[Sema] Mark the referenced destructor during transformation of a `CXXBindTemporaryExpr`

[akyrtzi]

Summary

Otherwise we will fail to generate the definition of a defaulted destructor,
if the only reference was in a templated temporary.

rdar://89366678

[jansvoboda11]

LGTM

[akyrtzi]

Make sure to check the destructor decl pointer for nil before passing to Sema::MarkFunctionReferenced()

[akyrtzi]

Move the const_cast to the call site.

[akyrtzi]

Add a target triple to the test, so it can pass on windows.

clang/lib/Sema/TreeTransform.h

 
 /// Transform a C++ temporary-binding expression.
 ///
 /// Since CXXBindTemporaryExpr nodes are implicitly generated, we just
 /// transform the subexpression and return that.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
+  if (auto *Dtor =
+          const_cast<CXXDestructorDecl *>(E->getTemporary()->getDestructor()))
+    SemaRef.MarkFunctionReferenced(E->getBeginLoc(), Dtor);
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 /// Transform a C++ expression that contains cleanups that should
 /// be run after the expression is evaluated.
 ///
 /// Since ExprWithCleanups nodes are implicitly generated, we
 /// just transform the subexpression and return that.

clang/test/SemaTemplate/defaulted-destructor-in-temporary.cpp

+// RUN: %clang_cc1 -std=c++11 %s -emit-llvm -o - | FileCheck %s
+
+// CHECK: define linkonce_odr {{.*}} @_ZN3StrD1Ev
+
+class A {
+public:
+  ~A();
+};
+class Str {
+  A d;
+
+public:
+  ~Str() = default;
+};
+class E {
+  Str s;
+  template <typename>
+  void h() {
+    s = {};
+  }
+  void f();
+};
+void E::f() {
+  h<int>();
+}