From hebert@ajax.serma.cea.fr Thu Dec 7 11:28:00 1995 Received: from trefle.saclay.cea.fr (trefle.saclay.cea.fr [132.166.192.212]) by dkuug.dk (8.6.12/8.6.12) with ESMTP id LAA19924 for ; Thu, 7 Dec 1995 11:27:46 +0100 From: hebert@ajax.serma.cea.fr Received: from oeillet.saclay.cea.fr by trefle.saclay.cea.fr (8.6.10/ CEANET-ROUTER-3.0) with ESMTP id LAA15903 for ; Thu, 7 Dec 1995 11:26:43 +0100 Received: from ajax by oeillet.saclay.cea.fr (8.6.10/ CEANET-ROUTER-3.0) with SMTP id LAA05533 for ; Thu, 7 Dec 1995 11:27:36 +0100 Message-Id: <199512071027.LAA05533@oeillet.saclay.cea.fr> Received: by ajax (1.38.193.4/CEANET.2.0.1) id AA09960; Thu, 7 Dec 1995 11:29:49 +0100 Subject: Major flaw in Fortran-95 standard -> memory leaking To: sc22wg5@dkuug.dk Date: Thu, 7 Dec 95 11:29:47 MET Mailer: Elm [revision: 70.85] I discovered a major flaw in the Fortran-90 standard which is succeptible to cause memory leakage when derived types are allocated with the POINTER attribute. The simplest way to illustrate this problem is to use the ISO_VARYING_STRING module (ISO/IEC 1539-2) and to code USE ISO_VARYING_STRING TYPE(VARYING_STRING),POINTER :: TEXT ALLOCATE(TEXT) TEXT='ABCDE' DEALLOCATE(TEXT) This simple example causes a memory leak due to the internal definition of the type VARYING_STRING: TYPE VARYING_STRING PRIVATE CHARACTER,DIMENSION(:),POINTER :: chars ENDTYPE VARYING_STRING The DEALLOCATE(TEXT) statement does not deallocate the char array. This behavior is typical of most derived types containing pointers components, and memory leakage is likely to occurs in all these cases. A solution to this problem would be to add the possibility to overload ALLOCATE and DEALLOCATE statements in Fortran-95 or 2000. In the ISO_VARYING_STRING module, one could write: ... !----- specification of publically accessible entities -----------------------! PUBLIC :: VARYING_STRING,VAR_STR,CHAR,LEN,GET,PUT,PUT_LINE,INSERT,REPLACE, & SPLIT,REMOVE,REPEAT,EXTRACT,INDEX,SCAN,VERIFY,LLT,LLE,LGE,LGT, & ASSIGNMENT(=),OPERATOR(//),OPERATOR(==),OPERATOR(/=),OPERATOR(<), & OPERATOR(<=),OPERATOR(>=),OPERATOR(>),LEN_TRIM,TRIM,IACHAR,ICHAR, & ADJUSTL,ADJUSTR,STATEMENT(DEALLOCATE) ^^^^^^^^^^^^^^^^^^^^^ ... !----- Deallocate statement --------------------------------------------------! INTERFACE STATEMENT(DEALLOCATE) MODULE PROCEDURE dealloc_s,dealloc_v ENDINTERFACE ... SUBROUTINE dealloc_s(string_a) type(VARYING_STRING),POINTER :: string_a IF(ASSOCIATED(string_a%char))DEALLOCATE(string_a%char) DEALLOCATE(string_a) ENDSUBROUTINE dealloc_s ! SUBROUTINE dealloc_v(string_a) type(VARYING_STRING),POINTER,DIMENSION(:) :: string_a DO I=1,SIZE(string_a) IF(ASSOCIATED(string_a(I)%char))DEALLOCATE(string_a(I)%char) ENDDO DEALLOCATE(string_a) ENDSUBROUTINE dealloc_v ... Any suggestion would be appreciated. Alain Hebert Commissariat a l'Energie Atomique France (1) 69 08 27 44