[PATCH, committed] Fix mixed ENTRY union ABI under -ff2c [PR95338]

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

https://gcc.gnu.org/g:490c7ba8d880f5a89d25c2791e4b8a95c533c45c

commit r16-8014-g490c7ba8d880f5a89d25c2791e4b8a95c533c45c
Author: Christopher Albert <[email protected]>
Date:   Tue Mar 10 19:44:29 2026 +0100

     fortran: Fix mixed ENTRY union ABI under -ff2c [PR95338]

     Mixed ENTRY masters store each result in a shared union.  Under -ff2c,
     default REAL entries use the C double ABI even though their Fortran result
     symbols remain default REAL.  Building the union directly from the Fortran
     result symbols therefore gives the entry wrapper a real(kind=8) return type
     but leaves the master union field at real(kind=4), which later trips the
     GIMPLE verifier with a non-trivial conversion in COMPONENT_REF.

     Build the mixed ENTRY union fields from the ABI return type instead, so
     default REAL entries under -ff2c contribute a real(kind=8) field.  Add a
     regression test for the original mixed INTEGER/REAL ENTRY reproducer.

     gcc/fortran/ChangeLog:

             PR fortran/95338
             * trans-types.cc (gfc_get_entry_result_type): New helper to use the
             ABI return type for mixed ENTRY union fields.
             (gfc_get_mixed_entry_union): Use it for each entry result field.

     gcc/testsuite/ChangeLog:

             PR fortran/95338
             * gfortran.dg/pr95338.f90: New test.

     Signed-off-by: Christopher Albert <[email protected]>