icc: command line warning #10006: ignoring unknown option '-cpp' about schism

[platipodium]

1. I dislike the aesthetics as well, so we should get rid of the problem.
2. It does create a real problem on some of my systems, where I have to sed '/-cpp/--preprocess/' CMaKeCache.txt. So the error message itself is helpful.

[platipodium]

So does it mean, it should pick up '--precpocess', '-cpp', '-fpp' based on the which fortran compiler it usues?

No, in theory, CMAKE should have settings for precompiled (CPP), C compiler (C/CXX) and fortran compiler. Whenever a compiler needs a preprocessor, it should use that one, compatible with PREPROCESS_FLAG. Unfortunately, most build systems seem to combine preprocess/build phase such that the compiler does also the precompiling ... At least that's how I perceive this (I may be wrong).

[platipodium]

Having a look at ./cmake/SCHISMCompile.cmake I see

if("${CMAKE_Fortran_COMPILER_ID}" STREQUAL "Intel")
    message(STATUS "DEBUG IS ${DEBUG}, SED IS ${USE_SED}, TVD_LIM IS ${TVD_LIM}")
    if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
         set ( CMAKE_Fortran_FLAGS_RELEASE_INIT "-O2 /names:lowercase ${WIN_FORTRAN_OPTIONS}")
         set ( CMAKE_Fortran_FLAGS_DEBUG_INIT "/names:lowercase ${WIN_FORTRAN_OPTIONS}")
         set ( CMAKE_Fortran_FLAGS_RELWITHDEBINFO_INIT "-O2 -debug inline_debug_info ${WIN_FORTRAN_OPTIONS}")
         set (CMAKE_EXE_LINKER_FLAGS "/INCREMENTAL:NO /NODEFAULTLIB:LIBCMT.lib;libifcoremt.lib ${WIN_LINKER_OPTIONS}")
         set( C_PREPROCESS_FLAG /cpp CACHE STRING "C Preprocessor Flag")
    else()
         set (SCHISM_INTEL_OPTIONS "-assume byterecl")
         set( CMAKE_Fortran_FLAGS_RELEASE_INIT "-O2 ${SCHISM_INTEL_OPTIONS}")
         set( CMAKE_Fortran_FLAGS_DEBUG_INIT "-g ${SCHISM_INTEL_OPTIONS}")
         set( CMAKE_Fortran_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -debug inline_debug_info ${SCHISM_INTEL_OPTIONS}")
         set( C_PREPROCESS_FLAG -cpp CACHE STRING "C Preprocessor Flag")
    endif()

Penultimate line set( C_PREPROCESS_FLAG -cpp could probably deleted for this platform.... better than a post-hoc fix with switching off the diags.

[platipodium]

Same with clang:

clang: warning: argument unused during compilation: '-cpp' [-Wunused-command-line-argument]

[jamal919]

Same here. Update: with intel compilers.

[platipodium]

The problem is with clang needing --preprocess while gfortran needs -cpp . So when we do a regular compile based on gnu fortran and the system is autodetecting a C/CXX compiler for parmetis, it may select clang and hiccup at the -cpp option.

I have not yet found a solution to set CMAKE_PREPROCESS_FLAG dependent on Fortran vs C. There should be solution somewhere on the net...

[jamal919]

Thanks @platipodium for the clarification of these options. To add to my previous comment (now edited), I was using intel compilers. So does it mean, it should pick up '--precpocess', '-cpp', '-fpp' based on the which fortran compiler it usues?

I am not very used to CMAKE things. Could setting directory specific CFLAGS will work with cmake? (a discussion from 2011 is here - https://cmake.org/pipermail/cmake/2011-April/043703.html)

[platipodium]

.. so much for theory, I could not find and references to selecting CMAKE_CPP_PROCESSOR (or similar) in their documentation :=(

[jamal919]

Thanks again for the explanation of cmake behaviour (or the expected one). In your experience, did this cause any problem with building the exec/lib? I guess not, but the "bad" aesthetics of recurring error/warning does bother me too.

[zeekus]

Why not just tell icc to run like this ?

icc -no-cpp your_file.cpp -o your_output

If you are using MPIICC, you should be able to modify the wrapper to use different flags.

#CC="icc"
CC="/modeling/spack/opt/spack/linux-centos7-skylake_avx512/gcc-9.2.0/intel-oneapi-compilers-2022.1.0-wlkegy4fwz4gpx7joqmouc7uiiz4sg5b/compiler/2022.1.0/linux/bin/intel64/icc"
CFLAGS="-no-ccp"
LDFLAGS="-ldl"
MPILIBNAME="mpi"

[platipodium]

@zeekus the real problem are mixed gfortran/clang compilations where the C_PROPROCESS_FLAG is handled differently by the fortran (gcc) and C (clang) compiler frontend.

In principle, we could just not use the -cpp on intel systems, but somehow that has not worked for me, either.

[zeekus]

I put in "-no-cpp" as a flag it didn't work as expected, but the cflag of "-diag-disable=10006" will mute this noise. Note, these are just warning messages.

[ 80%] Building C object ParMetis-4.0.3/libparmetis/CMakeFiles/parmetis.dir/wspace.c.o
icc: command line warning #10006: ignoring unknown option '-no-ccp'
icc: command line warning #10006: ignoring unknown option '-cpp'
icc: command line warning #10006: ignoring unknown option '-no-ccp'
icc: command line warning #10006: ignoring unknown option '-cpp'

Working solution.

#File: /opt/intel/mpi/2021.9.0/bin/mpiicc
CC="/modeling/spack/opt/spack/linux-centos7-skylake_avx512/gcc-9.2.0/intel-oneapi-compilers-2022.1.0-wlkegy4fwz4gpx7joqmouc7uiiz4sg5b/compiler/2022.1.0/linux/bin/intel64/icc"
CFLAGS="-diag-disable=10006"
LDFLAGS="-ldl"
MPILIBNAME="mpi"

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