http://d.puremagic.com/issues/show_bug.cgi?id=664

           Summary: is(func T == return) ignores variadic arguments
           Product: D
           Version: 0.176
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: thomas-dloop@kuehne.cn


according to is(... == return) all the functions below have the same argument
types:

void foo(int);
void foo(int ...);
void foo(int, ...);


-- 

d-bugmail@puremagic.com wrote:
> http://d.puremagic.com/issues/show_bug.cgi?id=664
> 
>            Summary: is(func T == return) ignores variadic arguments
>            Product: D
>            Version: 0.176
>           Platform: PC
>         OS/Version: Linux
>             Status: NEW
>           Severity: normal
>           Priority: P2
>          Component: DMD
>         AssignedTo: bugzilla@digitalmars.com
>         ReportedBy: thomas-dloop@kuehne.cn
> 
> 
> according to is(... == return) all the functions below have the same argument
> types:
> 
> void foo(int);
> void foo(int ...);
> void foo(int, ...);
> 
> 

perhaps you mean '== function' and not '== return' ?

-- 
Bruno Medeiros - MSc in CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D

http://d.puremagic.com/issues/show_bug.cgi?id=664


thomas-dloop@kuehne.cn changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|is(func T == return) ignores|is(func T == function)
                   |variadic arguments          |ignores variadic arguments




------- Comment #1 from thomas-dloop@kuehne.cn  2006-12-10 07:03 -------
"is(... == function)" instead of "is(... == return)"

Thanks to Bruno Medeiros for catching this.


-- 

d-bugmail@puremagic.com schrieb am 2006-12-10:
> http://d.puremagic.com/issues/show_bug.cgi?id=664

> ------- Comment #1 from thomas-dloop@kuehne.cn  2006-12-10 07:03 -------
> "is(... == function)" instead of "is(... == return)"
>
> Thanks to Bruno Medeiros for catching this.

Added to DStress as http://dsrtess.kuehne.cn/compile/i/is_16_A.d http://dsrtess.kuehne.cn/compile/i/is_16_B.d http://dsrtess.kuehne.cn/compile/i/is_16_C.d

Thomas

http://d.puremagic.com/issues/show_bug.cgi?id=664


Andrei Alexandrescu <andrei@metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei@metalanguage.com
         AssignedTo|nobody@puremagic.com        |bugzilla@digitalmars.com


--- Comment #3 from Andrei Alexandrescu <andrei@metalanguage.com> 2010-11-26 13:22:37 PST ---
Fixed URLs:

http://dstress.kuehne.cn/compile/i/is_16_A.d http://dstress.kuehne.cn/compile/i/is_16_B.d http://dstress.kuehne.cn/compile/i/is_16_C.d

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Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au


--- Comment #4 from Don <clugdbug@yahoo.com.au> 2011-12-07 02:29:39 PST ---
There are two ways to fix this:
(1) Change the spec to define that (is == function) returns the non-variadic
parameters.
(2) Create a '...' object inside the compiler, and allow it to be a member of a
tuple. Variadics are neither types nor expressions, nor symbols. Creates lots
of special cases all through the compiler.There are tricky examples like:

template baa(T...) {
    alias void function(T) a;  // OK, params are (char, ...)
    alias void function(T, ...) b; // illegal: (char, ..., ...)
    alias void function(T, int) c; // illegal: (char, ..., int)
}

alias baa!( is ( void function(char, ...) == function)).b baz;


And if we fix those problems, maybe we should allow this syntax:
alias baa!(char, ...).a foo;
because otherwise I don't know what to print when you do:
pragma(msg, T);
but then we have to make sure we can always distinguish variadic function
parameters from template variadics.

Is this issue important enough to justify (2) ?

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--- Comment #5 from Stewart Gordon <smjg@iname.com> 2011-12-17 18:27:18 PST ---
(3) Have function(char, ...) just not matching function(T) for any value of T.
... is a fundamentally different kind of thing from a type, so it doesn't seem
to make sense to allow it as an element of a type tuple.

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--- Comment #6 from Don <clugdbug@yahoo.com.au> 2011-12-19 04:59:44 PST ---
(In reply to comment #5)
> (3) Have function(char, ...) just not matching function(T) for any value of T.
> ... is a fundamentally different kind of thing from a type, so it doesn't seem
> to make sense to allow it as an element of a type tuple.


How does that solve the problem? The root cause is that is( ==function) assumes
that all of the function parameters can be returned in a tuple, but that isn't
true for ...
Or do you mean that is( x==function) should be an error if x has a variadic
parameter?

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--- Comment #7 from Stewart Gordon <smjg@iname.com> 2011-12-19 05:23:40 PST ---
(In reply to comment #6)
> How does that solve the problem? The root cause is that is( ==function) assumes that all of the function parameters can be returned in a tuple, but that isn't true for ...

In what way does it make that assumption?

> Or do you mean that is( x==function) should be an error if x has a variadic
> parameter?

Of course not.  What would be the point of that?

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--- Comment #8 from Don <clugdbug@yahoo.com.au> 2011-12-19 22:34:00 PST ---
(In reply to comment #7)
> (In reply to comment #6)
> > How does that solve the problem? The root cause is that is( ==function) assumes that all of the function parameters can be returned in a tuple, but that isn't true for ...
> 
> In what way does it make that assumption?

It declares T as a tuple containing all of the function arguments.

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