Open vim-plug window in a new tab (#1274)

* Open vim-plug window in a new tab not to disrupt the current window layout
* Open preview window on the right to better show the diff

If you prefer the old layout, use the following configuration:

    let g:plug_window = 'vertical topleft new'
    let g:plug_pwindow = 'above 12new'

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: junegunn

.github/ISSUE_TEMPLATE.md

@@ -10,7 +10,12 @@ Explain the problem here ...
 
 ------------------------------
 
-<!-- Put the contents of `:version` below -->
+<!-- Paste your Plug block (from `call plug#begin()` to `call plug#end()`) -->
+```
+
+```
+
+<!-- Paste the contents of `:version` below -->
 ```
 
 ```
@@ -24,7 +29,7 @@ Explain the problem here ...
 - OS:
     - [ ] All/Other
     - [ ] Linux
-    - [ ] OS X
+    - [ ] macOS
     - [ ] Windows
 - Vim:
     - [ ] Terminal Vim

.gitignore

@@ -0,0 +1 @@
+doc/tags

README.md

@@ -1,5 +1,30 @@
-<img src="https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.png" height="75" alt="vim-plug">[![travis-ci](https://travis-ci.org/junegunn/vim-plug.svg?branch=master)](https://travis-ci.org/junegunn/vim-plug)
-===
+<div align="center">
+<sup>Special thanks to:</sup>
+<br>
+<br>
+<a href="https://warp.dev/?utm_source=github&utm_medium=referral&utm_campaign=vimplug_20240209">
+  <div>
+    <img src="https://raw.githubusercontent.com/junegunn/i/master/warp.png" width="300" alt="Warp">
+  </div>
+  <b>Warp is a modern, Rust-based terminal with AI built in so you and your team can build great software, faster.</b>
+  <div>
+    <sup>Visit warp.dev to learn more.</sup>
+  </div>
+</a>
+<br>
+<hr>
+</div>
+<br>
+
+<h1 title="vim-plug">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" srcset="./plug-dark.png">
+    <img src="./plug.png" height="75" alt="vim-plug">
+  </picture>
+  <a href="https://github.com/junegunn/vim-plug/actions/workflows/test.yml?query=branch%3Amaster">
+    <img src="https://img.shields.io/github/actions/workflow/status/junegunn/vim-plug/test.yml?branch=master">
+  </a>
+</h1>
 
 A minimalist Vim plugin manager.
 
@@ -117,7 +142,7 @@ Plug 'https://github.com/junegunn/vim-github-dashboard.git'
 Plug 'SirVer/ultisnips' | Plug 'honza/vim-snippets'
 
 " On-demand loading
-Plug 'scrooloose/nerdtree', { 'on':  'NERDTreeToggle' }
+Plug 'preservim/nerdtree', { 'on': 'NERDTreeToggle' }
 Plug 'tpope/vim-fireplace', { 'for': 'clojure' }
 
 " Using a non-default branch
@@ -136,11 +161,62 @@ Plug 'junegunn/fzf', { 'dir': '~/.fzf', 'do': './install --all' }
 Plug '~/my-prototype-plugin'
 
