[clang] [clang] Support 'this' position for lifetimebound attribute (PR #115021)

[Gábor Horváth via cfe-commits]

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@@ -730,7 +731,9 @@ class YAMLConverter {
     }
   }
 
-  void convertParams(const ParamsSeq &Params, FunctionInfo &OutInfo) {
+  std::optional<ParamInfo> convertParams(const ParamsSeq &Params,
+                                         FunctionInfo &OutInfo) {
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Xazax-hun wrote:

I think we can do that change when we need additional implicit parameters (or make it return a struct instead of a `std::optional<ParamInfo>`. One of the main reasons why I prefer returning an optional at the moment because it makes some of the call sites more concise, e.g., the checking for trying to specify `self` or `this` for a free function. 

https://github.com/llvm/llvm-project/pull/115021