[Ada] Bootstrapping mainline GNAT fails

[Richard Kenner]

    Arr is a N_String_Literal node; I *think* the Etype of a
    String_Literal is not supposed to have a First_Index (the
    String_Literal_Low_Bound plays more or less the same role).  Please
    correct me if I'm wrong there.  

You are correct.

    However, 3.14p (apparently) has bugs in exception handling on
    i486-linux; the generated code jumps to an uninitialized pointer and
    crashes.

More precisely, the version you have has that bug.  Others versions of
"3.14p" do not.

    Incidentally, have you considered replacing the exception thrower
    linked into gnat1 with a stub that calls the back-end's fatal_error()?

No.  The exception *handler* does that, but there are places (in Pragma
processing) where an exception is *supposed* to occur and be handled and
does not indicate a fatal error.