fix: compilation with recent clang

[robertodr]

No description provided.

[msnik1999]

I have two fixes, which allow compilation on MacOS:

1. include "qmfunctions/Orbital.h" in Accelerator.h
2. a small fix for MRCPP I will include in this MRCPP PR

[robertodr]

Can you push 1 directly to this PR?

[robertodr]

🤔 actually, point 1 sounds suspicious. qmfunctions_fwd.h is imported, which forward-declares that stuff, and given how the stuff in Orbital.h is used in Accelerator.h, it should be enough...

[robertodr]

I think the problem was that in Accelerator.cpp, the include of Accelerator.h was not coming first. That's a mistake (and I think it's made in many places). In general, when you split the code for a class in header + source, the header should be included first thing in the corresponding source file.

[msnik1999]

No, the definition of std::deque<OrbitalVector> orbitals; in Accelerator.h already needs the Orbital.h include.
It won't compile without that incude.
A lot of changes have been made to std::deque in newer C++-versions (cppreference)

[msnik1999]

🤔 actually, point 1 sounds suspicious. qmfunctions_fwd.h is imported, which forward-declares that stuff, and given how the stuff in Orbital.h is used in Accelerator.h, it should be enough...

Even when I make the forward declaration in the file Accelerator.h, it doesn't compile. I also only know this to work for smart pointers? I've personally never seen it for vectors (or similar).

[robertodr]

You're right. But it's a total mystery why things worked before 🤷

[msnik1999]

You're right. But it's a total mystery why things worked before 🤷

In the past, we used different compilers. Now, we are dependent on newer compilers due to the inclusion of the C++-17 feature std::filesystem added about a year ago. Because we don't declare our C++-version anywhere in our CMake-structure (as far as I know), the newer compilers probably use newer C++-standards.

[robertodr]

We do fix the version of the standard to use: https://github.com/MRChemSoft/mrchem/blob/master/cmake/compiler_flags/CXXFlags.cmake#L16

[robertodr]

Why was I able to reproduce one compilation issue with Clang 21 on Linux, but not all of the ones you encountered?

[msnik1999]

We do fix the version of the standard to use: https://github.com/MRChemSoft/mrchem/blob/master/cmake/compiler_flags/CXXFlags.cmake#L16

Oh, haven't seen this before. But still, we need newer compilers and therefore introduce new errors and a lot of warnings.

[msnik1999]

Why was I able to reproduce one compilation issue with Clang 21 on Linux, but not all of the ones you encountered?

ARM on macOS works in mysterious ways ...

[robertodr]

well, thanks for keeping an eye out for new errors and warnings 🙌