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Re: [bug-gnulib] C++ support (1)


From: Bruno Haible
Subject: Re: [bug-gnulib] C++ support (1)
Date: Mon, 6 Nov 2006 19:52:02 +0100
User-agent: KMail/1.9.1

Bob Proulx wrote:
> > Compiling GNU gettext with a C++ compiler revealed a bug: an assignment
> > between an 'int' variable and an 'enum' variable that was not intended.
> 
> Although I am sure it was not intended, what bad consequences would
> have resulted from the enum and int mixup?

msgfmt, on a PO file containing messages extracted from an awk program, could
have reported unwarranted errors.

> I have been seeing lots and lots of casts being added to the code.  I
> think that is much more dangerous than a potential enum issue.

Can you explain what you find dangerous about a cast?

Before these patches, you could write

       int *array = xmalloc (new_size * sizeof (short)),

and the C compiler would accept it without complaints.

You could also write

       int *array = (int *) xmalloc (new_size * sizeof (short)),

and both the C and C++ compiler would accept it without complaints.
Furthermore, either way, there was no check against arithmetic overflow
in the multiplication.

Now you are encouraged to write

       int *array = XNMALLOC (new_size, short),

and both the C and C++ compiler will shout at you. Plus, arithmetic overflow
in the multiplication is caught.

Which of the three styles do you find the least dangerous?

Bruno




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