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merge C.151 into R.22, leaving a redirect behind (#1675)

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Sergey Zubkov 2020-10-01 14:10:13 -04:00 committed by GitHub
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@ -8040,25 +8040,7 @@ It also ensures exception safety in complex expressions.
### <a name="Rh-make_shared"></a>C.151: Use `make_shared()` to construct objects owned by `shared_ptr`s
##### Reason
`make_shared` gives a more concise statement of the construction.
It also gives an opportunity to eliminate a separate allocation for the reference counts, by placing the `shared_ptr`'s use counts next to its object.
##### Example
void test()
{
// OK: but repetitive; and separate allocations for the Bar and shared_ptr's use count
shared_ptr<Bar> p {new Bar{7}};
auto q = make_shared<Bar>(7); // Better: no repetition of Bar; one object
}
##### Enforcement
* Flag the repetitive usage of template specialization list`<Bar>`
* Flag variables declared to be `shared_ptr<Bar>`
See [R.22](#Rr-make_shared)
### <a name="Rh-array"></a>C.152: Never assign a pointer to an array of derived class objects to a pointer to its base
@ -9573,7 +9555,8 @@ This is more efficient:
##### Reason
If you first make an object and then give it to a `shared_ptr` constructor, you (most likely) do one more allocation (and later deallocation) than if you use `make_shared()` because the reference counts must be allocated separately from the object.
`make_shared` gives a more concise statement of the construction.
It also gives an opportunity to eliminate a separate allocation for the reference counts, by placing the `shared_ptr`'s use counts next to its object.
##### Example