 " Initialize plugin system
+" - Automatically executes `filetype plugin indent on` and `syntax enable`.
 call plug#end()
+" You can revert the settings after the call like so:
+"   filetype indent off   " Disable file-type-specific indentation
+"   syntax off            " Disable syntax highlighting
 ```
 
 Reload .vimrc and `:PlugInstall` to install plugins.
 
+#### Example (Lua configuration for Neovim)
+
+In Neovim, you can write your configuration in a Lua script file named
+`init.lua`. The following code is the Lua script equivalent to the VimScript
+example above.
+
+```lua
+local vim = vim
+local Plug = vim.fn['plug#']
+
+vim.call('plug#begin')
+
+-- Shorthand notation; fetches https://github.com/junegunn/vim-easy-align
+Plug('junegunn/vim-easy-align')
+
+-- Any valid git URL is allowed
+Plug('https://github.com/junegunn/vim-github-dashboard.git')
+
+-- Multiple Plug commands can be written in a single line using ; separators
+Plug('SirVer/ultisnips'); Plug('honza/vim-snippets')
+
+-- On-demand loading
+Plug('preservim/nerdtree', { ['on'] = 'NERDTreeToggle' })
+Plug('tpope/vim-fireplace', { ['for'] = 'clojure' })
+
+-- Using a non-default branch
+Plug('rdnetto/YCM-Generator', { ['branch'] = 'stable' })
+
+-- Using a tagged release; wildcard allowed (requires git 1.9.2 or above)
+Plug('fatih/vim-go', { ['tag'] = '*' })
+
+-- Plugin options
+Plug('nsf/gocode', { ['tag'] = 'v.20150303', ['rtp'] = 'vim' })
+
+-- Plugin outside ~/.vim/plugged with post-update hook
+Plug('junegunn/fzf', { ['dir'] = '~/.fzf', ['do'] = './install --all' })
+
+-- Unmanaged plugin (manually installed and updated)
+Plug('~/my-prototype-plugin')
+
+vim.call('plug#end')
+```
+
+More examples can be found in:
+
+* https://gitlab.com/sultanahamer/dotfiles/-/blob/master/nvim/lua/plugins.lua?ref_type=heads
+
 ### Commands
 
 | Command                             | Description                                                        |
@@ -174,8 +250,8 @@ Reload .vimrc and `:PlugInstall` to install plugins.
 | `g:plug_timeout`    | 60                                | Time limit of each task in seconds (*Ruby & Python*)   |
 | `g:plug_retries`    | 2                                 | Number of retries in case of timeout (*Ruby & Python*) |
 | `g:plug_shallow`    | 1                                 | Use shallow clone                                      |
-| `g:plug_window`     | `vertical topleft new`            | Command to open plug window                            |
-| `g:plug_pwindow`    | `above 12new`                     | Command to open preview window in `PlugDiff`           |
+| `g:plug_window`     | `-tabnew`                         | Command to open plug window                            |
+| `g:plug_pwindow`    | `vertical rightbelow new`         | Command to open preview window in `PlugDiff`           |
 | `g:plug_url_format` | `https://git::@github.com/%s.git` | `printf` format to build repo URL (Only applies to the subsequent `Plug` commands) |
 
 
@@ -203,7 +279,7 @@ call plug#end()
 
 ```vim
 " NERD tree will be loaded on the first invocation of NERDTreeToggle command
-Plug 'scrooloose/nerdtree', { 'on': 'NERDTreeToggle' }
+Plug 'preservim/nerdtree', { 'on': 'NERDTreeToggle' }
 
 " Multiple commands
 Plug 'junegunn/vim-github-dashboard', { 'on': ['GHDashboard', 'GHActivity'] }
@@ -242,8 +318,14 @@ If the value starts with `:`, it will be recognized as a Vim command.
 Plug 'fatih/vim-go', { 'do': ':GoInstallBinaries' }
 ```
 
+To call a Vim function, you can pass a lambda expression like so:
+
+```vim
+Plug 'junegunn/fzf', { 'do': { -> fzf#install() } }
+```
+
 If you need more control, you can pass a reference to a Vim function that
-takes a single argument.
+takes a dictionary argument.
 
 ```vim
 function! BuildYCM(info)
@@ -259,14 +341,13 @@ endfunction
 Plug 'ycm-core/YouCompleteMe', { 'do': function('BuildYCM') }
 ```
 
-Both forms of post-update hook are executed inside the directory of the plugin
-and only run when the repository has changed, but you can force it to run
-unconditionally with the bang-versions of the commands: `PlugInstall!` and
-`PlugUpdate!`.
+A post-update hook is executed inside the directory of the plugin and only run
+when the repository has changed, but you can force it to run unconditionally
+with the bang-versions of the commands: `PlugInstall!` and `PlugUpdate!`.
 
-Make sure to escape BARs and double-quotes when you write the `do` option inline
-as they are mistakenly recognized as command separator or the start of the
-trailing comment.
+Make sure to escape BARs and double-quotes when you write the `do` option
+inline as they are mistakenly recognized as command separator or the start of
+the trailing comment.
 
