I have a derived type that contains an allocatable array. A bound procedure exists that allows adding elements to that array. The adding involves a call to move_alloc. I call a procedure in a DLL with an argument of that derived type. The DLL procedure adds an element to the array. If after the return from the DLL procedure I add another element to the array -> crash.
I think this is somehow related to the fact that a Windows DLL has its own heap and pointers from allocations done in a DLL must not be used in the main program. However before I completely rework the way our derived type works, I would like to know if actually this is the cause or if it is perhaps a bug in my program or ifort (hope's small but you never know). Someone might even know a magic workaround !
Here is a small reproducer, our real code is a lot more complex:
the module that defines the derived type
module m_t_x
type t_x
integer, allocatable :: ints(:)
contains
procedure :: add
end type
contains
subroutine add(this, val)
class(t_x), intent(inout) :: this
integer, intent(in) :: val
integer, allocatable :: temp(:)
integer s
if (.not. allocated(this%ints)) then
allocate(this%ints(1:1))
this%ints(1) = val
else
s = size(this%ints)
allocate(temp(1:s+1))
temp(1:s) = this%ints
temp(s+1) = val
call move_alloc(temp, this%ints)
endif
end subroutine
end module
the dll:
subroutine add_dll(x,i)
!DEC$ ATTRIBUTES DLLEXPORT :: ADD_DLL
use m_t_x
type(t_x), intent(inout) :: x
integer, intent(in) :: i
call x%add(i)
end subroutine
and the main program:
program test
use m_t_x
type(t_x) :: var1, var2, var3, var4
interface
subroutine add_dll(x, i)
import
type(t_x), intent(inout) :: x
integer, intent(in) :: i
end subroutine
end interface
print *, "Adding local"
call var1%add(1)
print *, var1%ints
call var1%add(2)
print *, var1%ints
print *, "Add in dll"
call add_dll(var2,1)
print *, var2%ints
call add_dll(var2,2)
print *, var2%ints
print *, "Add local first, then in dll"
call var3%add(1)
print *, var3%ints
call add_dll(var3,2)
print *, var3%ints
! actually we never get here because the previous crashes
print *, "Add in dll first, then local"
call add_dll(var4,1)
print *, var4%ints
call var4%add(1)
print *, var4%ints
end program
I am running Windows 8.1 and the compiler version is
Intel(R) Visual Fortran Intel(R) 64 Compiler for applications running on Intel(R) 64, Version 16.0.0.110 Build 20150815
I build the example like this:
ifort mod.f90 /c ifort dll.f90 mod.obj /dll ifort test.f90 mod.obj dll.lib
And when I run it:
C:\TEMP\x>test
Adding local
1
1 2
Add in dll
1
1 2
Add local first, then in dll
1
forrtl: severe (157): Program Exception - access violation
Image PC Routine Line Source
ntdll.dll 00007FFF7E8F6CC9 Unknown Unknown Unknown
libifcoremd.dll 00007FFF628478D8 Unknown Unknown Unknown
libifcoremd.dll 00007FFF6284AB76 Unknown Unknown Unknown
libifcoremd.dll 00007FFF627BBD70 Unknown Unknown Unknown
dll.dll 00007FFF7A6A137F Unknown Unknown Unknown
dll.dll 00007FFF7A6A10C6 Unknown Unknown Unknown
test.exe 00007FF7E8AF1484 Unknown Unknown Unknown
test.exe 00007FF7E8B453DE Unknown Unknown Unknown
test.exe 00007FF7E8B31224 Unknown Unknown Unknown
KERNEL32.DLL 00007FFF7E6516AD Unknown Unknown Unknown
ntdll.dll 00007FFF7E9334A5 Unknown Unknown Unknown
C:\TEMP\x>
In our real program, the crash in Visual Studio looks like this:
Thanks for any feedback
Johny
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