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

[Gabriel Dos Reis <gdr@integrable-solutions.net>]

Robert Dewar <dewar@adacore.com> writes:

| Florian Weimer wrote:
| 
| > Probably it's hard to accept for hard-code C coders that a program
| > which generates correct machine code with all GCC versions released so
| > far (modulo bugs in GCC) can still be illegal C and exhibit undefined
| > behavior.  IIRC, I needed quite some time to realize the full impact
| > of this distinction.
| 
| Note that even making things implementation defined does not help the
| problem of learning by example from one implementation. It really is
| a good idea for people programming in language X to learn language X :-)

Then, one wonders why the GNAT is not bug free ;-p

| Back in the days of Algol-60 absolutely everyone read the report. Then
| we went through an era of standards which few people read (how many
| fortran programmers read the fortran standard, cobol programmers
| read the cobol standard, c programmers read the c standard etc). A
| rather nice achievment with Ada is that the standard is indeed a
| reference book that all Ada programmers have on their shelf and
| even though not all have read it through, they know it is the

oh, so it suffices to have it?  Not to understand it?

| important ultimate reference standard of what is and what is not
| allowed in valid programs, and you would be hard put to find a
| professional Ada programmer who has not frequently reached for
| the standard to look something up. In a big class of programmers
| nearly all of whom had done professional C programming a couple
| of years ago, only 2 out of 94 had held the C standard in their
| hands.
| 
| It's not an easy document, but it's also not that hard, it would
| be nice to promote its use more!

The issue is whether they need to become expect in red herring or just
know how to write good and correct programs.  Interestingly, backis
the old days K&R put emphasis on how to write good and useful programs
rather than academic exercise in "undefined behaviour".

-- Gaby