feat: '_' filetype to define fallback formatters

README.md

@@ -240,10 +240,14 @@ require("conform").setup({
     python = { "isort", "black" },
     -- Use a sub-list to run only the first available formatter
     javascript = { { "prettierd", "prettier" } },
-    -- Use the "*" filetype to run formatters on all files.
+    -- Use the "*" filetype to run formatters on all filetypes.
     -- Note that if you use this, you may want to set lsp_fallback = "always"
     -- (see :help conform.format)
-    ["*"] = { "trim_whitespace" },
+    ["*"] = { "codespell" },
+    -- Use the "_" filetype to run formatters on all filetypes
+    -- that don't have other formatters configured. Again, you may want to
+    -- set lsp_fallback = "always" when using this value.
+    ["_"] = { "trim_whitespace" },
   },
   -- If this is set, Conform will run the formatter on save.
   -- It will pass the table to conform.format().

doc/conform.txt

@@ -20,10 +20,14 @@ OPTIONS                                                          *conform-option
         python = { "isort", "black" },
         -- Use a sub-list to run only the first available formatter
         javascript = { { "prettierd", "prettier" } },
-        -- Use the "*" filetype to run formatters on all files.
+        -- Use the "*" filetype to run formatters on all filetypes.
         -- Note that if you use this, you may want to set lsp_fallback = "always"
         -- (see :help conform.format)
-        ["*"] = { "trim_whitespace" },
+        ["*"] = { "codespell" },
+        -- Use the "_" filetype to run formatters on all filetypes
+        -- that don't have other formatters configured. Again, you may want to
+        -- set lsp_fallback = "always" when using this value.
+        ["_"] = { "trim_whitespace" },
       },
       -- If this is set, Conform will run the formatter on save.
       -- It will pass the table to conform.format().

lua/conform/init.lua

@@ -171,7 +171,7 @@ M.list_formatters_for_buffer = function(bufnr)
     end
   end
 
-  table.insert(filetypes, "*")
+  table.insert(filetypes, "_")
   for _, filetype in ipairs(filetypes) do
     ---@type conform.FormatterUnit[]
     local ft_formatters = M.formatters_by_ft[filetype]
@@ -183,7 +183,18 @@ M.list_formatters_for_buffer = function(bufnr)
       end
 
       dedupe_formatters(ft_formatters, formatters)
+      break
+    end
+  end
+
+  local ft_formatters = M.formatters_by_ft["*"]
+  if ft_formatters then
+    -- support the old structure where formatters could be a subkey
+    if not vim.tbl_islist(ft_formatters) then
+      ---@diagnostic disable-next-line: undefined-field
+      ft_formatters = ft_formatters.formatters
     end
+    dedupe_formatters(ft_formatters, formatters)
   end
 
   return formatters

scripts/options_doc.lua

@@ -6,10 +6,14 @@ require("conform").setup({
     python = { "isort", "black" },
     -- Use a sub-list to run only the first available formatter
     javascript = { { "prettierd", "prettier" } },
-    -- Use the "*" filetype to run formatters on all files.
+    -- Use the "*" filetype to run formatters on all filetypes.
     -- Note that if you use this, you may want to set lsp_fallback = "always"
     -- (see :help conform.format)
-    ["*"] = { "trim_whitespace" },
+    ["*"] = { "codespell" },
+    -- Use the "_" filetype to run formatters on all filetypes
+    -- that don't have other formatters configured. Again, you may want to
+    -- set lsp_fallback = "always" when using this value.
+    ["_"] = { "trim_whitespace" },
   },
   -- If this is set, Conform will run the formatter on save.
   -- It will pass the table to conform.format().