Is this a bug or is it just me? It seems that the compiler dereference wrong.
----
import std.stdio;

void foo(bool[1]* test) {
	if (test[0])
		test[0] = false;
}

void main()
{
	bool[1] test = false;
	foo(&test);
}
----
prints: Error: expression test[0u] of type bool[1u] does not have a boolean value

This work:
----
if ((*test)[0])
    test[0] = false;
----

On Saturday, 29 June 2013 at 12:41:12 UTC, Namespace wrote:
> Is this a bug or is it just me? It seems that the compiler dereference wrong.
> ----
> import std.stdio;
>
> void foo(bool[1]* test) {
> 	if (test[0])
> 		test[0] = false;
> }
>
> void main()
> {
> 	bool[1] test = false;
> 	foo(&test);
> }
> ----
> prints: Error: expression test[0u] of type bool[1u] does not have a boolean value
>
> This work:
> ----
> if ((*test)[0])
>     test[0] = false;
> ----

bool[1]*: a pointer to a static array of bools of size 1.

Ergo test[0] is of type "bool[1]". Which can't be evaluated to bool.
When you write "test[0] = false", that is actually an *array assignement* (test[0] is the same as *test, which resolves to a bool[1]), and yo are assigning false to *all* (in this case, 1) elements of your array.

On the other hand, (*test)[0] first dereferences the pointer to obtain the array, and then obtains the first element... The assignment on the next line is still wrong though.

So I think it's just you ;)

But in your defense, (I think you have a C++ background?) the declaration syntax from D to C++ is completely different...

Related: I think this might actually give you a compiler warning about doing a range assign without slicing? Bearophile had suggested this shouldn't work unless you actually type:
"test[0][] = false;"
But I prefer:
"test[0] []= false;"

I can't test right now: Does your code emit no warnings with -w ?

I get this with -wi:
bug.d(5): Warning: explicit element-wise assignment (test[0u])[] = false is bett
er than test[0u] = false

That helps a bit. But I thought that D dereferences automatically? ;)

On Saturday, 29 June 2013 at 12:57:07 UTC, Namespace wrote:
> I get this with -wi:
> bug.d(5): Warning: explicit element-wise assignment (test[0u])[] = false is bett
> er than test[0u] = false
>
> That helps a bit. But I thought that D dereferences automatically? ;)

Only when making a function call (AFAIK), eg: "p.foo();"

This also takes precedence over UFCS:

----
struct S
{
    void foo(){writeln("val");}
}
void foo(S*){writeln("pointer");} //troll function trying to hijack p.foo()
void main()
{
    S* p = new S;
    p.foo();
}
--------
val
--------

monarch_dodra:

> Related: I think this might actually give you a compiler warning about doing a range assign without slicing? Bearophile had suggested this shouldn't work unless you actually type:
> "test[0][] = false;"
> But I prefer:
> "test[0] []= false;"
>
> I can't test right now: Does your code emit no warnings with -w ?

I have also suggested to have the "-wi" switch activated on default (as I think C# does, because people forget to use it all the time!), give a switch to disable on request the informational warnings (because once in a while you don't want warnings), and remove the -w switch (because it breaks the semantics of D programs) :-)

http://d.puremagic.com/issues/show_bug.cgi?id=10321

Bye,
bearophile

On Saturday, 29 June 2013 at 13:11:10 UTC, bearophile wrote:
> monarch_dodra:
>
>> Related: I think this might actually give you a compiler warning about doing a range assign without slicing? Bearophile had suggested this shouldn't work unless you actually type:
>> "test[0][] = false;"
>> But I prefer:
>> "test[0] []= false;"
>>
>> I can't test right now: Does your code emit no warnings with -w ?
>
> I have also suggested to have the "-wi" switch activated on default (as I think C# does, because people forget to use it all the time!), give a switch to disable on request the informational warnings (because once in a while you don't want warnings), and remove the -w switch (because it breaks the semantics of D programs) :-)
>
> http://d.puremagic.com/issues/show_bug.cgi?id=10321
>
> Bye,
> bearophile

Thanks for the link. I actually wanted to state that I think you were one of the people who thought the above should be mandatory syntax? I do.