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

[Tomas Kalibera]

My recommendation would be to try to minimize the example (package) as 
much as possible so that it still has the problem, and then try to 
investigate why exactly/where is the type mismatch. This is what helped 
me debug similar issues - sometimes it was hard to tell from the Fortran 
warnings where exactly the mismatched declarations were and why they 
were mismatched.

This process of minimization can already reveal the true source of the 
problem, and if not, others may try to debug for you using the minimal 
example. A useful tool is the Fortran option -fc-prototypes-external 
(see WRE for more details) and I've also used dumps of the compiler tree 
before (-fdump-tree-all, more in GCC documentation).

Best
Tomas

On 7/7/20 5:00 AM, Pierre Lafaye de Micheaux wrote:
> My file myzhpevx.cpp starts with:
>
> <quote>
> #define USE_FC_LEN_T
> #include <R.h>
> #include "Rmath.h"
>
> #ifdef FC_LEN_T
> extern "C" {
>
>    void zhpevxC(char **jobz, char **range, char **uplo, int *n, Rcomplex *ap,
>       double *vl, double *vu, int *il, int *iu, double *abstol, int *m,
>       double *w, Rcomplex *z, int *ldz, Rcomplex *work, double *rwork,
>       int *iwork, int *ifail, int *info) {
>
>            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);
> </quote>
>
> So if I understand correctly what you are saying, you suggest that FC_LEN_T was not correctly defined by the CRAN team?
>
> Should I just write something like (adding the middle instruction below to my existing code above)?:
>
> <quote>
> #ifdef FC_LEN_T
> typedef long long int FC_LEN_T;
> extern "C" {
> </quote>
>
> Thank you
> Pierre
> ________________________________
> From: William Dunlap <wdunlap using tibco.com>
> Sent: Tuesday, 7 July 2020 11:46
> To: Pierre Lafaye de Micheaux <lafaye using unsw.edu.au>
> Cc: Ivan Krylov <krylov.r00t using gmail.com>; r-package-devel using r-project.org <r-package-devel using r-project.org>
> Subject: Re: [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 using 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 using tibco.com>
>> Sent: Tuesday, 7 July 2020 08:36
>> To: Pierre Lafaye de Micheaux <lafaye using unsw.edu.au>
>> Cc: Ivan Krylov <krylov.r00t using gmail.com>; r-package-devel using r-project.org <r-package-devel using 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 using 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 using gmail.com>
>>> Sent: Tuesday, 7 July 2020 06:11
>>> To: Pierre Lafaye de Micheaux <lafaye using unsw.edu.au>
>>> Cc: r-package-devel using r-project.org <r-package-devel using 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 using 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 using r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-package-devel
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>
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