http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55207
Bug #: 55207
Summary: Automatic deallocation of variables declared in the
main program
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ja...@gcc.gnu.org
Although F95/F03/F08 only require automatic deallocation of local unsaved
variables upon termination of a procedure, gfortran currently also does it upon
termination of the main program.
Simple test case (for both scalars and arrays):
program main
integer, allocatable :: i
integer, allocatable, dimension(:) :: j
allocate(i)
allocate(j(1:5))
end program
The dump shows a block which automatically deallocates the variables at the end
of the main program:
finally
{
if (j.data != 0B)
{
__builtin_free ((void *) j.data);
}
j.data = 0B;
if (i != 0B)
{
__builtin_free ((void *) i);
}
}
>From F08:6.7.3.2:
"When the execution of a procedure is terminated by execution of a RETURN or
END statement, an unsaved allocatable local variable of the procedure retains
its allocation and definition status if it is a function result variable or a
subobject thereof; otherwise, it is deallocated."
This mentions only *procedures*, not the main program. Moreover, variables
declared in the main program are implicitly SAVEd in F08, cf. chapter 5.3.16:
"A variable, common block, or procedure pointer declared in the scoping unit of
a main program, module, or submodule implicitly has the SAVE attribute, which
may be confirmed by explicit specification. If a common block has the SAVE
attribute in any other kind of scoping unit, it shall have the SAVE attribute
in every scoping unit that is not of a main program, module, or submodule."
Currently we miss to flag this via attr.save = SAVE_IMPLICIT.
In F95 it is basically impossible to detect whether a compiler does
end-of-program auto-dealloc. However, in F03 it can be detected by using a
FINAL procedure, since deallocation (automatic or explicit) also implies
finalization (for finalizable variables).
