Thread overview
[Issue 6759] New: missing initialization in foreach with alias this
Oct 02, 2011
dawg@dawgfoto.de
Oct 02, 2011
Kenji Hara
Oct 02, 2011
Walter Bright
Oct 05, 2011
dawg@dawgfoto.de
October 02, 2011
http://d.puremagic.com/issues/show_bug.cgi?id=6759

           Summary: missing initialization in foreach with alias this
           Product: D
           Version: D2
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: dawg@dawgfoto.de


--- Comment #0 from dawg@dawgfoto.de 2011-10-02 05:03:02 PDT ---
struct Range
{
    size_t front() { return 0; }
    void popFront() { empty = true; }
    bool empty;
}

struct ARange
{
    Range range;
    alias range this;
}

void main()
{
    ARange arange;
    assert(arange.front == 0);
    foreach(e; arange)
    {}
}

---

Foreach creates a reference to arange.
The expression that initializes the reference is dropped
for alias this aggregates.

This is a regression introduced by https://github.com/D-Programming-Language/dmd/commit/6a2aefdb468d20aa8d498c8930c2613d78a91238 as a fix to #2781.

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--- Comment #1 from Kenji Hara <k.hara.pg@gmail.com> 2011-10-02 12:37:22 PDT ---
Your patch was already merged (commit: f53ff46), and it looks correct to me the fixing lack of merging prelude before semantic.

But, your sample code works before merging (commit: 07f719e), so that code is not test case of this issue.

Do you have right test case?

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Walter Bright <bugzilla@digitalmars.com> changed:

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


--- Comment #2 from Walter Bright <bugzilla@digitalmars.com> 2011-10-02 12:54:32 PDT ---
https://github.com/D-Programming-Language/dmd/commit/fed2faabc3ca9f67a429293eee82ae597061fea8

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--- Comment #3 from dawg@dawgfoto.de 2011-10-05 12:04:09 PDT ---
(In reply to comment #1)
> Your patch was already merged (commit: f53ff46), and it looks correct to me the fixing lack of merging prelude before semantic.
> 
> But, your sample code works before merging (commit: 07f719e), so that code is not test case of this issue.
> 
> Do you have right test case?

This is probably due to constant folding or optimization. The merged version has 'assert(e == 0);' in the loop body.

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