tcl-core

[TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

[<apn...@ya...>]

In Tcl 8.6, if TCL_WIDE_INT_IS_LONG was defined, Tcl_WideInt was typdef'ed
as "long".

 

In Tcl 9.0, even if TCL_WIDE_INT_IS_LONG was defined, Tcl_WideInt is
typdef'ed as "long long" (see gcc warning below)

 

 

../../src/column.c:5682:61: warning: passing argument 3 of
'__builtin_saddl_overflow' from incompatible pointer type
[-Wincompatible-pointer-types]

5682 |                 if (addfn_(pbucket[bucket_index], pdata[i],
&pbucket[bucket_index]))            \

      |
^~~~~~~~~~~~~~~~~~~~~~

      |                                                             |

      |
Tcl_WideInt * {aka long long int *}

 

 

 

 

In my extension's use case, to detect Tcl_WideInt overflow on addition, I
was calling one of the gcc builtins '__builtin_saddl_overflow' (note single
l indicating long) or '__builtin_saddll_overflow'  (note ll indicating long
long) depending on whether TCL_WIDE_INT_IS_LONG is defined or not. This
generates the above warning because TWIIL is defined but Tcl_WideInt is
defined as "long long" and not "long".

 

Could someone clarify - Is this difference between Tcl 8 and 9 intentional?
What is the purpose of the TCL_WIDE_INT_IS_LONG  #define if not to indicate
which Tcl_WideInt typedef was in effect? How else can I detect whether to
call the "long" version or "long long" of a runtime function for Tcl_WideInt
values?

 

(Platform Ubuntu 20, gcc 9)

 

/Ashok

Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

[Jan N. <jan...@gm...>]

>
> Could someone clarify - Is this difference between Tcl 8 and 9
> intentional? What is the purpose of the TCL_WIDE_INT_IS_LONG  #define if
> not to indicate which Tcl_WideInt typedef was in effect? How else can I
> detect whether to call the “long” version or “long long” of a runtime
> function for Tcl_WideInt values?
>

Tcl Improvement Proposals: TIP 476: Scan/Printf format consistency
<https://core.tcl-lang.org/tips/doc/trunk/tip/476.md>

Lessons:
   - don't use 'long', everything you do with it needs to be tested on both
32 and 64-bit platforms
   - In Tcl 9 - eventually - all uses of Tcl_WideInt can simply be replaced
with 'long long'

TCL_WIDE_INT_IS_LONG should be interpreted as
     TCL_WIDE_INT_HAS_SAME_SIZE_AS_LONG

But better, don't use it any more

Hope this helps,
           Jan Nijtmans

Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

[<apn...@ya...>]

Thanks for the link, Jan. I haven’t used TCL_WIDE_INT_IS_LONG before but was intending to use it as follows so the appropriate built-in is called in both 8.6 and 9.0 for all platforms.

 

Tcl_WideInt a, b, result;

int status;

#ifdef TCL_WIDE_INT_IS_LONG

    status = __builtin_saddl_overflow(a, b, &result);

#else

    status = __builtin_saddll_overflow(a, b, &result);

#endif

 

I’ve modified it now to be

 

#if TCL_MAJOR_VERSION < 9 && defined(TCL_WIDE_INT_IS_LONG)

 

Not ideal, suggestions for better approaches appreciated.

 

/Ashok

 

 

From: Jan Nijtmans <jan...@gm...> 
Sent: Thursday, November 28, 2024 2:11 PM
To: apn...@ya...
Cc: tcl...@li...
Subject: Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

 

Could someone clarify - Is this difference between Tcl 8 and 9 intentional? What is the purpose of the TCL_WIDE_INT_IS_LONG  #define if not to indicate which Tcl_WideInt typedef was in effect? How else can I detect whether to call the “long” version or “long long” of a runtime function for Tcl_WideInt values?

