[R-pkg-devel] warning: type of ‘zhpevx_’ does not match original declaration [-Wlto-type-mismatch]

With gcc 8.3.0, gfortran 8.3.0, and ld 2.33.1 from the mingw64 part of
rtools40 on Windows, if I misdefine the typedef FC_LEN_T and use the
-flto flag I get the sort of error messages that you report.

c:\tmp\fortran>cat main.c
#include <string.h>
#include <stdio.h>

#ifdef USE_INT
typedef int FC_LEN_T;
#endif
#ifdef USE_LONG
typedef long int FC_LEN_T;
#endif
#ifdef USE_LONG_LONG
typedef long long int FC_LEN_T;
#endif

extern void sub_(char* word, double *ret, FC_LEN_T word_len);

int main(int argc, char* argv[])
{
    if (argc == 2) {
        double ret = 3. ;
        FC_LEN_T word_len = strlen(argv[1]);
        sub_(argv[1], &ret, word_len);
        printf("sizeof(FC_LEN_T)=%d, ret=%g\n", (int)(sizeof(FC_LEN_T)), ret);
        return 0;
    } else {
        return -1;
    }
}

c:\tmp\fortran>gcc  -flto -DUSE_INT main.c sub.f -lgfortran
main.c:14:13: warning: type of 'sub_' does not match original
declaration [-Wlto-type-mismatch]
 extern void sub_(char* word, double *ret, FC_LEN_T word_len);
             ^
sub.f:1:1: note: type mismatch in parameter 3
       subroutine sub(word, ret)
 ^
sub.f:1:1: note: type 'long long int' should match type 'FC_LEN_T'
sub.f:1:1: note: 'sub' was previously declared here
sub.f:1:1: note: code may be misoptimized unless -fno-strict-aliasing is used

c:\tmp\fortran>gcc  -flto -DUSE_LONG main.c sub.f -lgfortran
main.c:14:13: warning: type of 'sub_' does not match original
declaration [-Wlto-type-mismatch]
 extern void sub_(char* word, double *ret, FC_LEN_T word_len);
             ^
sub.f:1:1: note: type mismatch in parameter 3
       subroutine sub(word, ret)
 ^
sub.f:1:1: note: type 'long long int' should match type 'FC_LEN_T'
sub.f:1:1: note: 'sub' was previously declared here
sub.f:1:1: note: code may be misoptimized unless -fno-strict-aliasing is used

c:\tmp\fortran>gcc  -flto -DUSE_LONG_LONG main.c sub.f -lgfortran
<no warnings or notes>

