4 files changed, 35 insertions, 15 deletions
diff --git a/runtime/autoload/health.vim b/runtime/autoload/health.vim
index f875c8b797..bd99a0e104 100644
--- a/runtime/autoload/health.vim
+++ b/runtime/autoload/health.vim
@@ -90,7 +90,7 @@ endfunction
 
 " Changes ':h clipboard' to ':help |clipboard|'.
 function! s:help_to_link(s) abort
-  return substitute(a:s, '\v:h%[elp] ([^|][^"\r\n]+)', ':help |\1|', 'g')
+  return substitute(a:s, '\v:h%[elp] ([^|][^"\r\n ]+)', ':help |\1|', 'g')
 endfunction
 
 " Format a message for a specific report item
diff --git a/runtime/autoload/health/provider.vim b/runtime/autoload/health/provider.vim
index ec20615f69..26db5b77b7 100644
--- a/runtime/autoload/health/provider.vim
+++ b/runtime/autoload/health/provider.vim
@@ -121,14 +121,14 @@ function! s:check_clipboard() abort
   call health#report_start('Clipboard (optional)')
 
   let clipboard_tool = provider#clipboard#Executable()
-  if empty(clipboard_tool)
+  if exists('g:clipboard') && empty(clipboard_tool)
+    call health#report_error(
+          \ provider#clipboard#Error(),
+          \ ["Use the example in :help g:clipboard as a template, or don't set g:clipboard at all."])
+  elseif empty(clipboard_tool)
     call health#report_warn(
-          \ 'No clipboard tool found. Clipboard registers will not work.',
+          \ 'No clipboard tool found. Clipboard registers (`"+` and `"*`) will not work.',
           \ [':help clipboard'])
-  elseif exists('g:clipboard') && (type({}) != type(g:clipboard)
-        \ || !has_key(g:clipboard, 'copy') || !has_key(g:clipboard, 'paste'))
-    call health#report_error(
-          \ 'g:clipboard exists but is malformed. It must be a dictionary with the keys documented at :help g:clipboard')
   else
     call health#report_ok('Clipboard tool found: '. clipboard_tool)
   endif
diff --git a/runtime/autoload/provider.vim b/runtime/autoload/provider.vim
index b46ae12b3c..7439b638c2 100644
--- a/runtime/autoload/provider.vim
+++ b/runtime/autoload/provider.vim
@@ -10,7 +10,9 @@ function! provider#stderr_collector(chan_id, data, event) dict
 endfunction
 
 function! provider#clear_stderr(chan_id)
-   silent! call remove(s:stderr, a:chan_id)
+  if has_key(s:stderr, a:chan_id)
+    call remove(s:stderr, a:chan_id)
+  endif
 endfunction
 
 function! provider#get_stderr(chan_id)
diff --git a/runtime/autoload/provider/clipboard.vim b/runtime/autoload/provider/clipboard.vim
index 8eb694e9fa..6454a01c2a 100644
--- a/runtime/autoload/provider/clipboard.vim
+++ b/runtime/autoload/provider/clipboard.vim
@@ -3,6 +3,7 @@
 " available.
 let s:copy = {}
 let s:paste = {}
+let s:clipboard = {}
 
 " When caching is enabled, store the jobid of the xclip/xsel process keeping
 " ownership of the selection, so we know how long the cache is valid.
@@ -23,7 +24,7 @@ function! s:selection.on_exit(jobid, data, event) abort
   call provider#clear_stderr(a:jobid)
 endfunction
 
-let s:selections = { '*': s:selection, '+': copy(s:selection)}
+let s:selections = { '*': s:selection, '+': copy(s:selection) }
 
 function! s:try_cmd(cmd, ...) abort
   let argv = split(a:cmd, " ")
@@ -31,7 +32,7 @@ function! s:try_cmd(cmd, ...) abort
   if v:shell_error
     if !exists('s:did_error_try_cmd')
       echohl WarningMsg
-      echomsg "clipboard: error: ".(len(out) ? out[0] : '')
+      echomsg "clipboard: error: ".(len(out) ? out[0] : v:shell_error)
       echohl None
       let s:did_error_try_cmd = 1
     endif
@@ -55,9 +56,15 @@ endfunction
 
 function! provider#clipboard#Executable() abort
   if exists('g:clipboard')
+    if type({}) isnot# type(g:clipboard)
+          \ || type({}) isnot# type(get(g:clipboard, 'copy', v:null))
+          \ || type({}) isnot# type(get(g:clipboard, 'paste', v:null))
+      let s:err = 'clipboard: invalid g:clipboard'
+      return ''
+    endif
     let s:copy = get(g:clipboard, 'copy', { '+': v:null, '*': v:null })
     let s:paste = get(g:clipboard, 'paste', { '+': v:null, '*': v:null })
-    let s:cache_enabled = get(g:clipboard, 'cache_enabled', 1)
+    let s:cache_enabled = get(g:clipboard, 'cache_enabled', 0)
     return get(g:clipboard, 'name', 'g:clipboard')
   elseif has('mac') && executable('pbcopy')
     let s:copy['+'] = 'pbcopy'
@@ -104,16 +111,17 @@ function! provider#clipboard#Executable() abort
     return 'tmux'
   endif
 
-  let s:err = 'clipboard: No clipboard tool available. :help clipboard'
+  let s:err = 'clipboard: No clipboard tool. :help clipboard'
   return ''
 endfunction
 
 if empty(provider#clipboard#Executable())
+  " provider#clipboard#Call() *must not* be defined if the provider is broken.
+  " Otherwise eval_has_provider() thinks the clipboard provider is
+  " functioning, and eval_call_provider() will happily call it.
   finish
 endif
 
-let s:clipboard = {}
-
 function! s:clipboard.get(reg) abort
   if s:selections[a:reg].owner > 0
     return s:selections[a:reg].data
@@ -154,9 +162,19 @@ function! s:clipboard.set(lines, regtype, reg) abort
     echohl WarningMsg
     echomsg 'clipboard: failed to execute: '.(s:copy[a:reg])
     echohl None
+    return 0
   endif
+  return 1
 endfunction
 
 function! provider#clipboard#Call(method, args) abort
-  return call(s:clipboard[a:method],a:args,s:clipboard)
+  if get(s:, 'here', v:false)  " Clipboard provider must not recurse. #7184
+    return 0
+  endif
+  let s:here = v:true
+  try
+    return call(s:clipboard[a:method],a:args,s:clipboard)
+  finally
+    let s:here = v:false
+  endtry
 endfunction