HeuristicResolver::getPointeeType discards qualifiers

[HighCommander4]

HeuristicResolver::getPointeeType() returns a Type * rather than a QualType, which means it necessarily discards any qualifiers on the returned pointee type.

Preserving the qualifiers can be important, as seen e.g. in clangd in the following code:

template <typename T>
struct Waldo {
  void find();
  void find() const;
};

template <typename T>
struct smart_ptr {
  T* operator->();
};

template <typename T>
void foo(smart_ptr<const Waldo<T>> s) {
  s->find();
}

Go-to-definition on the find token in s->find() offers both overloads of Waldo::find() as results, when it should only offer the const overload.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Nathan Ridge (HighCommander4)

`HeuristicResolver::getPointeeType()` returns a `Type *` rather than a `QualType`, which means it necessarily discards any qualifiers on the returned pointee type.

This can be important, as seen e.g. in clangd in the following code:

template <typename T>
struct Waldo {
  void find();
  void find() const;
};

template <typename T>
struct smart_ptr {
  T* operator->();
};

template <typename T>
void foo(smart_ptr<const Waldo<T>> s) {
  s->find();
}

Go-to-definition on the find token in s->find() offers both overloads of Waldo::find() as results, when it should only offer the const overload.

[llvmbot]

@llvm/issue-subscribers-clangd

Author: Nathan Ridge (HighCommander4)

`HeuristicResolver::getPointeeType()` returns a `Type *` rather than a `QualType`, which means it necessarily discards any qualifiers on the returned pointee type.

This can be important, as seen e.g. in clangd in the following code:

template <typename T>
struct Waldo {
  void find();
  void find() const;
};

template <typename T>
struct smart_ptr {
  T* operator->();
};

template <typename T>
void foo(smart_ptr<const Waldo<T>> s) {
  s->find();
}

Go-to-definition on the find token in s->find() offers both overloads of Waldo::find() as results, when it should only offer the const overload.

[HighCommander4]

Proposed fix: #123551