[Bug fortran/125535] Wrong-code for implied-do with allocatable-component derived type and transformational intrinsic

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125535

--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jerry DeLisle <jvdelisle@gcc.gnu.org>:

https://gcc.gnu.org/g:b5a3b874b8df2ea2ca82bd97fcd5906f7ebe82d8

commit r17-1410-gb5a3b874b8df2ea2ca82bd97fcd5906f7ebe82d8
Author: Jerry DeLisle <jvdelisle@gcc.gnu.org>
Date:   Fri Jun 5 13:20:05 2026 -0700

    fortran: [PR125535] wrong-code for implied-do with allocatable-component

    When a nested implied-do array constructor called a transformational
    intrinsic (e.g. RESHAPE) whose result type has allocatable components, the
    argument temporaries were freed before the result's allocatable components
    were deep-copied, causing a heap-use-after-free and wrong runtime values.

    Transformational library functions such as RESHAPE do a shallow byte-copy
    of the source array into the result, so the result's component pointers
    alias those of the argument temporaries. Freeing the temporaries first
    and then copying yielded use-after-free.

    Move gfc_add_block_to_block (&se->pre, &post) to after the deep-copy
    loop, so that the result's allocatable components are copied while the
    source storage is still live.

    Assisted by: Claude Sonnet 4.6

            PR fortran/125535

    gcc/fortran/ChangeLog:

            * trans-expr.cc (gfc_conv_procedure_call): Move post block append
            to after the deep copy of allocatable components for
transformational
            intrinsics, so that argument temporaries are not freed before the
            result components are copied.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/implied_do_alloc_comp_1.f90: New test.