From 3aa833e0d90204102bb8a90a5d7dc1323b882bfd Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Fri, 11 Apr 2025 16:45:14 +0800
Subject: [PATCH] vim-patch:5c84d12: runtime(filetype): make shell filetype
 detection more robust (#33421)

closes: vim/vim#17063

https://github.com/vim/vim/commit/5c84d12df104e976e8f56c43f9f975e54d9fd779

Co-authored-by: Aliaksei Budavei <0x000c70@gmail.com>
---
 runtime/lua/vim/filetype/detect.lua | 17 ++++++++++-------
 runtime/syntax/sh.vim               | 11 ++++++++---
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index fc0b45ecd8..96be7edbae 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/runtime/lua/vim/filetype/detect.lua
@@ -1502,33 +1502,36 @@ local function sh(path, contents, name)
 
   -- Get the name from the first line if not specified
   name = name or contents[1]
-  if matchregex(name, [[\<csh\>]]) then
+  if name:find('^csh$') or matchregex(name, [[^#!.\{-2,}\<csh\>]]) then
     -- Some .sh scripts contain #!/bin/csh.
     return M.shell(path, contents, 'csh')
+  elseif name:find('^tcsh$') or matchregex(name, [[^#!.\{-2,}\<tcsh\>]]) then
     -- Some .sh scripts contain #!/bin/tcsh.
-  elseif matchregex(name, [[\<tcsh\>]]) then
     return M.shell(path, contents, 'tcsh')
+  elseif name:find('^zsh$') or matchregex(name, [[^#!.\{-2,}\<zsh\>]]) then
     -- Some .sh scripts contain #!/bin/zsh.
-  elseif matchregex(name, [[\<zsh\>]]) then
     return M.shell(path, contents, 'zsh')
   end
 
   local on_detect --- @type fun(b: integer)?
 
-  if matchregex(name, [[\<ksh\>]]) then
+  if name:find('^ksh$') or matchregex(name, [[^#!.\{-2,}\<ksh\>]]) then
     on_detect = function(b)
       vim.b[b].is_kornshell = 1
       vim.b[b].is_bash = nil
       vim.b[b].is_sh = nil
     end
-  elseif vim.g.bash_is_sh or matchregex(name, [[\<\(bash\|bash2\)\>]]) then
+  elseif
+    vim.g.bash_is_sh
+    or name:find('^bash2?$')
+    or matchregex(name, [[^#!.\{-2,}\<bash2\=\>]])
+  then
     on_detect = function(b)
       vim.b[b].is_bash = 1
       vim.b[b].is_kornshell = nil
       vim.b[b].is_sh = nil
     end
-    -- Ubuntu links sh to dash
-  elseif matchregex(name, [[\<\(sh\|dash\)\>]]) then
+  elseif findany(name, { '^sh$', '^dash$' }) or matchregex(name, [[^#!.\{-2,}\<\%(da\)\=sh\>]]) then -- Ubuntu links "sh" to "dash"
     on_detect = function(b)
       vim.b[b].is_sh = 1
       vim.b[b].is_kornshell = nil
diff --git a/runtime/syntax/sh.vim b/runtime/syntax/sh.vim
index 298198274e..9e5320f1ce 100644
--- a/runtime/syntax/sh.vim
+++ b/runtime/syntax/sh.vim
@@ -9,6 +9,7 @@
 "		2025 Jan 18 add bash coproc, remove duplicate syn keywords (#16467)
 "		2025 Mar 21 update shell capability detection (#16939)
 "		2025 Apr 03 command substitution opening paren at EOL (#17026)
+"		2025 Apr 10 improve shell detection (#17084)
 " Version:		208
 " Former URL:		http://www.drchip.org/astronaut/vim/index.html#SYNTAX_SH
 " For options and settings, please use:      :help ft-sh-syntax
@@ -23,11 +24,13 @@ endif
 let b:is_sh = 1
 
 " If the shell script itself specifies which shell to use, use it
-if getline(1) =~ '\<ksh\>'
+let s:shebang = getline(1)
+
+if s:shebang =~ '^#!.\{-2,}\<ksh\>'
  let b:is_kornshell = 1
-elseif getline(1) =~ '\<bash\>'
+elseif s:shebang =~ '^#!.\{-2,}\<bash\>'
  let b:is_bash      = 1
-elseif getline(1) =~ '\<dash\>'
+elseif s:shebang =~ '^#!.\{-2,}\<dash\>'
  let b:is_dash      = 1
 " handling /bin/sh with is_kornshell/is_sh {{{1
 " b:is_sh will be set when "#! /bin/sh" is found;
@@ -70,6 +73,8 @@ elseif !exists("b:is_kornshell") && !exists("b:is_bash") && !exists("b:is_posix"
  endif
 endif
 
+unlet s:shebang
+
 " if b:is_dash, set b:is_posix too
 if exists("b:is_dash")
  let b:is_posix= 1