Fix Support for PowerShell under Windows with VIM 8+ (#1326)

The following 'vim-plug' commands would fail and/or display errors
when executed by VIM 8+ on a Windows platform with the 'shell' option
set to 'powershell' or 'pwsh':
  - PlugInstall
  - PlugUpdate
  - PlugClean
  - PlugStatus
  - PlugDiff

There were two causes for these errors:
  - A bug in VIM itself (resolved by patch 9.2.6) with how compound
    PowerShell commands are handled by the 'system()' vimscript
    function.
  - A bug in the 's:vim8' branch of the private 'vim-plug' function
    's:spawn()' where the actual command to be executed was escaped
    for 'cmd.exe' but the 'cd' prefix added by 's:with_cd()" was escaped
    for PowerShell.

README.md

@@ -1,21 +1,3 @@
-<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">

plug.vim

@@ -68,6 +68,7 @@ let s:mac_gui = has('gui_macvim') && has('gui_running')
 let s:is_win = has('win32')
 let s:nvim = has('nvim-0.2') || (has('nvim') && exists('*jobwait') && !s:is_win)
 let s:vim8 = has('patch-8.0.0039') && exists('*job_start')
+let s:shell_error = 0
 if s:is_win && &shellslash
   set noshellslash
   let s:me = resolve(expand('<sfile>:p'))
@@ -170,7 +171,7 @@ function! s:git_origin_branch(spec)
 
   " The command may not return the name of a branch in detached HEAD state
   let result = s:lines(s:system('git symbolic-ref --short HEAD', a:spec.dir))
-  return v:shell_error ? '' : result[-1]
+  return s:shell_error ? '' : result[-1]
 endfunction
 
 if s:is_win
@@ -372,8 +373,10 @@ function! plug#end()
 
   for [cmd, names] in items(lod.cmd)
     execute printf(
-    \ 'command! -nargs=* -range -bang -complete=file %s call s:lod_cmd(%s, "<bang>", <line1>, <line2>, <q-args>, %s)',
+    \ has('patch-7.4.1898')
-    \ cmd, string(cmd), string(names))
+    \ ? 'command! -nargs=* -range -bang -complete=file %s call s:lod_cmd(%s, "<bang>", <line1>, <line2>, <q-args>, <q-mods> ,%s)'
+    \ : 'command! -nargs=* -range -bang -complete=file %s call s:lod_cmd(%s, "<bang>", <line1>, <line2>, <q-args>, %s)'
+    \ , cmd, string(cmd), string(names))
   endfor
 
   for [map, names] in items(lod.map)
@@ -651,11 +654,19 @@ function! s:lod_ft(pat, names)
   call s:doautocmd('filetypeindent', 'FileType')
 endfunction
 
-function! s:lod_cmd(cmd, bang, l1, l2, args, names)
+if has('patch-7.4.1898')
+  function! s:lod_cmd(cmd, bang, l1, l2, args, mods, names)
+    call s:lod(a:names, ['ftdetect', 'after/ftdetect', 'plugin', 'after/plugin'])
+    call s:dobufread(a:names)
+    execute printf('%s %s%s%s %s', a:mods, (a:l1 == a:l2 ? '' : (a:l1.','.a:l2)), a:cmd, a:bang, a:args)
+  endfunction
+else
+  function! s:lod_cmd(cmd, bang, l1, l2, args, names)
     call s:lod(a:names, ['ftdetect', 'after/ftdetect', 'plugin', 'after/plugin'])
     call s:dobufread(a:names)
     execute printf('%s%s%s %s', (a:l1 == a:l2 ? '' : (a:l1.','.a:l2)), a:cmd, a:bang, a:args)
-endfunction
+  endfunction
+endif
 
 function! s:lod_map(map, names, with_prefix, prefix)
   call s:lod(a:names, ['ftdetect', 'after/ftdetect', 'plugin', 'after/plugin'])
@@ -986,7 +997,7 @@ function! s:bang(cmd, ...)
     let [sh, shellcmdflag, shrd] = s:chsh(a:0)
     " FIXME: Escaping is incomplete. We could use shellescape with eval,
     "        but it won't work on Windows.
-    let cmd = a:0 ? s:with_cd(a:cmd, a:1) : a:cmd
+    let cmd = a:0 ? s:with_cd(a:cmd, a:1, {'shell': s:is_win ? 'cmd.exe' : &shell}) : a:cmd
     if s:is_win
       let [batchfile, cmd] = s:batchfile(cmd)
     endif
@@ -1075,15 +1086,19 @@ function! s:hash_match(a, b)
   return stridx(a:a, a:b) == 0 || stridx(a:b, a:a) == 0
 endfunction
 
