topic Re:Problem with C_F_POINTER and the LOWER argument in Intel® Fortran Compiler

Problem with C_F_POINTER and the LOWER argument

Robert_van_Amerongen — Mon, 08 Apr 2024 10:31:44 GMT

In the most recent compiler the C_F_POINTER function accepts the LOWER argument . I have used it, but I see that someting is wrong. The shape of the result is not equal to the shape as it was supplied when calling the function. I add a small example. Is this a compiler bug or do I miss something?

Robert

Re: Problem with C_F_POINTER and the LOWER argument

FortranFan — Mon, 08 Apr 2024 15:00:30 GMT

It is a bug.

Intel Support team, this might be an issue with a naive implementation of the latest Fortran 2023 feature without any validation checking. It appears the upper bound of the result pointer that shall be an object defined by means of a Fortran processor gets set to -1 by Intel Fortran when lower bound is specified. Perhaps the Intel Fortran team will be interested in using another test case below?

use, intrinsic :: iso_c_binding, only : c_loc, c_f_pointer blk1: block character(len=:), allocatable, target :: x(:) character(len=:), pointer :: y(:) print *, "Block 1: intrinsic type character" x = [ character(len=4) :: "How", "are", "you?" ] call c_f_pointer( cptr=c_loc(x), fptr=y, shape=shape(x), lower=[ -1 ] ) print *, "lbound(y): ", lbound(y, dim=1), "; expected is -1" print *, "ubound(y): ", ubound(y, dim=1), "; expected is 1" print *, "y = ", y end block blk1 print * blk2: block integer, target :: x(5) integer, pointer :: y(:) print *, "Block 2: intrinsic type integer" x = [ 1, 2, 3, 4, 5 ] call c_f_pointer( cptr=c_loc(x), fptr=y, shape=shape(x), lower=[ -2 ] ) print *, "lbound(y): ", lbound(y, dim=1), "; expected is -2" print *, "ubound(y): ", ubound(y, dim=1), "; expected is 2" print *, "y = ", y end block blk2 print * blk3: block real, target :: x(7) real, pointer :: y(:) print *, "Block 3: intrinsic type real" x = [( real(i), integer :: i = 1, size(x) )] call c_f_pointer( cptr=c_loc(x), fptr=y, shape=shape(x), lower=[ -3 ] ) print *, "lbound(y): ", lbound(y, dim=1), "; expected is -3" print *, "ubound(y): ", ubound(y, dim=1), "; expected is 3" print *, "y = ", y end block blk3 end

C:\Temp>ifx /standard-semantics /free p.f Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 2024.1.0 Build 20240308 Copyright (C) 1985-2024 Intel Corporation. All rights reserved. Microsoft (R) Incremental Linker Version 14.36.32537.0 Copyright (C) Microsoft Corporation. All rights reserved. -out:p.exe -subsystem:console p.obj C:\Temp>p.exe Block 1: intrinsic type character lbound(y): -1 ; expected is -1 ubound(y): -1 ; expected is 1 y = Block 2: intrinsic type integer lbound(y): -2 ; expected is -2 ubound(y): -1 ; expected is 2 y = 1 2 Block 3: intrinsic type real lbound(y): -3 ; expected is -3 ubound(y): -1 ; expected is 3 y = 1.000000 2.000000 3.000000

Re: Problem with C_F_POINTER and the LOWER argument

Barbara_P_Intel — Wed, 10 Apr 2024 22:25:26 GMT

Thank you for reporting this,@Robert_van_Amerongen. Thanks, too, for the small reproducer.

Thank you, @FortranFan, for another reproducer! The Fortran compiler engineers appreciate that!

I file a bug report, CMPLRLLVM-57611, and included both reproducers. We'll let you know its progress to a fix.

Re: Problem with C_F_POINTER and the LOWER argument

Robert_van_Amerongen — Thu, 11 Apr 2024 08:40:02 GMT

Barbara and FortranFan,

thanks for your help.

Robert

Re:Problem with C_F_POINTER and the LOWER argument

Barbara_P_Intel — Mon, 22 Apr 2024 18:35:09 GMT

Good news! The Fortran compiler team got right on this! Look for the fix in the 2024.2 release planned for mid-2024.

Re: Re:Problem with C_F_POINTER and the LOWER argument

Robert_van_Amerongen — Tue, 23 Apr 2024 17:11:20 GMT

That is nice to read.

Tanks to te team.

And for you to let me know.

Robert