[fpc-devel] Warning: Conversion between ordinals and pointers is not portable
lazarus at mfriebe.de
Thu Dec 6 14:03:26 CET 2012
On 06/12/2012 12:06, Jonas Maebe wrote:
> That's because cardinal-cardinal results in an int64, because of a.o.
>> So actually the message is just downgraded from Warning to Hint.
> Yes, that's by design. The compiler has no special knowledge about the
> ptrint or ptruint types. It is almost impossible to fix all hints for
> non-trivial programs, and they only exist to help find possibly
> suspicious locations in code (and typecasting an integer into a
> pointer is such an expression). You can always disable a particular
> hint with -vqXXX if you are not interested in it.
I have no issue with the hint. I understand Ptr(u)Int are no different
from all other int types. Just aliases.
I now see that I get the warning, if the type-to-be-casted is 64 bit and
I am on a 32bit system.
a: int64; //qword;
p := Pointer(a);
project1.lpr(7,8) Warning: Conversion between ordinals and pointers is
Yet what I do not understand, is why I get that message as warning (as
opposed to a hint). If I understand it right (I have not tested, maybe
it gives a warning on 64 bit target too, if so ignore the rest), and I
compile for a 64bit target, then it downgrades to a hint again?
The only difference is, that in the above example, if compiled for a 32
bit system, I already may have broken code. But then what it actually
means is that I should get warning about a truncating the value.
b := byte(a);
Gives no warning at all.
It also truncates the warning. What is then special about potentially
truncating a value by using pointer(a)? If "pointer(a)" is worth a
warning (instead of a hint, why isn't byte(a)?
Not saying it needs to change. But trying to figure out the reason behind.
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