[C++ PR 78252] illformed lamda?

[Nathan Sidwell]

On 11/22/2016 02:26 PM, Nathan Sidwell wrote:
> template<typename T>
> void for2 (T &v)
> {
> }
>
> void Foo ()
> {
>   auto lam_1 = [](int &) { };
>   auto lam_2 = [](auto &) { }; // IIUC this is implicitly templatey
>
>   for2 (lam_1);
>   for2 (lam_2);  // What is the lambda's argument type?
> }
>
> We get 2 instantiations of for2:
>     .type    _Z4for2IZ3FoovEUlRiE_EvRT_, @function
>     .type    _Z4for2IZ3FoovEUlRT_E0_EvS1_, @function

Ok. looking further, I now think this is well formed.

lam_2's 'auto &' parameter creates an implicit templated function 
operator member function. We could have used 'Da' to refer to the auto 
parms, but we didn't.  I think that means that the demangler needs to be 
taught that 'T[n]_' occurring inside a lambda's argument encoding means 
'auto' and does not refer to any containing template instantiation name?

nathan

-- 
Nathan Sidwell