http://d.puremagic.com/issues/show_bug.cgi?id=7530

           Summary: Postblit not called structs returned from an array
                    index expr.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: wrong-code
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: sludwig@outerproduct.org


--- Comment #0 from Sönke Ludwig <sludwig@outerproduct.org> 2012-02-17 04:15:29 PST ---
Created an attachment (id=1076)
Reproduction case

Attached is a small example with a pseudo RefCount struct.
Running with the ternary operator enabled "dmd -version=BUG -run" yields:

---
1st pass
CREATE 18FE34 1
COPY 443FD0 2
DESTROY 18FE34 2 IN
DESTROY 18FE34 1 OUT
POS2: 443FD0 1
DESTROY 18FE5C 1 IN          <- destroys the object although the static
DESTROY 18FE5C -100 OUT         array should still hold a reference

2nd pass
POS1: 443FD0 0               <- the static variable now references an
POS2: 443FD0 0                  already destroyed object
DESTROY 18FE5C 0 IN
DESTROY 18FE5C -1 OUT
---

The line "return cnt[0];" fails to call the struct's postblit and causes the returned object to get destroyed as the ref count goes to zero.

running with "dmd -run" yields the expected output:

---
1st pass
CREATE 18FE34 1
COPY 4B3FD0 2
DESTROY 18FE34 2 IN
DESTROY 18FE34 1 OUT
POS2: 4B3FD0 1
COPY 18FE5C 2                 <- correctly copied on return
DESTROY 18FE5C 2 IN
DESTROY 18FE5C 1 OUT

2nd pass
POS1: 4B3FD0 1
POS2: 4B3FD0 1
COPY 18FE5C 2                 <- correctly copied on return
DESTROY 18FE5C 2 IN
DESTROY 18FE5C 1 OUT          <- the static reference is still there
---

"auto ret = cnt[0]; return ret;" will correctly call the postblit constructor.

Occurs at least in DMD 2.058 and 2.057.

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SomeDude <lovelydear@mailmetrash.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lovelydear@mailmetrash.com


--- Comment #1 from SomeDude <lovelydear@mailmetrash.com> 2012-04-20 01:00:49 PDT ---
See also issue 7516

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--- Comment #2 from Kenji Hara <k.hara.pg@gmail.com> 2012-05-10 19:38:07 PDT ---
Reduced test case:

void main()
{
    static struct S
    {
        int val;

        this(int n) { val = n; }
        this(this) { val *= 3; }
    }

    S[] sa = new S[](1);
    sa[0].val = 1;
    S foo()
    {
        return sa[0];  // postblit should run
    }
    auto s = foo();
    assert(s.val == 3);
}

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |johnaston.dev@gmail.com


--- Comment #3 from Kenji Hara <k.hara.pg@gmail.com> 2012-05-10 19:38:30 PDT ---
*** Issue 7541 has been marked as a duplicate of this issue. ***

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

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


--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2012-05-10 22:53:11 PDT ---
https://github.com/D-Programming-Language/dmd/pull/939

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--- Comment #5 from github-bugzilla@puremagic.com 2012-05-12 15:07:20 PDT ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/e72fa541029d2c09daa992e78f2adf33d1bd8045 fix Issue 7530 - Postblit not called structs returned from an array index expr.

https://github.com/D-Programming-Language/dmd/commit/481f5585639de6dbf94e6b80510f767dc5e81b64 Merge pull request #939 from 9rnsr/fix_postblit

Issue 7506 & 7530 more postblit fixes

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Walter Bright <bugzilla@digitalmars.com> changed:

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


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