fix(gx): visual selection, expand env vars

---
Rejected experiment: move vim.ui.open() to vim.env.open()

Problem:
`vim.ui` is where user-interface "providers" live, which can be
overridden. It would also be useful to have a "providers" namespace for
platform-specific features such as "open", clipboard, python, and the other
providers listed in `:help providers`. We could overload `vim.ui` to
serve that purpose as the single "providers" namespace, but
`vim.ui.nodejs()` for example seems awkward.

Solution:
`vim.env` currently has too narrow of a purpose. Overload it to also be
a namespace for `vim.env.open`.

diff --git a/runtime/lua/vim/_meta.lua b/runtime/lua/vim/_meta.lua
index 913f1fe20348..17d05ff37595 100644
--- a/runtime/lua/vim/_meta.lua
+++ b/runtime/lua/vim/_meta.lua
@@ -37,8 +37,28 @@ local options_info = setmetatable({}, {
   end,
 })

-vim.env = setmetatable({}, {
-  __index = function(_, k)
+vim.env = setmetatable({
+  open = setmetatable({}, {
+      __call = function(_, uri)
+        print('xxxxx'..uri)
+        return true
+      end,
+      __tostring = function()
+        local v = vim.fn.getenv('open')
+        if v == vim.NIL then
+          return nil
+        end
+        return v
+      end,
+    })
+  },
+  {
+  __index = function(t, k, ...)
+    if k == 'open' then
+      error()
+      -- vim.print({...})
+      -- return rawget(t, k)
+    end
     local v = vim.fn.getenv(k)
     if v == vim.NIL then
       return nil

3 files changed, 21 insertions, 21 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index f180471bde..b09e308e80 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -2344,28 +2344,26 @@ input({opts}, {on_confirm})                                   *vim.ui.input()*
                       entered), or `nil` if the user aborted the dialog.
 
 open({path})                                                   *vim.ui.open()*
-    Opens a path in the system's default handler. This function utilizes
-    `xdg-open`, `wslview`, `explorer`, or `open` commands depending on the
-    system to open the provided path.
+    Opens `path` with the system default handler (macOS `open`, Windows
+    `explorer.exe`, Linux `xdg-open`, …), or shows a message on failure.
 
-    Notifies the user if unsuccessful
+    Expands "~/" and environment variables in filesystem paths.
 
-    Example: >lua
+    Examples: >lua
 
      vim.ui.open("https://neovim.io/")
-
-     vim.ui.open("/path/to/file")
+     vim.ui.open("~/path/to/file")
+     vim.ui.open("$VIMRUNTIME")
 <
 
     Parameters: ~
-      • {path}  (string) Path to be opened
+      • {path}  (string) Path or URL to open
 
     Return: ~
-        SystemCompleted|nil result Result of command, if an appropriate one
-        could be found.
+        SystemCompleted|nil result Command result, or nil if not found.
 
     See also: ~
-      • |vim.system|
+      • |vim.system()|
 
 select({items}, {opts}, {on_choice})                         *vim.ui.select()*
     Prompts the user to pick from a list of items, allowing arbitrary
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index ed797f94ba..24e9dc917b 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -105,10 +105,10 @@ The following new APIs and features were added.
   https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint
 
 • Bundled treesitter parser and queries (highlight, folds) for Markdown,
-Python, and Bash.
+  Python, and Bash.
 
 • |vim.ui.open()| opens URIs using the system default handler (macOS `open`,
-Windows `explorer`, Linux `xdg-open`, etc.)
+  Windows `explorer`, Linux `xdg-open`, etc.)
 
 ==============================================================================
 CHANGED FEATURES                                                 *news-changed*
@@ -146,8 +146,9 @@ The following changes to existing APIs or features add new behavior.
 
 • |:Man| now respects 'wrapmargin'
 
-• The |gx| command now uses |vim.ui.open()| and not netrw. Continue using
-netrw with `vim.g.use_lua_gx = false`.
+• |gx| now uses |vim.ui.open()| and not netrw. To customize, you can redefine
+  `vim.ui.open` or remap `gx`. To continue using netrw (deprecated): >vim
+  :call netrw#BrowseX(expand(exists("g:netrw_gx")? g:netrw_gx : '<cfile>'), netrw#CheckIfRemote())<CR>
 
 ==============================================================================
 REMOVED FEATURES                                                 *news-removed*
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index de1c21b310..956c37fc0f 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -98,13 +98,14 @@ g8			Print the hex values of the bytes used in the
 			command won't move the cursor.
 
 							*gx*
-gx			Open the current path or URL under the cursor in the 
-			system's default handler with |vim.ui.open|.
+gx			Opens the current filepath or URL (decided by
+			|<cfile>|, 'isfname') at cursor using the system
+			default handler, by calling |vim.ui.open()|.
+
+							*v_gx*
+{Visual}gx		Opens the selected text using the system default
+			handler, by calling |vim.ui.open()|.
 
-			To use the netrw keymap, set `use_lua_gx` to false:
->lua
-    vim.g.use_lua_gx = false
-<
 						*:p* *:pr* *:print* *E749*
 :[range]p[rint] [flags]
 			Print [range] lines (default current line).