Re: signed is undefined and has been since 1992 (in GCC)

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

Andrew Pinski <pinskia@physics.uc.edu> writes:

| On Jun 28, 2005, at 1:12 AM, Gabriel Dos Reis wrote:
| 
| > Andrew Pinski <pinskia@physics.uc.edu> writes:
| >
| > | On Jun 28, 2005, at 12:34 AM, Gabriel Dos Reis wrote:
| > |
| > | > The attitude that "undefined behaviour" should be interpreted
| > | > as "we should not make things more useful when we can" is beyond
| > | > understanding.
| > |
| > | Then C/C++ aliasing rules go out the window really or maybe I
| > | misunderstand
| > | what you are trying to say?
| >
| > yes, you misunderstand what I'm saying.
| 
| But you did not explain your full then, I still don't understand.
| Here is the full quote from the C99 standard about what undefined
| behavior:

Andrew --

  Nobody is denying that signed interger overflow is "undefined behaviour".
So, your keeping saying "but, look the standard says it is undefined
beahviour" is irrelevant to the discussion; it is only recitation that
does not help making progress. 

What people are saying is that "undefined behaviour" does not
necessarily mean "Go'auld semantics".  Is that hard to understand?

[...]

| See it even points out integer overflow as a good example.  See also
| how it says
| the standard imposes no requirement, which means the compiler should
| be able
| to erase the hard drive each and every time you invoke undefined
| behavior.

and it should also be able to take your life.  Do you want it to actually
do it?  If yes, I suggest you create your own compiler that does that
and leave us work on a compiler that does something more positive.

-- Gaby