fix(filetype): source ftdetect/* after creating scripts.vim autocmds (#29445)

runtime/filetype.lua

@@ -39,15 +39,6 @@ vim.api.nvim_create_autocmd({ 'BufRead', 'BufNewFile', 'StdinReadPost' }, {
   end,
 })
 
--- These *must* be sourced after the autocommand above is created
-if not vim.g.did_load_ftdetect then
-  vim.cmd([[
-  augroup filetypedetect
-  runtime! ftdetect/*.{vim,lua}
-  augroup END
-  ]])
-end
-
 -- Set up the autocmd for user scripts.vim
 vim.api.nvim_create_autocmd({ 'BufRead', 'BufNewFile' }, {
   group = 'filetypedetect',
@@ -62,3 +53,10 @@ vim.api.nvim_create_autocmd('StdinReadPost', {
 if not vim.g.ft_ignore_pat then
   vim.g.ft_ignore_pat = '\\.\\(Z\\|gz\\|bz2\\|zip\\|tgz\\)$'
 end
+
+-- These *must* be sourced after the autocommands above are created
+vim.cmd([[
+  augroup filetypedetect
+  runtime! ftdetect/*.{vim,lua}
+  augroup END
+]])

test/functional/core/startup_spec.lua

@@ -1325,31 +1325,59 @@ describe('runtime:', function()
   end)
 
   it("loads ftdetect/*.{vim,lua} respecting 'rtp' order", function()
-    local ftdetect_folder = table.concat({ xconfig, 'nvim', 'ftdetect' }, pathsep)
+    local rtp_folder = table.concat({ xconfig, 'nvim' }, pathsep)
-    local after_ftdetect_folder = table.concat({ xconfig, 'nvim', 'after', 'ftdetect' }, pathsep)
+    local after_rtp_folder = table.concat({ rtp_folder, 'after' }, pathsep)
+    local ftdetect_folder = table.concat({ rtp_folder, 'ftdetect' }, pathsep)
+    local after_ftdetect_folder = table.concat({ after_rtp_folder, 'ftdetect' }, pathsep)
     mkdir_p(ftdetect_folder)
     mkdir_p(after_ftdetect_folder)
     finally(function()
       rmdir(ftdetect_folder)
       rmdir(after_ftdetect_folder)
     end)
+    write_file(table.concat({ rtp_folder, 'scripts.vim' }, pathsep), [[let g:aseq ..= 'S']])
+    write_file(table.concat({ after_rtp_folder, 'scripts.vim' }, pathsep), [[let g:aseq ..= 's']])
     -- A .lua file is loaded after a .vim file if they only differ in extension.
     -- All files in after/ftdetect/ are loaded after all files in ftdetect/.
-    write_file(table.concat({ ftdetect_folder, 'new-ft.vim' }, pathsep), [[let g:seq ..= 'A']])
+    write_file(
+      table.concat({ ftdetect_folder, 'new-ft.vim' }, pathsep),
+      [[
+        let g:seq ..= 'A'
+        autocmd BufRead,BufNewFile FTDETECT let g:aseq ..= 'A'
+      ]]
+    )
     write_file(
       table.concat({ ftdetect_folder, 'new-ft.lua' }, pathsep),
-      [[vim.g.seq = vim.g.seq .. 'B']]
+      [[
+        vim.g.seq = vim.g.seq .. 'B'
+        vim.api.nvim_create_autocmd({ 'BufRead', 'BufNewFile' }, {
+          pattern = 'FTDETECT',
+          command = "let g:aseq ..= 'B'",
+        })
+      ]]
     )
     write_file(
       table.concat({ after_ftdetect_folder, 'new-ft.vim' }, pathsep),
-      [[let g:seq ..= 'a']]
+      [[
+        let g:seq ..= 'a'
+        autocmd BufRead,BufNewFile FTDETECT let g:aseq ..= 'a'
+      ]]
     )
     write_file(
       table.concat({ after_ftdetect_folder, 'new-ft.lua' }, pathsep),
-      [[vim.g.seq = vim.g.seq .. 'b']]
+      [[
+        vim.g.seq = vim.g.seq .. 'b'
+        vim.api.nvim_create_autocmd({ 'BufRead', 'BufNewFile' }, {
+          pattern = 'FTDETECT',
+          command = "let g:aseq ..= 'b'",
+        })
+      ]]
     )
     clear { args_rm = { '-u' }, args = { '--cmd', 'let g:seq = ""' }, env = xenv }
     eq('ABab', eval('g:seq'))
+    command('let g:aseq = ""')
+    command('edit FTDETECT')
+    eq('SsABab', eval('g:aseq'))
   end)
 end)