Thread overview
[Issue 10394] New: opBinaryRight!"in" and tuple
Jun 17, 2013
Justin Whear
Jun 17, 2013
Andrej Mitrovic
Jun 17, 2013
Justin Whear
Jul 15, 2013
Justin Whear
Aug 26, 2013
Kenji Hara
Aug 27, 2013
Walter Bright
June 17, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394

           Summary: opBinaryRight!"in" and tuple
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: regression
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: justin@economicmodeling.com


--- Comment #0 from Justin Whear <justin@economicmodeling.com> 2013-06-17 13:48:39 PDT ---
The following code compiles with 2.062 but not with 2.063:
-------------------------------------------------------
import std.typetuple;

struct Cube
{
    alias Address = TypeTuple!(int, int);
    //alias Address = int;

    int* opBinaryRight(string op)(Address where)
    {
        return null;
    }
}

void main()
{
    Cube cube;
    cube.Address addr;
    auto ptr = addr in cube;
}
---------------------------------------------------------
In 2.063, DMD produces the following:
cube.d(18): Error: rvalue of in expression must be an associative array, not
Cube

Flipping the comments on the two "alias Address" lines causes the sample to compile under both, so the problem is triggered by the use of a tuple as the left side of the "in" operator.  Using DMD with -v indicates the trouble is during the semantic3 phase.

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June 17, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394


Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-06-17 15:52:18 PDT ---
You could use Tuple from std.typecons instead and it will work.

It seems to me what's going on is auto-expansion of a TypeTuple into two arguments, and opBinaryRight (or opIn_r) simply can't accept more than one argument.

I don't know why that even worked before, it might have been an accepts-invalid bug in 2.062 and earlier. Kenji Hara will probably know more.

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June 17, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394



--- Comment #2 from Justin Whear <justin@economicmodeling.com> 2013-06-17 16:08:36 PDT ---
(In reply to comment #1)
> You could use Tuple from std.typecons instead and it will work.
> 
> It seems to me what's going on is auto-expansion of a TypeTuple into two arguments, and opBinaryRight (or opIn_r) simply can't accept more than one argument.
> 
> I don't know why that even worked before, it might have been an accepts-invalid bug in 2.062 and earlier. Kenji Hara will probably know more.

From my perspective it'd be somewhat unfortunate to lose the ability to do this.  We make extensive use of "in" as a complement to indexing the same way associative arrays do: indexing returns the thing or throws if not present while "in" returns a pointer to the thing or null if not present. Because we use indexing with multiple "keys" it's nice to have a symmetric way of using "in".

As for your suggestion to use Tuple, we usually provide an overload for that as well, particularly because tuples can't be returned from functions.

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July 15, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394



--- Comment #3 from Justin Whear <justin@economicmodeling.com> 2013-07-15 15:45:23 PDT ---
An update on this issue: we have worked around this by switching away from "in" to a method-based approach, so this is no longer blocking for the reporter.  I think this issue remains valid until it's decided whether the "in" operator (or operators in general) will allow a tuple on the left hand side.  Here's a simplified example that matches with our use case:
-----------------------------
struct Graph(T, Address...)
{
    struct Node
    {
        Address address;
        T payload;
    }

   ...

   Node* opBinaryRight(string op)(Address address) if (op == "in)
   {
       ...
   }
}

void main()
{
    Graph!(double, int, string) graph;
    auto node = ...procure a node from somwhere...

    // node.address is preferred to tuple(node.address)
    if (auto inGraph = node.address in graph)
    {
        ...
    }
}
-----------------------------

As I said, we have worked around this because it's not unreasonable for binary operators to only allow one value on each side, but it was also nice to have this kind of syntax in 2.062 and previous.

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August 26, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394


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

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


--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2013-08-25 17:27:52 PDT ---
https://github.com/D-Programming-Language/dmd/pull/2497

I still have a doubt that this should be fixed... Even if the dmd implementation will be fixed in 2.064 release, we should continue discussion about the combination of operator-overloading and built-in tuple behavior.

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August 27, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394



--- Comment #5 from github-bugzilla@puremagic.com 2013-08-27 00:13:20 PDT ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/c4ca9257ed2863f8ef2c1be31e8690f2363a3ab9 fix Issue 10394 - opBinaryRight!"in" and tuple

https://github.com/D-Programming-Language/dmd/commit/73ca1a9b83ef6fcd8922fb7c5d6b2c0a0b576ca9 Merge pull request #2497 from 9rnsr/fix10394

[REG2.064a] Issue 10394 - opBinaryRight!"in" and tuple

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August 27, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10394


Walter Bright <bugzilla@digitalmars.com> changed:

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


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