 ```vim
 Plug 'junegunn/fzf', { 'do': 'yes \| ./install' }

doc/plug.txt

@@ -1,4 +1,4 @@
-plug.txt	plug	Last change: January 3 2022
+plug.txt	plug	Last change: March 7 2024
 PLUG - TABLE OF CONTENTS                                         *plug* *plug-toc*
 ==============================================================================
 
@@ -153,7 +153,7 @@ Example~
     Plug 'SirVer/ultisnips' | Plug 'honza/vim-snippets'
 
     " On-demand loading
-    Plug 'scrooloose/nerdtree', { 'on':  'NERDTreeToggle' }
+    Plug 'preservim/nerdtree', { 'on': 'NERDTreeToggle' }
     Plug 'tpope/vim-fireplace', { 'for': 'clojure' }
 
     " Using a non-default branch
@@ -172,7 +172,11 @@ Example~
     Plug '~/my-prototype-plugin'
 
     " Initialize plugin system
+    " - Automatically executes `filetype plugin indent on` and `syntax enable`.
     call plug#end()
+    " You can revert the settings after the call like so:
+    "   filetype indent off   " Disable file-type-specific indentation
+    "   syntax off            " Disable syntax highlighting
 <
                                                                   *:PlugInstall*
 
@@ -226,8 +230,8 @@ Reload .vimrc and `:PlugInstall` to install plugins.
   `g:plug_timeout`     | 60                                | Time limit of each task in seconds (Ruby & Python)
   `g:plug_retries`     | 2                                 | Number of retries in case of timeout (Ruby & Python)
   `g:plug_shallow`     | 1                                 | Use shallow clone
-  `g:plug_window`      |  `vertical topleft new`             | Command to open plug window
-  `g:plug_pwindow`     |  `above 12new`                      | Command to open preview window in  `PlugDiff`
+  `g:plug_window`      |  `-tabnew`                          | Command to open plug window
+  `g:plug_pwindow`     |  `vertical rightbelow new`          | Command to open preview window in  `PlugDiff`
   `g:plug_url_format`  |  `https://git::@github.com/%s.git`  |  `printf`  format to build repo URL (Only applies to the subsequent  `Plug`  commands)
  --------------------+-----------------------------------+-----------------------------------------------------------------------------------
 
@@ -260,7 +264,7 @@ Reload .vimrc and `:PlugInstall` to install plugins.
                                              *plug-on-demand-loading-of-plugins*
 >
     " NERD tree will be loaded on the first invocation of NERDTreeToggle command
-    Plug 'scrooloose/nerdtree', { 'on': 'NERDTreeToggle' }
+    Plug 'preservim/nerdtree', { 'on': 'NERDTreeToggle' }
 
     " Multiple commands
     Plug 'junegunn/vim-github-dashboard', { 'on': ['GHDashboard', 'GHActivity'] }
@@ -293,13 +297,15 @@ In that case, use the `do` option to describe the task to be performed.
     Plug 'ycm-core/YouCompleteMe', { 'do': './install.py' }
 <
 If the value starts with `:`, it will be recognized as a Vim command.
-
-                                                            *:GoInstallBinaries*
 >
     Plug 'fatih/vim-go', { 'do': ':GoInstallBinaries' }
 <
+To call a Vim function, you can pass a lambda expression like so:
+>
+    Plug 'junegunn/fzf', { 'do': { -> fzf#install() } }
+<
 If you need more control, you can pass a reference to a Vim function that
-takes a single argument.
+takes a dictionary argument.
 >
     function! BuildYCM(info)
       " info is a dictionary with 3 fields
@@ -313,10 +319,9 @@ takes a single argument.
 
     Plug 'ycm-core/YouCompleteMe', { 'do': function('BuildYCM') }
 <
-Both forms of post-update hook are executed inside the directory of the plugin
-and only run when the repository has changed, but you can force it to run
-unconditionally with the bang-versions of the commands: `PlugInstall!` and
-`PlugUpdate!`.
+A post-update hook is executed inside the directory of the plugin and only run
+when the repository has changed, but you can force it to run unconditionally
+with the bang-versions of the commands: `PlugInstall!` and `PlugUpdate!`.
 
