[PATCH v4] shell: exchange Dijkstra $(( )) evaluator..

[Steffen Nurpmeso]

Harald van Dijk wrote in
 <16238a7b-c165-796f-a137-d5d119bf8b45 at gigawatt.nl>:
 |On 07/09/2022 13:43, Steffen Nurpmeso wrote:
 |> Harald van Dijk wrote in
 |>   <92eff87d-3bfe-b1bb-03e1-5f280184434d at gigawatt.nl>:
 |>    ...
 |>|The supplied patch appears to fix both #1 and #2, but it has alignment
 |>|issues: when UBSAN is enabled, I see a lot of "runtime error: store to
 |>|misaligned address <...> for type 'char *', which requires 4 byte
 |>|alignment" warnings when using shell arithmetic.
 |> 
 |> ASAN works, UBSAN i have not tried.  How can char* require 4 byte
 |> alignment?
 |
 |This message means the char * object itself needs to be aligned on a 4 
 |byte boundary, and isn't. It doesn't say anything about what the char * 

I cannot reproduce this.

But yes, i hate it, i use BITENUM_IS(POD,ENUM) because there are
not bit-flag "enumerations", so that you have to use preprocessor
macros, which in turn results in no checks for content.
I do not have a VALENUM_IS(POD,SIZE,ENUM) do get around that
i think C++ compresses enumerations to the smallest possible size.
Normally i do use only integers thus for such fields.  Really.
I hate it.
Here not, for sac_error, for whatever reason, which could then
misalign anything after

   struct a_shexp_arith_ctx{
  -   enum a_shexp_arith_error sac_error;
  +   u32 sac_error;
      boole sac_have_error_track;
      u8 sac__pad[3];
      s64 sac_rv;

But not in C.

Thank you.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)