 

Tcl Improvement Proposals: TIP 476: Scan/Printf format consistency <https://core.tcl-lang.org/tips/doc/trunk/tip/476.md> 

 

Lessons:

   - don't use 'long', everything you do with it needs to be tested on both 32 and 64-bit platforms

   - In Tcl 9 - eventually - all uses of Tcl_WideInt can simply be replaced with 'long long'

 

TCL_WIDE_INT_IS_LONG should be interpreted as

     TCL_WIDE_INT_HAS_SAME_SIZE_AS_LONG

 

But better, don't use it any more

 

Hope this helps,

           Jan Nijtmans

 

Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

[Harald O. <har...@el...>]

Hi Ashok,
that looks interesting. What I read from the TIP, the correct the check 
would be:

#if defined(TCL_WIDE_INT_IS_LONG) && TCL_WIDE_INT_IS_LONG = 1

It would be great to mention this in the migration notes.
In Tcl 9:
-> Tcl_WideInt is now always "long long".
define "TCL_WIDE_INT_IS_LONG" is always 0.

Thanks,
Harald

Am 28.11.2024 um 11:27 schrieb apnmbx-public--- via Tcl-Core:
> Thanks for the link, Jan. I haven’t used TCL_WIDE_INT_IS_LONG before but 
> was intending to use it as follows so the appropriate built-in is called 
> in both 8.6 and 9.0 for all platforms.
> 
> Tcl_WideInt a, b, result;
> 
> int status;
> 
> #ifdef TCL_WIDE_INT_IS_LONG
> 
>      status = __builtin_saddl_overflow(a, b, &result);
> 
> #else
> 
>      status = __builtin_saddll_overflow(a, b, &result);
> 
> #endif
> 
> I’ve modified it now to be
> 
> #if TCL_MAJOR_VERSION < 9 && defined(TCL_WIDE_INT_IS_LONG)
> 
> Not ideal, suggestions for better approaches appreciated.
> 
> /Ashok
> 
> *From:*Jan Nijtmans <jan...@gm...>
> *Sent:* Thursday, November 28, 2024 2:11 PM
> *To:* apn...@ya...
> *Cc:* tcl...@li...
> *Subject:* Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 
> vs Tcl 9
> 
>     Could someone clarify - Is this difference between Tcl 8 and 9
>     intentional? What is the purpose of the TCL_WIDE_INT_IS_LONG 
>     #define if not to indicate which Tcl_WideInt typedef was in effect?
>     How else can I detect whether to call the “long” version or “long
>     long” of a runtime function for Tcl_WideInt values?
> 
> Tcl Improvement Proposals: TIP 476: Scan/Printf format consistency 
> <https://core.tcl-lang.org/tips/doc/trunk/tip/476.md>
> 
> Lessons:
> 
>     - don't use 'long', everything you do with it needs to be tested on 
> both 32 and 64-bit platforms
> 
>     - In Tcl 9 - eventually - all uses of Tcl_WideInt can simply be 
> replaced with 'long long'
> 
> TCL_WIDE_INT_IS_LONG should be interpreted as
> 
>       TCL_WIDE_INT_HAS_SAME_SIZE_AS_LONG
> 
> But better, don't use it any more
> 
> Hope this helps,
> 
>             Jan 

Re: [TCLCORE] Confusion around TCL_WIDE_INT_IS_LONG in Tcl 8 vs Tcl 9

[Jan N. <jan...@gm...>]

Op do 28 nov 2024 om 11:40 schreef Harald Oehlmann:

> Hi Ashok,
> that looks interesting. What I read from the TIP, the correct the check
> would be:
>
> #if defined(TCL_WIDE_INT_IS_LONG) && TCL_WIDE_INT_IS_LONG = 1
>

No, that's not correct. In Tcl 9.0 (and 8.7 as well)
TCL_WIDE_INT_IS_LONG is defined on 64-bit platforms,
undefined 32-bit platforms. It still can still be used to test
if LONG is 64-bit or 32-bit. That's how it is used inside Tcl

Hope this helps,
      Jan Nijtmans