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Mon, Jul 6, 2020 at 4:39 PM Pierre Lafaye de Micheaux
<lafaye at unsw.edu.au> wrote:
>
> Hello Bill,
>
> Thank you for your insight.
>
> First, my impression, is that the problem comes from how I declare the type of the function itself (and not its parameters), since the first (and only warning they seen on the CRAN) message is:
>
> <quote>
> myzhpevx.cpp:13:16: warning: type of ?zhpevx_? does not match original declaration [-Wlto-type-mismatch]
>            void F77_NAME(zhpevx)(char *jobz, char *range, char *uplo,
> </quote>
>
> What I did is the following:
>
> <quote>
> void F77_NAME(zhpevx)(char *jobz, char *range, char *uplo,
>       const int *n, Rcomplex *ap, const double *vl,
>       const double *vu, const int *il, const int *iu,
>       const double *abstol, int *m, double *w,
>       Rcomplex *z, const int *ldz, Rcomplex *work, double *rwork,
>       int *iwork, int *ifail, int *info,
>       FC_LEN_T jobz_len,  FC_LEN_T range_len,  FC_LEN_T uplo_len);
>
>  char cjobz[2];
>  strncpy(cjobz, jobz[0], 1);
>  cjobz[1] = '\0';
>  char crange[2];
>  strncpy(crange, range[0], 1);
>  crange[1] = '\0';
>  char cuplo[2];
>  strncpy(cuplo, uplo[0], 1);
>  cuplo[1] = '\0';
>
>  F77_CALL(zhpevx)(cjobz, crange, cuplo, &n[0], ap, &vl[0], &vu[0], &il[0], &iu[0], &abstol[0], &m[0],
>   w, z, &ldz[0], work, rwork, iwork, ifail, &info[0], strlen(cjobz), strlen(crange), strlen(cuplo));
> </quote>
>
> Do you see anything wrong with the above?
>
> Thank you
>
> Best
> Pierre
>
> ________________________________
> From: William Dunlap <wdunlap at tibco.com>
> Sent: Tuesday, 7 July 2020 08:36
> To: Pierre Lafaye de Micheaux <lafaye at unsw.edu.au>
> Cc: Ivan Krylov <krylov.r00t at gmail.com>; r-package-devel at r-project.org <r-package-devel at r-project.org>
> Subject: Re: [R-pkg-devel] warning: type of ?zhpevx_? does not match original declaration [-Wlto-type-mismatch]
>
> Have you tried what is recommended in
> https://gcc.gnu.org/onlinedocs/gfortran/Argument-passing-conventions.html
> ?
>
> <quote>
> For arguments of CHARACTER type, the character length is passed as a
> hidden argument at the end of the argument list. For deferred-length
> strings, the value is passed by reference, otherwise by value. The
> character length has the C type size_t (or INTEGER(kind=C_SIZE_T) in
> Fortran). Note that this is different to older versions of the GNU
> Fortran compiler, where the type of the hidden character length
> argument was a C int. In order to retain compatibility with older
> versions, one can e.g. for the following Fortran procedure
>
> subroutine fstrlen (s, a)
>    character(len=*) :: s
>    integer :: a
>    print*, len(s)
> end subroutine fstrlen
>
> define the corresponding C prototype as follows:
>
> #if __GNUC__ > 7
> typedef size_t fortran_charlen_t;
> #else
> typedef int fortran_charlen_t;
> #endif
>
> void fstrlen_ (char*, int*, fortran_charlen_t);
>
> In order to avoid such compiler-specific details, for new code it is
> instead recommended to use the ISO_C_BINDING feature.
>
> Note with C binding, CHARACTER(len=1) result variables are returned
> according to the platform ABI and no hidden length argument is used
> for dummy arguments; with VALUE, those variables are passed by value.
> </quote>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Mon, Jul 6, 2020 at 3:13 PM Pierre Lafaye de Micheaux
> <lafaye at unsw.edu.au> wrote:
> >
> > Dear Ivan,
> >
> > Thank you very much for your response.
> >
> > I do not have more information than the one I gave in my previous email. (And on top of that, the computer I was using with Debian SID, a recent version of gfortran and the last version of R-devel, just broke.)
> >
> > My problem is that the CRAN team won't accept to publish my package until this WARNING problem is solved. And because I am unable to observe the warning on my side (I could not with the desktop that just broke, and I still can't with my current laptop with Debian 10), I have no clue on how to suppress this warning.
> >
> > Thank you in advance for any other advice.
> >
> > Best regards,
> > Pierre
> > ________________________________
> > From: Ivan Krylov <krylov.r00t at gmail.com>
> > Sent: Tuesday, 7 July 2020 06:11
> > To: Pierre Lafaye de Micheaux <lafaye at unsw.edu.au>
> > Cc: r-package-devel at r-project.org <r-package-devel at r-project.org>
> > Subject: Re: [R-pkg-devel] warning: type of ?zhpevx_? does not match original declaration [-Wlto-type-mismatch]
> >
> > On Fri, 3 Jul 2020 00:15:27 +0000
> > Pierre Lafaye de Micheaux <lafaye at unsw.edu.au> wrote:
> >
> > >Found the following significant warnings:
> > >    myzhpevx.cpp:13:23: warning: type of _zhpevx__ does not match
> > > original declaration [-Wlto-type-mismatch]
> >
> > I managed to reproduce the warning on R-devel r78607 built with
> > --enable-lto using gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1):
> >
> > myzhpevx.cpp:13:16: warning: type of ?zhpevx_? does not match original declaration [-Wlto-type-mismatch]
> >            void F77_NAME(zhpevx)(char *jobz, char *range, char *uplo,
> >                 ^
> > zhpevx.f:232:7: note: type mismatch in parameter 20
> >        SUBROUTINE zhpevx( JOBZ, RANGE, UPLO, N, AP, VL, VU, IL, IU,
> >        ^
> > zhpevx.f:232:7: note: type ?int? should match type ?size_t?
> > /usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216:23: note: the incompatible type is defined here
> >  typedef __SIZE_TYPE__ size_t;
> >                        ^
> > zhpevx.f:232:7: note: ?zhpevx? was previously declared here
> >        SUBROUTINE zhpevx( JOBZ, RANGE, UPLO, N, AP, VL, VU, IL, IU,
> >        ^
> >
> > Do you have access to the notes produced by the compiler in addition
> > to the warnings? Do they spell the same difference?
> >
> > If yes, the warning is likely to be safe to ignore. m4/R.m4 notes that,
> > while gfortran < 8 uses int instead of size_t for hidden size arguments,
> > it doesn't make a practical difference.
> >
> > --
> > Best regards,
> > Ivan
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-package-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-package-devel