Fix #680 - Use --shadow-file to check for problems with mypy while you type

ale_linters/python/mypy.vim

@@ -7,19 +7,7 @@ let g:ale_python_mypy_options = get(g:, 'ale_python_mypy_options', '')
 let g:ale_python_mypy_use_global = get(g:, 'ale_python_mypy_use_global', 0)
 
 function! ale_linters#python#mypy#GetExecutable(buffer) abort
-    if !ale#Var(a:buffer, 'python_mypy_use_global')
-        let l:virtualenv = ale#python#FindVirtualenv(a:buffer)
-
-        if !empty(l:virtualenv)
-            let l:ve_mypy = l:virtualenv . '/bin/mypy'
-
-            if executable(l:ve_mypy)
-                return l:ve_mypy
-            endif
-        endif
-    endif
-
-    return ale#Var(a:buffer, 'python_mypy_executable')
+    return ale#python#FindExecutable(a:buffer, 'python_mypy', ['/bin/mypy'])
 endfunction
 
 function! ale_linters#python#mypy#GetCommand(buffer) abort
@@ -33,7 +21,7 @@ function! ale_linters#python#mypy#GetCommand(buffer) abort
     \   . ale#Escape(l:executable)
     \   . ' --show-column-numbers '
     \   . ale#Var(a:buffer, 'python_mypy_options')
-    \   . ' %s'
+    \   . ' --shadow-file %s %t %s'
 endfunction
 
 function! ale_linters#python#mypy#Handle(buffer, lines) abort
@@ -69,5 +57,4 @@ call ale#linter#Define('python', {
 \   'executable_callback': 'ale_linters#python#mypy#GetExecutable',
 \   'command_callback': 'ale_linters#python#mypy#GetCommand',
 \   'callback': 'ale_linters#python#mypy#Handle',
-\   'lint_file': 1,
 \})

autoload/ale/fixers/autopep8.vim

@@ -12,7 +12,7 @@ function! ale#fixers#autopep8#Fix(buffer) abort
     \   ['/bin/autopep8'],
     \)
 
-    if empty(l:executable)
+    if !executable(l:executable)
         return 0
     endif
 

autoload/ale/fixers/isort.vim

@@ -11,7 +11,7 @@ function! ale#fixers#isort#Fix(buffer) abort
     \   ['/bin/isort'],
     \)
 
-    if empty(l:executable)
+    if !executable(l:executable)
         return 0
     endif
 

autoload/ale/fixers/yapf.vim

@@ -11,7 +11,7 @@ function! ale#fixers#yapf#Fix(buffer) abort
     \   ['/bin/yapf'],
     \)
 
-    if empty(l:executable)
+    if !executable(l:executable)
         return 0
     endif
 

autoload/ale/python.vim

@@ -58,11 +58,5 @@ function! ale#python#FindExecutable(buffer, base_var_name, path_list) abort
         endfor
     endif
 
-    let l:global_executable = ale#Var(a:buffer, a:base_var_name . '_executable')
-
-    if executable(l:global_executable)
-        return l:global_executable
-    endif
-
-    return ''
+    return ale#Var(a:buffer, a:base_var_name . '_executable')
 endfunction

doc/ale-python.txt

@@ -107,6 +107,11 @@ g:ale_python_isort_use_global                   *g:ale_python_isort_use_global*
 -------------------------------------------------------------------------------
 mypy                                                          *ale-python-mypy*
 
+The minimum supported version of mypy that ALE supports is v0.4.4. This is
+the first version containing the `--shadow-file` option ALE needs to be able
+to check for errors while you type.
+
+
 g:ale_python_mypy_executable                     *g:ale_python_mypy_executable*
                                                  *b:ale_python_mypy_executable*
   Type: |String|

test/command_callback/test_mypy_command_callback.vader

@@ -20,7 +20,8 @@ Execute(The mypy callbacks should return the correct default values):
   \ 'mypy',
   \ ale_linters#python#mypy#GetExecutable(bufnr(''))
   AssertEqual
-  \ 'cd ''' . g:dir . ''' && ''mypy'' --show-column-numbers  %s',
+  \ 'cd ''' . g:dir . ''' && ''mypy'' --show-column-numbers  '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))
 
 Execute(The mypy executable should be configurable, and escaped properly):
@@ -30,14 +31,16 @@ Execute(The mypy executable should be configurable, and escaped properly):
   \ 'executable with spaces',
   \ ale_linters#python#mypy#GetExecutable(bufnr(''))
   AssertEqual
-  \ 'cd ''' . g:dir . ''' && ''executable with spaces'' --show-column-numbers  %s',
+  \ 'cd ''' . g:dir . ''' && ''executable with spaces'' --show-column-numbers  '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))
 
 Execute(The mypy command callback should let you set options):
   let g:ale_python_mypy_options = '--some-option'
 
   AssertEqual
-  \ 'cd ''' . g:dir . ''' && ''mypy'' --show-column-numbers --some-option %s',
+  \ 'cd ''' . g:dir . ''' && ''mypy'' --show-column-numbers --some-option '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))
 
 Execute(The mypy command should switch directories to the detected project root):
@@ -47,7 +50,8 @@ Execute(The mypy command should switch directories to the detected project root)
   \ 'mypy',
   \ ale_linters#python#mypy#GetExecutable(bufnr(''))
   AssertEqual
-  \ 'cd ''' . g:dir . '/python_paths/no_virtualenv/subdir'' && ''mypy'' --show-column-numbers  %s',
+  \ 'cd ''' . g:dir . '/python_paths/no_virtualenv/subdir'' && ''mypy'' --show-column-numbers  '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))
 
 Execute(The mypy callbacks should detect virtualenv directories and switch to the project root):
@@ -58,7 +62,8 @@ Execute(The mypy callbacks should detect virtualenv directories and switch to th
   \ ale_linters#python#mypy#GetExecutable(bufnr(''))
   AssertEqual
   \   'cd ''' . g:dir . '/python_paths/with_virtualenv/subdir'' && '''
-  \   . g:dir . '/python_paths/with_virtualenv/env/bin/mypy'' --show-column-numbers  %s',
+  \   . g:dir . '/python_paths/with_virtualenv/env/bin/mypy'' --show-column-numbers  '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))
 
 Execute(You should able able to use the global mypy instead):
@@ -69,5 +74,6 @@ Execute(You should able able to use the global mypy instead):
   \ 'mypy',
   \ ale_linters#python#mypy#GetExecutable(bufnr(''))
   AssertEqual
-  \ 'cd ''' . g:dir . '/python_paths/with_virtualenv/subdir'' && ''mypy'' --show-column-numbers  %s',
+  \ 'cd ''' . g:dir . '/python_paths/with_virtualenv/subdir'' && ''mypy'' --show-column-numbers  '
+  \   . '--shadow-file %s %t %s',
   \ ale_linters#python#mypy#GetCommand(bufnr(''))