When a vector is instantiated with a pointer type (`T` being `const
Foo*`), the inferred annotation becomes `push_back(const Foo*& value
[[clang::lifetime_capture_by(this)]])`.
For reference parameters, the `lifetime_capture_by` attribute treats the
lifetime as referring to the referenced object -- in this case, the
**pointer** itself, not the pointee object. In the `push_back`, we copy
the pointer's value, which does not establish a reference to the
pointer. This behavior is safe and does not capture the pointer's
lifetime.
The annotation should not be inferred for cases where `T` is a pointer
type, as the intended semantics do not align with the annotation.
Fixes#121391
We incorrectly annotate the iterator parameter for `insert` method
(`void insert(const_iterator, const value_type& value)`), because
iterator is also a gsl-pointer type.
This patch fixes it.
This implements the RFC
https://discourse.llvm.org/t/rfc-introduce-clang-lifetime-capture-by-x/81371
In this PR, we introduce `[[clang::lifetime_capture_by(X)]]` attribute
as discussed in the RFC.
As an implementation detail of this attribute, we store and use param
indices instead of raw param expressions. The parameter indices are
computed lazily at the end of function declaration since the function
decl (and therefore the subsequent parameters) are not visible yet while
parsing a parameter annotation.
In subsequent PR, we will infer this attribute for STL containers and
perform lifetime analysis to detect dangling cases.
