How do I enable LSP inlay hints to show types and parameter names inline in Neovim?

Explanation

Neovim 0.10 introduced built-in support for LSP inlay hints via vim.lsp.inlay_hint. Inlay hints are virtual text annotations injected by the language server directly into your code to show inferred types, parameter names, and return types — making the code more readable without changing the actual file content.

How it works

• Enable globally: :lua vim.lsp.inlay_hint.enable() turns on inlay hints for the current buffer
• Disable: :lua vim.lsp.inlay_hint.enable(false) or :lua vim.lsp.inlay_hint.enable(0, {enabled = false})
• Toggle: :lua vim.lsp.inlay_hint.enable(not vim.lsp.inlay_hint.is_enabled())
• In vimrc: vim.lsp.inlay_hint.enable() inside an LspAttach autocommand

Example

With rust-analyzer attached to a Rust file:

let x = add(1, 2);  →  let x /*: i32*/ = add(/*a:*/ 1, /*b:*/ 2);

The type : i32 and parameter names a:, b: appear as greyed-out virtual text.

Tips

• Inlay hints require the language server to support the textDocument/inlayHint capability (rust-analyzer, clangd, gopls, and tsserver all do)
• To enable globally on every LSP attach, add to your init.lua:

autocmd LspAttach * lua vim.lsp.inlay_hint.enable()

• Customize the appearance by linking the LspInlayHint highlight group to another group
• Use :lua print(vim.inspect(vim.lsp.inlay_hint.get())) to inspect the current buffer's hint list