Re: [PATCH v1 19/25] man/man3type/void.3type: HISTORY: Update first POSIX appearance of void(3type)

[Alejandro Colomar <alx@kernel.org>]

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Hi Seth,

On Sat, Jan 10, 2026 at 07:57:49AM +0000, Seth McDonald wrote:
> Hi Alex,
> 
> On Friday, 9 January 2026 at 20:34, Alejandro Colomar <alx@kernel.org> wrote:
> > Hi Seth,
> [...]
> > I think 'void*' is important enough that it would be useful to dig in
> > its history further. Was it an invention of C89? Or was it an
> > extension in some existing compilers? If the latter, it would be
> > interesting to document which systems had it before C89.
> >
> > I'm mentioning this just in case you know. Feel free to ignore
> > otherwise.
> 
> I know that the void pointer type was not mentioned or used in
> POSIX.1-1988.  Instead, the standard used the char pointer type for
> pointers to generic data.  POSIX.1-1990 seems to implicitly require void
> pointers - at least for conformance to "POSIX.1, C Language Binding (C
> Standard Language-Dependent System Support)" - by including them in some
> function prototypes.

Hmmm, since POSIX.1-1988 was already written after some C89 draft, it
seems void* was incorporated to C89 in a late draft.

> 
> Looking at C89, it did explicitly specify void pointers as part of the
> language, stating that "[a] pointer to void shall have the same
> representation and alignment requirements as a pointer to a character
> type."[1]
> 
> Looking* at K&R C, I skimmed through chapter 5 "Pointers and Arrays",
> and couldn't find any references to void pointers.  In fact, it seems to
> use char pointers instead, similar to POSIX.1-1988.

Yup, K&R C 1st ed. is too old and I wouldn't expect it to have
void*.  I have a physical copy of K&R C 2nd ed. (1988) and it does have
void*.

> So I think what happened (pure speculation) was between 1978 and 1989,
> void pointers increased in user popularity and compiler support enough
> that ANSI decided to extend the language by adding void pointers to its
> 1989 C standard.  Which would explain why POSIX.1-1988 also didn't have
> void pointers, but POSIX.1-1990 suddenly did.
> 
> With regard to implementation support for void pointers prior to C89,
> this is where my knowledge falls short.  I'm not the most educated on
> past implementations (yet).

That's fine.  If anyone else reading the list knows anything, it would
be welcome.

> *I found this[2] PDF online which appears to be a scan of a (heavily
> annotated) copy of the first edition of The C Programming Language.
> I don't know if it's authentic though, so take it with a grain of salt.

Being a scan, it could be authentic.  I don't have a physical copy of
the first edition, so can't compare.

Be careful of online copies of K&R C, though.  I once found one of the
second edition, and it was fake (by comparing it to the actual copy).

Much better to get the physical copy.  Although the first edition seems
difficult to find.


Cheers,
Alex

> ----
> [1] ANSI X3.159-1989 "Programming Language – C", Section 3.1.2.5
> "Types", p. 24.
> <https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub160.pdf>
> [2] Kernighan, Brian W., Ritchie, Dennis M. (1978). The C Programming
> Language (1st ed.).
> <https://retrofun.pl/wp-content/uploads/sites/2/2023/12/1978-ritchie-the-c-programming-language.pdf>
> 
> ----
> Seth McDonald.
> sethmcmail at pm dot me (mailing lists)
> 2336 E8D2 FEB1 5300 692C  62A9 5839 6AD8 9243 D369




-- 
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