Compilation failure on aarch64 with Arm Compiler for Linux's flang

[dslarm]

Using Spack to set up config and compile, the following error occurs: 5 errors found in build log.

It makes no difference if I disable the non-standard float16 - using an arg to cmake of: -DHDF5_ENABLE_NONSTANDARD_FEATURE_FLOAT16:BOOL=OFF

5 errors found in build log:
     3047    F90-S-0081-Illegal selector - KIND parameter has unknown value for data type  (/tmp/user/spack-stage/s
             pack-stage-hdf5-1.14.5-rzhstpbozkrcypkkfn5ntevpg2gwfof7/spack-build-rzhstpb/fortran/static/H5_gen.F90: 604
             9)
     3048      0 inform,   0 warnings,   1 severes, 0 fatal for h5pget_kind_16
     3049    F90-S-0081-Illegal selector - KIND parameter has unknown value for data type  (/tmp/user/spack-stage/s
             pack-stage-hdf5-1.14.5-rzhstpbozkrcypkkfn5ntevpg2gwfof7/spack-build-rzhstpb/fortran/static/H5_gen.F90: 609
             7)
     3050      0 inform,   0 warnings,   1 severes, 0 fatal for h5pregister_kind_16
     3051    F90-S-0081-Illegal selector - KIND parameter has unknown value for data type  (/tmp/user/spack-stage/s
             pack-stage-hdf5-1.14.5-rzhstpbozkrcypkkfn5ntevpg2gwfof7/spack-build-rzhstpb/fortran/static/H5_gen.F90: 614
             5)
     3052      0 inform,   0 warnings,   1 severes, 0 fatal for h5pinsert_kind_16
  >> 3053    make[2]: *** [fortran/src/CMakeFiles/hdf5_fortran-static.dir/build.make:325: fortran/src/CMakeFiles/hdf5_f
             ortran-static.dir/__/static/H5_gen.F90.o] Error 1
     3054    make[2]: Leaving directory '/tmp/user/spack-stage/spack-stage-hdf5-1.14.5-rzhstpbozkrcypkkfn5ntevpg2gw
             fof7/spack-build-rzhstpb'

This is using Arm Compiler for Linux - which is LLVM derivative but the NVIDIA/PGI fortran Flang.

As the float16 is disabled, it ought not to be trying to generate it?

[lrbison]

I see the same. At configure time I see:

-- Performing Test FORTRAN_CHAR_ALLOC - Success
-- ....NUMBER OF INTEGER KINDS FOUND 4
-- ....REAL KINDS FOUND {4,8,16}
-- ....INTEGER KINDS FOUND {1,2,4,8}
-- ....MAX DECIMAL PRECISION 15
-- ....LOGICAL KINDS FOUND {1,2,4,8}
-- ....FOUND SIZEOF for REAL KINDs {4,8,8}

A simple test tells me that armflang does not support REAL KIND=16, so I'm not sure how REAL KINDS FOUND contains 16. Additionally FOUND SIZEOF for REAL KINDs {4,8,8} is suspicious, since the last two kinds have the same sizeof.

The test seems to happen here:

hdf5/config/cmake/HDF5UseFortran.cmake

Line 295 in f0cffc9

# REALS

[lrbison]

There is a follow-up check here which seems to try and catch the problem:

hdf5/config/cmake/HDF5UseFortran.cmake

Lines 405 to 412 in f0cffc9

	# Remove the invalid kind from the list
	if (${${HDF_PREFIX}_HAVE_FLOAT128})
	if (NOT(16 EQUAL ${max_real_fortran_sizeof}) AND NOT(${${HDF_PREFIX}_FORTRAN_SIZEOF_LONG_DOUBLE} EQUAL ${max_real_fortran_sizeof})
	# Account for the fact that the C compiler can have 16-byte __float128 and the fortran compiler only has 8-byte doubles,
	# so we don't want to remove the 8-byte fortran doubles.
	AND NOT(${PAC_FORTRAN_NATIVE_DOUBLE_SIZEOF} EQUAL ${max_real_fortran_sizeof}))
	message (WARNING "
	Fortran REAL(KIND=${max_real_fortran_kind}) is $max_real_fortran_sizeof Bytes, but no corresponding C float type exists of that size

[lrbison]

Compiling with HDF5 1.12.0 works, and has the following configure output:

-- Performing Test FC_AVAIL_KINDS_RESULT - Success
-- ....NUMBER OF INTEGER KINDS FOUND 4
-- ....REAL KINDS FOUND {4,8}
-- ....INTEGER KINDS FOUND {1,2,4,8}
-- ....MAX DECIMAL PRECISION 15

So it seems the detection logic changed. Best guess would be 9b5d968

[lrbison]

I truly don't understand how REAL KINDS FOUND includes kind=16 for armflang...

tmp$ cat test_fortran_r16.f90
PROGRAM main
  USE ISO_C_BINDING
  USE, INTRINSIC :: ISO_FORTRAN_ENV, ONLY : stdout=>OUTPUT_UNIT
  IMPLICIT NONE
  REAL (KIND=16) a
  WRITE(stdout, '(I0)') SIZEOF(a)
END
tmp$ armflang test_fortran_r16.f90
F90-S-0081-Illegal selector - KIND parameter has unknown value for data type  (test_fortran_r16.f90: 5)
  0 inform,   0 warnings,   1 severes, 0 fatal for main
tmp$ echo $?
1

[lrbison]

@derobins could you shed any light on the desired configury path here?