feat(provider)!: remove support for python2 and python3.[3-5]

These versions of python has reached End-of-life. getting rid
of python2 support removes a lot of logic to support two
incompatible python versions in the same version.

9 files changed, 50 insertions, 149 deletions

diff --git a/runtime/autoload/health/nvim.vim b/runtime/autoload/health/nvim.vim
index 0bb343e198..ef680097d5 100644
--- a/runtime/autoload/health/nvim.vim
+++ b/runtime/autoload/health/nvim.vim
@@ -104,8 +104,8 @@ function! s:check_rplugin_manifest() abort
         if !has_key(existing_rplugins, script)
           let msg = printf('"%s" is not registered.', fnamemodify(path, ':t'))
           if python_version ==# 'pythonx'
-            if !has('python2') && !has('python3')
-              let msg .= ' (python2 and python3 not available)'
+            if !has('python3')
+              let msg .= ' (python3 not available)'
             endif
           elseif !has(python_version)
             let msg .= printf(' (%s not available)', python_version)
diff --git a/runtime/autoload/health/provider.vim b/runtime/autoload/health/provider.vim
index e6523aa215..8f0dbbab39 100644
--- a/runtime/autoload/health/provider.vim
+++ b/runtime/autoload/health/provider.vim
@@ -282,10 +282,10 @@ function! s:disabled_via_loaded_var(provider) abort
   return 0
 endfunction
 
-function! s:check_python(version) abort
-  call health#report_start('Python ' . a:version . ' provider (optional)')
+function! s:check_python() abort
+  call health#report_start('Python 3 provider (optional)')
 
-  let pyname = 'python'.(a:version == 2 ? '' : '3')
+  let pyname = 'python3'
   let python_exe = ''
   let venv = exists('$VIRTUAL_ENV') ? resolve($VIRTUAL_ENV) : ''
   let host_prog_var = pyname.'_host_prog'
@@ -301,7 +301,7 @@ function! s:check_python(version) abort
     call health#report_info(printf('Using: g:%s = "%s"', host_prog_var, get(g:, host_prog_var)))
   endif
 
-  let [pyname, pythonx_errors] = provider#pythonx#Detect(a:version)
+  let [pyname, pythonx_errors] = provider#pythonx#Detect(3)
 
   if empty(pyname)
     call health#report_warn('No Python executable found that can `import neovim`. '
@@ -405,7 +405,7 @@ function! s:check_python(version) abort
     " can import 'pynvim'. If so, that Python failed to import 'neovim' as
     " well, which is most probably due to a failed pip upgrade:
     " https://github.com/neovim/neovim/wiki/Following-HEAD#20181118
-    let [pynvim_exe, errors] = provider#pythonx#DetectByModule('pynvim', a:version)
+    let [pynvim_exe, errors] = provider#pythonx#DetectByModule('pynvim', 3)
     if !empty(pynvim_exe)
       call health#report_error(
             \ 'Detected pip upgrade failure: Python executable can import "pynvim" but '
@@ -416,14 +416,14 @@ function! s:check_python(version) abort
             \ . pynvim_exe ." -m pip install neovim  # only if needed by third-party software")
     endif
   else
-    let [pyversion, current, latest, status] = s:version_info(python_exe)
+    let [majorpyversion, current, latest, status] = s:version_info(python_exe)
 
-    if a:version != str2nr(pyversion)
+    if 3 != str2nr(majorpyversion)
       call health#report_warn('Unexpected Python version.' .
                   \ ' This could lead to confusing error messages.')
     endif
 
-    call health#report_info('Python version: ' . pyversion)
+    call health#report_info('Python version: ' . majorpyversion)
 
     if s:is_bad_response(status)
       call health#report_info(printf('pynvim version: %s (%s)', current, status))
@@ -751,8 +751,7 @@ endfunction
 