+function! s:disable_credential_helper()
+  return s:git_version_requirement(2) && get(g:, 'plug_disable_credential_helper', 1)
+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 credential_helper = s:disable_credential_helper() ? '-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
+    let error = s:shell_error
   endif
   return [output, error]
 endfunction
@@ -1289,7 +1304,7 @@ function! s:update_finish()
         let tag = spec.tag
         if tag =~ '\*'
           let tags = s:lines(s:system('git tag --list '.plug#shellescape(tag).' --sort -version:refname 2>&1', spec.dir))
-          if !v:shell_error && !empty(tags)
+          if !s:shell_error && !empty(tags)
             let tag = tags[0]
             call s:log4(name, printf('Latest tag for %s -> %s', spec.tag, tag))
             call append(3, '')
@@ -1297,7 +1312,7 @@ 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)
-        let error = v:shell_error
+        let error = s:shell_error
       endif
       if !error && filereadable(spec.dir.'/.gitmodules') &&
             \ (s:update.force || has_key(s:update.new, name) || s:is_updated(spec.dir))
@@ -1305,7 +1320,7 @@ function! s:update_finish()
         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)
+      let msg = s:format_message(error ? 'x': '-', name, out)
       if error
         call add(s:update.errors, name)
         call s:regress_bar()
@@ -1447,7 +1462,7 @@ function! s:spawn(name, spec, queue, opts)
   elseif s:vim8
     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)
+      let cmd = s:with_cd(cmd, a:opts.dir, {'shell': s:is_win ? 'cmd.exe' : 'sh', 'script': 0})
     endif
     let argv = s:is_win ? ['cmd', '/s', '/c', '"'.cmd.'"'] : ['sh', '-c', cmd]
     let jid = job_start(s:is_win ? join(argv, ' ') : argv, {
@@ -1466,7 +1481,7 @@ function! s:spawn(name, spec, queue, opts)
     endif
   else
     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.error = s:shell_error != 0
     let job.running = 0
   endif
 endfunction
@@ -1589,7 +1604,7 @@ while 1 " Without TCO, Vim stack is bound to explode
     let [error, _] = s:git_validate(spec, 0)
     if empty(error)
       if pull
-        let cmd = s:git_version_requirement(2) ? ['git', '-c', 'credential.helper=', 'fetch'] : ['git', 'fetch']
+        let cmd = s:disable_credential_helper() ? ['git', '-c', 'credential.helper=', 'fetch'] : ['git', 'fetch']
         if has_tag && !empty(globpath(spec.dir, '.git/shallow'))
           call extend(cmd, ['--depth', '99999999'])
         endif
@@ -2313,11 +2328,34 @@ function! s:format_message(bullet, name, message)
 endfunction
 
 function! s:with_cd(cmd, dir, ...)
-  let script = a:0 > 0 ? a:1 : 1
+  let opts = a:0 > 0 && type(a:1) == s:TYPE.dict ? a:1 : {}
-  let pwsh = s:is_powershell(&shell)
+  let opts.shell = get(opts, 'shell', &shell)
+  let opts.script = get(opts, 'script', 1)
+
+  let pwsh = s:is_powershell(opts.shell)
   let cd = s:is_win && !pwsh ? 'cd /d' : 'cd'
   let sep = pwsh ? ';' : '&&'
-  return printf('%s %s %s %s', cd, plug#shellescape(a:dir, {'script': script, 'shell': &shell}), sep, a:cmd)
+  let pwsh_block_required = pwsh && !has('patch-9.2.6')
+  let start = pwsh_block_required ? '& { ' : ''
+  let end = pwsh_block_required ? ' }' : ''
+
+  return printf('%s%s %s %s %s%s', start, cd, plug#shellescape(a:dir, opts), sep, a:cmd, end)
+endfunction
+
+function! s:system_job(cmd) abort
+  let tmp = tempname()
+  let job = job_start(['/bin/sh', '-c', a:cmd], {
+  \ 'out_io': 'file',
+  \ 'out_name': tmp,
+  \ 'err_io': 'out',
+  \})
+  while job_status(job) ==# 'run'
+    sleep 1m
+  endwhile
+  let s:shell_error = job_info(job).exitval
+  let result = filereadable(tmp) ? join(readfile(tmp, 'b'), "\n") : ''
+  silent! call delete(tmp)
+  return result
 endfunction
 
