vim-patch:9.1.1042: filetype: just files are not recognized

Problem:  filetype: just files are not recognized
Solution: adjust filetype detection pattern, detect just shebang line,
          include just ftplugin, indent and syntax plugin
          (Peter Benjamin)

closes: vim/vim#16466

vim/vim@72755b3

Co-authored-by: Peter Benjamin <[email protected]>

Author: clason

runtime/ftplugin/just.vim

@@ -0,0 +1,17 @@
+" Vim ftplugin file
+" Language:	Justfile
+" Maintainer:	Peter Benjamin <@pbnj>
+" Last Change:	2025 Jan 19
+" Credits:	The original author, Noah Bogart <https://github.com/NoahTheDuke/vim-just/>
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+  finish
+endif
+let b:did_ftplugin = 1
+
+setlocal iskeyword+=-
+setlocal comments=n:#
+setlocal commentstring=#\ %s
+
+let b:undo_ftplugin = "setlocal iskeyword< comments< commentstring<"

runtime/indent/just.vim

@@ -0,0 +1,51 @@
+" Vim indent file
+" Language:	Justfile
+" Maintainer:	Peter Benjamin <@pbnj>
+" Last Change:	2025 Jan 19
+" Credits:	The original author, Noah Bogart <https://github.com/NoahTheDuke/vim-just/>
+
+" Only load this indent file when no other was loaded yet.
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+setlocal indentexpr=GetJustfileIndent()
+setlocal indentkeys=0},0),!^F,o,O,0=''',0=\"\"\"
+
+let b:undo_indent = "setlocal indentexpr< indentkeys<"
+
+if exists("*GetJustfileIndent")
+  finish
+endif
+
+function GetJustfileIndent()
+  if v:lnum < 2
+    return 0
+  endif
+
+  let prev_line = getline(v:lnum - 1)
+  let last_indent = indent(v:lnum - 1)
+
+  if getline(v:lnum) =~ "\\v^\\s+%([})]|'''$|\"\"\"$)"
+    return last_indent - shiftwidth()
+  elseif prev_line =~ '\V#'
+    return last_indent
+  elseif prev_line =~ "\\v%([:{(]|^.*\\S.*%([^']'''|[^\"]\"\"\"))\\s*$"
+    return last_indent + shiftwidth()
+  elseif prev_line =~ '\\$'
+    if v:lnum == 2 || getline(v:lnum - 2) !~ '\\$'
+      if prev_line =~ '\v:\=@!'
+        return last_indent + shiftwidth() + shiftwidth()
+      else
+        return last_indent + shiftwidth()
+      endif
+    endif
+  elseif v:lnum > 2 && getline(v:lnum - 2) =~ '\\$'
+    return last_indent - shiftwidth()
+  elseif prev_line =~ '\v:\s*%(\h|\()' && prev_line !~ '\V:='
+    return last_indent + shiftwidth()
+  endif
+
+  return last_indent
+endfunction

runtime/lua/vim/filetype.lua

@@ -661,6 +661,8 @@ local extension = {
   jsp = 'jsp',
   jl = 'julia',
   just = 'just',
+  Just = 'just',
+  JUST = 'just',
   kl = 'karel',
   KL = 'karel',
   kdl = 'kdl',
@@ -1650,8 +1652,11 @@ local filename = {
   ['.vsconfig'] = 'jsonc',
   ['bun.lock'] = 'jsonc',
   ['.justfile'] = 'just',
+  ['.Justfile'] = 'just',
+  ['.JUSTFILE'] = 'just',
   ['justfile'] = 'just',
   ['Justfile'] = 'just',
+  ['JUSTFILE'] = 'just',
   Kconfig = 'kconfig',
   ['Kconfig.debug'] = 'kconfig',
   ['Config.in'] = 'kconfig',

runtime/lua/vim/filetype/detect.lua

@@ -1877,6 +1877,7 @@ local patterns_hashbang = {
   ruby = 'ruby',
   ['node\\(js\\)\\=\\>\\|js\\>'] = { 'javascript', { vim_regex = true } },
   ['rhino\\>'] = { 'javascript', { vim_regex = true } },
+  just = 'just',
   -- BC calculator
   ['^bc\\>'] = { 'bc', { vim_regex = true } },
   ['sed\\>'] = { 'sed', { vim_regex = true } },