Hello, After a lot (a LOT) of work, I've come up with this test case. The test case *appears* to run fine, but valgrind shows something is amiss, and in the full application (much more complex) there follow multiple segfaults. I did not find (so far) a way to have a test case both small and exibiting the error out of valgrind, hope you'll pardon me. The error: the ALLOCATABLE components of the ATX%A variable are detected as ALLOCATED, and seemingly are printed OK, but VALGRIND says they were already freed.
=============================================================================== [sfili...@donald bug23]$ gfortran -v Using built-in specs. COLLECT_GCC=gfortran COLLECT_LTO_WRAPPER=/usr/local/gnu46/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc/configure --prefix=/usr/local/gnu46 --enable-languages=c,c++,fortran Thread model: posix gcc version 4.6.0 20100830 (experimental) (GCC) [sfili...@donald bug23]$ gfortran -ggdb -o bug23 bug23.f03 [sfili...@donald bug23]$ ./bug23 New version Allocation status: T T T 0 0 4 5 0 0 2 3 0 0 0 0 0 0 0 0 0.0000000000000000 1.0000000000000000 2.0000000000000000 3.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 [sfili...@donald bug23]$ valgrind ./bug23 ==6940== Memcheck, a memory error detector ==6940== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==6940== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info ==6940== Command: ./bug23 ==6940== New version Allocation status: T T T ==6940== Invalid read of size 4 ==6940== at 0x4CC19B8: extract_int (write.c:450) ==6940== by 0x4CC27B1: write_integer (write.c:1260) ==6940== by 0x4CC5BDE: _gfortrani_list_formatted_write (write.c:1552) ==6940== by 0x4CBACA7: _gfortran_transfer_array (transfer.c:2000) ==6940== by 0x401834: MAIN__ (bug23.f03:308) ==6940== by 0x40197A: main (bug23.f03:284) ==6940== Address 0x5141450 is 0 bytes inside a block of size 16 free'd ==6940== at 0x4A04D72: free (vg_replace_malloc.c:325) ==6940== by 0x4CCB5A8: _gfortran_move_alloc (move_alloc.c:41) ==6940== by 0x400B90: __psb_d_csr_mat_mod_MOD_psb_d_mv_csr_from_fmt (bug23.f03:238) ==6940== by 0x401449: __psb_d_mat_mod_MOD_psb_d_mv_from (bug23.f03:277) ==6940== by 0x4016C6: MAIN__ (bug23.f03:302) ==6940== by 0x40197A: main (bug23.f03:284) ==6940== 1 3 4 5 1 1 2 3 0 0 0 0 0 0 0 0 ==6940== Invalid read of size 8 ==6940== at 0x4CC3795: write_float (write_float.def:1050) ==6940== by 0x4CC508C: _gfortrani_write_real (write.c:1470) ==6940== by 0x4CC5BAE: _gfortrani_list_formatted_write (write.c:1561) ==6940== by 0x4CBACA7: _gfortran_transfer_array (transfer.c:2000) ==6940== by 0x401904: MAIN__ (bug23.f03:310) ==6940== by 0x40197A: main (bug23.f03:284) ==6940== Address 0x5141510 is 0 bytes inside a block of size 96 free'd ==6940== at 0x4A04D72: free (vg_replace_malloc.c:325) ==6940== by 0x4CCB5A8: _gfortran_move_alloc (move_alloc.c:41) ==6940== by 0x400BDC: __psb_d_csr_mat_mod_MOD_psb_d_mv_csr_from_fmt (bug23.f03:240) ==6940== by 0x401449: __psb_d_mat_mod_MOD_psb_d_mv_from (bug23.f03:277) ==6940== by 0x4016C6: MAIN__ (bug23.f03:302) ==6940== by 0x40197A: main (bug23.f03:284) ==6940== 1.0000000000000000 1.0000000000000000 2.0000000000000000 3.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 ==6940== ==6940== HEAP SUMMARY: ==6940== in use at exit: 0 bytes in 0 blocks ==6940== total heap usage: 33 allocs, 33 frees, 4,938 bytes allocated ==6940== ==6940== All heap blocks were freed -- no leaks are possible ==6940== ==6940== For counts of detected and suppressed errors, rerun with: -v ==6940== ERROR SUMMARY: 28 errors from 2 contexts (suppressed: 6 from 6) -- Summary: [OOP] Inconsistent status of ALLOCATABLE components inside CLASS variables. Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: sfilippone at uniroma2 dot it GCC build triplet: x86_64-unknown-linux-gnu GCC host triplet: x86_64-unknown-linux-gnu GCC target triplet: x86_64-unknown-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45451