https://issues.dlang.org/show_bug.cgi?id=11012

Vladimir Panteleev <thecybershadow@gmail.com> changed:

           What    |Removed                     |Added
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           Keywords|                            |spec
                 CC|                            |thecybershadow@gmail.com

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https://issues.dlang.org/show_bug.cgi?id=11012

Andrei Alexandrescu <andrei@erdani.com> changed:

           What    |Removed                     |Added
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            Version|unspecified                 |D2

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https://issues.dlang.org/show_bug.cgi?id=11012

Alexander <ismailsiege@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |ismailsiege@gmail.com

--- Comment #2 from Alexander <ismailsiege@gmail.com> ---
void testf(){}

void main()
{
    static assert(!is(testf == function));        // OK
    static assert(is(typeof(testf) == function));    // OK
    static assert(is(typeof( (){} ) == delegate));    // fails
}

But "is" doesn't work with function literals themselves in the first place, it is intended to check whether type is equivalent to function pointer or not.

Same goes for:

static if (is(typeof((int, float){}) P == function))
    pragma(msg, P);
else
    static assert(0);    // fails

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https://issues.dlang.org/show_bug.cgi?id=11012

--- Comment #3 from Alexander <ismailsiege@gmail.com> ---
static assert(is(typeof( (){} ) == function));    // fails as well

This issue doesn't allow to get lambda parameter types tuple, and this blocks my development. I'll try to have a look at the dmd source.

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https://issues.dlang.org/show_bug.cgi?id=11012

Alexander <ismailsiege@gmail.com> changed:

           What    |Removed                     |Added
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             Status|NEW                         |ASSIGNED

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https://issues.dlang.org/show_bug.cgi?id=11012

Alexander <ismailsiege@gmail.com> changed:

           What    |Removed                     |Added
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             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |WONTFIX

--- Comment #4 from Alexander <ismailsiege@gmail.com> ---
Ok, I'll agree with Maxim, it's probably as it should be.

template isFunctionPointerType(T: FT*, FT)
{
    enum isFunctionPointerType = is(FT == function);
}

unittest
{
    auto p = (){};
    static assert(isFunctionPointerType!(typeof(p)));
}

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https://issues.dlang.org/show_bug.cgi?id=11012

ZombineDev <petar.p.kirov@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |petar.p.kirov@gmail.com

--- Comment #5 from ZombineDev <petar.p.kirov@gmail.com> ---
(In reply to Alexander from comment #3)
> static assert(is(typeof( (){} ) == function));	// fails as well
> 
> This issue doesn't allow to get lambda parameter types tuple, and this blocks my development. I'll try to have a look at the dmd source.

Is the blocking issue that in code similar to the following, there's an error on line 11:

---
import std.traits;

pragma (msg, ReturnType!( (){} )); // void
pragma (msg, Parameters!( (){} )); // ()

pragma (msg, ReturnType!( (int x, double y) => "test" )); // string
pragma (msg, Parameters!( (int x, double y) => "test" )); // (int, double)

void lambdaTypeWithParameter(alias lambda, Param)(Param p)
{
    pragma (msg, Parameters!(lambda)); // line 11 - doesn't compile

    alias RT = typeof(lambda(p));

    pragma (msg, RT); // line 15
}

void main()
{
    lambdaTypeWithParameter!(x => "test2")(true); // line 15 -> string
    lambdaTypeWithParameter!(x => x)(2);          // line 15 -> int
    lambdaTypeWithParameter!(x => 3.0 * x)(2);    // line 15 -> double
}
---

?

If that's the case, the error is expected since the lambda in that context is polymorphic - an un-instantiated function template meaning that its parameters are not bound to a specific type.

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https://issues.dlang.org/show_bug.cgi?id=11012

ZombineDev <petar.p.kirov@gmail.com> changed:

           What    |Removed                     |Added
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             Status|RESOLVED                    |REOPENED
         Resolution|WONTFIX                     |---

--- Comment #6 from ZombineDev <petar.p.kirov@gmail.com> ---
Let's keep the bug open until the language authors take an authoritative decision to keep or fix this issue.

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https://issues.dlang.org/show_bug.cgi?id=11012

--- Comment #7 from anonymous4 <dfj1esp02@sneakemail.com> ---
How it works now:
---
void f(){}
static assert(is(typeof(f)==function));
static assert(is(typeof(&f)==function));
---
line 3: Error: static assert (is(void function() == function)) is false

Looks like function pointer is not recognized as `function` by `is` expression.

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https://issues.dlang.org/show_bug.cgi?id=11012

anonymous4 <dfj1esp02@sneakemail.com> changed:

           What    |Removed                     |Added
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                URL|                            |https://dlang.org/spec/expr
                   |                            |ession.html#IsExpression

--- Comment #8 from anonymous4 <dfj1esp02@sneakemail.com> ---
static assert(is(typeof(&f)==delegate));
fails too, and spec doesn't specify how `is` expression works, which is
definitely a bug.

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