fix(symfony6): don't run command substitutions on tab completion (#14058)

The plugin is a copy of the completion script shipped by symfony/console.
It has not been updated since it was added, and two fixes made upstream
since then are missing.

The completion request was assembled as a string from the raw words of
the command line, then passed to "eval". Any command substitution present
in a word was therefore executed by the completion, before the user
validated the line. The request is now run as an array of arguments,
without being read again by the shell, and "_describe" is called directly
instead of through "eval". The alias of the command is resolved
explicitly, since that was the only useful effect of the "eval".

The request also runs with SHELL_VERBOSITY=0, so that completion keeps
working for users who exported SHELL_VERBOSITY=-1.

Ported from symfony/symfony#65818 and symfony/symfony#63859.

plugins/symfony6/symfony6.plugin.zsh

@@ -15,8 +15,8 @@
 #   - https://github.com/symfony/symfony/blob/5.4/src/Symfony/Component/Console/Resources/completion.bash
 #
 _sf_console() {
-    local lastParam flagPrefix requestComp out comp
-    local -a completions
+    local lastParam out comp sf_cmd
+    local -a completions flagPrefix requestComp inputs
 
     # The user could have moved the cursor backwards on the command-line.
     # We need to trigger completion from the $CURRENT location, so we need
@@ -29,11 +29,20 @@ _sf_console() {
     setopt local_options BASH_REMATCH
     if [[ "${lastParam}" =~ '-.*=' ]]; then
         # We are dealing with a flag with an =
-        flagPrefix="-P ${BASH_REMATCH}"
+        flagPrefix=(-P "${BASH_REMATCH}")
     fi
 
-    # Prepare the command to obtain completions
-    requestComp="${words[0]} ${words[1]} _complete --no-interaction -szsh -a1 -c$((CURRENT-1))" i=""
+    # Prepare the command to obtain completions. An alias is resolved here,
+    # because the request is no longer read again by the shell.
+    sf_cmd="${words[1]}"
+    if [[ -n "${aliases[$sf_cmd]}" ]]; then
+        requestComp=(${(z)aliases[$sf_cmd]})
+    else
+        requestComp=(${~sf_cmd})
+    fi
+
+    requestComp+=(_complete --no-interaction -szsh -a1 "-c$((CURRENT-1))")
+
     for w in ${words[@]}; do
         w=$(printf -- '%b' "$w")
         # remove quotes from typed values
@@ -47,19 +56,18 @@ _sf_console() {
         fi
         # empty values are ignored
         if [ ! -z "$w" ]; then
-            i="${i}-i${w} "
+            inputs+=("-i$w")
         fi
     done
 
     # Ensure at least 1 input
-    if [ "${i}" = "" ]; then
-        requestComp="${requestComp} -i\" \""
-    else
-        requestComp="${requestComp} ${i}"
+    if (( ! $#inputs )); then
+        inputs=(-i' ')
     fi
 
-    # Use eval to handle any environment variables and such
-    out=$(eval ${requestComp} 2>/dev/null)
+    # The request is run without being read again by the shell, so that a
+    # "$(...)" or a backtick typed on the command line is not executed
+    out=$(SHELL_VERBOSITY=0 "${requestComp[@]}" "${inputs[@]}" 2>/dev/null)
 
     while IFS='\n' read -r comp; do
         if [ -n "$comp" ]; then
@@ -75,7 +83,7 @@ _sf_console() {
     done < <(printf "%s\n" "${out[@]}")
 
     # Let inbuilt _describe handle completions
-    eval _describe "completions" completions $flagPrefix
+    _describe "completions" completions "${flagPrefix[@]}"
     return $?
 }