Re: new warnings with clang-21 / how const is Datum

On 01.09.25 08:47, Peter Eisentraut wrote:
> clang-21 shows some new warnings:
> 
> ../src/backend/access/common/toast_internals.c:296:33: error: variable 
> 'chunk_data' is uninitialized when passed as a const pointer argument 
> here [-Werror,-Wuninitialized-const-pointer]
>    296 |         t_values[2] = PointerGetDatum(&chunk_data);
> 
> ../src/backend/access/gist/gistutil.c:207:28: error: variable 'attrsize' 
> is uninitialized when passed as a const pointer argument here [-Werror,- 
> Wuninitialized-const-pointer]
>    207 |                 PointerGetDatum(&attrsize));
>        |                                  ^~~~~~~~
> ../src/backend/access/gist/gistutil.c:276:27: error: variable 'dstsize' 
> is uninitialized when passed as a const pointer argument here [-Werror,- 
> Wuninitialized-const-pointer]
>    276 |  PointerGetDatum(&dstsize));
>        |                   ^~~~~~~

Here is a quick-fix patch for this.  It silences these warnings by 
initializing the respective variables first.  This is already done 
similarly in nearby code.  This can be backpatched to PG16, where these 
warnings began.

The second patch is a bit of a more extensive code rearrangement to make 
the need for the workaround in the first patch go away.  This would be 
for master only.