http://d.puremagic.com/issues/show_bug.cgi?id=7713

           Summary: lambda inference doesn't work on template function
                    argument
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: k.hara.pg@gmail.com


--- Comment #0 from Kenji Hara <k.hara.pg@gmail.com> 2012-03-15 01:58:13 PDT ---
test case:
----
void foo(T)(T delegate(in Object) dlg)
{}
void main()
{
    foo( (in obj) { return 15; } );   // line 6
}

output:
----
test.d(6): Error: template test.foo(T) does not match any function template
declaration
test.d(6): Error: template test.foo(T) cannot deduce template function from
argument types !()(void)

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull


--- Comment #1 from Kenji Hara <k.hara.pg@gmail.com> 2012-03-15 21:50:30 PDT ---
https://github.com/D-Programming-Language/dmd/pull/814

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Alex Rønne Petersen <xtzgzorex@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xtzgzorex@gmail.com


--- Comment #2 from Alex Rønne Petersen <xtzgzorex@gmail.com> 2012-03-15 21:56:53 PDT ---
Question: Would this also allow:

void foo(T)(T t, bool delegate(T) dg)
{
}

void main()
{
    foo(1, (i) { return true; });
}

or is it limited to the return type of the delegate (or is this completely
unrelated to this bug?)?

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--- Comment #3 from Kenji Hara <k.hara.pg@gmail.com> 2012-03-15 22:49:51 PDT ---
(In reply to comment #2)
> Question: Would this also allow:
> 
> void foo(T)(T t, bool delegate(T) dg)
> {
> }
> 
> void main()
> {
>     foo(1, (i) { return true; });
> }
> 
> or is it limited to the return type of the delegate (or is this completely
> unrelated to this bug?)?

This is unrelated bug, and your sample is NEVER compiled. Because each parameter type inference runs in *parallel*.

[1] T                is deduced from argument   1
 -> T is deduced to int, OK.
[2] bool delegate(T) is deduced from argument   (i) { return true; }
 -> Before template parameter type deduction, the delegate parameter i is
    deduced to T from template function parameter type, but T is not a
    real type.
    Then compiler cannot determine the delegate literal type.
[1] succeeded but [2] failed, so whole IFTI would fail.

The point is [1] and [2] runs in parallel, so they have no dependency.

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--- Comment #4 from Alex Rønne Petersen <xtzgzorex@gmail.com> 2012-03-15 22:54:41 PDT ---
That makes sense. Thank you for the explanation.

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--- Comment #5 from github-bugzilla@puremagic.com 2012-03-20 14:12:18 PDT ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/8dba679462b3ee58bb589aa7a6b28135191c09be Merge pull request #814 from 9rnsr/fix7713

Issue 7713 - lambda inference doesn't work on template function argument

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |FIXED


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