http://d.puremagic.com/issues/show_bug.cgi?id=5730

           Summary: Error: variable has scoped destruction, cannot build
                    closure
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: samukha@voliacable.com


--- Comment #0 from Max Samukha <samukha@voliacable.com> 2011-03-11 10:22:17 PST ---
The below should compile without errors:

struct S
{
    ~this()
    {
    }
}

void main()
{
    S s;
    enum error = __traits(compiles, { auto s1 = s; }));
    static assert(!error); // line 1
}
----
Error: static assert  (!true) is false

Comment out "line 1" to get the error that explains the problem:

Error: variable test.main.s has scoped destruction, cannot build closure

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Walter Bright <bugzilla@digitalmars.com> changed:

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


--- Comment #1 from Walter Bright <bugzilla@digitalmars.com> 2011-03-12 00:50:04 PST ---
Right. {auto s1=s;} is a delegate literal. Delegate literals need to be able to survive the end of the function they are defined inside. Since s is destroyed upon the exit from main(), then this will not work, hence the error message.

This is expected behavior, not a bug.

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--- Comment #2 from Max Samukha <samukha@voliacable.com> 2011-03-12 01:53:09 PST ---
No, no. The bug is not about the impossibility to build a closure. It is about __traits(compiles) not handling the compilation error properly. It should suppress the error and evaluate to false.

Another example:

struct S
{
    ~this()
    {
    }
}

void main()
{
    S s;
    static if (__traits(compiles, { auto s1 = s; }))
        pragma(msg, "Can build closure");
    else
        pragma(msg, "Cannot build closure");
}
----
The compiler outputs:
Can build closure
Error: variable test.main.s has scoped destruction, cannot build closure


Instead, the above should compile successfully, printing "Cannot build closure" at compile time.

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Max Samukha <samukha@voliacable.com> changed:

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


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Max Samukha <samukha@voliacable.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Error: variable has scoped  |__traits(compiles) does not
                   |destruction, cannot build   |handle "variable has scoped
                   |closure                     |destruction, cannot build
                   |                            |closure" error correctly


--- Comment #3 from Max Samukha <samukha@voliacable.com> 2011-03-12 02:37:00 PST ---
Changed the title

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Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au


--- Comment #4 from Don <clugdbug@yahoo.com.au> 2011-03-12 11:48:11 PST ---
This is happening because the "has scoped destruction" error is generated in the glue layer, not in the front-end. The same issue applies to any error message generated in e2ir.c, toir.c, or s2ir.c.

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