[fpc-devel] [Suggestion] Enumeration range-check intrinsic

[Pierre Muller]

Just one point from current compiler implementation:

in trunk/fpcsrc/compiler/ninl.pas (around line 3180)

              in_pred_x,
              in_succ_x:
                begin
                   set_varstate(left,vs_read,[vsf_must_be_valid]);
                   resultdef:=left.resultdef;
                   if is_ordinal(resultdef) or is_typeparam(resultdef) then
                     begin
                       if (resultdef.typ=enumdef) and
                          (tenumdef(resultdef).has_jumps) and
                          not(m_delphi in current_settings.modeswitches) and
                          not(nf_internal in flags) then
                         CGMessage(type_e_succ_and_pred_enums_with_assign_not_possible);
                     end


This means that using pred() or succ() intrinsics on enumerated types with
holes will generate a Compile Time Error.

  To be consistent, I would propose that we also generate
a Compile Time Error if 'is' or 'as' keyword is used on such a type,
unless there is a code that really check that the value is not in
one of the holes ...

Pierre