[Bug fortran/85625] New: Intenal Compiler Error for coindexed assignment

[Bader at lrz dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85625

            Bug ID: 85625
           Summary: Intenal Compiler Error for coindexed assignment
           Product: gcc
           Version: 8.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Bader at lrz dot de
  Target Milestone: ---

Created attachment 44054
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44054&action=edit
reproducer for described problem

The attached Fortran file produces an ICE when built with

gfortran -fcoarray=lib dummycoarray_04_pos.f90

The error message that is issued is:

dummycoarray_04_pos.f90:11:0:

        x[i] = x

internal compiler error: in gfc_dep_resolver, at fortran/dependency.c:2258
0x6f7d66 gfc_dep_resolver(gfc_ref*, gfc_ref*, gfc_reverse*)
        ../../gcc/fortran/dependency.c:2258
0x748bc5 conv_caf_send
        ../../gcc/fortran/trans-intrinsic.c:1863
0x74f085 gfc_conv_intrinsic_subroutine(gfc_code*)
        ../../gcc/fortran/trans-intrinsic.c:10981
0x701e52 trans_code
        ../../gcc/fortran/trans.c:1887
0x7653d3 gfc_trans_if_1
        ../../gcc/fortran/trans-stmt.c:1433
0x76d78a gfc_trans_if(gfc_code*)
        ../../gcc/fortran/trans-stmt.c:1464
0x701db7 trans_code
        ../../gcc/fortran/trans.c:1916
0x72812b gfc_generate_function_code(gfc_namespace*)
        ../../gcc/fortran/trans-decl.c:6507
0x7056d9 gfc_generate_module_code(gfc_namespace*)
        ../../gcc/fortran/trans.c:2222
0x6b8dab translate_all_program_units
        ../../gcc/fortran/parse.c:6108
0x6b8dab gfc_parse_file()
        ../../gcc/fortran/parse.c:6324
0x6ff14f gfc_be_parse_file
        ../../gcc/fortran/f95-lang.c:204
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

Replacing the RHS by an auxiliary variable that holds a copy of x does not
trigger the error. However, since significant changes to existing codes may be
required, I think this is a quite serious regression and should be fixed soon.