DUChain support of defaulted/deleted functions again

[Milian Wolff]

On Saturday 18 June 2011 17:19:22 Milian Wolff wrote:
> Hey there,
> 
> Nicolas made me aware of some more details of defaulted/deleted functions
> in C++0x yesterday. Here is an example of all the cases I could think of
> which compiles just fine with g++ 4.6 and -std=c++0x:
> 
> class A {
>   A() = default;
>   A(const A&) = delete;
>   virtual ~A();
> };
> A::~A() = default;
> void foo(int) = delete;
> int main() {
>     return 0;
> }
> 
> Generally:
> - defaulted or deleted functions are definitions
> - deleted functions can only be declared once
> - the definition of defaulted functions can be out-of-line
> - non-member functions can be deleted (i.e. to prevent implicit conversion)
> 
> Questions:
> - I can't think of an example of using =default on a non-member function
> generally, it's not that clear to me what can and what cannot be defaulted.
> a whitelist would be cool, or if someone could point me to the correct
> part in the spec that defines this
> 
> - what do we want to track in the duchain, and where?
> * personally I'd like to report errors when someone tries to use deleted
> functions and hide them from code completion
> * defaulted otoh is not really neccessary to track imo, or can someone
> think of a reason why this should be accessible from the duchain?
> 
> It's pretty clear to me that my current approach is wrong and I'll revert
> it. Instead I think assing a m_isDeleted : 1 or similar to DeclarationData
> would be a good thing:
> This would increase the count of size-one bitfields to 8, i.e. shouldn't
> increase the overall size if I'm not mistaken. Furthermore we can then do
> the checks for isDeleted without any dynamic casts.

I've done this now, what do you think:

http://quickgit.kde.org/?p=clones/kdevplatform/mwolff/kdevplatform.git&a=commit&h=160eab0c90ab644eac806fa000ebb3ae40c4e135

and

http://commits.kde.org/kdevelop/f812a2c7bf10ea3fdd3628b94cd689576ea21c4b

> I just don't know whether putting it directly into Declaration is a good
> place. For one thing this is a pure C++0x feature, I don't know of any
> other language with a similar feature. To make matters worse only
> FunctionDeclarations can be deleted in C++0x... If preferred I could simply
> create a CppFunctionDeclaration that also tracks the isSignal/isSlot and
> thus cleans our API a bit of Cpp-Isms...

I'm still interested in this question though

bye
-- 
Milian Wolff
mail at milianw.de
http://milianw.de
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