http://d.puremagic.com/issues/show_bug.cgi?id=9091

           Summary: Perhaps another forward referencing bug.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: turkeyman@gmail.com


--- Comment #0 from Manu <turkeyman@gmail.com> 2012-11-28 04:08:31 PST ---
I've created a new bug from this thread:
http://d.puremagic.com/issues/show_bug.cgi?id=9065
That thread has forked into unrelated conversations, and I suspect this is a
separate bug anyway...

Kenji: I boiled this down as much as I could...




class Test
{
    void func()
    {
        void templateFunc( T )( ref const T obj )
        {
            foreach( m; __traits( allMembers, T ) )
            {
                pragma(msg, m);
                static if( isVariable!( __traits(getMember, T, m) ) )
                {
                    //...
                }
            }
        }

        templateFunc( this );
    }

    // some class members
    int x;
}

isVariable throws lots of errors when considering the class members.

Note:
  __traits(allMembers, T) and __traits(getMember, T, m)

These should also work with class instances, not just types, eg:
  __traits(allMembers, obj) and __traits(getMember, obj, m)

And these combinations should also work:
  __traits(allMembers, T) and __traits(getMember, obj, m)
  __traits(allMembers, obj) and __traits(getMember, T, m)

All these configurations throw errors, and the errors are different for each configuration.


Depends on:

/**
 * Detect whether symbol or type $(D X) is a function.
 */
template isFunction(X...) if (X.length == 1)
{
    static if (is(typeof(&X[0]) U : U*) && is(U == function) ||
               is(typeof(&X[0]) U == delegate))
    {
        // x is a (nested) function symbol.
        enum isFunction = true;
    }
    else static if (is(X[0] T))
    {
        // x is a type.  Take the type of it and examine.
        enum isFunction = is(T == function);
    }
    else
        enum isFunction = false;
}

/**
 * Detect whether symbol $(D X) is a run-time variable.
 */
template isVariable(X...) if (X.length == 1)
{
    static if (!is(X[0]) &&
               !is(typeof(X[0]) == void) &&
               !isFunction!(X[0]))
    {
        enum isVariable =
            is(typeof({ auto ptr = &X[0]; }))
         || is(typeof({ enum off = X[0].offsetof; }));
    }
    else
        enum isVariable = false;
}

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Manu <turkeyman@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |major


--- Comment #1 from Manu <turkeyman@gmail.com> 2012-11-29 04:20:58 PST ---
I have a hard deadline (like, proper hard) tomorrow, I'd really like to have this fix in there. Is there anyone who can possibly look into/comment on it?

I bumped the priority to help it get noticed...

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--- Comment #2 from Kenji Hara <k.hara.pg@gmail.com> 2012-11-30 20:04:31 PST ---
Furthermore reduced case:

template isVariable(X...) if (X.length == 1)
{ enum isVariable = true; }

class C
{
    int x;
    void func()
    {
        enum is_x = isVariable!(__traits(getMember, C, "x"));
    }
}

I posted a report bug 9100 to explain the current semantic analysis weird behavior on template argument. I think that it is the root cause of this bug.

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Perhaps another forward     |Using __traits(getMember)
                   |referencing bug.            |on template argument fails
                   |                            |inside member function


--- Comment #3 from Kenji Hara <k.hara.pg@gmail.com> 2012-11-30 20:08:21 PST ---
Changed summary.

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull, rejects-valid


--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2012-11-30 21:17:32 PST ---
https://github.com/D-Programming-Language/dmd/pull/1340

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--- Comment #5 from github-bugzilla@puremagic.com 2012-12-09 12:52:00 PST ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/a4fb02fb3572c1616e7aad55fdd07b22b12242b8
fix Issue 9091 - Using __traits(getMember) on template argument fails inside
member function

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yebblies <yebblies@gmail.com> changed:

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


--- Comment #6 from yebblies <yebblies@gmail.com> 2013-01-13 17:31:27 EST ---
Fixed?

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--- Comment #7 from Manu <turkeyman@gmail.com> 2013-01-13 00:54:56 PST ---
(In reply to comment #6)
> Fixed?

Kenji was working on these, the prototypes he gave me worked for me, I'm not sure if it was accepted/merged though. @Kenji?

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--- Comment #8 from Kenji Hara <k.hara.pg@gmail.com> 2013-01-17 20:14:14 PST ---
Unfortunately, this still not be fixed completely.

https://github.com/D-Programming-Language/dmd/pull/1406

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--- Comment #9 from github-bugzilla@puremagic.com 2013-03-01 01:32:04 PST ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/8a781342c90c0fc93a52876ceb972500a1603d42
fix Issue 9091 - Using __traits(getMember) on template argument fails inside
member function

Use ThisExp instead of VarExp to avoid interpretation on template arguments.

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