[R-pkg-devel] R, BLAS, and FCLEN

[Göran Broström]

A followup question: Is it possible to call a BLAS/LAPACK subroutine, 
where one parameter is character, from FORTRAN (77) code called by 
.Fortran? (No problem "in the past".)

And if yes, how?  Documentation describes calls from C to Fortran and 
vice versa, but not this situation (AFAICS).

Yes, I know that .Fortran is not well seen these days, but my fortran 
code is ancient, from the before-R era, and I would like to leave it as-is.

G,

Den 2019-09-01 kl. 21:46, skrev Göran Broström:
> 
> 
> On 2019-08-31 18:47, Göran Broström wrote:
>> I'm having difficulties updating my package eha: When I run standard 
>> checks 'at home' everything is fine, but 'CRAN-submissions' reports 
>> (among other things):
>>
>> geomsup.f:324:9: warning: type of ‘dgemv’ does not match original 
>> declaration [-Wlto-type-mismatch]
>>    324 |      &     one, score, ione)
>>        |         ^
>> /home/tmp/R-d-gcc-LTO/include/R_ext/BLAS.h:107:1: note: type mismatch 
>> in parameter 12
>>    107 | F77_NAME(dgemv)(const char *trans, const int *m, const int *n,
>>        | ^
>>
>> This is odd since the LAPACK subroutine dgemv takes only 11 
>> parameters. However, in include/R_ext/BLAS.h we have
>>
>> F77_NAME(dgemv)(const char *trans, const int *m, const int *n,
>>          const double *alpha, const double *a, const int *lda,
>>          const double *x, const int *incx, const double *beta,
>>          double *y, const int *incy FCLEN);
>>
>> with a 12th parameter FCLEN?? How am I supposed to fix this, and what 
>> the ... is FCLEN? googling leads to nothing useful (for me). It seems 
>> as if R is redefining some standard LAPACK routines.
>>
>> Also a note I do not understand (in this context):
>>
>> note: type ‘void’ should match type ‘long int’
>>
>> Any help is much appreciated.
>>
>> Best, Göran
>>
>> PS. How can I trigger these Warnings 'at home'?
> 
> See https://www.stats.ox.ac.uk/pub/bdr/LTO/README.txt (thanks to Uwe 
> Ligges).
> 
> Another relevant document seems to be (2019-05-15):
> 
> https://developer.r-project.org/Blog/public/2019/05/15/gfortran-issues-with-lapack/index.html 
> 
> 
> First sentence:
> "Recent version of the GNU Fortran compiler (7, 8, 9) include 
> optimizations that break interoperability between C and Fortran code 
> with BLAS/LAPACK."
> 
> And later:
> "For the time being, everyone should use -fno-optimize-sibling-calls 
> with GFortran version 7 and newer."
> 
> G,
> 
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