================
@@ -3918,6 +3918,75 @@ have their lifetimes extended.
}];
}
+def LifetimeCaptureByDocs : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+ Similar to `lifetimebound`_, the ``lifetime_capture_by(X)`` attribute on a
function
+parameter or implicit object parameter indicates that that objects that are
referred to
+by that parameter may also be referred to by the capturing entity ``X``.
+
+By default, a reference is considered to refer to its referenced object, a
+pointer is considered to refer to its pointee, a ``std::initializer_list<T>``
+is considered to refer to its underlying array, and aggregates (arrays and
+simple ``struct``\s) are considered to refer to all objects that their
+transitive subobjects refer to.
+
+The capturing entity ``X`` can be one of the following:
+- Another (named) function parameter.
+
+ .. code-block:: c++
+
+ void addToSet(std::string_view a [[clang::lifetime_capture_by(s)]],
std::set<std::string_view>& s) {
+ s.insert(a);
+ }
+
+- ``this`` (in case of member functions).
+
+ .. code-block:: c++
+
+ class S {
+ void addToSet(std::string_view a [[clang::lifetime_capture_by(this)]]) {
+ s.insert(a);
+ }
+ std::set<std::string_view> s;
+ };
+
+- 'global', 'unknown' (without quotes).
+
+ .. code-block:: c++
+
+ std::set<std::string_view> s;
+ void addToSet(std::string_view a [[clang::lifetime_capture_by(global)]]) {
+ s.insert(a);
+ }
+ void addSomewhere(std::string_view a
[[clang::lifetime_capture_by(unknown)]]);
+
+The attribute can be applied to the implicit ``this`` parameter of a member
+function by writing the attribute after the function type:
+
+.. code-block:: c++
+
+ struct S {
+ const char *data(std::set<S*>& s) [[clang::lifetime_capture_by(s)]] {
+ s.insert(this);
+ }
+ };
+
+The attribute supports specifying more than one capturing entities:
+
+.. code-block:: c++
+
+ void addToSets(std::string_view a [[clang::lifetime_capture_by(s1, s2)]],
+ std::set<std::string_view>& s1,
+ std::set<std::string_view>& s2) {
+ s1.insert(a);
+ s2.insert(a);
+ }
+
+.. _`lifetimebound`:
https://clang.llvm.org/docs/AttributeReference.html#lifetimebound
----------------
aaronpuchert wrote:
There is no need for an external link within the same page. In fact, this
breaks the existing `lifetimebound` anchor. The fix is to simply remove this
line. (#142967)
https://github.com/llvm/llvm-project/pull/115823
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