On 04.04.2018 18:53, Jonas Maebe wrote:
On 04/04/18 18:44, Ondrej Pokorny wrote:
I want to stress that the compiler emits a warning on code that does
not have (and also cannot have) an error
An error is wrong code behaviour. If you do not initialise a variable
with the correct value, then you can have an error.
No, no, no and again no. Do you try to convince me that I cannot rely on
well documented compiler behavior? Even Sven stated earlier in this
thread that the FPC docs are correct in case of managed variables:
"Managed types are an exception to this rule: Managed types are always
initialized: in general this means setting the reference count to zero,
or setting the pointer value of the type to Nil." and "It should be
stressed that initialized variables are initialized when they come into
scope" https://www.freepascal.org/docs-html/ref/refse24.html
Again, the code
procedure Test;
var S: string; I: Integer;
begin
for I := 0 to 1 do
S := S + '1';
Writeln(S);
end;
does not have an error, cannot have an error and the behavior is
guaranteed and well documented => no warning should be here.
+ Do you try to convince me that the code below can have an error and
should emit a warning as well because it does not initialize the FS and
FI fields?
program Project1;
type
TMyObject = class
private
FS: string;
FI: Integer;
public
property S: string read FS write FS;
property I: Integer read FI write FI;
end;
begin
with TMyObject.Create do
begin
Writeln(S);
Writeln(I);
Free;
end;
end.
It's the same case - object fields are documented to be initialized. You
mean I should not rely on this feature and it is an error that I did not
initialize them with the correct values?
This correct value can be different from "empty string" or "nil".
If I want to have a different value from "empty string" or "nil" I know
I have to initialize it by myself. I don't need a warning for it.
For the same reason, we also warn about uninitialised global variables
(if this can be detected without interprocedural analysis, i.e., if
they are only used in the main program code; but that is merely due to
a limitation of the analysis).
Uninitialised global variables are the same case: the compiler should
not emit a warning here because again, it is well documented that they
are implicitely initialized (at least in the Object Pascal Language
Guide from Borland from 2002 it is documented).
Ondrej
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