On Mon, 2012-07-09 at 18:50 -0700, David Rientjes wrote: > On Mon, 9 Jul 2012, Joe Perches wrote: > > > CodingStyle already does suggest parenthesis around sizeof > > > > 3.1: Spaces > > > > Linux kernel style for use of spaces depends (mostly) on > > function-versus-keyword usage. Use a space after (most) keywords. The > > notable exceptions are sizeof, typeof, alignof, and __attribute__, which > > look > > somewhat like functions (and are usually used with parentheses in Linux, > > although they are not required in the language, as in: "sizeof info" after > > "struct fileinfo info;" is declared). > > > > So use a space after these keywords: > > if, switch, case, for, do, while > > but not with sizeof, typeof, alignof, or __attribute__. E.g., > > s = sizeof(struct file); > > > > This doesn't suggest parenthesis for sizeof at all times,
Depends on interpretation. Linus' email from 2008 is pretty clear. > it's saying that > Linux doesn't use the gcc, glibc, C99 way of doing "sizeof (struct file)" > for type names as I've already said three times and rather prefers > "sizeof(struct file)". That's fine. > > I'm talking about the C99 specification that says the sizeof operator act > on unary expressions, i.e. not type names that you keep talking about and > apparently don't understand the difference between. Casts are done with > type names, you can't do "unsigned long ptr", you do "(unsigned long)ptr". > Sizeof operators using type names do the same thing: > "sizeof (unsigned long)". The space is just a stylistic difference. > > You may not understand the difference between a type and a unary > expression, but other C programmers do, i.e. those who have implemented > the over 1000 places in the kernel that already do this because they > learned from K&R. I don't really care what style a large block of code uses. I care that it mostly has the same form. fyi: I learned C from K&R and Bill Joy in the mid 70's. > I guarantee you that those who learned from K&R don't > think sizeof(unsigned long) "looks like a function". Tell that to Linus. He wrote the email I referenced which you so apparently blithely elided. Repeating it: "Another example of this is "sizeof". The kernel universally (I hope) has parenthesis around the sizeof argument, even though it's clearly not required by the C language." > And typeof is a gnu extension, it's not part of the C99 standard. Irrelevant as Linux uses it. > You realize your patch doesn't catch kmalloc(sizeof *p, ...) since it's > checking for lval and the unary operator '*' is not considered part of an > identifier, right? Oh look, useful feedback instead of useless carping about how much I know or don't know c. > Perhaps you should propose a patch that actually works > first because yours is busted. I have one here. I'll forward it soonish. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
