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digitalmars.D.bugs - [Issue 9656] New: Built-in dup result should behave as like unique array, if it is possible.

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9656

           Summary: Built-in dup result should behave as like unique
                    array, if it is possible.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: k.hara.pg gmail.com



In below, narr = [1,2,3].dup should work.

class C {}
struct S {
    immutable int[] narr;
    immutable C[] carr;
    this(int n) {
        narr = new int[](3); // OK, expected
        narr = [1,2,3].dup;  // NG, rejects-valid
        carr = [new C].dup;  // NG, expected
    }
}

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Mar 06 2013
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9656


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc





A simple question: Why is this not valid?

carr = [new C].dup;  // NG, expected

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Mar 06 2013
prev sibling next sibling parent d-bugmail puremagic.com writes:
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 A simple question: Why is this not valid?
 
 carr = [new C].dup;  // NG, expected


That's right, the dup result is essentially unique in it.

Correct NG case is:

  auto c = new C;
  carr = [c].dup;

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Mar 06 2013
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Kenji Hara <k.hara.pg gmail.com> changed:

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



https://github.com/D-Programming-Language/dmd/pull/1943

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Apr 28 2013
prev sibling next sibling parent d-bugmail puremagic.com writes:
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 https://github.com/D-Programming-Language/dmd/pull/1943


The patch seems nice. But maybe we should have a language-level way (like an
annotation) to denote some reference data as unique.

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Apr 28 2013
prev sibling next sibling parent d-bugmail puremagic.com writes:
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 But maybe we should have a language-level way (like an
 annotation) to denote some reference data as unique.


I am ignorant regarding the compiler, but ,aybe in the meantime it's enough to
have an invisible "unique" attribute used just by the compiler-front end, like
the various PUREimpure, PUREfwdref, etc used in the compiler.

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Apr 30 2013
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/f5528d3f1f9dbac5e0ca6cb15d25e17bb40db15e
fix Issue 9656 - Built-in dup result should behave as like unique array, if it
is possible

https://github.com/D-Programming-Language/dmd/commit/50e32e6ffae6e2051e0296f4779eb3aa2ce9c2b3


Issue 9656 - Built-in dup result should behave as like unique array, if it is
possible.

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May 10 2013
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9656


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |yebblies gmail.com
         Resolution|                            |FIXED




 I am ignorant regarding the compiler, but ,aybe in the meantime it's enough to
 have an invisible "unique" attribute used just by the compiler-front end, like
 the various PUREimpure, PUREfwdref, etc used in the compiler.


So far we've been going in the direction of 'unique expressions' whereby the
fact they allocate new memory or call pure functions etc is enough to ensure
they are unique.

The funny thing about this one is that this function:

int[] dup(const(int)[] data) pure
{
    return data.dup;
}

was already creating a unique result, while the builtin was not.  (I haven't
tested that exact code, but something along those lines should work)

The purity+allocation pattern for normal functions should allow many library
types to create unique data, without needing additional attributes.

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May 10 2013