 function! health#provider#check() abort
   call s:check_clipboard()
-  call s:check_python(2)
-  call s:check_python(3)
+  call s:check_python()
   call s:check_virtualenv()
   call s:check_ruby()
   call s:check_node()
diff --git a/runtime/autoload/provider/python.vim b/runtime/autoload/provider/python.vim
deleted file mode 100644
index 8a1d162784..0000000000
--- a/runtime/autoload/provider/python.vim
+++ /dev/null
@@ -1,45 +0,0 @@
-" The Python provider uses a Python host to emulate an environment for running
-" python-vim plugins. :help provider
-"
-" Associating the plugin with the Python host is the first step because plugins
-" will be passed as command-line arguments
-
-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) ? 1 : 2
-
-function! provider#python#Prog() abort
-  return s:prog
-endfunction
-
-function! provider#python#Error() abort
-  return s:err
-endfunction
-
-" The Python provider plugin will run in a separate instance of the Python
-" host.
-call remote#host#RegisterClone('legacy-python-provider', 'python')
-call remote#host#RegisterPlugin('legacy-python-provider', 'script_host.py', [])
-
-function! provider#python#Call(method, args) abort
-  if s:err != ''
-    return
-  endif
-  if !exists('s:host')
-    let s:rpcrequest = function('rpcrequest')
-
-    " Ensure that we can load the Python host before bootstrapping
-    try
-      let s:host = remote#host#Require('legacy-python-provider')
-    catch
-      let s:err = v:exception
-      echohl WarningMsg
-      echomsg v:exception
-      echohl None
-      return
-    endtry
-  endif
-  return call(s:rpcrequest, insert(insert(a:args, 'python_'.a:method), s:host))
-endfunction
diff --git a/runtime/autoload/provider/pythonx.vim b/runtime/autoload/provider/pythonx.vim
index 0eeb35cba8..5b299b322c 100644
--- a/runtime/autoload/provider/pythonx.vim
+++ b/runtime/autoload/provider/pythonx.vim
@@ -6,10 +6,8 @@ endif
 let s:loaded_pythonx_provider = 1
 
 function! provider#pythonx#Require(host) abort
-  let ver = (a:host.orig_name ==# 'python') ? 2 : 3
-
   " Python host arguments
-  let prog = (ver == '2' ?  provider#python#Prog() : provider#python3#Prog())
+  let prog = provider#python3#Prog()
   let args = [prog, '-c', 'import sys; sys.path = list(filter(lambda x: x != "", sys.path)); import neovim; neovim.start_host()']
 
 
@@ -23,14 +21,12 @@ function! provider#pythonx#Require(host) abort
 endfunction
 
 function! s:get_python_executable_from_host_var(major_version) abort
-  return expand(get(g:, 'python'.(a:major_version == 3 ? '3' : '').'_host_prog', ''), v:true)
+  return expand(get(g:, 'python'.(a:major_version == 3 ? '3' : execute("throw 'unsupported'")).'_host_prog', ''), v:true)
 endfunction
 
 function! s:get_python_candidates(major_version) abort
   return {
-        \ 2: ['python2', 'python2.7', 'python2.6', 'python'],
-        \ 3: ['python3', 'python3.10', 'python3.9', 'python3.8', 'python3.7',
-        \     'python3.6', 'python']
+        \ 3: ['python3', 'python3.10', 'python3.9', 'python3.8', 'python3.7', 'python']
         \ }[a:major_version]
 endfunction
 
@@ -82,7 +78,7 @@ function! provider#pythonx#CheckForModule(prog, module, major_version) abort
     return [0, a:prog . ' not found in search path or not executable.']
   endif
 
-  let min_version = (a:major_version == 2) ? '2.6' : '3.3'
+  let min_version = '3.7'
 
   " Try to load module, and output Python version.
   " Exit codes:
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 4a307c0d13..800604b506 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -5806,7 +5806,6 @@ has({feature})	Returns 1 if {feature} is supported, 0 otherwise.  The
 					this is not present).
 			mac		MacOS system.
 			nvim		This is Nvim.
-			python2		Legacy Vim |python2| interface. |has-python|
 			python3		Legacy Vim |python3| interface. |has-python|
 			pythonx		Legacy Vim |python_x| interface. |has-pythonx|
 			ttyin		input is a terminal (tty)
diff --git a/runtime/doc/if_pyth.txt b/runtime/doc/if_pyth.txt
index fea47de220..afdf039aa8 100644
--- a/runtime/doc/if_pyth.txt
+++ b/runtime/doc/if_pyth.txt
@@ -1,10 +1,10 @@
 *if_pyth.txt*   Nvim
 
 
-		  VIM REFERENCE MANUAL    by Paul Moore
+		  NVIM REFERENCE MANUAL
 
 
-The Python Interface to Vim				*if_pyth* *python* *Python*
+The Python Interface to NVim				*if_pyth* *python* *Python*
 
 See |provider-python| for more information.
 
@@ -134,7 +134,7 @@ Instead, put the Python command in a function and call that function:
 Note that "EOF" must be at the start of the line.
 
 ==============================================================================
-The vim module						*python-vim* *python2*
+The vim module							*python-vim*
 
 Python code gets all of its access to vim (with one exception - see
 |python-output| below) via the "vim" module.  The vim module implements two
@@ -322,14 +322,13 @@ Output from Python					*python-output*
 	supported, and may cause the program to crash.  This should probably be
 	fixed.
 
-		    *python2-directory* *python3-directory* *pythonx-directory*
+				  *python3-directory* *pythonx-directory*
 Python 'runtimepath' handling				*python-special-path*
 
 In python vim.VIM_SPECIAL_PATH special directory is used as a replacement for
 the list of paths found in 'runtimepath': with this directory in sys.path and
 vim.path_hooks in sys.path_hooks python will try to load module from
-{rtp}/python2 (or python3) and {rtp}/pythonx (for both python versions) for
-each {rtp} found in 'runtimepath'.
+{rtp}/python3 and {rtp}/pythonx for each {rtp} found in 'runtimepath'.
 
