[Bug fortran/64933] ASSOCIATE on a character variable does not allow substring expressions

["olivier.marsden at ecmwf dot int" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64933

--- Comment #1 from Olivier Marsden <olivier.marsden at ecmwf dot int> ---
Comment on attachment 34662
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34662
gfortran 5.0  ICE output for test case

>
> print *, should_work(5:15)
> 1
>internal compiler error: Segmentation fault
>0xb7c62f crash_signal
>        ../../gcc-5-20150201/gcc/toplev.c:383
>0x6ebf4b gfc_conv_scalarized_array_ref
>        ../../gcc-5-20150201/gcc/fortran/trans-array.c:3068
>0x6ec911 gfc_conv_array_ref(gfc_se*, gfc_array_ref*, gfc_expr*, locus*)
>        ../../gcc-5-20150201/gcc/fortran/trans-array.c:3205
>0x719865 gfc_conv_variable
>        ../../gcc-5-20150201/gcc/fortran/trans-expr.c:2203
>0x716f92 gfc_conv_expr(gfc_se*, gfc_expr*)
>        ../../gcc-5-20150201/gcc/fortran/trans-expr.c:6836
>0x71c3e4 gfc_conv_expr_reference(gfc_se*, gfc_expr*)
>        ../../gcc-5-20150201/gcc/fortran/trans-expr.c:6928
>0x742c0f gfc_trans_transfer(gfc_code*)
>        ../../gcc-5-20150201/gcc/fortran/trans-io.c:2394
>0x6e2777 trans_code
>        ../../gcc-5-20150201/gcc/fortran/trans.c:1853
>0x740670 build_dt
>        ../../gcc-5-20150201/gcc/fortran/trans-io.c:1921
>0x6e2797 trans_code
>        ../../gcc-5-20150201/gcc/fortran/trans.c:1825
>0x75a11c gfc_trans_block_construct(gfc_code*)
>        ../../gcc-5-20150201/gcc/fortran/trans-stmt.c:1457
>0x6e2887 trans_code
>        ../../gcc-5-20150201/gcc/fortran/trans.c:1755
>0x70e088 gfc_generate_function_code(gfc_namespace*)
>        ../../gcc-5-20150201/gcc/fortran/trans-decl.c:5844
>0x69f880 translate_all_program_units
>        ../../gcc-5-20150201/gcc/fortran/parse.c:5341
>0x69f880 gfc_parse_file()
>        ../../gcc-5-20150201/gcc/fortran/parse.c:5538
>0x6df605 gfc_be_parse_file
>        ../../gcc-5-20150201/gcc/fortran/f95-lang.c:228
>Please submit a full bug report,
>with preprocessed source if appropriate.
>Please include the complete backtrace with any bug report.
>