 Make sure to escape BARs and double-quotes when you write the `do` option
 inline as they are mistakenly recognized as command separator or the start of

plug.vim

@@ -22,7 +22,7 @@
 "   Plug 'SirVer/ultisnips' | Plug 'honza/vim-snippets'
 "
 "   " On-demand loading
-"   Plug 'scrooloose/nerdtree', { 'on':  'NERDTreeToggle' }
+"   Plug 'preservim/nerdtree', { 'on': 'NERDTreeToggle' }
 "   Plug 'tpope/vim-fireplace', { 'for': 'clojure' }
 "
 "   " Using a non-default branch
@@ -352,7 +352,7 @@ function! plug#end()
   endif
   let lod = { 'ft': {}, 'map': {}, 'cmd': {} }
 
-  if exists('g:did_load_filetypes')
+  if get(g:, 'did_load_filetypes', 0)
     filetype off
   endif
   for name in g:plugs_order
@@ -391,6 +391,9 @@ function! plug#end()
       if !empty(types)
         augroup filetypedetect
         call s:source(s:rtp(plug), 'ftdetect/**/*.vim', 'after/ftdetect/**/*.vim')
+        if has('nvim-0.5.0')
+          call s:source(s:rtp(plug), 'ftdetect/**/*.lua', 'after/ftdetect/**/*.lua')
+        endif
         augroup END
       endif
       for type in types
@@ -438,6 +441,9 @@ endfunction
 
 function! s:load_plugin(spec)
   call s:source(s:rtp(a:spec), 'plugin/**/*.vim', 'after/plugin/**/*.vim')
+  if has('nvim-0.5.0')
+    call s:source(s:rtp(a:spec), 'plugin/**/*.lua', 'after/plugin/**/*.lua')
+  endif
 endfunction
 
 function! s:reload_plugins()
@@ -655,6 +661,9 @@ function! s:lod(names, types, ...)
     let rtp = s:rtp(g:plugs[name])
     for dir in a:types
       call s:source(rtp, dir.'/**/*.vim')
+      if has('nvim-0.5.0')  " see neovim#14686
+        call s:source(rtp, dir.'/**/*.lua')
+      endif
     endfor
     if a:0
       if !s:source(rtp, a:1) && !empty(s:glob(rtp, a:2))
@@ -869,7 +878,7 @@ function! s:lastline(msg)
 endfunction
 
 function! s:new_window()
-  execute get(g:, 'plug_window', 'vertical topleft new')
+  execute get(g:, 'plug_window', '-tabnew')
 endfunction
 
 function! s:plug_window_exists()
@@ -1031,6 +1040,11 @@ function! s:is_updated(dir)
 endfunction
 
 function! s:do(pull, force, todo)
+  if has('nvim')
+    " Reset &rtp to invalidate Neovim cache of loaded Lua modules
+    " See https://github.com/junegunn/vim-plug/pull/1157#issuecomment-1809226110
+    let &rtp = &rtp
+  endif
   for [name, spec] in items(a:todo)
     if !isdirectory(spec.dir)
       continue
@@ -1092,12 +1106,14 @@ endfunction
 function! s:checkout(spec)
   let sha = a:spec.commit
   let output = s:git_revision(a:spec.dir)
+  let error = 0
   if !empty(output) && !s:hash_match(sha, s:lines(output)[0])
     let credential_helper = s:git_version_requirement(2) ? '-c credential.helper= ' : ''
     let output = s:system(
           \ 'git '.credential_helper.'fetch --depth 999999 && git checkout '.plug#shellescape(sha).' --', a:spec.dir)
+    let error = v:shell_error
   endif
-  return output
+  return [output, error]
 endfunction
 
 function! s:finish(pull)
@@ -1158,7 +1174,7 @@ function! s:update_impl(pull, force, args) abort
   let threads = (len(args) > 0 && args[-1] =~ '^[1-9][0-9]*$') ?
                   \ remove(args, -1) : get(g:, 'plug_threads', 16)
 
-  let managed = filter(copy(g:plugs), 's:is_managed(v:key)')
+  let managed = filter(deepcopy(g:plugs), 's:is_managed(v:key)')
   let todo = empty(args) ? filter(managed, '!v:val.frozen || !isdirectory(v:val.dir)') :
                          \ filter(managed, 'index(args, v:key) >= 0')
 
