[PATCH] D103750: [analyzer] Handle std::make_unique for SmartPtrModeling

[Deep Majumder via Phabricator via cfe-commits]

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Comment at: clang/test/Analysis/smart-ptr-text-output.cpp:339
+void makeUniqueForOverwriteReturnsNullUniquePtr() {
+  auto P = std::make_unique_for_overwrite<A>(); // expected-note {{std::unique_ptr 'P' constructed by std::make_unique_for_overwrite is null}}
+  *P;                                           // expected-warning {{Dereference of null smart pointer 'P' [alpha.cplusplus.SmartPtr]}}
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NoQ wrote:
> Mmm wait a sec, that doesn't look like what the spec says.
> 
> https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique:
> > Same as (1), except that the object is default-initialized. This overload participates in overload resolution only if T is not an array type. The function is equivalent to `unique_ptr<T>(new T)`
> 
> It zero-initializes the //pointee//, not the //pointer//.
> 
> The difference between `std::make_unique<A>()` and `std::make_unique_for_overwrite<A>()` is the difference between value-initialization (invoking the default constructor) and zero-initialization (simply filling the buffer with `0`s).
Oops! Look like I completely misunderstood the spec.
So basically, the inner pointer is //not// null, and we have the same assumptions that apply for `std::make_unique`. Only problem is that, for primitive types, the value obtained on de-referencing is undefined.


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  https://reviews.llvm.org/D103750/new/

https://reviews.llvm.org/D103750