refactor: remove vim.g.oil declarative config

Problem: the `vim.g.oil` configuration path was added prematurely.
It adds a second config entrypoint before the plugin has stabilized
enough to justify it.

Solution: remove `vim.g.oil` support from `plugin/oil.lua`,
`config.setup()`, docs, and tests. Users configure via
`require("oil").setup({})`.

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -70,8 +70,8 @@ body:
           spec = {
             {
               'barrettruth/canola.nvim',
-              init = function()
-                vim.g.oil = {}
+              config = function()
+                require('oil').setup({})
               end,
             },
           },

doc/oil.txt

@@ -48,25 +48,12 @@ REQUIREMENTS                                                    *oil-requirement
 --------------------------------------------------------------------------------
 CONFIG                                                                *oil-config*
 
-Oil can be configured in two ways:
-
-1. The traditional `setup()` call: >lua
+Configure oil via `setup()`: >lua
     require("oil").setup({
       -- your opts here
     })
 <
 
-2. Declarative configuration via `vim.g.oil`, which does not require calling
-   `setup()`: >lua
-    vim.g.oil = {
-      -- your opts here
-    }
-<
-
-   When `vim.g.oil` is set, oil initializes automatically during plugin
-   loading. If `setup()` is called with explicit opts, those take precedence
-   over `vim.g.oil`.
-
 The full list of options with their defaults:
 
 >lua

doc/upstream.md

@@ -33,7 +33,7 @@ issues against this fork.
 ## Issues
 
 | Issue                                                   | Description                                                | Status                                                                                                      |
-| ------------------------------------------------------- | ---------------------------------------------------------- | --------------------------------------------------------------------------------------------- |
+| ------------------------------------------------------- | ---------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------- |
 | [#85](https://github.com/stevearc/oil.nvim/issues/85)   | Git status column                                          | open                                                                                                        |
 | [#95](https://github.com/stevearc/oil.nvim/issues/95)   | Undo after renaming files                                  | open                                                                                                        |
 | [#117](https://github.com/stevearc/oil.nvim/issues/117) | Move file into new dir via slash in name                   | open                                                                                                        |

lua/oil/config.lua

@@ -422,7 +422,7 @@ local M = {}
 ---@field border? string|string[] Window border
 
 M.setup = function(opts)
-  opts = opts or vim.g.oil or {}
+  opts = opts or {}
 
   local new_conf = vim.tbl_deep_extend('keep', opts, default_config)
   if not new_conf.use_default_keymaps then

plugin/oil.lua

@@ -1,3 +1 @@
-if vim.g.oil ~= nil then
-  require('oil').setup()
-end
+

spec/config_spec.lua

@@ -1,27 +1,15 @@
 local config = require('oil.config')
 
 describe('config', function()
-  after_each(function()
-    vim.g.oil = nil
-  end)
-
-  it('falls back to vim.g.oil when setup() is called with no args', function()
-    vim.g.oil = { delete_to_trash = true, cleanup_delay_ms = 5000 }
-    config.setup()
-    assert.is_true(config.delete_to_trash)
-    assert.equals(5000, config.cleanup_delay_ms)
-  end)
-
-  it('uses defaults when neither opts nor vim.g.oil is set', function()
-    vim.g.oil = nil
+  it('uses defaults when setup() is called with no args', function()
     config.setup()
     assert.is_false(config.delete_to_trash)
     assert.equals(2000, config.cleanup_delay_ms)
   end)
 
-  it('prefers explicit opts over vim.g.oil', function()
-    vim.g.oil = { delete_to_trash = true }
-    config.setup({ delete_to_trash = false })
-    assert.is_false(config.delete_to_trash)
+  it('applies explicit opts', function()
+    config.setup({ delete_to_trash = true, cleanup_delay_ms = 5000 })
+    assert.is_true(config.delete_to_trash)
+    assert.equals(5000, config.cleanup_delay_ms)
   end)
 end)