issue COMPILER-DIAGNOSTICS, version 9

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

I favor COMPILER-DIAGNOSTICS:USE-HANDLER, but there are two
things that I think need to be changed:

  Conditions of type WARNING may be signalled by the compiler in 
  situations where ... the compiler can determine 
  that a situation that "is an error" would result at runtime.

We don't use the term "is an error" any more, do we?  In the old
CLtL terms, I think both "is an error" and "signals an error"
situations would justify a warning.  I think this part should
be updated to the new error terminology and also should state that
all error situations justify warnings.  Of course explicit calls
to the function ERROR don't justify warnings; I don't know whether
the proposal can be phrased in such a way as to make that clear,
or whether it will have to be left to common sense.

    (3) Require COMPILE and COMPILE-FILE to handle the ABORT restart by
    aborting the smallest feasible part of the compilation.

I think this is wrong.  The only documentation of the ABORT restart
that I could find says

  The purpose of the ABORT restart is generally to allow return to the
  innermost ``command level.''

I agree with this, and I believe it means that it is wrong for any
function other than one that establishes a read-eval-print loop or
a command-level to establish an ABORT restart.  It would be useful
to have some restart that aborts a portion of the compilation, but
it should be given some other name.