Feature request: Only show diagnostics on modified lines about null-ls.nvim

[jose-elias-alvarez]

If I understand the request correctly, I think you could do this using the vim.diagnostic API independently of null-ls. Here is a non-functional sketch of one way you might use:

local diagnostics = vim.diagnostics.get(0)
vim.diagnostics.reset(nil, bufnr)

local filtered_diagnostics = {}
for _, diagnostic in ipairs(diagnostics)
    -- use whatever logic to filter diagnostics
    if should_keep(diagnostic) then
        table.insert(filtered_diagnostics, diagnostic)
    end
end

local ns = vim.api.nvim_create_namespace("diff_diagnostics") -- doesn't matter
vim.diagnostic.set(ns, 0, filtered_diagnostics)

[nitnelave]

I was afraid of the "use whatever logic to filter diagnostics" :D
I quickly looked into it, but it doesn't seem trivial to extract the modified lines from git, and the git-gutter-like plugins don't expose an API.

Anyway, thanks for your answer!