Disable completion while entering python multiline statements

The "legacy" completion mechanism sends newlines to the running python
process to get the list of completions, which confuses things if the
user is in the middle of entering a multiline statement (Bug#28051).
It's better to disable completion in this case.
* lisp/progmodes/python.el (python-shell--block-prompt): New variable.
(python-shell-prompt-set-calculated-regexps): Set it.
(python-shell-completion-at-point): Return 'ignore' as the completion
function when the current prompt is a block prompt.

1 files changed, 15 insertions, 1 deletions

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index e73b2a8488c..444167f536e 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -2212,6 +2212,11 @@ machine then modifies `tramp-remote-process-environment' and
 Do not set this variable directly, instead use
 `python-shell-prompt-set-calculated-regexps'.")
 
+(defvar python-shell--block-prompt nil
+  "Input block prompt for inferior python shell.
+Do not set this variable directly, instead use
+`python-shell-prompt-set-calculated-regexps'.")
+
 (defvar python-shell--prompt-calculated-output-regexp nil
   "Calculated output prompt regexp for inferior python shell.
 Do not set this variable directly, instead use
@@ -2366,6 +2371,7 @@ and `python-shell-output-prompt-regexp' using the values from
         (dolist (prompt (butlast detected-prompts))
           (setq prompt (regexp-quote prompt))
           (cl-pushnew prompt input-prompts :test #'string=))
+        (setq python-shell--block-prompt (nth 1 detected-prompts))
         (cl-pushnew (regexp-quote
                      (car (last detected-prompts)))
                     output-prompts :test #'string=))
@@ -2726,6 +2732,7 @@ variable.
   (set (make-local-variable 'python-shell-interpreter-args)
        (or python-shell--interpreter-args python-shell-interpreter-args))
   (set (make-local-variable 'python-shell--prompt-calculated-input-regexp) nil)
+  (set (make-local-variable 'python-shell--block-prompt) nil)
   (set (make-local-variable 'python-shell--prompt-calculated-output-regexp) nil)
   (python-shell-prompt-set-calculated-regexps)
   (setq comint-prompt-regexp python-shell--prompt-calculated-input-regexp)
@@ -3632,7 +3639,14 @@ using that one instead of current buffer's process."
                        ;; Also, since pdb interaction is single-line
                        ;; based, this is enough.
                        (string-match-p python-shell-prompt-pdb-regexp prompt))
-                   #'python-shell-completion-get-completions)
+                   (if (or (equal python-shell--block-prompt prompt)
+                           (string-match-p
+                            python-shell-prompt-block-regexp prompt))
+                       ;; The non-native completion mechanism sends
+                       ;; newlines to the interpreter, so we can't use
+                       ;; it during a multiline statement (Bug#28051).
+                       #'ignore
+                     #'python-shell-completion-get-completions))
                   (t #'python-shell-completion-native-get-completions)))))
     (list start end
           (completion-table-dynamic