Add inline function refactoring

[Padmashree06]

Explanation:

Add refactoring to inline function at function call.

1. If the function body consists of a single return statement, the returned expression is inlined directly.
2. For multi-statement or void functions, the body is wrapped in a closure and invoked.
3. Function parameters are replaced by arguments provided at function call.

Test cases are written for the same.

Scope:

This will provide refactoring to inline functions at function call and will be wired as a codeAction in sourcekit-lsp.

Issues:

swiftlang/sourcekit-lsp#2508

Original PRs:

Not Applicable

Risk:

This is a standalone feature and does not change the existing structure or functionality of the code.
It is a additional feature.

Testing:

Added unit tests covering:

• Simple return expression inlining
• Multiple parameters
• Multi-statement functions (closure wrapping)
• Void functions
• Failure cases (missing function, argument mismatch, method calls)

All tests pass locally using swift test.

Reviewers:

Not Applicable

[ahoppen]

I have not looked at the PR in detail, but based on the size of it, I don’t think that it correctly handles argument to parameter matching. See swiftlang/sourcekit-lsp#2506 (comment) for some pointers of what the tricky areas here are. A prerequisite for this refactoring action would be to have a library that allows mapping arguments in arbitrary function calls to the parameters on their declaration.

[Padmashree06]

Thank you I'll look into it.