@@ -1292,9 +1308,11 @@ function! s:update_finish()
       if !pos
         continue
       endif
+      let out = ''
+      let error = 0
       if has_key(spec, 'commit')
         call s:log4(name, 'Checking out '.spec.commit)
-        let out = s:checkout(spec)
+        let [out, error] = s:checkout(spec)
       elseif has_key(spec, 'tag')
         let tag = spec.tag
         if tag =~ '\*'
@@ -1307,19 +1325,16 @@ function! s:update_finish()
         endif
         call s:log4(name, 'Checking out '.tag)
         let out = s:system('git checkout -q '.plug#shellescape(tag).' -- 2>&1', spec.dir)
-      else
-        let branch = s:git_origin_branch(spec)
-        call s:log4(name, 'Merging origin/'.s:esc(branch))
-        let out = s:system('git checkout -q '.plug#shellescape(branch).' -- 2>&1'
-              \. (has_key(s:update.new, name) ? '' : ('&& git merge --ff-only '.plug#shellescape('origin/'.branch).' 2>&1')), spec.dir)
+        let error = v:shell_error
       endif
-      if !v:shell_error && filereadable(spec.dir.'/.gitmodules') &&
+      if !error && filereadable(spec.dir.'/.gitmodules') &&
             \ (s:update.force || has_key(s:update.new, name) || s:is_updated(spec.dir))
         call s:log4(name, 'Updating submodules. This may take a while.')
         let out .= s:bang('git submodule update --init --recursive'.s:submodule_opt.' 2>&1', spec.dir)
+        let error = v:shell_error
       endif
       let msg = s:format_message(v:shell_error ? 'x': '-', name, out)
-      if v:shell_error
+      if error
         call add(s:update.errors, name)
         call s:regress_bar()
         silent execute pos 'd _'
@@ -1382,7 +1397,9 @@ function! s:job_out_cb(self, data) abort
   if !self.running || self.tick % len(s:jobs) == 0
     let bullet = self.running ? (self.new ? '+' : '*') : (self.error ? 'x' : '-')
     let result = self.error ? join(self.lines, "\n") : s:last_non_empty_line(self.lines)
-    call s:log(bullet, self.name, result)
+    if len(result)
+      call s:log(bullet, self.name, result)
+    endif
   endif
 endfunction
 
@@ -1406,16 +1423,17 @@ function! s:nvim_cb(job_id, data, event) dict abort
     \ s:job_cb('s:job_exit_cb', self, 0, a:data)
 endfunction
 
-function! s:spawn(name, cmd, opts)
-  let job = { 'name': a:name, 'running': 1, 'error': 0, 'lines': [''],
-            \ 'new': get(a:opts, 'new', 0) }
+function! s:spawn(name, spec, queue, opts)
+  let job = { 'name': a:name, 'spec': a:spec, 'running': 1, 'error': 0, 'lines': [''],
+            \ 'new': get(a:opts, 'new', 0), 'queue': copy(a:queue) }
+  let Item = remove(job.queue, 0)
+  let argv = type(Item) == s:TYPE.funcref ? call(Item, [a:spec]) : Item
   let s:jobs[a:name] = job
 
   if s:nvim
     if has_key(a:opts, 'dir')
       let job.cwd = a:opts.dir
     endif
-    let argv = a:cmd
     call extend(job, {
     \ 'on_stdout': function('s:nvim_cb'),
     \ 'on_stderr': function('s:nvim_cb'),
@@ -1431,7 +1449,7 @@ function! s:spawn(name, cmd, opts)
             \ 'Invalid arguments (or job table is full)']
     endif
   elseif s:vim8
-    let cmd = join(map(copy(a:cmd), 'plug#shellescape(v:val, {"script": 0})'))
+    let cmd = join(map(copy(argv), 'plug#shellescape(v:val, {"script": 0})'))
     if has_key(a:opts, 'dir')
       let cmd = s:with_cd(cmd, a:opts.dir, 0)
     endif
@@ -1451,27 +1469,34 @@ function! s:spawn(name, cmd, opts)
       let job.lines   = ['Failed to start job']
     endif
   else
-    let job.lines = s:lines(call('s:system', has_key(a:opts, 'dir') ? [a:cmd, a:opts.dir] : [a:cmd]))
+    let job.lines = s:lines(call('s:system', has_key(a:opts, 'dir') ? [argv, a:opts.dir] : [argv]))
     let job.error = v:shell_error != 0
     let job.running = 0
   endif
 endfunction
 
