Removed old-style-cast from Plumed.h

[Iximiel]

Description

I removed the old-style casts in Plumed.h.

Now when Plumed.h is in "c++ mode" will use static_cast or reintrpet_cast

I used -Werror=old-style-cast to find the casts and i changed to static when gcc suggested to change to static and reintepret otherwise or when no suggestion were made.

I am not 100% sure to have changed every casts, but at least the ones that affects the gromacs compilation are done plus some more found with searching \(.*?\)\w.

Target release

I would like my code to appear in release 2.10

Type of contribution

• [X] changes to code or doc authored by PLUMED developers, or additions of code in the core or within the default modules
• [ ] changes to a module not authored by you
• [ ] new module contribution or edit of a module authored by you

Copyright

• [X] I agree to transfer the copyright of the code I have written to the PLUMED developers or to the author of the code I am modifying.

• [ ] the module I added or modified contains a COPYRIGHT file with the correct license information. Code should be released under an open source license. I also used the command cd src && ./header.sh mymodulename in order to make sure the headers of the module are correct.

Tests

• [ ] I added a new regtest or modified an existing regtest to validate my changes.
• [ ] I verified that all regtests are passed successfully on GitHub Actions.

[GiovanniBussi]

For clarity, I would:

• remove __PLUMED_WRAPPER_CAST
• replace the few places where it is used with reinterpret_cast

Indeed, I see you only use it in regions of the code that are C++ only, so no reason to use this macro

Thanks!

[Iximiel]

Indeed, I see you only use it in regions of the code that are C++ only, so no reason to use this macro

I changed it in the std::filesystem part but some of them are in the f2c, c2f, c2v and v2c functions that are wrapped by __PLUMED_WRAPPER_C_BEGIN/END, are also these only c++?

Then I run astyle, and should be ready

[GiovanniBussi]

You are right, those are also for C. So we can either keep it as is or maybe you can put explicit reinterpret_cast in the filesystem part, just because it's clearer...

[Iximiel]

You are right, those are also for C. So we can either keep it as is or maybe you can put explicit reinterpret_cast in the filesystem part, just because it's clearer...

i changed CAST to REINTERPRET_CAST, so it is clearer, and in the c++ parts I wrote it explicitly

[Iximiel]

The changes should not be accepted, using clang12 for compiling raises a warning about some of the cast to be undefined behaviour. I think I should address this before considering the work done

[Iximiel]

I think I solved the issue, I do not get anymore the UB warnings. And the solution should be compatible with C++98

[GiovanniBussi]

@Iximiel I think I can merge this, but you should first make it "not draft" I think