Thread overview
[Issue 7549] New: typeof of overloaded function picks the lexically first one
Feb 19, 2012
timon.gehr@gmx.ch
Feb 19, 2012
Kenji Hara
Feb 19, 2012
timon.gehr@gmx.ch
Nov 15, 2012
Denis Shelomovskij
May 20, 2013
Martin Nowak
May 20, 2013
timon.gehr@gmx.ch
February 19, 2012
http://d.puremagic.com/issues/show_bug.cgi?id=7549

           Summary: typeof of overloaded function picks the lexically
                    first one
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: timon.gehr@gmx.ch


--- Comment #0 from timon.gehr@gmx.ch 2012-02-19 14:48:36 PST ---
void foo(){}
void foo(int){}

Without further information, a declaration that contains typeof(foo) should
fail.

static assert(!is({typeof(foo)* x;}));

OTOH, 'foo' has some type, we just don't know which one.

static if(is(typeof(foo));

The simplest way to resolve this would be to define typeof(overloadset):=void.

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--- Comment #1 from Kenji Hara <k.hara.pg@gmail.com> 2012-02-19 15:25:42 PST ---
I think typeof(overloadset):=void is not good.
Because, in this case, calculating typeof(foo) to void is valid by translating
foo to foo() first.

So introducing new ambiguous function type instead of void is much better. (My idea is here: https://github.com/D-Programming-Language/dmd/pull/71)

void foo();
void foo(int);
static assert(is(typeof(foo) == void));  // without -property switch
static if (is(typeof(foo) R)) {} // evaluated to false with -property switch,
                                 // because R is ambiguous type, not exact
type.
@property int foo();
@property void foo(int);
static assert(is(typeof(foo) == int));  // always true

void foo(int);
void foo(long);
static assert(is(typeof(foo)));  // always true, because foo has some type,
                                 // even if it is ambiguous type.
static if (is(typeof(foo) R)) {} // evaluated to false,
                                 // because R is ambiguous type, not exact
type.

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--- Comment #2 from timon.gehr@gmx.ch 2012-02-19 15:33:25 PST ---
I agree with your design.

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November 15, 2012
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Denis Shelomovskij <verylonglogin.reg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |blood.of.life@gmail.com


--- Comment #3 from Denis Shelomovskij <verylonglogin.reg@gmail.com> 2012-11-15 11:27:45 MSK ---
*** Issue 6263 has been marked as a duplicate of this issue. ***

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Andrei Alexandrescu <andrei@erdani.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrei@erdani.com


--- Comment #4 from Andrei Alexandrescu <andrei@erdani.com> 2013-02-03 07:00:13 PST ---
Let me add one more case that doesn't involve any property-related stuff:

unittest
{
    class C1 {
        int fun(string) { return 1; }
        int fun() { return 1; }
    }
    auto c1 = new C1;
    writeln(typeof(&c1.fun).stringof);
}

This should fail with ambiguity error, but actually prints the type of the first overload.

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Martin Nowak <code@dawg.eu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |code@dawg.eu


--- Comment #5 from Martin Nowak <code@dawg.eu> 2013-05-20 11:50:59 PDT ---
This seems to happen for any type deduction.

void foo() {}
void foo(int) {}

auto val1 = &foo;                                    // should be ambiguous
auto val2 = cast(void function(int))&foo;            // works
void function(int) val3 = &foo;                      // works

auto bar1() { return &foo; }                         // should be ambiguous
auto bar2() { return cast(void function(int))&foo; } // works
void function(int) bar3() { return &foo; }           // works

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--- Comment #6 from timon.gehr@gmx.ch 2013-05-20 12:06:39 PDT ---
(In reply to comment #2)
> I agree with your design.

Actually, I think is(typeof(foo)) should be consistent with whether or not foo
compiles.

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