From 6dcd250f4fa39e3ac414338adbf6f95fc66fc04f Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Sat, 25 Apr 2020 21:27:48 +1200
Subject: Handle invalid XDG cache home

---
 vim/autoload/xdg.vim |  2 +-
 vim/vimrc            | 46 +++++++++++++++++++++++++++++-----------------
 2 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/vim/autoload/xdg.vim b/vim/autoload/xdg.vim
index b1bc523a..675cf460 100644
--- a/vim/autoload/xdg.vim
+++ b/vim/autoload/xdg.vim
@@ -27,7 +27,7 @@ function! xdg#CacheDir(name) abort
   let name = a:name
   let home = s:Get('XDG_CACHE_HOME')
   if !s:Absolute(home)
-    return
+    return ''
   endif
   return join([home, name], '/')
 endfunction
diff --git a/vim/vimrc b/vim/vimrc
index 27a79a6f..8afb52d0 100644
--- a/vim/vimrc
+++ b/vim/vimrc
@@ -110,8 +110,12 @@ for s:configdir in reverse(xdg#ConfigDirs('vim'))
 endfor
 "" Cache; put this first so that e.g. spellfiles get created in it
 let s:cachedir = xdg#CacheDir('vim')
-execute 'set runtimepath^='
-      \.option#Escape(option#item#Escape(s:cachedir))
+if strlen(s:cachedir)
+  execute 'set runtimepath^='
+        \.option#Escape(option#item#Escape(s:cachedir))
+else
+  unlet s:cachedir
+endif
 "" Data
 let s:datadir = xdg#DataDirs('vim')[0]
 
@@ -144,8 +148,10 @@ command! -bang -bar -complete=dir -nargs=1 CreatePath
 "
 " <https://github.com/vim/vim/releases/tag/v8.1.0716>
 "
-execute 'set viminfo+='.option#Escape('n'.s:cachedir.'/viminfo')
-call path#Create(s:cachedir)
+if exists('s:cachedir')
+  execute 'set viminfo+='.option#Escape('n'.s:cachedir.'/viminfo')
+  call path#Create(s:cachedir)
+endif
 
 " Speaking of recorded data in viminfo files, the default Vim limit of a mere
 " 50 entries for command and search history is pretty stingy.  Because I don’t
@@ -190,10 +196,12 @@ set history=10000
 " 'backupfullname', 'swapfilefullname' would have been clearer.
 "
 set backup
-execute 'set backupdir^='.option#Escape(option#item#Escape(
-      \ s:cachedir.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
-      \))
-call path#Create(s:cachedir.'/backup')
+if exists('s:cachedir')
+  execute 'set backupdir^='.option#Escape(option#item#Escape(
+        \ s:cachedir.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
+        \))
+  call path#Create(s:cachedir.'/backup')
+endif
 
 " Files in certain directories on Unix-compatible filesystems should not be
 " backed up, for security reasons.  This is particularly important if editing
@@ -229,10 +237,12 @@ endif
 " option has supported that hint for much longer than 'backupdir' has.  We
 " apply path#Create() to attempt to create the path, if needed.
 "
-let s:swap = s:cachedir.'/swap'
-execute 'set directory^='
-      \.option#Escape(option#item#Escape(s:swap.'//'))
-call path#Create(s:swap)
+if exists('s:cachedir')
+  let s:swap = s:cachedir.'/swap'
+  execute 'set directory^='
+        \.option#Escape(option#item#Escape(s:swap.'//'))
+  call path#Create(s:swap)
+endif
 
 " Keep tracked undo history for files permanently, in a dedicated cache
 " directory, so that the u/:undo and CTRL-R/:redo commands will work between
@@ -249,10 +259,12 @@ call path#Create(s:swap)
 "
 if has#('persistent_undo')
   set undofile
-  let s:undodir = s:cachedir.'/undo'
-  execute 'set undodir^='
-        \.option#Escape(option#item#Escape(s:undodir.'//'))
-  call path#Create(s:undodir)
+  if exists('s:cachedir')
+    let s:undodir = s:cachedir.'/undo'
+    execute 'set undodir^='
+          \.option#Escape(option#item#Escape(s:undodir.'//'))
+    call path#Create(s:undodir)
+  endif
 endif
 
 " Set up a directory for files generated by :mkview.  To date, I think I have
@@ -260,7 +272,7 @@ endif
 " directories of this type.  This isn't a comma-separated list like the others
 " ('backupdir', 'directory', 'spell', 'undodir')
 "
-if has#('mksession')
+if has#('mksession') && exists('s:cachedir')
   let s:viewdir = s:cachedir.'/view'
   execute 'set viewdir='
         \.option#Escape(option#item#Escape(s:viewdir))
-- 
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