init: improve handling of import errors (#840)

* jedi_vim.jedi_import_error: add location

This is useful for debugging.  It contains e.g. the path to parso, if
importing failed from there.

Example:

> Error: jedi-vim failed to initialize Python: jedi#setup_python_imports: could not import jedi: cannot import name 'PythonTokenTypes' (in /…/jedi-vim/pythonx/jedi/jedi/api/completion.py:1). (in function jedi#init_python[3]..<SNR>44_init_python[27]..jedi#setup_python_imports, line 37)

* init: handle jedi_vim.jedi_import_error in Vim plugin

Using `set shortmess+=F` would suppress the `:echom` used in
`jedi_vim.no_jedi_warning` [1].

This patch makes `jedi#setup_python_imports` handle the error instead.

1: https://github.com/neovim/neovim/issues/8675

* Revisit error handling with loading jedi_vim

* jedi#debug_info: display parso submodule separately

* Fix jedi#reinit_python

* fixup! Revisit error handling with loading jedi_vim

* display_debug_info: handle exceptions with environment.get_sys_path

* fixup! Revisit error handling with loading jedi_vim

[ci skip]

autoload/jedi.vim

@@ -91,7 +91,7 @@ endfunction
 
 
 function! jedi#reinit_python() abort
-    unlet! s:_init_python
+    let s:_init_python = -1
     call jedi#init_python()
 endfunction
 
@@ -99,13 +99,29 @@ endfunction
 let s:_init_python = -1
 function! jedi#init_python() abort
     if s:_init_python == -1
+        let s:_init_python = 0
         try
             let s:_init_python = s:init_python()
-        catch
+            let s:_init_python = 1
-            let s:_init_python = 0
+        catch /^jedi/
+            " Only catch errors from jedi-vim itself here, so that for
+            " unexpected Python exceptions the traceback will be shown
+            " (e.g. with NameError in jedi#setup_python_imports's code).
             if !exists('g:jedi#squelch_py_warning')
-                echoerr 'Error: jedi-vim failed to initialize Python: '
+                let error_lines = split(v:exception, '\n')
-                            \ .v:exception.' (in '.v:throwpoint.')'
+                let msg = 'Error: jedi-vim failed to initialize Python: '
+                            \ .error_lines[0].' (in '.v:throwpoint.')'
+                if len(error_lines) > 1
+                    echohl ErrorMsg
+                    echom 'jedi-vim error: '.error_lines[0]
+                    for line in error_lines[1:]
+                        echom line
+                    endfor
+                    echohl None
+                    let msg .= '. See :messages for more information.'
+                endif
+                redraw  " Redraw to only have the main message by default.
+                echoerr msg
             endif
         endtry
     endif
@@ -127,42 +143,27 @@ function! jedi#setup_python_imports(py_version) abort
 
     execute 'command! -nargs=1 PythonJedi '.cmd_exec.' <args>'
 
-    let s:init_outcome = 0
+    let g:_jedi_init_error = 0
     let init_lines = [
           \ 'import vim',
           \ 'try:',
           \ '    import jedi_vim',
+          \ '    if hasattr(jedi_vim, "jedi_import_error"):',
+          \ '        from jedi_vim_debug import format_exc_info',
+          \ '        vim.vars["_jedi_init_error"] = format_exc_info(jedi_vim.jedi_import_error)',
           \ 'except Exception as exc:',
-          \ '    if isinstance(exc, SyntaxError):',
+          \ '    from jedi_vim_debug import format_exc_info',
-          \ '        exc_msg = repr(exc)',
+          \ '    vim.vars["_jedi_init_error"] = format_exc_info()',
-          \ '    else:',
+          \ ]
-          \ '        exc_msg = "%s: %s" % (exc.__class__.__name__, exc)',
-          \ '    vim.command(''let s:init_outcome = "could not import jedi_vim: {0}"''.format(exc_msg))',
-          \ 'else:',
-          \ '    vim.command(''let s:init_outcome = 1'')']
-    try
     exe 'PythonJedi exec('''.escape(join(init_lines, '\n'), "'").''')'
-    catch
+    if g:_jedi_init_error isnot 0
-        throw printf('jedi#setup_python_imports: failed to run Python for initialization: %s.', v:exception)
+        throw printf('jedi#setup_python_imports: %s', g:_jedi_init_error)
-    endtry
-    if s:init_outcome is 0
-        throw 'jedi#setup_python_imports: failed to run Python for initialization.'
-    elseif s:init_outcome isnot 1
-        throw printf('jedi#setup_python_imports: %s.', s:init_outcome)
     endif
     return 1
 endfunction
 
 
 function! jedi#debug_info() abort
-    if s:python_version ==# 'null'
-        try
-            call s:init_python()
-        catch
-            echohl WarningMsg | echom v:exception | echohl None
-            return
-        endtry
-    endif
     if &verbose
       if &filetype !=# 'python'
         echohl WarningMsg | echo 'You should run this in a buffer with filetype "python".' | echohl None
@@ -187,7 +188,9 @@ function! jedi#debug_info() abort
     echo ' - jedi-vim git version: '
     echon substitute(system('git -C '.s:script_path.' describe --tags --always --dirty'), '\v\n$', '', '')
     echo ' - jedi git submodule status: '
-    echon substitute(system('git -C '.s:script_path.' submodule status'), '\v\n$', '', '')
+    echon substitute(system('git -C '.s:script_path.' submodule status pythonx/jedi'), '\v\n$', '', '')
+    echo ' - parso git submodule status: '
+    echon substitute(system('git -C '.s:script_path.' submodule status pythonx/parso'), '\v\n$', '', '')
     echo "\n"
     echo '##### Settings'
     echo '```'

plugin/jedi.vim

@@ -48,7 +48,21 @@ endif
 " Pyimport command
 command! -nargs=1 -complete=custom,jedi#py_import_completions Pyimport :call jedi#py_import(<q-args>)
 
