How to launch gvim.exe from cscope-win32 when run from cmd.exe?

Question

For years now my Windows C tagging/scoping solution has almost worked. I can build the filelist, build the tags (via Exuberant Ctags) for vim/gvim navigation, build cscope.out, and tag around within gvim.exe windows I launch by clicking on C source files.

The final piece that eludes me is that I can't seem to get cscope in cmd.exe to launch my editor when I select an item. I made sure gvim.exe is in my Path environment variable. I made sure the CSCOPE_EDITOR environment variable is set (more on that below). But when I select a line item from within cscope the editor is not launched. Instead I get one of the two following failures:

1. If CSCOPE_EDITOR is either gvim.exe -f or "gvim.exe -f" then I see that printed at the top of the cmd.exe window followed by the line offset and the filename (e.g. "gvim.exe -f +72 myfile.c") and then it quickly returns to cscope without the editor ever popping.
2. If CSCOPE_EDITOR is gvim.exe (without the -f option) then a gvim.exe process is kicked off (I see it in Windows Task Manager under Processes) but it never comes to the foreground as an application. Furthermore, the cscope window in cmd.exe goes blank and is unresponsive until I manually kill the gvim.exe process that was spawned.

For reference:
cscope -V returns "cscope: version 15.8a" and was downloaded from this site: http://code.google.com/p/cscope-win32/
My version of gvim.exe is 7.3 which the latest available from http://www.vim.org/

Also, I have tagged this post with "C" because, while this is not a C language question, cscope and ctags are primarily used for C programming and thus I think the C tag is relevant. (Thought I'd point that out before someone comes along and removes the tag and says this isn't a C question, since C programmers are the most likely people to have the answer.)

Answer 1

With help from @mattn and @mMontu and a lot of trial-and-error and an ugly but simple hack I finally have this working. Here are the problems I encountered:

1. cscope-win32 does not handle spaces in the EDITOR or CSCOPE_EDITOR environment variables. I tried every space-escape trick I could think of (single-quotes, double-quotes, backslash escapes) and nothing worked.

2. When gvim.exe is successfully launched by cscope-win32, if that gvim.exe tries to add the same cscope.out database (via cs add cscope.out) the add command hangs. If the add is part of a vimrc file then the editor will hang during opening (with the gvim.exe and cscope.exe processes starting but the application window never appearing). If the add is done after the editor window opens then the window will hang. This appears related to multiple cscope-win32 processes being attempted in the same process tree, but I have no actual proof of that.

Here's my solution to the problem. Like I said, it is an ugly but simple hack.

1. Create a wrapper batch file. I named mine gvim_cscope.bat. Make sure it is in a directory that exists in your PATH environment variable. You can verify this in a cmd.exe shell by calling "where gvim_cscope.bat".

2. Edit the batch file and add your editor command but precede it with the windows start command. For example, my batch file contains the following:

   start gvim.exe %*

3. Create/Update your CSCOPE_EDITOR environment variable to be "gvim_cscope.bat". In case you've never modified a Windows environment variable before, you can get to them (on Windows 7 anyway) via Start -> right-click Computer -> Properties -> Advanced System Settings -> Environment Variables.

That's all I needed to get things working. Open a new cmd.exe window (so the updated environment variable is pulled in) and open cscope.exe and everything works. I am able to pop multiple gvim.exe windows from within cscope.exe, each with its own connection to the cscope.out database. The first problem is avoided by using the wrapper batch file (no more spaces in the command) and the second problem is avoided by using the windows start command so that gvim.exe is started as a separate process.

Thanks for the help @mattn and @mMontu. So nice to have things working right!