Hello:
FPC: 3.0.4 (Realease from Lazarus 1.8.4 SVN: 57972) OS: Windows7 32bits / Linux 64Bits

I have this code and I get a hint

---------- var  Entity:Longword;FullParagraph:string; pIni:Integer;
begin .... Entity:=Entity*10+ord(FullParagraph[pIni])-48; // <=== Hint
.... end; -----------

Hint: Converting the operands to "Int64" before doing the add could prevent overflow errors.
I can't see why it mentions int64, there are integer and longword variables, but no Int64 one.

I have replaced it by

Entity:=Entity*10+LongWord(ord(FullParagraph[pIni]))-48;

That is, I have casted the result of "ord()" to longword. But I get the same hint.
What should I do to remove the hint?

There is you know.

https://www.freepascal.org/docs-html/current/ref/refsu4.html#x26-250003.1.1

I have replaced it by Entity:=Entity*10+LongWord(ord(FullParagraph[pIni]))-48; That is, I have casted the result of "ord()" to longword. But I get the same hint.What should I do to remove the hint?

----------
var
   Entity:Longword;
   FullParagraph:string;
   pIni:Integer;
begin
   ....
   Entity:=Entity*10+ord(FullParagraph[pIni])-48; // <=== Hint
   ....
end;
  -----------
Do you mean that Entity is promoted to int64 in a 32bits system?

The operands Entity*10 and 10+ord(FullParagraph[pIni])-48 are both 32 bits, but the addition could overflow. The compiler writer's trying to be nice to you, quit kvetching :-)

Santiago A. wrote

---------- var Entity:Longword;FullParagraph:string; pIni:Integer; begin .... Entity:=Entity*10+ord(FullParagraph[pIni])-48; // <=== Hint .... end; -----------

Compiling with -vp shows that the result of the subtraction is a signed Longint. That makes this an expression mixing Longword and Longint, which is always computed in Int64 and because of that causes this hint.

The thing I'm missing is the "Mixing signed expressions and longwords gives a 64bit result" hint. Is that because something detects that this was an internal typeconvn?