fix(_comp_dequote): set the literal value to REPLY as a fallback

It is more useful to set the literal value of $1 to REPLY even when $1
is an unsafe word.  When the caller wants to use the result only when
REPLY is a safe string and suceceds without failglob, the caller can
reference the exit status $?.  When the caller wants to use any
string, it is more useful if REPLY contains a fallback value.

This patch changes the behavior so that REPLY is set to be the literal
value of $1 even when an unsafe value is specified to $1.  We also
change the exit status to be 0 only when at least one word is
generated by a safe string.

Author: akinomyoga

bash_completion

@@ -190,11 +190,11 @@ _comp_dequote__initialize()
 _comp_dequote__initialize
 
 # This function expands a word using `eval` in a safe way.  This function can
-# be typically used to get the expanded value of `${word[i]}` as
-# `_comp_dequote "${word[i]}"`.  When the word contains unquoted shell special
-# characters, command substitutions, and other unsafe strings, the function
-# call fails before applying `eval`.  Otherwise, `eval` is applied to the
-# string to generate the result.
+# be typically used to get the expanded value of `${word[i]}` as `_comp_dequote
+# "${word[i]}"`.  When the word contains unquoted shell special characters,
+# command substitutions, and other unsafe strings, the function call fails
+# before applying `eval` and REPLY is set to be the literal string.  Otherwise,
+# `eval` is applied to the string to generate the result.
 #
 # @param    $1  String to be expanded.  A safe word consists of the following
 #               sequence of substrings:
@@ -209,7 +209,12 @@ _comp_dequote__initialize
 #                 quotations, parameter expansions are allowed.
 #
 # @var[out] REPLY  Array that contains the expanded results.  Multiple words or
-#                  no words may be generated through pathname expansions.
+#                  no words may be generated through pathname expansions.  If
+#                  $1 is not a safe word, REPLY contains the literal value of
+#                  $1.
+#
+# @return 0 if $1 is a safe word and the expansion result contains one word at
+#     least, or 1 otherwise.
 #
 # Note: This function allows parameter expansions as safe strings, which might
 # cause unexpected results:
@@ -237,8 +242,15 @@ _comp_dequote__initialize
 _comp_dequote()
 {
     REPLY=() # fallback value for unsafe word and failglob
-    [[ $1 =~ $_comp_dequote__regex_safe_word ]] || return 1
-    eval "REPLY=($1)" 2>/dev/null # may produce failglob
+    if [[ ${1-} =~ $_comp_dequote__regex_safe_word ]]; then
+        eval "REPLY=($1)" 2>/dev/null # may produce failglob
+        ((${#REPLY[@]} > 0))
+        return "$?"
+    else
+        # shellcheck disable=SC2178
+        REPLY=${1-}
+        return 1
+    fi
 }
 
 # Unset the given variables across a scope boundary. Useful for unshadowing
@@ -1625,7 +1637,7 @@ _comp_compgen_help__get_help_lines()
         --) shift 1 ;&
         *)
             local REPLY
-            _comp_dequote "${comp_args[0]-}" || REPLY=${comp_args[0]-}
+            _comp_dequote "${comp_args[0]-}"
             help_cmd=("${REPLY:-false}" "$@")
             ;;
     esac
@@ -2921,7 +2933,7 @@ _comp_command_offset()
     if ((COMP_CWORD == 0)); then
         _comp_compgen_commands
     else
-        _comp_dequote "${COMP_WORDS[0]}" || REPLY=${COMP_WORDS[0]}
+        _comp_dequote "${COMP_WORDS[0]}"
         local cmd=${REPLY-} compcmd=${REPLY-}
         local cspec=$(complete -p -- "$cmd" 2>/dev/null)
 

completions/java

@@ -114,7 +114,7 @@ _comp_cmd_java__packages()
     local -a sourcepaths=("${REPLY[@]}")
 
     local REPLY
-    _comp_dequote "$cur" || REPLY=$cur
+    _comp_dequote "$cur"
     local cur_val=${REPLY-}
 
