https://issues.dlang.org/show_bug.cgi?id=15505

Manu <turkeyman@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|cxtern(C++) array parameter |extern(C++) array parameter
                   |mangling gains surprise     |mangling gains surprise
                   |const                       |const

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https://issues.dlang.org/show_bug.cgi?id=15505

Vladimir Panteleev <dlang-bugzilla@thecybershadow.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |C++
           Hardware|x86_64                      |All
           Severity|enhancement                 |normal

--- Comment #1 from Vladimir Panteleev <dlang-bugzilla@thecybershadow.net> ---
Only occurs when targeting the MS toolchain (-m64 / -m32mscoff).

-m32mscoff:
mangled: ?f@@YAXQAY03H@Z
demangled: void __cdecl f(int (* const)[4])

-m64:
mangled: ?f@@YAXQEAY03H@Z
demangled: void __cdecl f(int (* __ptr64 const)[4])

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https://issues.dlang.org/show_bug.cgi?id=15505

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |mangling
                 CC|                            |bugzilla@digitalmars.com

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https://issues.dlang.org/show_bug.cgi?id=15505

Manu <turkeyman@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |industry

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https://issues.dlang.org/show_bug.cgi?id=15505

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

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

--- Comment #2 from Dlang Bot <dlang-bot@dlang.rocks> ---
@thewilsonator created dlang/dmd pull request #10020 "Fix issue 15505 - extern(C++) array parameter mangling gains surprise const" fixing this issue:

- Fix issue 15505 - extern(C++) array parameter mangling gains surprise const

https://github.com/dlang/dmd/pull/10020

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https://issues.dlang.org/show_bug.cgi?id=15505

Nicholas Wilson <iamthewilsonator@hotmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |iamthewilsonator@hotmail.co
                   |                            |m

--- Comment #3 from Nicholas Wilson <iamthewilsonator@hotmail.com> ---
This is the * const problem all over again.

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https://issues.dlang.org/show_bug.cgi?id=15505

kinke@gmx.net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kinke@gmx.net

--- Comment #4 from kinke@gmx.net ---
(In reply to Manu from comment #0)
> Nobody uses *const in C++.

Don't forget Microsoft; you've already reported a similar MS-specific issue a while back, with the C++ new operator or some other allocator IIRC.

Well, here we go again:

C++: short test27(int arg[6]); // or `int arg[]`, same thing

Win64: ?test27@@YAFQEAH@Z [short test27(int * const)]
Linux: _Z6test27Pi [test27(int *)]

I don't think this C++ function can be declared directly and portably in D anyway.

But due to this const-hack, it apparently works in higher dimensions: one can represent C++ `int p[][6]` as `int[6]* p` in D, and that does indeed work portably for both MSVC and Itanium.

https://github.com/dlang/dmd/blob/7538ed0125531d3a49ea6d2e266f7bae6e83556f/src/dmd/cppmanglewin.d#L282-L283:

> attention: D int[1][2]* arr mapped to C++ int arr[][2][1]; (because it's more typical situation)
> There is not way to map int C++ (*arr)[2][1] to D

Still, I think that special case is not worth it and more confusing than useful. It's been there since 2014 or longer: https://github.com/dlang/dmd/pull/3160

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https://issues.dlang.org/show_bug.cgi?id=15505

--- Comment #5 from Manu <turkeyman@gmail.com> ---
I don't follow your examples:
C++:
  void test(int arg[6]);
  void test(int arg[]);

These are identical in C++, and they should mangle the same; with no size. And yes, we see that MSVC has `* const` here. This is actually uninteresting, because there's no way to make a declaration like this in D. In C++, it's just a lame way to pass an un-sized array, and would almost always just use a pointer.


This is what's interesting:

C++:
  void test(int (&arg)[6]);
  void test(int (*arg)[6]);

These are interesting because they have meaningful D counterparts:
  void test(ref int[6]);
  void test(int[6]*);

These cases should be fixed in our mangler, they are useful functions that appear relatively often and are the proper way to pass static-arrays in C++.

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https://issues.dlang.org/show_bug.cgi?id=15505

Iain Buclaw <ibuclaw@gdcproject.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P1                          |P3

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