Include Cleaner fails for symbols forward-declared and aliased

[graveljp]

Clangd's include cleaner fails for symbols from one file forward-declared and aliased in a different file. In the following example, both "forward.h" and "impl.h" are required for the code to compile. Yet, clangd claims "impl.h" is unused. It's not unused since it's providing Foo::kValue.

impl.h

#pragma once

namespace impl {
enum class Foo : int {
  kValue = 0
};
}

forward.h

#pragma once

namespace impl {
  enum class Foo : int;
}

using impl::Foo;

main.cc

#include "forward.h"
#include "impl.h"  // Clangd warns: "Included header impl.h is not used directly "

int main() {
  Foo foo = Foo::kValue;
  return 1;
}

System information

Output of clangd --version:
clangd version 19.0.0git (https://github.com/llvm/llvm-project.git 55e59083cb610f30ad21fe8c8cdb9900534937ec)
Features: linux
Platform: x86_64-unknown-linux-gnu

Editor/LSP plugin:
VSCode

Operating system:
Linux