Thread overview
[Issue 4053] New: To avoid struct ctor/opCall conflicts
Jan 06, 2011
Adam D. Ruppe
Apr 28, 2011
kennytm@gmail.com
Jun 21, 2011
Kenji Hara
April 03, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4053

           Summary: To avoid struct ctor/opCall conflicts
           Product: D
           Version: future
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: diagnostic
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2010-04-02 17:03:42 PDT ---
This is a D2 program:


struct Foo {
    this(int x=0) {}
    static void opCall(int x, int y) {}
}
void main() {
    auto f2 = Foo(1);    // line 6, OK
    auto f3 = Foo(1, 2); // line 7, Err, opCall not found
    auto f1 = Foo();     // line 8, Err, conflicts with opCall again
}


dmd 2.042 gives:

test.d(7): Error: constructor test.Foo.this (int x = 0) is not callable using
argument types (int,int)
test.d(7): Error: expected 1 arguments, not 2 for non-variadic function type
ref Foo(int x = 0)
test.d(8): Error: function test.Foo.opCall (int x, int y) is not callable using
argument types ()
test.d(8): Error: expected 2 function arguments, not 0
test.d(8): Error: variable test.main.f1 voids have no value
test.d(8): Error: expression opCall() is void and has no value


My suggestion is in structs to disallow opCall() if a this() is present.
This makes the program more tidy, and avoids that conflict with opCall when
Foo() is used with no arguments.

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January 06, 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4053


Adam D. Ruppe <destructionator@gmail.com> changed:

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


--- Comment #1 from Adam D. Ruppe <destructionator@gmail.com> 2011-01-06 05:18:58 PST ---
An important addition to the suggestion: *static* opCall is the real problem here. There should be no problem between an instance opCall and a constructor.

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--- Comment #2 from bearophile_hugs@eml.cc 2011-03-08 00:32:29 PST ---
This (modified) example from Tom shows problems with not static opCall too:


struct Foo {
    int i;
    this(int i) { this.i = i; }
    void opCall(int x, int y) {}
}
void main() {
    Foo foo;
    foo(1, 2);
}

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--- Comment #3 from bearophile_hugs@eml.cc 2011-03-08 09:53:38 PST ---
See also bug 4253

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April 28, 2011
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kennytm@gmail.com changed:

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


--- Comment #4 from kennytm@gmail.com 2011-04-28 11:41:16 PDT ---
Probably the same as issue 1840.

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June 21, 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4053


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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |k.hara.pg@gmail.com
         Resolution|                            |DUPLICATE


--- Comment #5 from Kenji Hara <k.hara.pg@gmail.com> 2011-06-21 07:03:40 PDT ---
*** This issue has been marked as a duplicate of issue 6036 ***

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