https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104391
Bug ID: 104391 Summary: Gfortran 9 regression with bind(C) and allocatable or pointer attribute Product: gcc Version: 9.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: michael at scivision dot dev Target Milestone: --- The `bind(C)` on a procedure appears to break `pointer` and `allocatable` attributes of a variable with regard to index start. Specifically, on exiting a procedure with `bind(c)`, the variable(s) have their indices shifted to zero-based. example that works with GCC <= 8.5 and GCC 12 (broken for GCC 9, 10, 11). ``` program test_bounds use iso_fortran_env, only : error_unit implicit none real, allocatable :: a(:) integer :: L1,L2, U1,U2 allocate(a(1:2)) L1 = lbound(a,1) U1 = ubound(a,1) call c_bounder(a) L2 = lbound(a,1) U2 = ubound(a,1) if (L1 /= L2 .or. U1 /= U2) then write(error_unit, '(a,2i2,a,2i2)') 'FAIL: bounds changed before/after lower:', L1,L2, " upper: ", U1,U2 error stop endif print '(a)', "bounds check OK" contains subroutine c_bounder(a) bind(c) real, intent(inout) :: a(:) end subroutine c_bounder end program ```