[clang] Add support for capture_by on method declarations (PR #219423)

[Utkarsh Saxena via cfe-commits]

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@@ -252,19 +252,62 @@ void initializer_list_capture() {
 // Implicit object param 'this' is captured
 // ****************************************************************************
 namespace this_is_captured {
-struct X {} x;
+struct X {} x;    // cfg-note {{this global dangles}}
 struct S {
   void capture(X &x) [[clang::lifetime_capture_by(x)]];
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usx95 wrote:

nit: consider renaming into `gets_captured_by` or something to distinguish between "this gets captured" vs "this captures something"

https://github.com/llvm/llvm-project/pull/219423