     # convert package syntax to path syntax

completions/make

@@ -121,7 +121,7 @@ _comp_cmd_make()
                 # Expand tilde expansion
                 local REPLY
                 _comp_dequote "${words[i + 1]-}" &&
-                    [[ -d ${REPLY-} ]] &&
+                    [[ -d $REPLY ]] &&
                     makef_dir=(-C "$REPLY")
                 break
             fi
@@ -134,7 +134,7 @@ _comp_cmd_make()
                 # Expand tilde expansion
                 local REPLY
                 _comp_dequote "${words[i + 1]-}" &&
-                    [[ -f ${REPLY-} ]] &&
+                    [[ -f $REPLY ]] &&
                     makef=(-f "$REPLY")
                 break
             fi

completions/mutt

@@ -32,7 +32,7 @@ _comp_cmd_mutt__get_muttrc()
         shift
     done
 
-    if [[ ! $REPLY ]]; then
+    if [[ ! ${REPLY-} ]]; then
         if [[ -f ~/.${muttcmd}rc ]]; then
             REPLY=\~/.${muttcmd}rc
         elif [[ -f ~/.${muttcmd}/${muttcmd}rc ]]; then
@@ -52,7 +52,7 @@ _comp_cmd_mutt__get_conffiles()
     local file
     for file; do
         _comp_dequote "$file"
-        _comp_cmd_mutt__get_conffiles__visit "$REPLY"
+        _comp_cmd_mutt__get_conffiles__visit "${REPLY-}"
     done
     ((${#conffiles[@]})) || return 1
     REPLY=("${conffiles[@]}")

completions/pkgutil

@@ -33,8 +33,7 @@ _comp_cmd_pkgutil()
             catalog_files=("$REPLY")
         elif [[ ${words[i]} == --config ]]; then
             local REPLY
-            _comp_dequote "${words[i + 1]}"
-            [[ ${REPLY-} ]] && configuration_files=("$REPLY")
+            _comp_dequote "${words[i + 1]}" && configuration_files=("$REPLY")
         elif [[ ${words[i]} == -@([iurdacUS]|-install|-upgrade|-remove|-download|-available|-compare|-catalog|-stream) ]]; then
             command="${words[i]}"
         fi

completions/ssh

@@ -586,7 +586,7 @@ _comp_xfunc_scp_compgen_local_files()
     fi
 
     local REPLY
-    _comp_dequote "$cur" || REPLY=$cur
+    _comp_dequote "$cur"
     local cur_val=${REPLY-}
 
     local files

test/t/unit/test_unit_dequote.py

@@ -25,7 +25,7 @@ def test_2_str(self, bash, functions):
         assert output.strip() == "<abc>"
 
     def test_3_null(self, bash, functions):
-        output = assert_bash_exec(bash, "__tester ''", want_output=True)
+        output = assert_bash_exec(bash, "! __tester ''", want_output=True)
         assert output.strip() == ""
 
     def test_4_empty(self, bash, functions):
@@ -108,25 +108,25 @@ def test_unsafe_1(self, bash, functions):
         output = assert_bash_exec(
             bash, "! __tester '$(echo hello >&2)'", want_output=True
         )
-        assert output.strip() == ""
+        assert output.strip() == "<$(echo hello >&2)>"
 
     def test_unsafe_2(self, bash, functions):
         output = assert_bash_exec(
             bash, "! __tester '|echo hello >&2'", want_output=True
         )
-        assert output.strip() == ""
+        assert output.strip() == "<|echo hello >&2>"
 
     def test_unsafe_3(self, bash, functions):
         output = assert_bash_exec(
             bash, "! __tester '>| important_file.txt'", want_output=True
         )
-        assert output.strip() == ""
+        assert output.strip() == "<>| important_file.txt>"
 
     def test_unsafe_4(self, bash, functions):
         output = assert_bash_exec(
             bash, "! __tester '`echo hello >&2`'", want_output=True
         )
-        assert output.strip() == ""
+        assert output.strip() == "<`echo hello >&2`>"
 
     def test_glob_default(self, bash, functions):
         with bash_env_saved(bash) as bash_env:
@@ -160,6 +160,6 @@ def test_glob_nullglob(self, bash, functions):
             bash_env.shopt("failglob", False)
             bash_env.shopt("nullglob", True)
             output = assert_bash_exec(
-                bash, "__tester 'non-existent-*.txt'", want_output=True
+                bash, "! __tester 'non-existent-*.txt'", want_output=True
             )
             assert output.strip() == ""