vim-patch:9.0.1478: filetypes for *.v files not detected properly (#23282)

* vim-patch:9.0.1478: filetypes for *.v files not detected properly

Problem:    Filetypes for *.v files not detected properly.
Solution:   Use the file contents to detect the filetype. (Turiiya,
            closes vim/vim#12281)

80406c2618

Co-authored-by: Turiiya <34311583+tobealive@users.noreply.github.com>
Co-authored-by: Jonas Strittmatter <40792180+smjonas@users.noreply.github.com>

runtime/lua/vim/filetype.lua

@@ -1091,7 +1091,9 @@ local extension = {
   vr = 'vera',
   vri = 'vera',
   vrh = 'vera',
-  v = 'verilog',
+  v = function(path, bufnr)
+    return require('vim.filetype.detect').v(bufnr)
+  end,
   va = 'verilogams',
   vams = 'verilogams',
   vhdl = 'vhdl',

runtime/lua/vim/filetype/detect.lua

@@ -1322,6 +1322,24 @@ function M.txt(bufnr)
   end
 end
 
+-- Determine if a .v file is Verilog, V, or Coq
+function M.v(bufnr)
+  if vim.fn.did_filetype() ~= 0 then
+    -- Filetype was already detected
+    return
+  end
+  for _, line in ipairs(getlines(bufnr, 1, 200)) do
+    if not line:find('^%s*/') then
+      if findany(line, { ';%s*$', ';%s*/' }) then
+        return 'verilog'
+      elseif findany(line, { '%.%s*$', '%.%s*%(%*' }) then
+        return 'coq'
+      end
+    end
+  end
+  return 'v'
+end
+
 -- WEB (*.web is also used for Winbatch: Guess, based on expecting "%" comment
 -- lines in a WEB file).
 function M.web(bufnr)