[Bug fortran/41807] [4.5/4.4 Regression] data statement with nested type constructors

[Paul Richard Thomas]

Dear Jerry,

Many thanks for fixing this.  My attention has been completely
elsewhere these last few weeks so I could not help you.

The bug was my doing, although I have to say that it is both
unacceptable and unanticipated that gfc_is_constant_expr have side
effects like that.  Should we, perhaps copy the expression within
gfc_is_constant_expr, test that and free the new expression before
exiting?

Cheers

Paul