fix(utils): path_expand always use backslash for windows

doc/telescope.txt

@@ -2545,9 +2545,8 @@ utils.path_expand({path})                      *telescope.utils.path_expand()*
     non-existent paths when dealing with valid absolute paths.
 
     Other paths will have '~' and environment variables expanded. Unlike
-    `vim.fs.normalize()`, backslashes are preserved. This has better
-    compatibility with `plenary.path` and also avoids mangling valid Unix paths
-    with literal backslashes.
+    `vim.fs.normalize()`, Windows paths are converted to use backslashes for
+    compatibility with `plenary.path`.
 
     Trailing slashes are trimmed. With the exception of root paths. eg. `/` on
     Unix or `C:\` on Windows

lua/telescope/utils.lua

@@ -25,9 +25,8 @@ utils.iswin = vim.loop.os_uname().sysname == "Windows_NT"
 --- non-existent paths when dealing with valid absolute paths.
 ---
 --- Other paths will have '~' and environment variables expanded.
---- Unlike `vim.fs.normalize()`, backslashes are preserved. This has better
---- compatibility with `plenary.path` and also avoids mangling valid Unix paths
---- with literal backslashes.
+--- Unlike `vim.fs.normalize()`, Windows paths are converted to use backslashes
+--- for compatibility with `plenary.path`.
 ---
 --- Trailing slashes are trimmed. With the exception of root paths.
 --- eg. `/` on Unix or `C:\` on Windows
@@ -39,26 +38,31 @@ utils.path_expand = function(path)
     path = { path, { "string" } },
   }
 
+  if path:match "^[%%#<]" then
+    path = vim.fn.expand(path)
+  end
+
+  local os_sep = utils.get_separator()
+  if utils.iswin then
+    path = path:gsub("/", os_sep)
+  end
+
   if utils.is_uri(path) then
     return path
   end
 
-  if path:match "^[%%#<]" then
-    path = vim.fn.expand(path)
-  end
+  path = path:gsub(os_sep .. "+", os_sep)
 
   if path:sub(1, 1) == "~" then
     local home = vim.loop.os_homedir() or "~"
-    if home:sub(-1) == "\\" or home:sub(-1) == "/" then
+    if home:sub(-1) == os_sep then
       home = home:sub(1, -2)
     end
     path = home .. path:sub(2)
   end
 
   path = path:gsub("%$([%w_]+)", vim.loop.os_getenv)
-  path = path:gsub("/+", "/")
   if utils.iswin then
-    path = path:gsub("\\+", "\\")
     if path:match "^%w:\\$" then
       return path
     else

lua/tests/automated/utils_spec.lua

@@ -3,25 +3,35 @@ local utils = require "telescope.utils"
 
 local eq = assert.are.equal
 
+local os_sep = utils.get_separator()
+
+local function new_relpath(unix_path)
+  return Path:new(unpack(vim.split(unix_path, "/"))).filename
+end
+
+local function new_abspath(unix_path)
+  unix_path = unix_path:gsub("^[/]+", "")
+  return new_relpath(vim.loop.os_homedir() .. os_sep .. unix_path)
+end
+
 describe("path_expand()", function()
   it("removes trailing os_sep", function()
-    if utils.iswin then
-      eq([[C:\Users\a\b]], utils.path_expand [[C:\Users\a\b\]])
-    else
-      eq("/home/user", utils.path_expand "/home/user/")
-    end
+    local path = new_abspath "a/b"
+    eq(path, utils.path_expand(path .. os_sep))
   end)
 
   it("works with root dir", function()
     if utils.iswin then
       eq([[C:\]], utils.path_expand [[C:\]])
+      eq([[C:\]], utils.path_expand [[C:/]])
     else
       eq("/", utils.path_expand "/")
     end
   end)
 
   it("works with ~", function()
-    eq(vim.loop.os_homedir() .. "/src/foo", utils.path_expand "~/src/foo")
+    local path = new_abspath "src/foo"
+    eq(path, utils.path_expand "~/src/foo")
   end)
 
   it("handles duplicate os_sep", function()
@@ -33,11 +43,16 @@ describe("path_expand()", function()
   end)
 
   it("preserves fake whitespace characters and whitespace", function()
-    local path_space = "/home/user/hello world"
+    local path_space = new_relpath "foo/hello world"
     eq(path_space, utils.path_expand(path_space))
-    local path_newline = [[/home/user/hello\nworld]]
-    eq(path_newline, utils.path_expand(path_newline))
+
+    -- backslash is always path sep in windows
+    if not utils.iswin then
+      local path_newline = [[/home/user/hello\nworld]]
+      eq(path_newline, utils.path_expand(path_newline))
+    end
   end)
+
   describe("early return for uri", function()
     local uris = {
       [[https://www.example.com/index.html]],
@@ -58,6 +73,14 @@ describe("path_expand()", function()
       end)
     end
   end)
+
+  it("handles % expand", function()
+    eq(vim.fn.expand "%", utils.path_expand "%")
+  end)
+
+  it("handles < expand", function()
+    eq(vim.fn.expand "<cfile>", utils.path_expand "<cfile>")
+  end)
 end)
 
 describe("is_uri", function()
@@ -191,10 +214,6 @@ describe("transform_path", function()
     end
   end)()
 
-  local function new_relpath(unix_path)
-    return Path:new(unpack(vim.split(unix_path, "/"))).filename
-  end
-
   local function assert_path(path_display, path, expect)
     local opts = { cwd = cwd, __length = 15 }
     if type(path_display) == "string" then