[fpc-devel] Do bitwise operation (1 or 2) acre about the sign ? (Giving sign related hints on compilation)

[Jonas Maebe]

On 14 Jan 2013, at 16:44, Martin wrote:

> This is casting a "set of bits" (neither signed, nor unsigned - a  
> set is not a number at all) into a number. This only needs to have a  
> definition, if it should cast to signed or unsigned type.

It has to be signed, because otherwise any negative number in the  
operation would trigger a range check error when it gets converted to  
a (larger) unsigned type. The nature of the operation that is used  
afterwards is irrelevant, range checking always operates in exactly  
the same way when performing a type conversion from one type to  
another. This is required to have predictable behaviour in a  
programming language.


Jonas
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