 Implementation is similar to the following, but written in C: >
 
@@ -401,8 +400,8 @@ vim._get_paths						*python-_get_paths*
 	hook. You should not rely on this method being present in future
 	versions, but can use it for debugging.
 
-	It returns a list of {rtp}/python2 (or {rtp}/python3) and
-	{rtp}/pythonx directories for each {rtp} in 'runtimepath'.
+	It returns a list of {rtp}/python3 and {rtp}/pythonx
+	directories for each {rtp} in 'runtimepath'.
 
 ==============================================================================
 Buffer objects						*python-buffer*
@@ -590,6 +589,11 @@ functions to evaluate Python expressions and pass their values to Vim script.
 ==============================================================================
 Python 3						*python3*
 
+As Python 3 is the only supported version in Nvim, "python" is synonymous
+with "python3" in the current version. However, code that aims to support older
+versions of Neovim, as well as Vim, should prefer to use "python3"
+variants explicitly if Python 3 is required.
+
 							*:py3* *:python3*
 :[range]py3 {stmt}
 :[range]py3 << [endmarker]
@@ -619,31 +623,26 @@ Raising SystemExit exception in python isn't endorsed way to quit vim, use: >
 	:py vim.command("qall!")
 <
 							*has-python*
-You can test what Python version is available with: >
-	if has('python')
-	  echo 'there is Python 2.x'
+You can test if Python is available with: >
+	if has('pythonx')
+	  echo 'there is Python'
 	endif
   	if has('python3')
 	  echo 'there is Python 3.x'
 	endif
 
+Python 2 is no longer supported. Thus `has('python')` always returns
+zero for backwards compatibility reasons.
+
 ==============================================================================
 Python X						*python_x* *pythonx*
 
-Because most python code can be written so that it works with Python 2.6+ and
-Python 3, the pyx* functions and commands have been written.  They work the
-same as the Python 2 and 3 variants, but select the Python version using the
-'pyxversion' setting.
-
-Set 'pyxversion' in your |vimrc| to prefer Python 2 or Python 3 for Python
-commands. Changing this setting at runtime risks losing the state of plugins
-(such as initialization).
-
-If you want to use a module, you can put it in the {rtp}/pythonx directory.
-See |pythonx-directory|.
+The "pythonx" and "pyx" prefixes were introduced for python code which
+works with Python 2.6+ and Python 3. As Nvim only supports Python 3,
+all these commands are now synonymous to their "python3" equivalents.
 
 							*:pyx* *:pythonx*
-`:pyx` and `:pythonx` work similar to `:python`.  To check if `:pyx` works: >
+`:pyx` and `:pythonx` work the same as `:python3`.  To check if `:pyx` works: >
 	:pyx print("Hello")
 
 To see what version of Python is being used: >
@@ -651,34 +650,16 @@ To see what version of Python is being used: >
 	:pyx print(sys.version)
 <
 					*:pyxfile* *python_x-special-comments*
-`:pyxfile` works similar to `:pyfile`.  But you can add a "shebang" comment to
-force Vim to use `:pyfile` or `:py3file`: >
-  #!/any string/python2		" Shebang. Must be the first line of the file.
-  #!/any string/python3		" Shebang. Must be the first line of the file.
-  # requires python 2.x		" Maximum lines depend on 'modelines'.
-  # requires python 3.x		" Maximum lines depend on 'modelines'.
-Unlike normal modelines, the bottom of the file is not checked.
-If none of them are found, the 'pyxversion' option is used.
-							*W20* *W21*
-If Vim does not support the selected Python version a silent message will be
-printed.  Use `:messages` to read them.
+`:pyxfile` works the same as `:py3file`. 
 
 							*:pyxdo*
-`:pyxdo` works similar to `:pydo`.
+`:pyxdo` works the same as `:py3do`.
 
 							*has-pythonx*
-To check if pyx* functions and commands are available: >
+To check if `pyx*` functions and commands are available: >
 	if has('pythonx')
 	  echo 'pyx* commands are available. (Python ' . &pyx . ')'
 	endif
 
-If you prefer Python 2 and want to fallback to Python 3, set 'pyxversion'
-explicitly in your |.vimrc|.  Example: >
-	if has('python')
-	  set pyx=2
-	elseif has('python3')
-	  set pyx=3
-	endif
-
 ==============================================================================
  vim:tw=78:ts=8:noet:ft=help:norl:
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 13a19d8991..5e7d709584 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -4637,26 +4637,11 @@ A jump table for the options with a short description can be found at |Q_op|.
 	nudged to fit on the screen.
 
