http://d.puremagic.com/issues/show_bug.cgi?id=6211

           Summary: __traits (compile) return wrong result when the bug
                    happen
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: ld@galador.net


--- Comment #0 from Lloyd Dupont <ld@galador.net> 2011-06-24 18:30:57 PDT ---
I'm using DMD2.053 on Windows7 x64

My test case:
- I have a all in one console application which output "true true"
- I have a project with the exact same code split into a static lib and an
exe and it output "false false"

The bug is that the output is different!

=== first the all in one, outputing "true, true" ========= module main;

import std.variant;
import std.stdio;
import std.metastrings : Format;
import std.traits;

public mixin template property(T, string name)
{
    mixin(Format!("private T _%s;
                  @property public T %s() { return _%s; }
                  @property public void %s(T value) { _%s = value; }", name,
name, name, name, name));
}

interface IInter
{
}

class Foo : IInter
{
    static this()
    {
        Compiled!(Foo, "FP");
        Compiled!(Foo, "Subfoo");
    }

    @property public Foo FP() { return new Foo(); }
    @property public void FP(Foo f) { }

    mixin property!(Foo, "Subfoo");
}

int main(string[] argv)
{
    return 0;
}
void Compiled(T, string memberName)()
{
    T t;
    writeln(mixin( "__traits(compiles, t." ~memberName ~" = ("
~typeof(__traits(getMember, T, memberName)).stringof  ~").init)" ));
}
==============================================


now the splitted program, outputting "false, false"
whereas it should output "true, true" just like above, shouldn't it!?!

===== lib.d ====
module lib;

import std.variant;
import std.stdio;
import std.metastrings : Format;
import std.traits;

public mixin template property(T, string name)
{
    mixin(Format!("private T _%s;
                  @property public T %s() { return _%s; }
                  @property public void %s(T value) { _%s = value; }", name,
name, name, name, name));
}

interface IInter
{
}

void Compiled(T, string memberName)()
{
    T t;
    writeln(mixin( "__traits(compiles, t." ~memberName ~" = "
~typeof(__traits(getMember, T, memberName)).stringof  ~").init" ));
}
====== main.d =====
module main;

import lib;

class Foo : IInter
{
    static this()
    {
        Compiled!(Foo, "FP");
        Compiled!(Foo, "Subfoo");
    }

    @property public Foo FP() { return new Foo(); }
    @property public void FP(Foo f) { }

    mixin property!(Foo, "Subfoo");
}

int main(string[] argv)
{
    return 0;
}
===================== buildrun.bat =========
dmd -lib -g -debug -X -of"lib1.lib" lib.d
dmd -g -debug -X main.d lib1.lib
main
====================================

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Vladimir Panteleev <thecybershadow@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |thecybershadow@gmail.com
         Resolution|                            |INVALID


--- Comment #1 from Vladimir Panteleev <thecybershadow@gmail.com> 2011-06-24 18:38:13 PDT ---
This is not a bug. See section "Instantiation Scope" of http://www.d-programming-language.org/template.html .

> TemplateInstantances are always performed in the scope of where the TemplateDeclaration is declared, with the addition of the template parameters being declared as aliases for their deduced types.

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--- Comment #2 from Lloyd Dupont <ld@galador.net> 2011-06-24 19:03:57 PDT ---
How does the template scope has anything to do with this bug?

In plain English I'm testing that the property can be set.
I.e.
class Foo
{
 @property public Foo Subfoo() {}

 @property public Foo Subfoo2() {}
 @property public void Subfoo2(Foo f) {}
}

in the above class Subfoo can't be set, Subfoo2 can.
I'm testing it with
Foo f,
__traits(compile, f.Suboo = Foo.init)
__traits(compile, f.Suboo2 = Foo.init)

This seems to work erratically!

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--- Comment #3 from Lloyd Dupont <ld@galador.net> 2011-06-24 20:24:36 PDT ---
Not understanding the explanation I can't claim it wrong...

Nonetheless the work around I found seems to indicate to me that the explanation was, at the very least (for what I understand) completely irrelevant.

I replaced:
writeln(mixin( "__traits(compiles, t." ~memberName ~" =
("~typeof(__traits(getMember, T, memberName)).stringof  ~").init)" ));


With:
writeln(mixin( "__traits(compiles, t." ~memberName ~" = (typeof(t."~memberName
~")).init)" ));


And it worked. Still using library and exe.

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Vladimir Panteleev <thecybershadow@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |


--- Comment #4 from Vladimir Panteleev <thecybershadow@gmail.com> 2011-06-24 20:29:43 PDT ---
Sorry, it looked like you were instantiating a template in a scope where a symbol passed by name as a string didn't exist. You may want to reduce your example to the smallest amount of code which illustrates the bug for clarity.

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--- Comment #5 from Lloyd Dupont <ld@galador.net> 2011-06-24 21:01:19 PDT ---
I found a way to reduce the sample even further.

1st no need to have 2 project (lib & exe). All in the same exe (but different
module) is enough to cause the bug.

==== main.d ====
module main;

import lib;

class Foo
{
    static this()
    {
        Compiled!(Foo, "Subfoo");
    }

    @property public Foo Subfoo() { return null; }
    @property public void Subfoo(Foo f) { }
}

int main(string[] argv)
{
    return 0;
}
====== lib.d ======
module lib;

import std.traits;
import std.stdio;

void Compiled(T, string memberName)()
{
    T t;
    writeln(mixin( "__traits(compiles, t." ~memberName ~" = ("
~typeof(__traits(getMember, T, memberName)).stringof  ~").init)" ));
}
===============

this output "false", whereas it should output "true"

a work around (and simpler code in fact) is to use the following simpler mixin
(in Compiled)
---
writeln(mixin( "__traits(compiles, t." ~memberName ~" = (typeof(t." ~memberName
~")).init)" ));
---

Yet I do think this sample highlight a compiler bug

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

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


--- Comment #6 from Kenji Hara <k.hara.pg@gmail.com> 2011-07-11 01:24:01 PDT ---
This is not bug.
In lib.d, you can't access Foo by name (without importing main).

---- lib.d ----
void Compiled(T, string memberName)()
{
    T t;      // ok
    Foo foo;  // error!
}
----

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