 function! s:reap(name)
-  let job = s:jobs[a:name]
+  let job = remove(s:jobs, a:name)
   if job.error
     call add(s:update.errors, a:name)
   elseif get(job, 'new', 0)
     let s:update.new[a:name] = 1
   endif
-  let s:update.bar .= job.error ? 'x' : '='
 
-  let bullet = job.error ? 'x' : '-'
+  let more = len(get(job, 'queue', []))
+  let bullet = job.error ? 'x' : more ? (job.new ? '+' : '*') : '-'
   let result = job.error ? join(job.lines, "\n") : s:last_non_empty_line(job.lines)
-  call s:log(bullet, a:name, empty(result) ? 'OK' : result)
-  call s:bar()
+  if len(result)
+    call s:log(bullet, a:name, result)
+  endif
 
-  call remove(s:jobs, a:name)
+  if !job.error && more
+    let job.spec.queue = job.queue
+    let s:update.todo[a:name] = job.spec
+  else
+    let s:update.bar .= job.error ? 'x' : '='
+    call s:bar()
+  endif
 endfunction
 
 function! s:bar()
@@ -1524,6 +1549,16 @@ function! s:update_vim()
   call s:tick()
 endfunction
 
+function! s:checkout_command(spec)
+  let a:spec.branch = s:git_origin_branch(a:spec)
+  return ['git', 'checkout', '-q', a:spec.branch, '--']
+endfunction
+
+function! s:merge_command(spec)
+  let a:spec.branch = s:git_origin_branch(a:spec)
+  return ['git', 'merge', '--ff-only', 'origin/'.a:spec.branch]
+endfunction
+
 function! s:tick()
   let pull = s:update.pull
   let prog = s:progress_opt(s:nvim || s:vim8)
@@ -1538,13 +1573,18 @@ while 1 " Without TCO, Vim stack is bound to explode
 
   let name = keys(s:update.todo)[0]
   let spec = remove(s:update.todo, name)
-  let new  = empty(globpath(spec.dir, '.git', 1))
+  let queue = get(spec, 'queue', [])
+  let new = empty(globpath(spec.dir, '.git', 1))
 
-  call s:log(new ? '+' : '*', name, pull ? 'Updating ...' : 'Installing ...')
-  redraw
+  if empty(queue)
+    call s:log(new ? '+' : '*', name, pull ? 'Updating ...' : 'Installing ...')
+    redraw
+  endif
 
   let has_tag = has_key(spec, 'tag')
-  if !new
+  if len(queue)
+    call s:spawn(name, spec, queue, { 'dir': spec.dir })
+  elseif !new
     let [error, _] = s:git_validate(spec, 0)
     if empty(error)
       if pull
@@ -1555,7 +1595,11 @@ while 1 " Without TCO, Vim stack is bound to explode
         if !empty(prog)
           call add(cmd, prog)
         endif
-        call s:spawn(name, cmd, { 'dir': spec.dir })
+        let queue = [cmd, split('git remote set-head origin -a')]
+        if !has_tag && !has_key(spec, 'commit')
+          call extend(queue, [function('s:checkout_command'), function('s:merge_command')])
+        endif
+        call s:spawn(name, spec, queue, { 'dir': spec.dir })
       else
         let s:jobs[name] = { 'running': 0, 'lines': ['Already installed'], 'error': 0 }
       endif
@@ -1570,7 +1614,7 @@ while 1 " Without TCO, Vim stack is bound to explode
     if !empty(prog)
       call add(cmd, prog)
     endif
-    call s:spawn(name, extend(cmd, [spec.uri, s:trim(spec.dir)]), { 'new': 1 })
+    call s:spawn(name, spec, [extend(cmd, [spec.uri, s:trim(spec.dir)]), function('s:checkout_command'), function('s:merge_command')], { 'new': 1 })
   endif
 