 						*'pyxversion'* *'pyx'*
-'pyxversion' 'pyx'	number	(default depends on the build)
+'pyxversion' 'pyx'	number	(default 3)
 			global
 	Specifies the python version used for pyx* functions and commands
-	|python_x|.  The default value is as follows:
-
-		|provider| installed	    Default ~
-		|+python| and |+python3|	0
-		only |+python|			2
-		only |+python3|			3
-
-	Available values are 0, 2 and 3.
-	If 'pyxversion' is 0, it is set to 2 or 3 after the first execution of
-	any python2/3 commands or functions.  E.g. `:py` sets to 2, and `:py3`
-	sets to 3. `:pyx` sets it to 3 if Python 3 is available, otherwise sets
-	to 2 if Python 2 is available.
-	See also: |has-pythonx|
-
-	If only |+python| or |+python3| are available,
-	'pyxversion' has no effect. The pyx* functions and commands are
-	always the same as the installed version.
+	|python_x|.  As only Python 3 is supported, this always has the value
+	`3`. Setting any other value is an error.
 
 	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
diff --git a/runtime/doc/provider.txt b/runtime/doc/provider.txt
index b785010699..9fd35f19c5 100644
--- a/runtime/doc/provider.txt
+++ b/runtime/doc/provider.txt
@@ -20,11 +20,12 @@ Run the |:checkhealth| command, and review the sections below.
 ==============================================================================
 Python integration				*provider-python*
 
-Nvim supports Python |remote-plugin|s and the Vim legacy |python2| and
-|python3| interfaces (which are implemented as remote-plugins).
+Nvim supports Python |remote-plugin|s and the Vim legacy |python3| and
+|pythonx| interfaces (which are implemented as remote-plugins).
 
 Note: Only the Vim 7.3 legacy interface is supported, not later features such
-as |python-bindeval| (Vim 7.4); use the Nvim API instead.
+as |python-bindeval| (Vim 7.4); use the Nvim API instead. Python 2 is not
+supported.
 
 
 PYTHON QUICKSTART ~
@@ -38,11 +39,6 @@ For Python 3 plugins:
 2. Install the module (try "python" if "python3" is missing): >
    python3 -m pip install --user --upgrade pynvim
 
-For Python 2 plugins:
-1. Make sure Python 2.7 is available in your $PATH.
-2. Install the module (try "python" if "python2" is missing): >
-   python2 -m pip install --user --upgrade pynvim
-
 The pip `--upgrade` flag ensures that you get the latest version even if
 a previous version was already installed.
 
@@ -56,22 +52,12 @@ If you run into problems, uninstall _both_ then install "pynvim" again: >
 
 
 PYTHON PROVIDER CONFIGURATION ~
-						*g:python_host_prog*
-Command to start Python 2 (executable, not directory). Setting this makes
-startup faster. Useful for working with virtualenvs. Must be set before any
-check for has("python2").  >
-    let g:python_host_prog  = '/path/to/python'
-<
 						*g:python3_host_prog*
 Command to start Python 3 (executable, not directory). Setting this makes
 startup faster. Useful for working with virtualenvs. Must be set before any
 check for has("python3").  >
     let g:python3_host_prog = '/path/to/python3'
 <
-						*g:loaded_python_provider*
-To disable Python 2 support: >
-    let g:loaded_python_provider = 0
-<
 						*g:loaded_python3_provider*
 To disable Python 3 support: >
     let g:loaded_python3_provider = 0
@@ -81,8 +67,8 @@ PYTHON VIRTUALENVS ~
 						*python-virtualenv*
 If you plan to use per-project virtualenvs often, you should assign one
 virtualenv for Neovim and hard-code the interpreter path via
-|g:python3_host_prog| (or |g:python_host_prog|) so that the "pynvim" package
-is not required for each virtualenv.
+|g:python3_host_prog| so that the "pynvim" package is not required
+for each virtualenv.
 
 Example using pyenv: >
     pyenv install 3.4.4
diff --git a/runtime/doc/quickfix.txt b/runtime/doc/quickfix.txt
index 873fbd8971..bb4d807413 100644
--- a/runtime/doc/quickfix.txt
+++ b/runtime/doc/quickfix.txt
@@ -1446,7 +1446,7 @@ error message (line numbers are not part of the actual output):
      4	Traceback (most recent call last):
      5	  File "unittests/dbfacadeTest.py", line 89, in testFoo
      6	    self.assertEquals(34, dtid)
-     7	  File "/usr/lib/python2.2/unittest.py", line 286, in
+     7	  File "/usr/lib/python3.8/unittest.py", line 286, in
      8	 failUnlessEqual
      9	    raise self.failureException, \
     10	AssertionError: 34 != 33