"Process failed to start" when many files are unstaged

[idbrii]

I hit a git error while switching branches and git left many files from my destination branch unstaged (not fugitive's problem). I didn't realize that's what was wrong, but running :Git resulted in an error and no status buffer (in neovim):

E903: Process failed to start: name too long: "C:/Users/iiiiiiii/scoop/shims/git.EXE"

I think the command is too long and not the process name. I put some debug code in s:JobExecute() to store a:argv and it's git followed by some options and -- and then 12,000 filenames.

In the end, my solution was to git reset --hard HEAD to remove those files, but it'd be nice if fugitive failed more gracefully. I had to use the command line to get useful info.

My failure occurred in Win11, but I tried the same in Ubuntu (WSL) and vim hung.

---

According to the vim callstack, this line is the failing call to fugitive#Execute:

vim-fugitive/autoload/fugitive.vim

Line 2827 in 61b51c0

let stat.diff['Unstaged'] = fugitive#Execute(diff_cmd + ['--'] + map(copy(unstaged), 'stat.work_tree . "/" . v:val.relative[0]'), function('len'))

Should it have some kind of limit? I thought these diff patches were generated on-demand, so maybe that's an even better solution?

[tpope]

Should it have some kind of limit?

Passing in the list of changed files is a performance optimization so that Git doesn't have to scan the whole repository a second time. A limit would be a reasonable compromise here. You could try something like this:

diff --git i/autoload/fugitive.vim w/autoload/fugitive.vim
index 2df3a1e6..0cba1f8c 100644
--- i/autoload/fugitive.vim
+++ w/autoload/fugitive.vim
@@ -2824,7 +2824,11 @@ function! s:StatusProcess(result, stat, ...) abort
       let stat.diff['Staged'] = fugitive#Execute(diff_cmd + ['--cached'], function('len'))
     endif
     if len(unstaged)
-      let stat.diff['Unstaged'] = fugitive#Execute(diff_cmd + ['--'] + map(copy(unstaged), 'stat.work_tree . "/" . v:val.relative[0]'), function('len'))
+      let unstaged_diff_cmd = diff_cmd + ['--']
+      if len(unstaged) < 100
+        call extend(unstaged_diff_cmd, map(copy(unstaged), 'stat.work_tree . "/" . v:val.relative[0]'))
+      endif
+      let stat.diff['Unstaged'] = fugitive#Execute(unstaged_diff_cmd, function('len'))
     endif
 
     let [stat.staged, stat.unstaged, stat.untracked] = [staged, unstaged, untracked]

I thought these diff patches were generated on-demand, so maybe that's an even better solution?

For conceptual simplicity, I'd rather the diff capture the state of things when the buffer is loaded, not the state of things when you expand individual diffs.