 function! s:system(cmd, ...)
@@ -2329,7 +2367,9 @@ function! s:system(cmd, ...)
       " but it cannot set the working directory for the command.
       " Assume that the command does not rely on the shell.
       if has('nvim') && a:0 == 0
-        return system(a:cmd)
+        let ret = system(a:cmd)
+        let s:shell_error = v:shell_error
+        return ret
       endif
       let cmd = join(map(copy(a:cmd), 'plug#shellescape(v:val, {"shell": &shell, "script": 0})'))
       if s:is_powershell(&shell)
@@ -2339,12 +2379,17 @@ function! s:system(cmd, ...)
       let cmd = a:cmd
     endif
     if a:0 > 0
-      let cmd = s:with_cd(cmd, a:1, type(a:cmd) != s:TYPE.list)
+      let cmd = s:with_cd(cmd, a:1, {'script': type(a:cmd) != s:TYPE.list})
     endif
-    if s:is_win && type(a:cmd) != s:TYPE.list
+    if s:is_win && type(a:cmd) != s:TYPE.list && !s:is_powershell(&shell)
       let [batchfile, cmd] = s:batchfile(cmd)
     endif
-    return system(cmd)
+    if s:vim8 && has('gui_running') && !s:is_win
+      return s:system_job(cmd)
+    endif
+    let ret = system(cmd)
+    let s:shell_error = v:shell_error
+    return ret
   finally
     let [&shell, &shellcmdflag, &shellredir] = [sh, shellcmdflag, shrd]
     if s:is_win && filereadable(batchfile)
@@ -2355,7 +2400,7 @@ endfunction
 
 function! s:system_chomp(...)
   let ret = call('s:system', a:000)
-  return v:shell_error ? '' : substitute(ret, '\n$', '', '')
+  return s:shell_error ? '' : substitute(ret, '\n$', '', '')
 endfunction
 
 function! s:git_validate(spec, check_branch)
@@ -2369,7 +2414,9 @@ function! s:git_validate(spec, check_branch)
       let err = join(['Invalid URI: '.remote,
                     \ 'Expected:    '.a:spec.uri,
                     \ 'PlugClean required.'], "\n")
-    elseif a:check_branch && has_key(a:spec, 'commit')
+    elseif !a:check_branch
+      return ['', 0]
+    elseif has_key(a:spec, 'commit')
       let sha = s:git_revision(a:spec.dir)
       if empty(sha)
         let err = join(add(result, 'PlugClean required.'), "\n")
@@ -2378,18 +2425,16 @@ function! s:git_validate(spec, check_branch)
                               \ a:spec.commit[:6], sha[:6]),
                       \ 'PlugUpdate required.'], "\n")
       endif
-    elseif a:check_branch
+    elseif has_key(a:spec, 'tag')
-      let current_branch = result[0]
-      " Check tag
-      let origin_branch = s:git_origin_branch(a:spec)
-      if has_key(a:spec, 'tag')
       let tag = s:system_chomp('git describe --exact-match --tags HEAD 2>&1', a:spec.dir)
       if a:spec.tag !=# tag && a:spec.tag !~ '\*'
         let err = printf('Invalid tag: %s (expected: %s). Try PlugUpdate.',
               \ (empty(tag) ? 'N/A' : tag), a:spec.tag)
       endif
-      " Check branch
+    elseif a:check_branch
-      elseif origin_branch !=# current_branch
+      let current_branch = result[0]
+      let origin_branch = s:git_origin_branch(a:spec)
+      if origin_branch !=# current_branch
         let err = printf('Invalid branch: %s (expected: %s). Try PlugUpdate.',
               \ current_branch, origin_branch)
       endif
@@ -2398,7 +2443,7 @@ function! s:git_validate(spec, check_branch)
           \ 'git', 'rev-list', '--count', '--left-right',
           \ printf('HEAD...origin/%s', origin_branch)
           \ ], a:spec.dir)), '\t')
-        if v:shell_error || len(ahead_behind) != 2
+        if s: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
@@ -2548,7 +2593,7 @@ function! s:upgrade()
 
   try
     let out = s:system(['git', 'clone', '--depth', '1', s:plug_src, tmp])
-    if v:shell_error
+    if s:shell_error
       return s:err('Error upgrading vim-plug: '. out)
     endif