[PATCH, committed] Fortran: Fix asan problems with PDT testcases [PR121972]

Mostly Paul's patch with some edits by myself.

Regression tested and pushed.

Thanks Paul for your work.


The master branch has been updated by Jerry DeLisle <[email protected]>:

https://gcc.gnu.org/g:95dbc32189ab0433283f337b4b490bfcec0bd475

commit r17-2071-g95dbc32189ab0433283f337b4b490bfcec0bd475
Author: Paul Thomas <[email protected]>
Date:   Wed Jul 1 17:14:25 2026 +0100

     Fortran: Fix asan problems with PDT testcases [PR121972]

     Co-authored-by: Jerry DeLisle <[email protected]>

             PR fortran/121972

     gcc/fortran
             * expr.cc (has_parameterized_comps): Return false if the DT
             is neither a pdt_type nor has PDT components. Correct the
             logic for a PDT component.
             * trans-expr.cc (alloc_scalar_allocatable_for_assignment): Use
             calloc for types with paramterized components as well as those
             with allocatable components.
             * trans-stmt.cc (gfc_trans_allocate): Merge the allocation of
             parameterized components of PDTs and class PDTs into one block
             If an allocate type_spec is present that has allocatable comps
             where the class declared type does not, nullify the allocatable
             components.

     gcc/testsuite/
             * gfortran.dg/asan/pdt_46.f03: Copy of original with tree dump
             for counts of frees, mallocs and callocs removed.
             * gfortran.dg/asan/pdt_77.f03: Ditto.
             * gfortran.dg/pdt_46.f03: Calloc count added, corresponding to
             reduction in mallocs..
             * gfortran.dg/pdt_50.f03: Ditto.