[Bug fortran/83705] [8 Regression] ICE/wrong code with large values of REPEAT after revision r256284

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83705

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
With

  integer(8), parameter :: n=2_8**31 - 1_8

I get (compilation time ~4 minutes)

           2147483647
 'xxx', 'xxx'

With

  integer(8), parameter :: n=2_8**32

I get (compilation time ~4 minutes)

           4294967296
 '', ''

For n=2_8**31 and n=2_8**32-1, the compilation did not finished in more than
hour and I gave up).

Is there a way to check that the type of expr->value.character.length in
gfc_conv_substring_expr (fortran/trans-expr.c) is gfc_charlen_t?