Vimdiff failing with “Cannot read or write temp files”

Question

I\'m using Vim 7.4 on Windows 7.

I do have a custom _vimrc file, but both Vim and gVim work fine. When I try to run vimdiff .\\xxxxx .\\yyyyy, it gives the

Answer 1

I installed Vim 8.0 on Windows 7. After adding the directory containg vim to my PATH variable "diffthis" etc. worked out of the box if called from a CMD command line. But calling gvim from a cygwin bash resulted in error "E97: cannot create diff".

The following _vimrc (inspired by this and this post) solved the problem with cygwin and it also works with Windows commandline:

runtime vimrc_example.vim
" Change path to bash with your workstation specific path
set shell=C:\Programme\cygwin\bin\bash
" Override value of TMP from cygwin (normally set to /tmp)
let $TMP="c:/tmp"

Note that with the _vimrc above you lose gvim's Windows-specific behavior like using CTRL-V for pasting etc (you can use SHIFT-Ins anyhow). But with enabled Windows-specific behavior (like in the generated _vimrc during install) gvim failed to perform "diffthis" with "E97:..." error.