[Clang] Do not allow [[clang::lifetime_bound]] on explicit object member functions

Author: MitalAshok

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -9999,8 +9999,9 @@ def warn_null_ret : Warning<
   InGroup<NonNull>;
 
 def err_lifetimebound_no_object_param : Error<
-  "'lifetimebound' attribute cannot be applied; %select{static |non-}0member "
-  "function has no implicit object parameter">;
+  "'lifetimebound' attribute cannot be applied; "
+  "%select{non-|static |explicit object }0"
+  "member function has no implicit object parameter">;
 def err_lifetimebound_ctor_dtor : Error<
   "'lifetimebound' attribute cannot be applied to a "
   "%select{constructor|destructor}0">;

clang/lib/Sema/SemaDecl.cpp

@@ -7072,9 +7072,16 @@ static void checkAttributesAfterMerging(Sema &S, NamedDecl &ND) {
       // by applying it to the function type.
       if (const auto *A = ATL.getAttrAs<LifetimeBoundAttr>()) {
         const auto *MD = dyn_cast<CXXMethodDecl>(FD);
-        if (!MD || MD->isStatic()) {
+        int NoImplicitObjectError = -1;
+        if (!MD)
+          NoImplicitObjectError = 0;
+        else if (MD->isStatic())
+          NoImplicitObjectError = 1;
+        else if (MD->isExplicitObjectMemberFunction())
+          NoImplicitObjectError = 2;
+        if (NoImplicitObjectError != -1) {
           S.Diag(A->getLocation(), diag::err_lifetimebound_no_object_param)
-              << !MD << A->getRange();
+              << NoImplicitObjectError << A->getRange();
         } else if (isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD)) {
           S.Diag(A->getLocation(), diag::err_lifetimebound_ctor_dtor)
               << isa<CXXDestructorDecl>(MD) << A->getRange();