Index: lib/Sema/SemaOverload.cpp
===================================================================
--- lib/Sema/SemaOverload.cpp
+++ lib/Sema/SemaOverload.cpp
@@ -11788,8 +11788,11 @@
       TheCall->getMethodDecl()->isPure()) {
     const CXXMethodDecl *MD = TheCall->getMethodDecl();
 
-    if (isa<CXXThisExpr>(MemExpr->getBase()->IgnoreParenCasts())) {
-      Diag(MemExpr->getLocStart(), 
+    // If the member access is fully qualified, (i.e. X::f), treat
+    // it as a non-virtual call and don't warn.
+    if (isa<CXXThisExpr>(MemExpr->getBase()->IgnoreParenCasts()) &&
+       !(MemExpr->getQualifier())) {
+      Diag(MemExpr->getLocStart(),
            diag::warn_call_to_pure_virtual_member_function_from_ctor_dtor)
         << MD->getDeclName() << isa<CXXDestructorDecl>(CurContext)
         << MD->getParent()->getDeclName();
Index: test/SemaCXX/warn-pure-virtual-call-from-ctor-dtor.cpp
===================================================================
--- test/SemaCXX/warn-pure-virtual-call-from-ctor-dtor.cpp
+++ test/SemaCXX/warn-pure-virtual-call-from-ctor-dtor.cpp
@@ -12,3 +12,11 @@
   B() { a->f(); };
   ~B() { a->f(); };
 };
+
+// Don't warn if the call is fully qualified. (PR23215)
+struct C {
+    virtual void f() = 0;
+    C() {
+        C::f();
+    }
+};