fix: Recover $? after completion.

Before this change, the value of $? was lost when doing a completion as
it required running a command, so $? became the status code of the
completion command.

So if you typed:

> false
> ech<TAB> $?

You would get 0 instead of 1, set by false.

This change stores the value of $? first thing before executing any
command, then have __ebcret restore it. The status code that bash
completion, the one that's embedded in the next prompt, remains the
status code of the completion command, but $? is the status code of the
last user command, before completion was run.

issue #77

Author: szermatt

bash-completion.el

@@ -294,7 +294,7 @@ Bash processes.")
 (defconst bash-completion-special-chars "[ -$&-*,:-<>?[-^`{-}]"
   "Regexp of characters that must be escaped or quoted.")
 
-(defconst bash-completion--ps1 "'==emacs==ret=$?==.'"
+(defconst bash-completion--ps1 "'==emacs==ret=${__ebcret:-$?}==.'"
   "Value for the special PS1 prompt set for completions, quoted.")
 
 (eval-when-compile
@@ -1532,12 +1532,12 @@ Return the status code of the command, as a number."
             ;; single process, assume __ebcpre is already defined
             ((not define-functions)
              (concat
-              "if type __ebcpre &>/dev/null; then "
+              "__ebcor=$?; if type __ebcpre &>/dev/null; then "
               "  __ebcpre; %s; __ebcret $?; "
               "else "
               "  echo ==emacs==nopre=${BASH_VERSION}==.; "
-              "  __ebcp=(\"$PS1\" \"$PROMPT_COMMAND\");"
-              "  unset PS1 PROMPT_COMMAND;"
+              "  __ebcp=(\"$PS1\" \"$PROMPT_COMMAND\" $__ebcor);"
+              "  unset PS1 PROMPT_COMMAND __ebcor;"
               "fi;\n"))
             ;; single process, define __ebcpre
             (t
@@ -1549,23 +1549,23 @@ Return the status code of the command, as a number."
                "  fi;"
                "  history -d $c &>/dev/null || true;"
                "} ; function __ebcret {"
-               "  __ebcret=t;"
-               "  return $1;"
+               "  __ebcret=$1;"
+               "  return ${__ebcp[2]};"
                "} ; function __ebctrap {"
-               " if [[ \"$__ebcret\" = \"t\" && ${#__ebcp[@]} -gt 0 ]]; then"
+               " if [[ -n \"$__ebcret\" && ${#__ebcp[@]} -gt 0 ]]; then"
                "  PS1=\"${__ebcp[0]}\";"
                "  PROMPT_COMMAND=\"${__ebcp[1]}\";"
-               "  unset __ebcp;"
-               "  unset __ebcret;"
+               "  unset __ebcp __ebcret;"
                " fi;"
                "} ; trap __ebctrap DEBUG ; function __ebcpre {"
+               "  __ebcor=${__ebcor:-$?}; "
                "  set +x; set +o emacs; set +o vi;"
                "  echo \"==emacs==bash=${BASH_VERSION}==.\";"
                "  if [[ ${#__ebcp[@]} = 0 ]]; then "
-               "    __ebcp=(\"$PS1\" \"$PROMPT_COMMAND\");"
+               "    __ebcp=(\"$PS1\" \"$PROMPT_COMMAND\" $__ebcor);"
                "  fi;"
                "  PS1=" bash-completion--ps1 ";"
-               "  unset PROMPT_COMMAND;"
+               "  unset PROMPT_COMMAND __ebcor;"
                "  __ebcnohistory 1;"
                "} ; { __ebcpre; %s; __ebcret $?; }\n")))
            commandline)))

test/bash-completion-integration-test.el

@@ -926,4 +926,38 @@ $ ")))))
    (should (equal (bash-completion_test-buffer-string)
                   "$ dummy dummy\n--$ --\n$ dummy dummy\n--$ --\n$ "))))
 
+(ert-deftest bash-completion-integration-recover-status-code ()
+  (bash-completion_test-with-shell-harness
+   (concat ; .bashrc
+    "function failwith { return $1; }\n"
+    "function dummy { echo $?; }\n"
+    "function _dummy {\n"
+    "    COMPREPLY=( dummy )\n"
+    "}\n"
+    "complete -F _dummy dummy\n"
+    "PS1='\$ '")
+   nil
+   ;; The first time initializes completion, the second time executes
+   ;; an already initialized completion. The two cases behave very
+   ;; differently, so we test both.
+   (dotimes (i 2)
+     (bash-completion_test-send (format "failwith %s" (+ 100 i)))
+     (should (equal
+              "dummy dummy "
+              (bash-completion_test-complete "dummy dum")))
+     (let ((start (line-beginning-position)))
+       (comint-send-input)
+       (bash-completion_test-wait-for-prompt start)))
+   ;; The status code printed by the dummy function should be the one
+   ;; from testfail, so 123, and not the one from the completion
+   ;; command executed to do completion for the dummy function.
+   (should (equal (bash-completion_test-buffer-string)
+                  (concat "$ failwith 100\n"
+                          "$ dummy dummy\n"
+                          "100\n"
+                          "$ failwith 101\n"
+                          "$ dummy dummy\n"
+                          "101\n"
+                          "$ ")))))
+
 ;;; bash-completion-integration-test.el ends here