[c++] Make operators new and delete weak symbols by default

[ASMfreaK]

This change makes operators new and delete weak symbols by default. See #746

[salkinium]

Hm, so would it also solve the issue if we left the operator delete functions empty by default? Then the new/malloc would still trigger the linker error message, but not this issue right? And then only if the modm:platform:heap module is added we implement the operator delete as it's now implemented?

[salkinium]

I mean, an application which is never calling new in the first place cannot call delete and expect that to work?

[chris-durand]

I mean, an application which is never calling new in the first place cannot call delete and expect that to work?

👍 , sounds reasonable.

[salkinium]

I'll push a commit to implement this, but we're keeping the weak symbols, they could be useful.

[ASMfreaK]

Hm, so would it also solve the issue if we left the operator delete functions empty by default?

I'd prefer to put modm_assert() there maybe not by default, but behind a macro/lbuild option.

[ASMfreaK]

And then only if the modm:platform:heap module is added we implement the operator delete as it's now implemented?

Honestly, this was the behavior I was expecting. If modm:platform:heap is added implement operators, otherwise they are left unimplented.

[salkinium]

Thanks, always nice to fix another corner case!