The MIT error

The MIT error

[Morten Welinder]

After the isspace/BSD conflict I looked into what reserved symbols are
being used by git.  Quite a few, it turns out.

--M.


The C standard says you should not use identifiers matching:

    (is|to)[a-z].*                         <-- such as isize
    E[0-9A-Z].*                         <-- such as EMIT
    str[a-z].*                              <-- such as strbuf
    (PRI|SCN)[a-zX].*
    LC_[A-Z].*
    (SIG|SIG_)[A-Z].*
    (uint|int).*_t
    (UINT|INT).*_(MIN|MAX|C)
    wcs[a-z].*

The three top ones are the easiest to violate.  While fixing the existing
violations is probably pointless, new code ought not make things worse.

Just as isspace is reserved by the C implementation...

       7.26.2  Character handling <ctype.h>

       [#1]  Function  names that begin with either is or to, and a
       lowercase letter (possibly followed by  any  combination  of
       digits,  letters,  and  underscore)  may  be  added  to  the
       declarations in the <ctype.h> header.

[so there goes any use of "isize"], so are macro names EMIT, ETHIS,
and ETHAT, at least when <errno.h> is included.

      7.26.3  Errors <errno.h>

       [#1] Macros that begin with E  and  a  digit  or  E  and  an
       uppercase  letter  (possibly  followed by any combination of
       digits,  letters,  and  underscore)  may  be  added  to  the
       declarations in the <errno.h> header.

quote.c:#undef EMIT
quote.c:#define EMIT(x) ( (++len < n) && (*bp++ = (x)) )
quote.c:#define EMITQ() EMIT('\\')
server-info.c:#define EMITTED   04
tar-tree.c:#define EXT_HEADER_PATH              1
tar-tree.c:#define EXT_HEADER_LINKPATH  2
ls-files.c:#define EXC_CMDL 0
ls-files.c:#define EXC_DIRS 1
ls-files.c:#define EXC_FILE 2
epoch.h:#define EPOCH_H
update-index.c:static inline void *ERR_PTR(long error)

        7.26.10  General utilities <stdlib.h>

       [#1] Function names that begin  with  str  and  a  lowercase
       letter  (possibly  followed  by  any  combination of digits,
       letters, and underscore) may be added to the declarations in
       the <stdlib.h> header.

Re: The MIT error

[Horst von Brand]

Morten Welinder <mwelinder@gmail.com> wrote:
> After the isspace/BSD conflict I looked into what reserved symbols are
> being used by git.  Quite a few, it turns out.

[...]

> Just as isspace is reserved by the C implementation...
> 
>        7.26.2  Character handling <ctype.h>
> 
>        [#1]  Function  names that begin with either is or to, and a
>        lowercase letter (possibly followed by  any  combination  of
>        digits,  letters,  and  underscore)  may  be  added  to  the
>        declarations in the <ctype.h> header.

There go is_space(), etc as suggested by the relevant patches... in any
case, if you /don't/ #include <ctype.h>, you are safe (standardwise),
aren't you? [Yes, idiots who #include that in system headers are way
broken, but...]
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

Re: The MIT error

[Andreas Ericsson]

Horst von Brand wrote:
> Morten Welinder <mwelinder@gmail.com> wrote:
> 
>>After the isspace/BSD conflict I looked into what reserved symbols are
>>being used by git.  Quite a few, it turns out.
> 
> 
> [...]
> 
> 
>>Just as isspace is reserved by the C implementation...
>>
>>       7.26.2  Character handling <ctype.h>
>>
>>       [#1]  Function  names that begin with either is or to, and a
>>       lowercase letter (possibly followed by  any  combination  of
>>       digits,  letters,  and  underscore)  may  be  added  to  the
>>       declarations in the <ctype.h> header.
> 
> 
> There go is_space(), etc as suggested by the relevant patches...


No they don't. "begin with either is or to and a lowercase letter", 
meaning (is|to)[a-z].*, just as Morten wrote. is_.* doesn't fall into 
this category. The underscore exemption is so that users can write their 
own is_file(), is_whatever() str_replace() and such. Some thought has 
gone into the standard.

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Re: The MIT error

[H. Peter Anvin]

Andreas Ericsson wrote:
> 
> No they don't. "begin with either is or to and a lowercase letter", 
> meaning (is|to)[a-z].*, just as Morten wrote. is_.* doesn't fall into 
> this category. The underscore exemption is so that users can write their 
> own is_file(), is_whatever() str_replace() and such. Some thought has 
> gone into the standard.
> 

Also, note that we don't include <ctype.h>, and the reasons to stay out 
of its namespace are:

a. potential for confusion (different semantics), and
b. broken system headers.

	-hpa