Date: Mon, 11 Mar 1996 13:04:20 +0100 (MET) From: Wolfram Schneider <wosch@cs.tu-berlin.de> To: Bruce Evans <bde@zeta.org.au> Cc: current@FreeBSD.org Subject: Re: *.mk wishes Message-ID: <199603111204.NAA23816@caramba.cs.tu-berlin.de> In-Reply-To: <199603102124.IAA15692@godzilla.zeta.org.au> References: <199603102124.IAA15692@godzilla.zeta.org.au>
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Bruce Evans writes: >newfs/mkfs.c passes an uncast 0 for a pointer and an uncast 0 for an off_t. >rpc.statd passes an uncast NULL for a pointer and an uncast 0 for an off_t. >I would't worry about fixing this. There must be a prototype in scope for >the uncast 0 for an off_t to work, and it isn't a bug to omit the casts iff >there is a prototype in scope. Just fix the configuration. Do we have a >working mmap? :-) http://www.lysator.liu.se/c/ten-commandments.html 3 Thou shalt cast all function arguments to the expected type if they are not of that type already, even when thou art convinced that this is unnecessary, lest they take cruel vengeance upon thee when thou least expect it. A programmer should understand the type structure of his language, lest great misfortune befall him. Contrary to the heresies espoused by some of the dwellers on the Western Shore, `int' and `long' are not the same type. The moment of their equivalence in size and representation is short, and the agony that awaits believers in their interchangeability shall last forever and ever once 64-bit machines become common. Also, contrary to the beliefs common among the more backward inhabitants of the Polluted Eastern Marshes, `NULL' does not have a pointer type, and must be cast to the correct type whenever it is used as a function argument. (The words of the prophet Ansi, which permit NULL to be defined as having the type `void *', are oft taken out of context and misunderstood. The prophet was granting a special dispensation for use in cases of great hardship in wild lands. Verily, a righteous program must make its own way through the Thicket Of Types without lazily relying on this rarely-available dispensation to solve all its problems. In any event, the great deity Dmr who created C hath wisely endowed it with many types of pointers, not just one, and thus it would still be necessary to convert the prophet's NULL to the desired type.) It may be thought that the radical new blessing of ``prototypes'' might eliminate the need for caution about argument types. Not so, brethren. Firstly, when confronted with the twisted strangeness of variable numbers of arguments, the problem returns... and he who has not kept his faith strong by repeated practice shall surely fall to this subtle trap. Secondly, the wise men have observed that reliance on prototypes doth open many doors to strange errors, and some indeed had hoped that prototypes would be decreed for purposes of error checking but would not cause implicit conversions. Lastly, reliance on prototypes causeth great difficulty in the Real World today, when many cling to the old ways and the old compilers out of desire or necessity, and no man knoweth what machine his code may be asked to run on tomorrow.
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