fix: support blame for git < 2.41

Fixes #1093

lua/gitsigns/cache.lua

@@ -87,12 +87,23 @@ function CacheEntry:run_blame(lnum, opts)
   local bufnr = self.bufnr
   local blame --- @type table<integer,Gitsigns.BlameInfo?>?
   local lnum0 --- @type integer?
+
+  -- Always send contents if buffer represents an editable file on disk.
+  -- Otherwise do not sent contents buffer revision is from tree and git version
+  -- is below 2.41.
+  --
+  -- This avoids the error:
+  --   "fatal: cannot use --contents with final commit object name"
+  local send_contents = vim.bo[bufnr].buftype == ''
+    or (not self.git_obj:from_tree() and not require('gitsigns.git.version').check(2, 41))
+
   repeat
     local buftext = util.buf_lines(bufnr, true)
+    local contents = send_contents and buftext or nil
     local tick = vim.b[bufnr].changedtick
     lnum0 = #buftext > BLAME_THRESHOLD_LEN and lnum or nil
     -- TODO(lewis6991): Cancel blame on changedtick
-    blame = self.git_obj:run_blame(buftext, lnum0, self.git_obj.revision, opts)
+    blame = self.git_obj:run_blame(contents, lnum0, self.git_obj.revision, opts)
     async.scheduler()
     if not vim.api.nvim_buf_is_valid(bufnr) then
       return {}

lua/gitsigns/diffthis.lua

@@ -99,7 +99,7 @@ local function create_revision_buf(bufnr, base)
   end
 
   -- allow editing the index revision
-  if not bcache.git_obj.revision then
+  if not base then
     vim.bo[dbuf].buftype = 'acwrite'
 
     api.nvim_create_autocmd('BufReadCmd', {

lua/gitsigns/git.lua

@@ -125,7 +125,7 @@ end
 --- @param silent? boolean
 --- @return Gitsigns.FileInfo
 function Obj:file_info_index(file, silent)
-  local has_eol = check_version({ 2, 9 })
+  local has_eol = check_version(2, 9)
 
   -- --others + --exclude-standard means ignored files won't return info, but
   -- untracked files will. Unlike file_info_tree which won't return untracked
@@ -272,13 +272,13 @@ function Obj:unstage_file()
 end
 
 --- @async
---- @param lines string[]
+--- @param contents? string[]
 --- @param lnum? integer
 --- @param revision? string
 --- @param opts? Gitsigns.BlameOpts
 --- @return table<integer,Gitsigns.BlameInfo?>
-function Obj:run_blame(lines, lnum, revision, opts)
-  return require('gitsigns.git.blame').run_blame(self, lines, lnum, revision, opts)
+function Obj:run_blame(contents, lnum, revision, opts)
+  return require('gitsigns.git.blame').run_blame(self, contents, lnum, revision, opts)
 end
 
 --- @async

lua/gitsigns/git/blame.lua

@@ -195,20 +195,21 @@ local function bufferred_line_reader(f)
 end
 
 --- @param obj Gitsigns.GitObj
---- @param lines string[]
+--- @param contents? string[]
 --- @param lnum? integer
 --- @param revision? string
 --- @param opts? Gitsigns.BlameOpts
 --- @return table<integer, Gitsigns.BlameInfo>
-function M.run_blame(obj, lines, lnum, revision, opts)
+function M.run_blame(obj, contents, lnum, revision, opts)
   local ret = {} --- @type table<integer,Gitsigns.BlameInfo>
 
   if not obj.object_name or obj.repo.abbrev_head == '' then
+    assert(contents, 'contents must be provided for untracked files')
     -- As we support attaching to untracked files we need to return something if
     -- the file isn't isn't tracked in git.
     -- If abbrev_head is empty, then assume the repo has no commits
     local commit = not_committed(obj.file)
-    for i in ipairs(lines) do
+    for i in ipairs(contents) do
       ret[i] = {
         orig_lnum = 0,
         final_lnum = i,
@@ -219,7 +220,10 @@ function M.run_blame(obj, lines, lnum, revision, opts)
     return ret
   end
 
-  local args = { 'blame', '--contents', '-', '--incremental' }
+  local args = { 'blame', '--incremental' }
+  if contents then
+    vim.list_extend(args, { '--contents', '-' })
+  end
 
   opts = opts or {}
 
@@ -255,8 +259,10 @@ function M.run_blame(obj, lines, lnum, revision, opts)
     reader(data)
   end
 
+  local contents_str = contents and table.concat(contents, '\n') or nil
+
   local _, stderr =
-    obj.repo:command(args, { stdin = lines, stdout = on_stdout, ignore_error = true })
+    obj.repo:command(args, { stdin = contents_str, stdout = on_stdout, ignore_error = true })
 
   if stderr then
     error_once('Error running git-blame: ' .. stderr)

lua/gitsigns/git/repo.lua

@@ -213,7 +213,7 @@ end
 function M.get_info(cwd, gitdir, toplevel)
   -- Does git rev-parse have --absolute-git-dir, added in 2.13:
   --    https://public-inbox.org/git/20170203024829.8071-16-szeder.dev@gmail.com/
-  local has_abs_gd = check_version({ 2, 13 })
+  local has_abs_gd = check_version(2, 13)
 
   -- Wait for internal scheduler to settle before running command (#215)
   async.scheduler()

lua/gitsigns/git/version.lua

@@ -73,28 +73,24 @@ end
 
 --- @async
 --- Usage: check_version{2,3}
---- @param version {[1]: integer, [2]:integer, [3]:integer}?
+--- @param major? integer
+--- @param minor? integer
+--- @param patch? integer
 --- @return boolean
-function M.check(version)
+function M.check(major, minor, patch)
   if not M.version then
     set_version()
   end
 
   if not M.version then
     return false
-  end
-
-  if not version then
+  elseif not major or not minor then
     return false
-  end
-
-  if M.version.major < version[1] then
+  elseif M.version.major < major then
     return false
-  end
-  if version[2] and M.version.minor < version[2] then
+  elseif minor and M.version.minor < minor then
     return false
-  end
-  if version[3] and M.version.patch < version[3] then
+  elseif patch and M.version.patch < patch then
     return false
   end
   return true