readability-qualified-auto

Adds pointer and const qualifications to auto-typed variables that are deduced to pointers and const pointers.

LLVM Coding Standards advises to make it obvious if a auto typed variable is a pointer, constant pointer or constant reference. This check will transform auto to auto * when the type is deduced to be a pointer, as well as adding const when applicable to auto pointers or references

for (auto &Data : MutatableContainer) {
  change(Data);
}
for (auto &Data : ConstantContainer) {
  observe(Data);
}
for (auto Data : MutatablePtrContainer) {
  change(*Data);
}
for (auto Data : ConstantPtrContainer) {
  observe(*Data);
}

Would be transformed into:

for (auto &Data : MutatableContainer) {
  change(Data);
}
for (const auto &Data : ConstantContainer) {
  observe(Data);
}
for (auto *Data : MutatablePtrContainer) {
  change(*Data);
}
for (const auto *Data : ConstantPtrContainer) {
  observe(*Data);
}

Note const volatile qualified types will retain their const and volatile qualifiers.

const auto Foo = cast<int *>(Baz1);
const auto Bar = cast<const int *>(Baz2);
volatile auto FooBar = cast<int*>(Baz3);

Would be transformed into:

auto *const Foo = cast<int *>(Baz1);
const auto *const Bar = cast<const int *>(Baz2);
auto *volatile FooBar = cast<int*>(Baz3);

This check helps to enforce this LLVM Coding Standards recommendation.