added constness_ptr as pointer wrapper to ensure actual method constness

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There's std::experimental::propagate_const as pointed out here: llvm/llvm-project#64988 (comment). Looks quite familiar.

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We do not have many pointer left in the code so this should be taking a reference now.

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We do not have many pointer left in the code so this should be taking a reference now.

I will tackle references later on - let's start with the pointers which are not supposed to be references yet.

[danmar]

I don't really understand what we achieve with this safe_ptr class. Does it prevent some lifetime issue?

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From https://en.cppreference.com/w/cpp/experimental/propagate_const:

It treats the wrapped pointer as a pointer to const when accessed through a const access path, hence the name. 

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The name is misleading though. I think this started as something totally different. Not sure what to call it - constness_ptr, propagate_const_ptr, ptr_wrapper, ...?

[danmar]

I feel a bit skeptic about this spontanously. But yeah some name that indicates that const is propagated sounds good. But at the same time it shouldn't be too long.

I wonder how people would feel about a cppcheck checker that tells them about accessing non-const member data using const pointers. Spontanously it seems wrong to do that and I could use that in our selfchecks at least. or do you know a use case when we would want to write such data?

I considered such a checker a long time ago but I dropped the idea for some reason. I don't remember why. But I guess it was simply because of limited time and there are plenty of undefined behavior to discover so I rather wanted to work on that.

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I wonder how people would feel about a cppcheck checker that tells them about accessing non-const member data using const pointers. Spontanously it seems wrong to do that and I could use that in our selfchecks at least. or do you know a use case when we would want to write such data?

https://trac.cppcheck.net/ticket/11127

Not really a use case but something which will cause a lot of const to be dropped if this is fully applied (I think that might include references - not sure about this, it has been too long) is the ErrorLogger usage.

On a side note I wonder if there is a simple trick to propagate that a function should not be const. Like adding (void)this; to avoid a function to be static.

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I renamed it constness_ptr. Feels awkward but basically describes what it does.

[danmar]

I renamed it constness_ptr. Feels awkward but basically describes what it does.

I like that name better.

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I implemented it in simplecpp - see danmar/simplecpp#548.