[llvm-bugs] [Bug 28265] New: Type-dependent explicit destructor call behaves improperly

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=28265

            Bug ID: 28265
           Summary: Type-dependent explicit destructor call behaves
                    improperly
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++
          Assignee: unassignedclangbugs at nondot.org
          Reporter: aaron at aaronballman.com
                CC: dgregor at apple.com, llvm-bugs at lists.llvm.org
    Classification: Unclassified

There are two likely-related bugs with explicit destructor calls for a
dependent type. The first bug is that the same diagnostic is trigger multiple
times when it should only be triggered once. The second bug is that the
diagnostic includes a fixit that should not be triggered for dependent types.

Given:

template<typename T>
struct TypeDependent {
 void Destruct(T *T1) {
  T1->~T(); // No fixit should be suggested because T is type dependent.
 }
};

template <typename T>
struct NotTypeDependent {
  void Destruct(struct Derived *P) {
    P->~Derived(); // It's fine to suggest a fixit because P isn't type
dependent.
  }
};

struct Base {
 virtual void f() = 0;
};

struct Derived : Base {
 virtual void f() override;
};

void f() {
  TypeDependent<Derived> BadProblem;
  NotTypeDependent<Derived> FineProblem;

  BadProblem.Destruct(nullptr);
  FineProblem.Destruct(nullptr);
}

E:\llvm\2015>clang -fsyntax-only -Wall -std=c++11 E:\Desktop\ForAaron2.cpp
E:\Desktop\ForAaron2.cpp:4:3: warning: destructor called on non-final 'Derived'
that has virtual functions but
      non-virtual destructor [-Wdelete-non-virtual-dtor]
  T1->~T(); // No fixit should be suggested because T is type dependent.
  ^
E:\Desktop\ForAaron2.cpp:27:14: note: in instantiation of member function
'TypeDependent<Derived>::Destruct' requested
      here
  BadProblem.Destruct(nullptr);
             ^
E:\Desktop\ForAaron2.cpp:4:8: note: qualify call to silence this warning
  T1->~T(); // No fixit should be suggested because T is type dependent.
       ^
       Derived::
E:\Desktop\ForAaron2.cpp:11:5: warning: destructor called on non-final
'Derived' that has virtual functions but
      non-virtual destructor [-Wdelete-non-virtual-dtor]
    P->~Derived(); // It's fine to suggest a fixit because P isn't type
dependent.
    ^
E:\Desktop\ForAaron2.cpp:11:8: note: qualify call to silence this warning
    P->~Derived(); // It's fine to suggest a fixit because P isn't type
dependent.
       ^
       Derived::
E:\Desktop\ForAaron2.cpp:11:5: warning: destructor called on non-final
'Derived' that has virtual functions but
      non-virtual destructor [-Wdelete-non-virtual-dtor]
    P->~Derived(); // It's fine to suggest a fixit because P isn't type
dependent.
    ^
E:\Desktop\ForAaron2.cpp:28:15: note: in instantiation of member function
'NotTypeDependent<Derived>::Destruct'
      requested here
  FineProblem.Destruct(nullptr);
              ^
E:\Desktop\ForAaron2.cpp:11:8: note: qualify call to silence this warning
    P->~Derived(); // It's fine to suggest a fixit because P isn't type
dependent.
       ^
       Derived::
3 warnings generated.

The dependent case should not recommend T->Derived::~T() as a fixit, and the
non-dependent case should not trigger two diagnostics for the same issue.

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