Don't use an implicit attribute so that it'll be passed on to the function definition.

Author: bwendling

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -6767,8 +6767,6 @@ def err_counted_by_attr_pointee_unknown_size : Error<
     ""
   "}2">;
 def err_count_attr_func_cannot_be_a_call : Error<"function must not be a call">;
-def err_count_attr_func_must_be_pure_or_const
-    : Error<"function must be either 'pure' or 'const'">;
 def err_count_attr_func_must_have_one_param
     : Error<"function must have only one parameter">;
 

clang/lib/Sema/SemaBoundsSafety.cpp

@@ -162,18 +162,17 @@ bool Sema::CheckCountedByAttrOnField(FieldDecl *FD, Expr *E, bool CountInBytes,
     // Check a function argument.
     bool Ret = false;
 
-    if (!CountFD->hasAttr<PureAttr>() && !CountFD->hasAttr<ConstAttr>()) {
-      Diag(E->getBeginLoc(), diag::err_count_attr_func_must_be_pure_or_const)
-          << CountDecl << E->getSourceRange();
-      Ret = true;
-    }
+    // FIXME: We should check that the function is either pure or const.
 
     if (CountFD->getNumParams() != 1) {
       Diag(E->getBeginLoc(), diag::err_count_attr_func_must_have_one_param)
           << CountDecl << E->getSourceRange();
       Ret = true;
     }
 
+    if (!Ret && !CountFD->hasAttr<UsedAttr>())
+      CountFD->addAttr(UsedAttr::Create(Context, CountFD->getSourceRange()));
+
     return Ret;
   }