-command! -nargs=0 -bar JediDebugInfo call jedi#debug_info()
+function! s:jedi_debug_info()
+    " Ensure the autoload file has been loaded (and ignore any errors, which
+    " will be displayed with the debug info).
+    let unset = {}
+    let saved_squelch_py_warning = get(g:, 'jedi#squelch_py_warning', unset)
+    let g:jedi#squelch_py_warning = 1
+    call jedi#init_python()
+    if saved_squelch_py_warning is unset
+        unlet g:jedi#squelch_py_warning
+    else
+        let g:jedi#squelch_py_warning = saved_squelch_py_warning
+    endif
+    call jedi#debug_info()
+endfunction
+command! -nargs=0 -bar JediDebugInfo call s:jedi_debug_info()
 command! -nargs=0 -bang JediClearCache call jedi#clear_cache(<bang>0)
 
 " vim: set et ts=4:

pythonx/jedi_vim.py

@@ -110,10 +110,9 @@ sys.path.insert(0, parso_path)
 
 try:
     import jedi
-except ImportError as e:
+except ImportError:
-    no_jedi_warning(str(e))
     jedi = None
-    jedi_import_error = str(e)
+    jedi_import_error = sys.exc_info()
 else:
     try:
         version = jedi.__version__

pythonx/jedi_vim_debug.py

@@ -1,35 +1,60 @@
 """Used in jedi-vim's jedi#debug_info()"""
+import sys
+
 import vim
+from jedi_vim import PythonToVimStr
 
 
 def echo(msg):
-    vim.command('echo {0}'.format(msg))
+    vim.command('echo %r' % PythonToVimStr(msg))
+
+
+def echo_error(msg):
+    vim.command('echohl ErrorMsg')
+    echo(msg)
+    vim.command('echohl None')
+
+
+def format_exc_info(exc_info=None, tb_indent=2):
+    import traceback
+
+    if exc_info is None:
+        exc_info = sys.exc_info()
+
+    exc_msg = traceback.format_exception_only(exc_info[0], exc_info[1])
+    lines = ''.join(exc_msg).rstrip('\n').split('\n')
+
+    lines.append('Traceback (most recent call last):')
+    tb = traceback.format_tb(exc_info[2])
+    lines.extend(''.join(tb).rstrip('\n').split('\n'))
+
+    indent = ' ' * tb_indent
+    return '{0}'.format(('\n' + indent).join(lines))
 
 
 def display_debug_info():
-    echo("printf(' - global sys.version: `%s`', {0!r})".format(
+    echo(' - global sys.version: `{0}`'.format(
         ', '.join([x.strip()
-                   for x in __import__('sys').version.split('\n')])))
+                   for x in sys.version.split('\n')])))
-    echo("printf(' - global site module: `%s`', {0!r})".format(
+    echo(' - global site module: `{0}`'.format(__import__('site').__file__))
-        __import__('site').__file__))
 
     try:
         import jedi_vim
-    except Exception as e:
+    except Exception:
-        echo("printf('ERROR: jedi_vim is not available: %s: %s', "
+        echo_error('ERROR: could not import jedi_vim: {0}'.format(
-             "{0!r}, {1!r})".format(e.__class__.__name__, str(e)))
+            format_exc_info()))
         return
 
-    try:
     if jedi_vim.jedi is None:
-            echo("'ERROR: could not import the \"jedi\" Python module.'")
+        if hasattr(jedi_vim, 'jedi_import_error'):
-            echo("printf('       The error was: %s', {0!r})".format(
+            error_msg = format_exc_info(jedi_vim.jedi_import_error)
-                getattr(jedi_vim, "jedi_import_error", "UNKNOWN")))
         else:
-            echo("printf('Jedi path: `%s`', {0!r})".format(
+            error_msg = 'unknown error'
-                jedi_vim.jedi.__file__))
+        echo_error('ERROR: could not import the "jedi" Python module: {0}'.format(
-            echo("printf(' - version: %s', {0!r})".format(
+            error_msg))
-                jedi_vim.jedi.__version__))
+    else:
+        echo('Jedi path: `{0}`'.format(jedi_vim.jedi.__file__))
+        echo(' - version: {0}'.format(jedi_vim.jedi.__version__))
 
         try:
             environment = jedi_vim.get_environment(use_cache=False)
@@ -40,18 +65,14 @@ def display_debug_info():
             except AttributeError:
                 sys_path = script_evaluator.sys_path
         else:
-                echo("printf(' - environment: %s', {0!r})".format(
+            echo(' - environment: `{0}`'.format(environment))
-                    str(environment)))
+            try:
                 sys_path = environment.get_sys_path()
+            except Exception:
+                echo_error('ERROR: failed to get sys path from environment: {0}'.format(
+                    format_exc_info()))
+                return
 
-            echo("' - sys_path:'")
+        echo(' - sys_path:')
         for p in sys_path:
-                echo("printf('    - `%s`', {0!r})".format(p))
+            echo('    - `{0}`'.format(p))
-    except Exception as e:
-        vim.command('echohl ErrorMsg')
-        echo("printf('There was an error accessing jedi_vim.jedi: %s', {0!r})".format(
-            str(e)))
-        import traceback
-        for l in traceback.format_exc().splitlines():
-            echo("printf('%s', {0!r})".format(l))
-        vim.command('echohl None')