   if !s:jobs[name].running
@@ -2346,18 +2390,21 @@ function! s:git_validate(spec, check_branch)
               \ current_branch, origin_branch)
       endif
       if empty(err)
-        let [ahead, behind] = split(s:lastline(s:system([
-        \ 'git', 'rev-list', '--count', '--left-right',
-        \ printf('HEAD...origin/%s', origin_branch)
-        \ ], a:spec.dir)), '\t')
-        if !v:shell_error && ahead
-          if behind
+        let ahead_behind = split(s:lastline(s:system([
+          \ 'git', 'rev-list', '--count', '--left-right',
+          \ printf('HEAD...origin/%s', origin_branch)
+          \ ], a:spec.dir)), '\t')
+        if v:shell_error || len(ahead_behind) != 2
+          let err = "Failed to compare with the origin. The default branch might have changed.\nPlugClean required."
+        else
+          let [ahead, behind] = ahead_behind
+          if ahead && behind
             " Only mention PlugClean if diverged, otherwise it's likely to be
             " pushable (and probably not that messed up).
             let err = printf(
                   \ "Diverged from origin/%s (%d commit(s) ahead and %d commit(s) behind!\n"
                   \ .'Backup local changes and run PlugClean and PlugUpdate to reinstall it.', origin_branch, ahead, behind)
-          else
+          elseif ahead
             let err = printf("Ahead of origin/%s by %d commit(s).\n"
                   \ .'Cannot update until local changes are pushed.',
                   \ origin_branch, ahead)
@@ -2621,26 +2668,34 @@ function! s:preview_commit()
 
   let sha = matchstr(getline('.'), '^  \X*\zs[0-9a-f]\{7,9}')
   if empty(sha)
-    return
+    let name = matchstr(getline('.'), '^- \zs[^:]*\ze:$')
+    if empty(name)
+      return
+    endif
+    let title = 'HEAD@{1}..'
+    let command = 'git diff --no-color HEAD@{1}'
+  else
+    let title = sha
+    let command = 'git show --no-color --pretty=medium '.sha
+    let name = s:find_name(line('.'))
   endif
 
-  let name = s:find_name(line('.'))
   if empty(name) || !has_key(g:plugs, name) || !isdirectory(g:plugs[name].dir)
     return
   endif
 
-  if exists('g:plug_pwindow') && !s:is_preview_window_open()
-    execute g:plug_pwindow
-    execute 'e' sha
+  if !s:is_preview_window_open()
+    execute get(g:, 'plug_pwindow', 'vertical rightbelow new')
+    execute 'e' title
   else
-    execute 'pedit' sha
+    execute 'pedit' title
     wincmd P
   endif
-  setlocal previewwindow filetype=git buftype=nofile nobuflisted modifiable
+  setlocal previewwindow filetype=git buftype=nofile bufhidden=wipe nobuflisted modifiable
   let batchfile = ''
   try
     let [sh, shellcmdflag, shrd] = s:chsh(1)
-    let cmd = 'cd '.plug#shellescape(g:plugs[name].dir).' && git show --no-color --pretty=medium '.sha
+    let cmd = 'cd '.plug#shellescape(g:plugs[name].dir).' && '.command
     if s:is_win
       let [batchfile, cmd] = s:batchfile(cmd)
     endif
@@ -2766,9 +2821,9 @@ function! s:snapshot(force, ...) abort
   1
   let anchor = line('$') - 3
   let names = sort(keys(filter(copy(g:plugs),
-        \'has_key(v:val, "uri") && !has_key(v:val, "commit") && isdirectory(v:val.dir)')))
+        \'has_key(v:val, "uri") && isdirectory(v:val.dir)')))
   for name in reverse(names)
-    let sha = s:git_revision(g:plugs[name].dir)
+    let sha = has_key(g:plugs[name], 'commit') ? g:plugs[name].commit : s:git_revision(g:plugs[name].dir)
     if !empty(sha)
       call append(anchor, printf("silent! let g:plugs['%s'].commit = '%s'", name, sha))
       redraw

test/run

@@ -62,7 +62,7 @@ EOF
 
 gitinit() (
   cd "$PLUG_FIXTURES/$1"
-  git init
+  git init -b master
   git commit -m 'commit' --allow-empty
 )
 
