[clang] [clang] Implement lifetime analysis for lifetime_capture_by(X) (PR #115921)

[Utkarsh Saxena via cfe-commits]

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@@ -3951,7 +3958,7 @@ The capturing entity ``X`` can be one of the following:
       std::set<std::string_view> s;
     };
 
-- 'global', 'unknown' (without quotes).
+- `global`, `unknown`.
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usx95 wrote:

We would give an error:
'lifetime_capture_by' attribute argument "global" is not a known function parameter; must be a function parameter, 'this', 'global' or 'unknown'.

https://github.com/llvm/llvm-project/pull/115921