feat(linting): ability to configure global and fallback linters (#1727)

* feat(linting): ability to configure global and fallback linters

* fix: use nvim-lint's logic to get linters

---------

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>

lua/lazyvim/plugins/linting.lua

@@ -7,6 +7,10 @@ return {
       events = { "BufWritePost", "BufReadPost", "InsertLeave" },
       linters_by_ft = {
         fish = { "fish" },
+        -- Use the "*" filetype to run linters on all filetypes.
+        -- ['*'] = { 'global linter' },
+        -- Use the "_" filetype to run linters on filetypes that don't have other linters configured.
+        -- ['_'] = { 'fallback linter' },
       },
       -- LazyVim extension to easily override linter options
       -- or add custom linters.
@@ -23,6 +27,8 @@ return {
       },
     },
     config = function(_, opts)
+      local Util = require("lazyvim.util")
+
       local M = {}
 
       local lint = require("lint")
@@ -47,14 +53,32 @@ return {
       end
 
       function M.lint()
-        local names = lint.linters_by_ft[vim.bo.filetype] or {}
+        -- Use nvim-lint's logic first:
+        -- * checks if linters exist for the full filetype first
+        -- * otherwise will split filetype by "." and add all those linters
+        -- * this differs from conform.nvim which only uses the first filetype that has a formatter
+        local names = lint._resolve_linter_by_ft(vim.bo.filetype)
+
+        -- Add fallback linters.
+        if #names == 0 then
+          vim.list_extend(names, lint.linters_by_ft["_"] or {})
+        end
+
+        -- Add global linters.
+        vim.list_extend(names, lint.linters_by_ft["*"] or {})
+
+        -- Filter out linters that don't exist or don't match the condition.
         local ctx = { filename = vim.api.nvim_buf_get_name(0) }
         ctx.dirname = vim.fn.fnamemodify(ctx.filename, ":h")
         names = vim.tbl_filter(function(name)
           local linter = lint.linters[name]
+          if not linter then
+            Util.warn("Linter not found: " .. name, { title = "nvim-lint" })
+          end
           return linter and not (type(linter) == "table" and linter.condition and not linter.condition(ctx))
         end, names)
 
+        -- Run linters.
         if #names > 0 then
           lint.try_lint(names)
         end