Crash, cannot handle psl prev

[cderrien]

A ghdl bug occurs when the input file contains the psl function prev.

See files below.

entity prev is
  port (
    clk : in bit;
    ena : in boolean
    );
end entity;

architecture behaviour of prev is

  signal rindex : natural := 0;

begin

  default clock is rising_edge(clk);
  psl_assertion : assert always ena |=> (rindex = prev(rindex));

end architecture;

ghdl -a --std=08 prev.vhdl

Ghdl was compiled from source (commit f9086ac), with the llvm back-end, on Ubuntu 22.
See bug box and the error message below.

translate_expression: cannot handle IIR_KIND_PSL_PREV (prev.vhdl:16:51)

******************** GHDL Bug occurred ***************************
Please report this bug on https://github.com/ghdl/ghdl/issues
GHDL release: 4.0.0-dev (3.0.0.r857.gf9086ac6c) [Dunoon edition]
Compiled with GNAT Version: 10.5.0
Target: x86_64-linux-gnu
<redacted>
Command line:
/usr/local/bin/ghdl1-llvm --std=08 -P/usr/local/lib/ghdl/ieee/v08/ -P/usr/local/lib/ghdl/ -fpic -c -o prev.o prev.vhdl
Exception TYPES.INTERNAL_ERROR raised
Exception information:
raised TYPES.INTERNAL_ERROR : vhdl-errors.adb:30
Call stack traceback locations:
0x55cae6f9d0f4 0x55cae71a5d09 0x55cae719a8d4 0x55cae71a557d 0x55cae7203d08 0x55cae7203ea4 0x55cae72053c7 0x55cae7207f0f 0x55cae71bdfca 0x55cae71aff4e 0x55cae72135df 0x55cae7215031 0x55cae7216685 0x55cae6dc8ff1 0x7f805b279d8e 0x7f805b279e3e 0x55cae6dc7823 0xfffffffffffffffe
******************************************************************```

[tgingold]

Yes, currently it is supported only by synthesis.