Re: Request for a C++ warning for undefined behaviour

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

skaller <skaller@ozemail.com.au> writes:

| On Wed, 2003-08-13 at 22:22, Gabriel Dos Reis wrote:
| > skaller <skaller@ozemail.com.au> writes:
|  
| > | No, I don't agree. It is certainly possible to be coding
| > | in a good style and make an honest mistake.
| > 
| > "honest mistake" is meaningless.
| 
| It means "you were trying to do the right thing,
| but typed something wrong by accident".
| 
| rather than:
| 
| "you are using a practice which is known
| to be fraught with errors"

Well, initialization within the member-initalizer list is taught to be 
good style; and initialization within the constructor body is also
"known fraught with errors".

| There really is something called "good design"
| and "bad design" even though it isn't so easy
| to say exactly what it is in most cases.

Yes.

[...]

| > | Nope, I'd never use a ctor-initialiser to initialise a variable 
| > | or base other than with a parameter to the constructor, or, at worst,
| > | a component of a structure.
| > 
| > But not every member is default constructed. 
| 
| So what? If the member isn't default constructed,
| AND i need to do a calculation to initialise it,
| there is a design error somewhere in there.

I don't think that necessary follows.  I would say that there is a
design error -depending- on the kind of calculations that need to be
carried out.  Not just because there is a calculation.

| >  You have a particular
| > coding style.  Fine.  But I see no reason to force people to follow
| > one signle style.  In particular, initializing member in  the
| > member-initializer-list does make sense. 
| 
| Of course it does. Initialising it with a complex
| expression, however, is just bad coding practice,
| or, if it seems necessary, bad design.

That is different from previous assertions of yours.  And I can be
made to agree with the new formulation.

| 
| >  Of course, if you put in 
| > gardage, you get garbage out.  Matt was asking for a flag that would
| > assist him to detect when a garbage is inadvertently being put in.  
| 
| >From the example I conclude otherwise. I conclude Michael 
| is asking for the flag to help detect garbage within garbage
| which was *deliberately* put in, and my reaction is:

We have no evidence that the garbage was deliberately being put in.
That can come from ignorance also.

| it hardly seems worthwhile trying to help people sort out
| their garbage when they're supposed to be programming.
| 
| They ought to learn how to program at school, it isn't
| gcc's job to teach them: its a compiler, not an interactive
| tutorial :-)

sure, but then we should remove all warnings :-/

| This comment refers to the original coder and NOT to
| Michael, who appears to have been stuck with having to fix it.

that comment is not very useful for Matt.

-- Gaby