[Bug libfortran/90374] Fortran 2018: Support d0.d, e0.d, es0.d, en0.d, g0.d and ew.d e0 edit descriptors for output

[thenlich+gccbug at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90374

--- Comment #23 from Thomas Henlich <thenlich+gccbug at gmail dot com> ---
(In reply to Jerry DeLisle from comment #21)
> Author: jvdelisle
> Date: Thu Jan  2 00:57:31 2020
> New Revision: 279828
> 
> URL: https://gcc.gnu.org/viewcvs?rev=279828&root=gcc&view=rev

Jerry, please note that the standard requires that the minimum exponent width
is only selected in case of Ew.dE0 editing (including E0.dE0), but not for E0.d
editing in general.

Your latest patch changes this behaviour.

See Table 13.1: E and D exponent forms

Edit                  Absolute Value           Form of
Descriptor            of Exponent              Exponent (1)

Ew.d                  |exp| ≤ 99               E±z1z2 or ±0z1z2
                      99 < |exp| ≤ 999         ±z1z2z3

Ew.d Ee with e > 0    |exp| ≤ 10^e − 1         E±z1z2 . . . ze

Ew.d E0               any                      E±z1z2 . . . zs

Dw.d                  |exp| ≤ 99               D±z1z2 or E±z1z2
                                               or ±0z1z2
                      99 < |exp| ≤ 999         ±z1z2z3

(1) where each z is a digit, and s is the minimum number of digits
required to represent the exponent.