https://issues.dlang.org/show_bug.cgi?id=22854

Dennis <dkorpel@live.nl> changed:

           What    |Removed                     |Added
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                 CC|                            |dkorpel@live.nl

--- Comment #1 from Dennis <dkorpel@live.nl> ---
digger bisect:

```
digger: 8be5c8b0111b68ca23e23c36a6fd1cc746a9c0cc is the first bad commit
commit 8be5c8b0111b68ca23e23c36a6fd1cc746a9c0cc
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Wed Jun 9 12:34:57 2021 +0200

    dmd: static foreach: Delay running ctfeInterpret until the lowering stage
```

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https://issues.dlang.org/show_bug.cgi?id=22854

--- Comment #2 from FeepingCreature <default_357-line@yahoo.de> ---
Further reduced:

void main() {
    static foreach (ch; SomeContainer().range) { }
}

struct SomeContainer {
    SomeRange range() { return SomeRange(); }
    TypeWithDestructor data;
}

struct TypeWithDestructor { ~this() { } }

struct SomeRange {
    int front() { return 0; }
    bool empty() { return true; }
    void popFront() { }
}

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https://issues.dlang.org/show_bug.cgi?id=22854

Iain Buclaw <ibuclaw@gdcproject.org> changed:

           What    |Removed                     |Added
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                 CC|                            |ibuclaw@gdcproject.org

--- Comment #3 from Iain Buclaw <ibuclaw@gdcproject.org> ---
(In reply to FeepingCreature from comment #0)
> From looking at the longer DMD debug mode backtrace on master, there seems to be a stack variable destructor call that reads dead stack memory?
As far as I can tell, possibly an artificial/temporary variable that has not been declared properly.

--

https://issues.dlang.org/show_bug.cgi?id=22854

--- Comment #4 from Iain Buclaw <ibuclaw@gdcproject.org> ---
Tweaking the code to use a regular foreach:
---
void main() {
    foreach (ch; SomeContainer().range) { }
}
pragma(msg, main());
---

This is where the temporary gets *pushed* onto the CTFE stack.
---
// If the comma returns a temporary variable, it needs to be an lvalue
// (this is particularly important for struct constructors)
if (e.e1.op == EXP.declaration &&
    e.e2.op == EXP.variable &&
    e.e1.isDeclarationExp().declaration == e.e2.isVarExp().var &&
    e.e2.isVarExp().var.storage_class & STC.ctfe)
{
    VarExp ve = e.e2.isVarExp();
    VarDeclaration v = ve.var.isVarDeclaration();
    ctfeGlobals.stack.push(v);  // <--- here
---

However for `static foreach`, this is never done because of the equality condition (declaration == var) is not true.

This despite both declarationexp and varexp having the same identifier name
(__slSomeCo3).

Obviously, *something* has been copied that really shouldn't have been.

--

https://issues.dlang.org/show_bug.cgi?id=22854

Dlang Bot <dlang-bot@dlang.rocks> changed:

           What    |Removed                     |Added
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           Keywords|                            |pull

--- Comment #5 from Dlang Bot <dlang-bot@dlang.rocks> ---
@ibuclaw created dlang/dmd pull request #14724 "fix Issue 22854 - [REG 2.099-rc.1] static foreach byCodepoint segfault" fixing this issue:

- fix Issue 22854 - static foreach byCodepoint segfault (2.099-rc.1)

https://github.com/dlang/dmd/pull/14724

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https://issues.dlang.org/show_bug.cgi?id=22854

Dlang Bot <dlang-bot@dlang.rocks> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #6 from Dlang Bot <dlang-bot@dlang.rocks> ---
dlang/dmd pull request #14724 "fix Issue 22854 - [REG  2.099-rc.1] static foreach byCodepoint segfault" was merged into stable:

- 650a3a730abd2d4fa65b126ef4c25f2519470db4 by Iain Buclaw:
  fix Issue 22854 - static foreach byCodepoint segfault (2.099-rc.1)

https://github.com/dlang/dmd/pull/14724

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https://issues.dlang.org/show_bug.cgi?id=22854

--- Comment #7 from Dlang Bot <dlang-bot@dlang.rocks> ---
dlang/dmd pull request #14765 "merge stable" was merged into master:

- 77935bf4944c257736a3d0d76be3fdaef54cfb60 by Iain Buclaw:
  fix Issue 22854 - static foreach byCodepoint segfault (2.099-rc.1)

https://github.com/dlang/dmd/pull/14765

--