Re: [Tinycc-devel] Add max_align_t to stddef.h and C11

[Christian Jullien]

Petr, I also agree with you.

If gcc more or less "governs" tcc behavior,  _Alignof and _Generic should be
defined by default whatever -std=cxx is used.

Here is a quick test I've made.

#include <stdio.h>

#define tt(X) _Generic((X), \
                       int: "int", \
                       default: "other")

int
main() {
  printf("__STDC_VERSION__ %d\n", __STDC_VERSION__);
  printf("_Alignof(double) %d\n", _Alignof(double));
  printf("_Generic(int)    %s\n", tt(42));
}

address@hidden ~]$ gcc -std=c11 foo.c -o foo && ./foo
__STDC_VERSION__ 201112
_Alignof(double) 8
_Generic(int)    int
address@hidden ~]$ gcc -std=c99 foo.c -o foo && ./foo
__STDC_VERSION__ 199901
_Alignof(double) 8
_Generic(int)    int

You can see that with -std=c99 the two macros are available

Only -pedantic flag makes gcc protest

address@hidden ~]$ gcc -std=c99 -pedantic foo.c -o foo && ./foo
foo.c: In function 'main':
foo.c:10:35: warning: ISO C99 does not support '_Alignof' [-Wpedantic]
   printf("_Alignof(double) %d\n", _Alignof(double));
                                   ^~~~~~~~
foo.c:3:15: warning: ISO C99 does not support '_Generic' [-Wpedantic]
 #define tt(X) _Generic((X), \
               ^~~~~~~~


-----Original Message-----
From: Tinycc-devel [mailto:address@hidden
On Behalf Of Petr Skocík
Sent: vendredi 11 janvier 2019 00:05
To: address@hidden
Subject: Re: [Tinycc-devel] Add max_align_t to stddef.h and C11

Having __STDC_VERSION__ reflect the -std= command option is great.
However, I think that disallowing _Generic and _Alignof at lower
versions is unnecessarily pedantic (as in a behavior more suitable for
compiler runs invoked with `-pedantic`). Unlike max_align_t, _Generic
and _Alignof are reserved identifiers in any C version. They shouldn't
ever need to be hidden. Hiding them can unnecessarily break some project
builds that use tcc with  _Generic or _Alignof and without -std=c11.

Petr S.


On 1/10/19 11:47 PM, uso ewin wrote:
> On Thu, Jan 10, 2019 at 2:47 PM Christian Jullien <address@hidden>
wrote:
>>
>> Matthias,
>>
>>
>> I'm happy you like my patch. I was waiting for comments before pushing
this
>> patch.
>> As you said, no one protested (or care), so it is committed in mod.
>>
>> It let you add the logic for the C11.
>>
>> Christian
>>
>> -----Original Message-----
>> From: Tinycc-devel
[mailto:address@hidden
>> On Behalf Of uso ewin
>> Sent: jeudi 10 janvier 2019 11:13
>> To: address@hidden
>> Subject: Re: [Tinycc-devel] Add max_align_t to stddef.h and C11
>>
>> On Tue, Jan 8, 2019 at 6:02 PM Christian Jullien <address@hidden>
wrote:
>>>
>>>> Maybe add a global variable
>>>
>>> Not global but a new member of TCCState, for example cversion
>>>
>>> If (s->cversion >= 201112) {
>>>   /* Hello C11 */
>>> }
>>>
>>> Diff becomes:
>>>
>>> address@hidden:~/new-tcc $ git diff
>>> diff --git a/libtcc.c b/libtcc.c
>>> index df7adab..7883734 100644
>>> --- a/libtcc.c
>>> +++ b/libtcc.c
>>> @@ -1790,8 +1790,16 @@ reparse:
>>>              s->static_link = 1;
>>>              break;
>>>          case TCC_OPTION_std:
>>> -           /* silently ignore, a current purpose:
>>> -              allow to use a tcc as a reference compiler for "make
test"
>> */
>>> +            if (*optarg == '=') {
>>> +                ++optarg;
>>> +                if (strcmp(optarg, "c11") == 0) {
>>> +                   tcc_undefine_symbol(s, "__STDC_VERSION__");
>>> +                   tcc_define_symbol(s, "__STDC_VERSION__", "201112L");
>>> +                   s->cversion = 201112;
>>> +                }
>>> +            }
>>> +             /* silently ignore other values, a current purpose:
>>> +                allow to use a tcc as a reference compiler for "make
>> test"
>>> */
>>>              break;
>>>          case TCC_OPTION_shared:
>>>              x = TCC_OUTPUT_DLL;
>>> diff --git a/tcc.c b/tcc.c
>>> index f780389..2d4e1ea 100644
>>> --- a/tcc.c
>>> +++ b/tcc.c
>>> @@ -33,6 +33,8 @@ static const char help[] =
>>>      "  -o outfile  set output filename\n"
>>>      "  -run        run compiled source\n"
>>>      "  -fflag      set or reset (with 'no-' prefix) 'flag' (see tcc
>> -hh)\n"
>>> +    "  -std=c99    Conform to the ISO 1999 C standard (default).\n"
>>> +    "  -std=c11    Conform to the ISO 2011 C standard.\n"
>>>      "  -Wwarning   set or reset (with 'no-' prefix) 'warning' (see tcc
>>> -hh)\n"
>>>      "  -w          disable all warnings\n"
>>>      "  -v -vv      show version, show search paths or loaded files\n"
>>> diff --git a/tcc.h b/tcc.h
>>> index cc85291..8416cc5 100644
>>> --- a/tcc.h
>>> +++ b/tcc.h
>>> @@ -651,6 +651,7 @@ struct TCCState {
>>>      int rdynamic; /* if true, all symbols are exported */
>>>      int symbolic; /* if true, resolve symbols in the current module
first
>>> */
>>>      int filetype; /* file type for compilation (NONE,C,ASM) */
>>> +    int cversion; /* supported C ISO version, either 0 (199901),
201112,
>>> ... */
>>>
>>>      char *tcc_lib_path; /* CONFIG_TCCDIR or -B option */
>>>      char *soname; /* as specified on the command line (-soname) */
>>>
>>>
>>>
>>> _______________________________________________
>>> Tinycc-devel mailing list
>>> address@hidden
>>> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
>>
>> I like the version with cversion in tcc state.
>>
>> As no one protest, I guess you can push.
>> Do you want to patch existing C11 code too ?
>> if not I can do it, but I need this patch to be merge.
>>
>> Matthias,
>>
>> _______________________________________________
>> Tinycc-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
>>
>>
>> _______________________________________________
>> Tinycc-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
> 
> Hi,
> 
> I've push the patch to allow _Alignof and _Generic only when -std=c11 is
use.
> 
> Matthias,
> 
> _______________________________________________
> Tinycc-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
> 


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