https://issues.dlang.org/show_bug.cgi?id=22737

Tim <tim.dlang@t-online.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |C++, rejects-valid

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https://issues.dlang.org/show_bug.cgi?id=22737

Tim <tim.dlang@t-online.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Segnementation fault in     |Segmentation fault in
                   |CppMangleVisitor.getTiNames |CppMangleVisitor.getTiNames
                   |pace                        |pace

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https://issues.dlang.org/show_bug.cgi?id=22737

moonlightsentinel@disroot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |moonlightsentinel@disroot.o
                   |                            |rg
           Severity|normal                      |regression

--- Comment #1 from moonlightsentinel@disroot.org ---
Slightly reduced / modified:

==================================================
template Identity(T)
{
        alias T Identity;
}

extern(C++) Identity!T identity(T)()
{
    return Identity!T.init;
}
void main()
{
    identity!int();
}
==================================================

Up to      2.063  : Success and no output
2.064   to 2.066.0: Segfault and no output
2.067.1 to 2.083.1: Success and no output
Since      2.084.1: Segfault and no output

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https://issues.dlang.org/show_bug.cgi?id=22737

Mathias LANG <pro.mathias.lang@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pro.mathias.lang@gmail.com

--- Comment #2 from Mathias LANG <pro.mathias.lang@gmail.com> ---
I see where the issue is. I'm wondering whether this should be rejected by the frontend or not. Essentially we just "see through" the `Identity` template. However, I don't think that's possible in C++. There might also be some other expectations (what if `Identity` has an `extern(C++)` and namespace declaration?).

Note:
We hit `headOfType`:
https://github.com/dlang/dmd/blob/cefa9ff9d0d68ca21049ffc2d6f08dd1d8c7843c/src/dmd/cppmangle.d#L1376-L1395
with our `res` as `int`, and a few places don't account for types not having
Dsymbol.

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https://issues.dlang.org/show_bug.cgi?id=22737

Tim <tim.dlang@t-online.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=22760

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https://issues.dlang.org/show_bug.cgi?id=22737

Tim <tim.dlang@t-online.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=22739

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https://issues.dlang.org/show_bug.cgi?id=22737

--- Comment #3 from Iain Buclaw <ibuclaw@gdcproject.org> ---
This issue has the tag "rejects-valid" - but where's the valid C++ code?

If this template has no C++ equivalent, then it should be accepts-invalid, and we issue an error at semantic-time as Matthias has already mentioned.

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https://issues.dlang.org/show_bug.cgi?id=22737

--- Comment #4 from Tim <tim.dlang@t-online.de> ---
In my original code this happened for a utility function, which did not come from C++. I used extern(C++): for the whole file, so the utility function also got it, but I have solve it by making this function extern(D).

The following code should be equivalent C++:

==================================================
template <class T>
using Identity = T;

template <class T>
Identity<T> identity(T val)
{
    return Identity<T>(val);
}

int main()
{
    int x = identity(5);
    return 0;
}
==================================================

Making this issue accepts-invalid would also work for me, because templates with alias can probably just be marked as extern(D).

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