Buffering a signal.

--- Quote Start ---

It depends where signal_0_synch comes from. If this is the only process it is driven from then yes, assuming it does something else as otherwise it will always just be '0'.

If it is driven elsewhere then no, its not valid as it's like connecting two wires together and you get multiple driver errors and unknowns in your simulation.

--- Quote End ---

I see. So it could be something like this?

process(reset_n, clk0)
    begin
      if reset_n='0' then
         signal_1_synch  <= '0';
         signal_2_synch  <= '0';
      elsif (clk0'event and clk0 = '1') then
         
         case cond is
               when 1 => ------------
               when 2 => signal_0_synch <= '1';
         end case;
         signal_1_synch  <= signal_0_synch;
         signal_2_synch  <= signal_1_synch;
         signal_0_synch  <= '0';
      end if;
    end process;

This way I store the signal_0_synch and reset it. I need some buffer for another process to read the signal. If I reset it to quick It might be missed by other process.