[fpc-devel] Oddity: Longint being converted automatically to int64 and then assignment/conversion operator used/applied for/to structure variable...(i386) branch (2.4.2)

Skybuck Flying skybuck2000 at hotmail.com
Thu Apr 7 08:01:24 CEST 2011


I am currently inspecting the following compiler unit of 2.4.2 
branch/release ninl.pas:

line 1371:                  enum:=tenumsym(tenumdef(def).firstenum);
line 1372:                         v:=tenumdef(def).maxval;

Problem is with line 1372.

.maxval is apperently an integer.

v however only knows int64 implicit conversions (operators)

v is defined as
line 1352:   v    : tconstexprint;

tconstexprint is defined as in constexp.pas:

type  Tconstexprint=record
        case signed:boolean of

With conversion operators:

operator := (const u:qword):Tconstexprint;inline;
operator := (const s:int64):Tconstexprint;inline;
operator := (const c:Tconstexprint):qword;
operator := (const c:Tconstexprint):int64;
operator := (const c:Tconstexprint):bestreal;

(Notice the missing conversion operators for integer/longint)

Therefore at least in theory it does not know how to convert an integer to 
an int64.

Further proof that this is indeed what's happening:

tenumdef is defined as follows in symdef.pas:

line 563:       tenumdef = class(tstoreddef)
                      maxval    : aint;

aint is defined as follows in globtype.pas:

line 51:

       { Natural integer register type and size for the target machine }
{$ifdef cpu64bitalu}
       AWord = qword;
       AInt = Int64;

       AIntBits = 64;
{$endif cpu64bitalu}
{$ifdef cpu32bitalu}
       AWord = longword;
       AInt = longint;

       AIntBits = 32;
{$endif cpu32bitalu}
{$ifdef cpu16bitalu}
       AWord = Word;
       AInt = Smallint;

Assumption is that conditional cpu32bitalu is active (for i386)

Therefore Aint = longint;

So to me it seems a bit of an oddity... at least it's an integer which is 
being tried to assign to an int64... so at least no overflow...

However v is a structure and .maxvalue is an integer...

So how come a conversion is being done ? (there is no conversion operator 
for this situation ?)

So I am guessing free pascal does some conversion from integer to int64 and 
then assign int64 to v ?

Isn't that a bit weird ? I guess it's kinda beautifull as well.. it 
automatically detects a conversion path... however this is not what Delphi 
XE would do...
so a slight deviation... causing me headaches... but I'll have to deal with 

Unless ofcourse you guys actually think it's a bug... then it's up to you to 
fix it... but for now I will add some conversion operators to try and get it 


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