Issues with Importing Custom C++ Library into Swift Using C++ Interoperability in Swift 5.9

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I am trying to use C++ libraries in my Swift project using the new C++ interoperability feature in Swift 5.9. However, I am facing issues while trying to import C++ header files and utilize them in Swift. Specifically, I am getting errors when trying to call C++ functions, and the compiler cannot find the module map for my custom C++ library.

I followed the instructions from the Swift documentation (site.www.swift.org/documentation/cxx-interop/#importing-c-standard-library) and created the module map for my forestLib library, but I am still encountering errors like "Module 'forestLib' not found" or "Cannot call C++ functions in Swift."

Here's the simplified code I have:
C++ Code:

// forest.h
enum class TreeKind {
  Oak,
  Redwood,
  Willow
};

class Tree {
public:
  Tree(TreeKind kind);
private:
  TreeKind kind;
};

Swift Code:

import forestLib

let tree = Tree(.Oak)

Despite correctly setting up the module map as described in the documentation, I am unable to import forestLib and the Swift compiler throws errors related to the module not being found.

Question:

What might be going wrong here? How can I ensure that Swift correctly imports my C++ headers and that the module map is recognized by the build system?