refactor: deprecate util.path.is_absolute

Work on #2079.

lua/lspconfig/util.lua

@@ -111,16 +111,6 @@ M.path = (function()
     end
   end
 
-  --- @param filename string
-  --- @return boolean
-  local function is_absolute(filename)
-    if iswin then
-      return filename:match '^%a:' or filename:match '^\\\\'
-    else
-      return filename:match '^/'
-    end
-  end
-
   local function path_join(...)
     return table.concat(M.tbl_flatten { ... }, '/')
   end
@@ -180,7 +170,6 @@ M.path = (function()
 
   return {
     escape_wildcards = escape_wildcards,
-    is_absolute = is_absolute,
     join = path_join,
     traverse_parents = traverse_parents,
     iterate_parents = iterate_parents,
@@ -370,6 +359,13 @@ M.path.dirname = vim.fs.dirname
 --- @deprecated use `vim.fs.normalize` instead
 M.path.sanitize = vim.fs.normalize
 
+--- @deprecated use `vim.fn.isabsolutepath(filename) == 1` instead
+--- @param filename string
+--- @return boolean
+function M.path.is_absolute(filename)
+  return vim.fn.isabsolutepath(filename) == 1
+end
+
 --- @deprecated use `vim.loop.fs_stat` instead
 --- @param filename string
 --- @return string|false

test/lspconfig_spec.lua

@@ -25,19 +25,6 @@ describe('lspconfig', function()
         end)
       end)
 
-      describe('is_absolute', function()
-        it('is absolute', function()
-          local lspconfig = require 'lspconfig'
-          eq(true, lspconfig.util.path.is_absolute '/foo/bar' ~= nil)
-        end)
-
-        it('is not absolute', function()
-          local lspconfig = require 'lspconfig'
-          assert.is_nil(lspconfig.util.path.is_absolute 'foo/bar')
-          assert.is_nil(lspconfig.util.path.is_absolute '../foo/bar')
-        end)
-      end)
-
       describe('join', function()
         it('', function()
           local lspconfig = require 'lspconfig'