https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97046
Bug ID: 97046
Summary: Bad interaction between lbound/ubound, allocatable
arrays and bind(C) subroutine with dimension(..)
parameter
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: igor.gayday at mu dot edu
Target Milestone: ---
Consider the following code:
MODULE FOO
INTERFACE
SUBROUTINE dummyc(x0) BIND(C, name="sync")
type(*), dimension(..) :: x0
END SUBROUTINE
END INTERFACE
contains
SUBROUTINE dummy(x0)
type(*), dimension(..) :: x0
call dummyc(x0)
END SUBROUTINE
END MODULE
PROGRAM main
USE FOO
IMPLICIT NONE
integer :: before(2), after(2)
INTEGER, parameter :: n = 1
DOUBLE PRECISION, ALLOCATABLE :: buf(:)
DOUBLE PRECISION :: buf2(n)
ALLOCATE(buf(n))
before(1) = LBOUND(buf,1)
before(2) = UBOUND(buf,1)
CALL dummy (buf)
after(1) = LBOUND(buf,1)
after(2) = UBOUND(buf,1)
if (before(1) .NE. after(1)) stop 1
if (before(2) .NE. after(2)) stop 2
before(1) = LBOUND(buf2,1)
before(2) = UBOUND(buf2,1)
CALL dummy (buf2)
after(1) = LBOUND(buf2,1)
after(2) = LBOUND(buf2,1)
if (before(1) .NE. after(1)) stop 3
if (before(2) .NE. after(2)) stop 4
END PROGRAM
lbound() and ubound() of an allocatable array return different values
before and after a Fortran subroutine with dimension(..) parameter (that
in turns invokes a bind(C) subroutine) is invoked.
Note that if the main program directly CALL dummyc(buf) (instead of
dummy(buf)), then the error does not occur.
gcc versions 9.2.0, 10.2.0 and the latest master branch are all affected.
In particular, this causes issues with mpi_f08 module, see:
https://stackoverflow.com/questions/63824065/lbound-of-an-array-changes-after-call-to-mpi-gatherv-when-using-mpi-f08-module
This might be a duplicate of Bug #94070.
