Messages in this thread | | | Date | Mon, 7 Nov 2005 12:46:53 -0800 | From | Greg KH <> | Subject | Re: typedefs and structs [was Re: [PATCH 16/42]: PCI: PCI Error reporting callbacks] |
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On Mon, Nov 07, 2005 at 02:41:36PM -0600, linas wrote: > On Mon, Nov 07, 2005 at 12:02:57PM -0800, Greg KH was heard to remark: > > On Mon, Nov 07, 2005 at 01:36:00PM -0600, linas wrote: > > > On Mon, Nov 07, 2005 at 11:02:45AM -0800, Greg KH was heard to remark: > > > > > > > > No, never typedef a struct. That's just wrong. > > > > > > Its a defacto convention for most C-language apps, see, for > > > example Xlib, gtk and gnome. > > > > The kernel is not those projects. > > !!
Yeah, anyone who thinks that Xlib is the paradigm for coding style...
> > > Also, "grep typedef include/linux/*" shows that many kernel device > > > drivers use this convention. > > > > They are wrong and should be fixed. > > What, precisely, is wrong? > > > See my old OLS paper on all about the problems of using typedefs in > > kernel code. > > Is this on the web somewhere? Google is having trouble finding it.
http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_paper/codingstyle.ps and the presentation is at: http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/
> > > > gcc should warn you > > > > just the same if you pass the wrong struct pointer > > > > > > There were many cases where it did not warn (I don't remember > > > the case of subr calls). I beleive this had to do with ANSI-C spec > > > issues dating to the 1990's; traditional C is weakly typed. > > > > > > Its not just gcc; anyoe who coded for a while eventually discovered > > > that tyedefs where strongly typed, but "struct blah *" were not. > > > > Sorry, but you are using a broken compiler if it doesn't complain about > > this. > > Uhh, gcc?
Try it in the kernel today. You will get a warning if you pass in a pointer to a different structure type than it was defined as.
> I was simply stating a fact about gcc and about standard ANSI-C > type-checking that is "well known" to anyone who's been around the > block. I was not trying to start an argument.
Then let's end it here...
thanks,
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