fix(editorconfig): handle root separately from properties

Problem: A child root=false masks a parent root=true during merging.

Solution: Return the search boundary separately from string properties.
Exclude root from property callbacks and b:editorconfig.

AI-assisted

1 files changed, 15 insertions, 10 deletions

diff --git a/runtime/lua/editorconfig.lua b/runtime/lua/editorconfig.lua
index 9941a7ccdc..9ac54096e2 100644
--- a/runtime/lua/editorconfig.lua
+++ b/runtime/lua/editorconfig.lua
@@ -59,7 +59,7 @@
 
 local nvim_on = require('vim._core.util').nvim_on
 
---- @type table<string,fun(bufnr: integer, val: string, opts: table)>
+--- @type table<string,fun(bufnr: integer, val: string, opts: table<string,string>)>
 local properties = {}
 
 --- Modified version of the builtin assert that does not include error position information
@@ -82,8 +82,9 @@ end
 --- If "true", then stop searching for `.editorconfig` files in parent
 --- directories. This property must be at the top-level of the
 --- `.editorconfig` file (i.e. it must not be within a glob section).
+--- It only controls the search and is excluded from property callbacks and [b:editorconfig].
 function properties.root()
-  -- Unused
+  -- Documentation only. The parser handles root separately.
 end
 
 --- One of `"utf-8"`, `"utf-8-bom"`, `"latin1"`, `"utf-16be"`, or `"utf-16le"`.
@@ -267,13 +268,16 @@ end
 --- Parse options from an `.editorconfig` file
 --- @param filepath string File path of the file to apply EditorConfig settings to
 --- @param dir string Current directory
---- @return table<string,string|boolean> Table of options to apply to the given file
+--- @return table<string,string> options to apply to the given file
+--- @return boolean is_root Whether to stop searching parent directories
 local function parse(filepath, dir)
   local pat --- @type vim.regex?
-  local opts = {} --- @type table<string,string|boolean>
+  local opts = {} --- @type table<string,string>
+  local is_root = false
   local f = io.open(dir .. '/.editorconfig')
   if f then
     for line in f:lines() do
+      --- @cast line string
       local glob, key, val = parse_line(line)
       if glob then
         glob = glob:find('/') and (dir .. '/' .. glob:gsub('^/', '')) or ('**/' .. glob)
@@ -287,7 +291,7 @@ local function parse(filepath, dir)
       elseif key ~= nil and val ~= nil then
         if key == 'root' then
           assert(val == 'true' or val == 'false', 'root must be either "true" or "false"')
-          opts.root = val == 'true'
+          is_root = val == 'true'
         elseif pat and pat:match_str(filepath) then
           opts[key] = val
         end
@@ -295,7 +299,7 @@ local function parse(filepath, dir)
     end
     f:close()
   end
-  return opts
+  return opts, is_root
 end
 
 local M = {}
@@ -317,20 +321,21 @@ function M.config(buf)
     return
   end
 
-  local opts = {} --- @type table<string,string|boolean>
+  local opts = {} --- @type table<string,string>
   for parent in vim.fs.parents(path) do
-    for k, v in pairs(parse(path, parent)) do
+    local parent_opts, is_root = parse(path, parent)
+    for k, v in pairs(parent_opts) do
       if opts[k] == nil then
         opts[k] = v
       end
     end
 
-    if opts.root then
+    if is_root then
       break
     end
   end
 
-  local applied = {} --- @type table<string,string|boolean>
+  local applied = {} --- @type table<string,string>
   for opt, val in pairs(opts) do
     if val ~= 'unset' then
       local func = M.properties[opt]