From f79430e2ce2e952dc9a9e1ff54826ed4e45360da Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Sun, 10 Aug 2025 07:27:53 +0800
Subject: [PATCH] vim-patch:9.1.1615: diff format erroneously detected (#35276)
MIME-Version: 1.0
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Problem:  diff format erroneously detected
          (Tomáš Janoušek)
Solution: Make the regex to detect normal diff format a bit stricter,
          while at it, fix wrong test content from patch v9.1.1606

fixes: vim/vim#17946

https://github.com/vim/vim/commit/887b4981e7e929ce8676b1b524e47a7fb5a8288b

Co-authored-by: Christian Brabandt <cb@256bit.org>
---
 runtime/lua/vim/filetype/detect.lua |  3 ++-
 test/old/testdir/test_filetype.vim  | 17 ++++++++++++++---
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index 2ace52f4fc..f20f2a0ecd 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/runtime/lua/vim/filetype/detect.lua
@@ -2063,6 +2063,7 @@ local patterns_text = {
   -- Diff file:
   -- - "diff" in first line (context diff)
   -- - "Only in " in first line
+  -- - "34,35c34,35" normal diff format output
   -- - "--- " in first line and "+++ " in second line (unified diff).
   -- - "*** " in first line and "--- " in second line (context diff).
   -- - "# It was generated by makepatch " in the second line (makepatch diff).
@@ -2071,7 +2072,7 @@ local patterns_text = {
   -- - "=== ", "--- ", "+++ " (bzr diff, common case)
   -- - "=== (removed|added|renamed|modified)" (bzr diff, alternative)
   -- - "# HG changeset patch" in first line (Mercurial export format)
-  ['^\\(diff\\>\\|Only in \\|\\d\\+\\(,\\d\\+\\)\\=[cda]\\d\\+\\>\\|# It was generated by makepatch \\|Index:\\s\\+\\f\\+\\r\\=$\\|===== \\f\\+ \\d\\+\\.\\d\\+ vs edited\\|==== //\\f\\+#\\d\\+\\|# HG changeset patch\\)'] = {
+  ['^\\(diff\\>\\|Only in \\|\\d\\+\\(,\\d\\+\\)\\=[cda]\\d\\+\\(,\\d\\+\\)\\=\\>$\\|# It was generated by makepatch \\|Index:\\s\\+\\f\\+\\r\\=$\\|===== \\f\\+ \\d\\+\\.\\d\\+ vs edited\\|==== //\\f\\+#\\d\\+\\|# HG changeset patch\\)'] = {
     'diff',
     { vim_regex = true },
   },
diff --git a/test/old/testdir/test_filetype.vim b/test/old/testdir/test_filetype.vim
index d38c4a45d9..f1c84718bf 100644
--- a/test/old/testdir/test_filetype.vim
+++ b/test/old/testdir/test_filetype.vim
@@ -2993,7 +2993,7 @@ endfunc
 func Test_info_file()
   filetype on
 
-  call writefile(['File: coreutils.info,  Node: Top,  Next: Introduction,  Up: (dir)', 'D'], 'Xfile', 'D')
+  call writefile(['File: coreutils.info,  Node: Top,  Next: Introduction,  Up: (dir)'], 'Xfile', 'D')
   split Xfile
   call assert_equal('info', &filetype)
   bwipe!
@@ -3004,7 +3004,7 @@ endfunc
 func Test_mail_file()
   filetype on
 
-  call writefile(['Return-path: <lgc@debian.home.arpa>', 'D'], 'Xfile', 'D')
+  call writefile(['Return-path: <lgc@debian.home.arpa>'], 'Xfile', 'D')
   split Xfile
   call assert_equal('mail', &filetype)
   bwipe!
@@ -3015,7 +3015,7 @@ endfunc
 func Test_terminfo_file()
   filetype on
 
-  call writefile(['#	Reconstructed via infocmp from file: /etc/terminfo/x/xterm', 'D'], 'Xfile', 'D')
+  call writefile(['#	Reconstructed via infocmp from file: /etc/terminfo/x/xterm'], 'Xfile', 'D')
   split Xfile
   call assert_equal('terminfo', &filetype)
   bwipe!
@@ -3035,4 +3035,15 @@ func Test_pacmanlog()
   filetype off
 endfunc
 
+func Test_diff_format()
+  filetype on
+
+  call writefile(['0d555557  1 (John John   2025-01-01 00:00:00 +0000  1) foo'], 'Xdiff', 'D')
+  split Xdiff
+  call assert_true(empty(&filetype))
+  bwipe!
+
+  filetype off
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab