2 files changed, 30 insertions, 1 deletions
diff --git a/runtime/filetype.lua b/runtime/filetype.lua
index 3f2a7c2960..4880ed55ef 100644
--- a/runtime/filetype.lua
+++ b/runtime/filetype.lua
@@ -11,7 +11,12 @@ vim.api.nvim_create_autocmd({ 'BufRead', 'BufNewFile', 'StdinReadPost' }, {
     if not vim.api.nvim_buf_is_valid(args.buf) then
       return
     end
-    local ft, on_detect = vim.filetype.match({ filename = args.match, buf = args.buf })
+    local ft, on_detect = vim.filetype.match({
+      -- The unexpanded file name is needed here. #27914
+      -- Neither args.file nor args.match are guaranteed to be unexpanded.
+      filename = vim.fn.bufname(args.buf),
+      buf = args.buf,
+    })
     if not ft then
       -- Generic configuration file used as fallback
       ft = require('vim.filetype.detect').conf(args.file, args.buf)
diff --git a/test/functional/lua/filetype_spec.lua b/test/functional/lua/filetype_spec.lua
index 8b0e0a8beb..3ef650a1d2 100644
--- a/test/functional/lua/filetype_spec.lua
+++ b/test/functional/lua/filetype_spec.lua
@@ -5,6 +5,10 @@ local api = helpers.api
 local clear = helpers.clear
 local pathroot = helpers.pathroot
 local command = helpers.command
+local mkdir = helpers.mkdir
+local rmdir = helpers.rmdir
+local write_file = helpers.write_file
+local uv = vim.uv
 
 local root = pathroot()
 
@@ -161,10 +165,30 @@ describe('vim.filetype', function()
 end)
 
 describe('filetype.lua', function()
+  before_each(function()
+    mkdir('Xfiletype')
+  end)
+
+  after_each(function()
+    rmdir('Xfiletype')
+  end)
+
   it('does not override user autocommands that set filetype #20333', function()
     clear({
       args = { '--clean', '--cmd', 'autocmd BufRead *.md set filetype=notmarkdown', 'README.md' },
     })
     eq('notmarkdown', api.nvim_get_option_value('filetype', {}))
   end)
+
+  it('uses unexpanded path for matching when editing a symlink #27914', function()
+    mkdir('Xfiletype/.config')
+    mkdir('Xfiletype/actual')
+    write_file('Xfiletype/actual/config', '')
+    uv.fs_symlink(assert(uv.fs_realpath('Xfiletype/actual')), 'Xfiletype/.config/git')
+    finally(function()
+      uv.fs_unlink('Xfiletype/.config/git')
+    end)
+    clear({ args = { '--clean', 'Xfiletype/.config/git/config' } })
+    eq('gitconfig', api.nvim_get_option_value('filetype', {}))
+  end)
 end)