provider: g:loaded_xx_provider=2 means "enabled and working"

Value of 1 cannot be used, because users might set that in their vimrc
to _disable_ a provider, which would confuse :checkhealth and has().

runtime/autoload/provider/clipboard.vim

@@ -5,11 +5,11 @@
 if exists('g:loaded_clipboard_provider')
   finish
 endif
-" Default to FALSE.  Set by provider#clipboard#Executable() later.
+" Default to 1.  provider#clipboard#Executable() may set 2.
 " To force a reload:
 "   :unlet g:loaded_clipboard_provider
 "   :runtime autoload/provider/clipboard.vim
-let g:loaded_clipboard_provider = 0
+let g:loaded_clipboard_provider = 1
 
 let s:copy = {}
 let s:paste = {}
@@ -197,4 +197,4 @@ function! provider#clipboard#Call(method, args) abort
 endfunction
 
 " eval_has_provider() decides based on this variable.
-let g:loaded_clipboard_provider = !empty(provider#clipboard#Executable())
+let g:loaded_clipboard_provider = empty(provider#clipboard#Executable()) ? 1 : 2

runtime/autoload/provider/node.vim

@@ -1,7 +1,7 @@
 if exists('g:loaded_node_provider')
   finish
 endif
-let g:loaded_node_provider = 0
+let g:loaded_node_provider = 1
 
 function! s:is_minimum_version(version, min_major, min_minor) abort
   if empty(a:version)
@@ -140,9 +140,9 @@ endfunction
 
 let s:err = ''
 let s:prog = provider#node#Detect()
-let g:loaded_node_provider = !empty(s:prog)
+let g:loaded_node_provider = empty(s:prog) ? 1 : 2
 
-if !g:loaded_node_provider
+if g:loaded_node_provider != 2
   let s:err = 'Cannot find the "neovim" node package. Try :checkhealth'
 endif
 

runtime/autoload/provider/python.vim

@@ -8,7 +8,7 @@ if exists('g:loaded_python_provider')
   finish
 endif
 let [s:prog, s:err] = provider#pythonx#Detect(2)
-let g:loaded_python_provider = !empty(s:prog)
+let g:loaded_python_provider = empty(s:prog) ? 1 : 2
 
 function! provider#python#Prog() abort
   return s:prog

runtime/autoload/provider/python3.vim

@@ -8,7 +8,7 @@ if exists('g:loaded_python3_provider')
   finish
 endif
 let [s:prog, s:err] = provider#pythonx#Detect(3)
-let g:loaded_python3_provider = !empty(s:prog)
+let g:loaded_python3_provider = empty(s:prog) ? 1 : 2
 
 function! provider#python3#Prog() abort
   return s:prog

runtime/autoload/provider/ruby.vim

@@ -2,7 +2,7 @@
 if exists('g:loaded_ruby_provider')
   finish
 endif
-let g:loaded_ruby_provider = 0
+let g:loaded_ruby_provider = 1
 
 function! provider#ruby#Detect() abort
   return s:prog
@@ -62,9 +62,9 @@ endfunction
 let s:err = ''
 let s:prog = s:detect()
 let s:plugin_path = expand('<sfile>:p:h') . '/script_host.rb'
-let g:loaded_ruby_provider = !empty(s:prog)
+let g:loaded_ruby_provider = empty(s:prog) ? 1 : 2
 
-if !g:loaded_ruby_provider
+if g:loaded_ruby_provider != 2
   let s:err = 'Cannot find the neovim RubyGem. Try :checkhealth'
 endif
 

runtime/doc/develop.txt

@@ -106,12 +106,12 @@ in eval.c:
 - eval_call_provider(name, method, arguments): calls provider#{name}#Call
   with the method and arguments.
 - eval_has_provider(name): Checks the `g:loaded_{name}_provider` variable
-  which must be set by the provider script to indicate whether it is enabled
-  and working. Called by |has()| to check if features are available.
+  which must be set to 2 by the provider script to indicate that it is
+  "enabled and working". Called by |has()| to check if features are available.
 
 For example, the Python provider is implemented by the
 "autoload/provider/python.vim" script, which sets `g:loaded_python_provider`
-to TRUE only if a valid external Python host is found.  Then `has("python")`
+to 2 only if a valid external Python host is found.  Then `has("python")`
 reflects whether Python support is working.
 
 							*provider-reload*

runtime/doc/provider.txt

@@ -68,11 +68,11 @@ startup faster. Useful for working with virtualenvs.  >
 <
 						*g:loaded_python_provider*
 To disable Python 2 support: >
-    let g:loaded_python_provider = 1
+    let g:loaded_python_provider = 0
 <
 						*g:loaded_python3_provider*
 To disable Python 3 support: >
-    let g:loaded_python3_provider = 1
+    let g:loaded_python3_provider = 0
 
 
 PYTHON VIRTUALENVS ~
@@ -111,7 +111,7 @@ Run |:checkhealth| to see if your system is up-to-date.
 RUBY PROVIDER CONFIGURATION ~
 						*g:loaded_ruby_provider*
 To disable Ruby support: >
-    let g:loaded_ruby_provider = 1
+    let g:loaded_ruby_provider = 0
 <
 						*g:ruby_host_prog*
 Command to start the Ruby host. By default this is "neovim-ruby-host". With
@@ -142,7 +142,7 @@ Run |:checkhealth| to see if your system is up-to-date.
 NODEJS PROVIDER CONFIGURATION~
 						*g:loaded_node_provider*
 To disable Node.js support: >
-    :let g:loaded_node_provider = 1
+    :let g:loaded_node_provider = 0
 <
 						*g:node_host_prog*
 Command to start the Node.js host. Setting this makes startup faster.

src/nvim/eval.c

@@ -23996,7 +23996,9 @@ bool eval_has_provider(const char *provider)
     }
   }
 
-  return (tv.v_type == VAR_NUMBER) ? !!tv.vval.v_number : false;
+  return (tv.v_type == VAR_NUMBER)
+    ? 2 == tv.vval.v_number  // Value of 2 means "loaded and working".
+    : false;
 }
 
 /// Writes "<sourcing_name>:<sourcing_lnum>" to `buf[bufsize]`.

test/functional/fixtures/autoload/provider/brokencall.vim

@@ -1,2 +1,2 @@
 " A dummy test provider
-let g:loaded_brokencall_provider = 1
+let g:loaded_brokencall_provider = 2

test/functional/fixtures/autoload/provider/clipboard.vim

@@ -1,4 +1,4 @@
-let g:loaded_clipboard_provider = 1
+let g:loaded_clipboard_provider = 2
 
 let g:test_clip = { '+': [''], '*': [''], }