Re: FFI in interpreter mode
- From: Tony Finch <dot@xxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 24 May 2012 12:17:19 +0100
James McKaskill <james@xxxxxxxxxxxx> wrote:
>
> > * Similarly, something was typedef'd as an unsigned int and turned into an
> > enum later:
> > * type 'enum ' previously declared as 'unsigned int'
>
> Wow. You learn something new every day. I didn't even know this was
> legal C. Filed as https://github.com/jmckaskill/luaffi/issues/30
It is not. You cannot declare a typedef name more than once, whether or
not the types match. (Where C allows redeclarations - of external objects
and structure tags - the duplicates have to be the same thing.)
With reference to C99 incorporating all three technical corrigenda:
http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1256.pdf
Section 6.2.2p6:
The following identifiers have no linkage: an identifier declared to be
anything other than an object or a function; an identifier declared to
be a function parameter; a block scope identifier for an object declared
without the storage-class specifier extern.
Section 6.7p3
If an identifier has no linkage, there shall be no more than one
declaration of the identifier (in a declarator or type specifier) with
the same scope and in the same name space, except for tags as specified
in 6.7.2.3.
$ cat typedef.c
typedef int thingy;
typedef int thingy;
$ gcc -c typedef.c
typedef.c:2: error: redefinition of typedef 'thingy'
typedef.c:1: error: previous declaration of 'thingy' was here
Tony.
--
f.anthony.n.finch <dot@xxxxxxxx> http://dotat.at/
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