Re: Where did the warning go?

["Eivind LM" <eivliste at online dot no>]

On Tue, 24 Feb 2009 18:52:32 +0100, Ian Lance Taylor <iant@google.com>  
wrote:

> "Eivind LM" <eivliste@online.no> writes:
>
> > It does of course depend on each case whether a warning is easy to
> > avoid  or not, and also if it warns about a real problem or not. But
> > in any case,  a warning can help me write code that more surely will
> > do what I intend.  For example the following code is not doing what I
> > intended:
> >
> >   #include <stdio.h>
> >   void print(int a) { printf("%d\n", a); };
> >   int main() { print(2.5); return 0; };
> >
> > I think the problem in the code is both easy to avoid and serious, but
> > I  get no warning with -Wall and -Wextra (g++ 4.3).
> >
> > Instead of adding -Wconversion (and to search for any other flags I
> > might  find useful, but that I don't know of yet), I would rather
> > compile my  project with something like "-Weverything" from the
> > beginning, and then  disable the warnings that turns out to not fit my
> > programming style.
>
> I think the issue here is that there is disagreement about whether the
> -Wconversion warnings rise to the level of being questionable.  It would
> be reasonable to propose having -Wconversion under -Wall, if you want to
> send in a proposed patch.  It might be interesting to try building some
> packages with such a change, notably gcc itself.

Maybe everything implied with -Wconversion is too much. But the code above  
gave me a warning with g++ 4.1 (even without any flags to g++ at all). So  
seems like these kinds of warnings are not new as defaults to gcc.

However, seems like 4.1 without flags gives less warnings than 4.3 with  
the -Wconversion flag, so it might seem like only parts of -Wconversion  
were included in 4.1.

For example this statement needs -Wconversion with 4.1 to create a warning:

  float b = 123456789000;

So maybe I'm asking for only parts of -Wconversion to be included in  
-Wall. Anyway, I'm afraid I will have to climb a few more steps in C  
before I'm ready to submit patches to gcc :) Thanks for listening to my  
opinions anyway.

Eivind