[clang] [LifetimeSafety] Add suggestion and inference for implicit this (PR #176703)

[Kashika Akhouri via cfe-commits]

================
@@ -60,6 +60,14 @@ class LifetimeSafetyReporter {
   virtual void suggestAnnotation(SuggestionScope Scope,
                                  const ParmVarDecl *ParmToAnnotate,
                                  const Expr *EscapeExpr) {}
+
+  // Suggests lifetime bound annotations for implicit this
+  virtual void suggestAnnotation(SuggestionScope Scope, const CXXMethodDecl *MD,
+                                 const Expr *EscapeExpr) {}
+
+  // Adds inferred lifetime bound attribute for implicit this to its
+  // TypeSourceInfo
+  virtual void addLifetimeBoundToImplicitThis(const CXXMethodDecl *MD) {}
----------------
kashika0112 wrote:

The implementation of addLifetimeBoundToImplicitThis requires modifying the TSI, which is done using the TypeLocBuilder utility. TypeLocBuilder is an internal header within libSema and is not exposed to libAnalysis. I added this function in LifetimeSafetyReporter as it already holds a reference to Sema.

One way I can think of is move the actual implementation of this TSI transformation to a static helper in SemaDecl.cpp or keep it as a private helper in AnalysisBasedWarnings.cpp. Let me know which is more suitable here. 

https://github.com/llvm/llvm-project/pull/176703