On Jun 17, 2005, at 5:59 PM, Paul Schlie wrote:
From: Andrew Pinski <[EMAIL PROTECTED]>
On Jun 17, 2005, at 8:20 PM, Paul Schlie wrote:
["undefined" only provides liberties within the constrains of what
is specifically specified as being undefined, but none beyond
that.]
That is not true. Undefined means it can run "rm /" if you ever
invoke
the undefined code.
- If the semantics of an operation are "undefined", I'd agree; but if
control is returned to the program, the program's remaining specified
semantics must be correspondingly obeyed, including the those which
may utilize the resulting value of the "undefined" operation.
- If the result value is "undefined", just the value is undefined.
(Unless one advocates that any undefined result implies undefined
semantics,
which enables anything to occur, including the arbitrary corruption of
the remaining program's otherwise well defined semantics; in which
case any
invocation of implementation specific behavior may then validly result
in
arbitrary remaining program behavior.)
Which I'd hope isn't advocated.
You are wrong, and this really isn't a matter of opinion. The standard
defines exactly
what it means by "undefined behavior":
3.4.3 1 undefined behavior
behavior, upon use of a nonportable or erroneous program construct or
of erroneous data,
for which this International Standard imposes no requirements
2 NOTE Possible undefined behavior ranges from ignoring the situation
completely with
unpredictable results, to behaving during translation or program
execution in a documented
manner characteristic of the environment (with or without the issuance
of a diagnostic message),
to terminating a translation or execution (with the issuance of a
diagnostic message).