@@ -98,7 +98,7 @@ DOC
 
   rm -rf $TEMP/new-branch
   cd $TEMP
-  git init new-branch
+  git init new-branch -b master
   cd new-branch
   mkdir plugin
   echo 'let g:foo = 1' > plugin/foo.vim

test/workflow.vader

@@ -371,6 +371,9 @@ Execute (PlugDiff - 'No updates.'):
   q
 
 Execute (New commits on remote, PlugUpdate, then PlugDiff):
+  let g:plug_window = 'vertical topleft new'
+  let g:plug_pwindow = 'above 12new'
+
   for repo in ['seoul256.vim', 'vim-emoji']
     for _ in range(2)
       call system(printf('cd /tmp/vim-plug-test/junegunn/%s && git commit --allow-empty -m "update"', repo))
@@ -393,6 +396,14 @@ Execute (New commits on remote, PlugUpdate, then PlugDiff):
   let lnum = line('.')
   AssertEqual 3, col('.')
 
+  " Open full diff (empty)
+  execute "normal \<cr>"
+  wincmd P
+  AssertEqual 1, &previewwindow
+  AssertEqual 'git', &filetype
+  AssertEqual [''], getline(1, '$')
+  pclose
+
   " Open commit preview
   execute "normal j\<cr>"
   wincmd P
@@ -450,6 +461,8 @@ Execute (New commits on remote, PlugUpdate, then PlugDiff):
   AssertEqual 1, &previewwindow
   pclose
 
+  unlet g:plug_window g:plug_pwindow
+
 Execute (Test g:plug_pwindow):
   let g:plug_pwindow = 'below 5new'
   PlugDiff
@@ -975,7 +988,8 @@ Execute (PlugInstall!):
   Assert filereadable(g:plugs['vim-easy-align'].dir.'/installed2'),
     \ 'vim-easy-align/installed2 should exist'
   AssertEqual '7f8cd78cb1fe52185b98b16a3749811f0cc508af', GitCommit('vim-pseudocl')
-  AssertEqual 'no-t_co', GitBranch('seoul256.vim')
+  " Was updated to the default branch of origin by previous PlugUpdate
+  AssertEqual 'master', GitBranch('seoul256.vim')
   AssertEqual '1.5.3', GitTag('goyo.vim')
 
 Execute (When submodules are not initialized):
@@ -1620,10 +1634,12 @@ Execute (Commit hash support):
   Assert empty(mapcheck('X'))
   Assert !empty(mapcheck("\<cr>"))
 
-  " Nor in PlugSnapshot output
+  " The exact hash values in PlugSnapshot output
   PlugSnapshot
   Log getline(1, '$')
-  AssertEqual 8, line('$')
+  AssertEqual "silent! let g:plugs['goyo.vim'].commit = 'ffffffff'", getline(6)
+  AssertEqual "silent! let g:plugs['vim-emoji'].commit = '9db7fcfee0d90dafdbcb7a32090c0a9085eb054a'", getline(7)
+  AssertEqual 10, line('$')
   q
 
 Execute (Commit hash support - cleared):
@@ -1698,6 +1714,8 @@ Execute (#530 - Comparison of incompatible git URIs):
   Assert !CompareURI('https://github.com/junegunn/vim-plug.git', 'https://github.com:12345/junegunn/vim-plug.git')
 
 Execute (#532 - Reuse plug window):
+  let g:plug_window = 'vertical topleft new'
+  let g:plug_pwindow = 'above 12new'
   call plug#begin()
   Plug 'junegunn/goyo.vim'
   call plug#end()
@@ -1724,6 +1742,8 @@ Execute (#532 - Reuse plug window):
   AssertEqual 2, winnr('$'), 'Three windows after PlugStatus (but got '.winnr('$').')'
   q
 
+  unlet g:plug_window g:plug_pwindow
+
 Execute (#766 - Allow cloning into an empty directory):
   let d = '/tmp/vim-plug-test/goyo-already'
   call system('rm -rf ' . d)