Is it defined somewhere that auto functions are not authorized inside main?

void main()
{
    auto fun(string s) { return s;} // this does not compile
}

error:

main.d|6|found 's' when expecting ')'|
main.d|6|semicolon expected, not ')'|
main.d|6|found ')' instead of statement|
main.d|7|unrecognized declaration|
||=== Build finished: 4 errors, 0 warnings ===|


So it's not even parsed?

I couldn't find a bugzilla entry for this and I cannot believe no one ever tried to put an auto fun inside main!

Is that part of the spec?

Philippe

Philippe Sigaud:
> I couldn't find a bugzilla entry for this and I cannot believe no one ever tried to put an auto fun inside main!

Maybe auto funcs are seen as instantiated templates, and templates can't be defined inside functions. Anyway, I think you can file this as enhancement request.

Bye,
bearophile

On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud <philippe.sigaud@gmail.com> wrote:

> Is it defined somewhere that auto functions are not authorized inside main?
>
> void main()
> {
>     auto fun(string s) { return s;} // this does not compile
> }
>
> error:
>
> main.d|6|found 's' when expecting ')'|
> main.d|6|semicolon expected, not ')'|
> main.d|6|found ')' instead of statement|
> main.d|7|unrecognized declaration|
> ||=== Build finished: 4 errors, 0 warnings ===|
>
>
> So it's not even parsed?
>
> I couldn't find a bugzilla entry for this and I cannot believe no one ever
> tried to put an auto fun inside main!
>
> Is that part of the spec?
>
> Philippe

Hope this isn't a stupid question, but how would you access this function if it did work?
Would it be fun("asdf")?
Is this just shorthand for:
auto fun = function(string s) {return s;};



-Rory

Hello Rory,

> On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
> <philippe.sigaud@gmail.com> wrote:
> 
>> void main()
>> {
>> auto fun(string s) { return s;} // this does not compile
>> }
>
> Hope this isn't a stupid question, but how would you access this
> function
> if it did work?
> Would it be fun("asdf")?
> Is this just shorthand for:
> auto fun = function(string s) {return s;};

I would look almost the same to the user but should in fact be a normal local function.

-- 
... <IXOYE><

On Mon, 28 Jun 2010 16:07:43 +0200, Philippe Sigaud <philippe.sigaud@gmail.com> wrote:

> On Mon, Jun 28, 2010 at 15:40, Rory McGuire <rmcguire@neonova.co.za> wrote:

>>> void main()
>>> {
>>>    auto fun(string s) { return s;} // this does not compile
>>> }


>> Hope this isn't a stupid question, but how would you access this
>> function if it did work?
>> Would it be fun("asdf")?

> Yes, that's what I had in mind. Basically, just using it as any other auto inner function.

> void main()
> {
> auto fun(string s) { return s;}
> auto s = fun("abc");
> auto t = fun("def");
> }
>
>> Is this just shorthand for:
>> auto fun = function(string s) {return s;};

> That'd be about the same, yes. Fact is, I don't really _need_ this, I
> was just astonished to be bitten by this.
> Why can I do

> void main()
> {
>    string foo(string s) { return s;}
> }

> and not

> void main()
> {
>    auto foo(string s) { return s;}
> }

> ?

> ***

> OK, I tested it some more, and it seems you cannot define auto function inside any other function. So auto function cannot be inner functions. I'm quite astonished I never did that when using D, but OK.

> I filed a bug report, at least to update the docs. It's bug #4401.


> Philippe




Right! I get what you're saying, didn't realise because it was formatted
more how I would format a anon delegate.
You're saying "surely the compiler can infer the return type for a inner
function just as much as it can infer the return type of a normal function.

Must be a compiler bug.

-Rory

On Mon, 28 Jun 2010 16:01:46 +0200, BCS <none@anon.com> wrote:

> Hello Rory,
>
>> On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
>> <philippe.sigaud@gmail.com> wrote:
>>
>>> void main()
>>> {
>>> auto fun(string s) { return s;} // this does not compile
>>> }
>>
>> Hope this isn't a stupid question, but how would you access this
>> function
>> if it did work?
>> Would it be fun("asdf")?
>> Is this just shorthand for:
>> auto fun = function(string s) {return s;};
>
> I would look almost the same to the user but should in fact be a normal local function.
>

Ye I got it now.

My brain was interpreting it as a delegate that wasn't being assigned to anything for some reason.

Now I get that it is just return type inferance doesn't work for inner functions.

-Rory