    __truncxfhf2                        gcore/CMakeFiles/gcore.dir/rasterio.cpp.o
    __truncsfhf2                        gcore/CMakeFiles/gcore.dir/gdalrasterband.cpp.o
    __eqhf2                             alg/CMakeFiles/alg.dir/gdalwarpkernel.cpp.o
    __nehf2                             alg/CMakeFiles/alg.dir/gdalwarpkernel.cpp.o
    ld: fatal: symbol referencing errors. No output written to libgdal.so.37.3.11.0

I think this is:

  https://github.com/llvm/llvm-project/issues/105181

Looking in gdal 3.11.0's CMakeLists.txt, the test for Float16 is

  # Check whether std::float16_t is available and is working
  include(CheckCXXSourceCompiles)
  check_cxx_source_compiles(
    "
      #include <cmath>
      #include <stdfloat>
      int main() {
        std::float16_t x = 0;
        using std::nextafter;
        std::float16_t y = nextafter(x, x);
        return y == 0 ? 0 : 1;
      }
    "
    HAVE_STD_FLOAT16_T
  )

It fails, whcih is good because it seems this platform has troubled
float16.

But somehow, float16 functions get added to to link.

Has anyone built/tested gdal on Solaris-ish?