Fix remaining two code-review findings, both verified live: 30-selfdiag.sh regex-metachar breakage (g++), fx.sh dedup collision on ] in candidate text

contrib/fx/fx.sh

@@ -79,11 +79,17 @@ fx() {
             out=$("$src" "$cmd" 2>/dev/null)
             if [ -n "$out" ]; then
                 printf '%s\n' "$out" | while IFS= read -r line; do
-                    [ -n "$line" ] && printf '[%s] %s\n' "$label" "$line"
+                    [ -n "$line" ] && printf '%s\t%s\n' "$label" "$line"
                 done
                 [ -n "$FX_AUTO" ] && break
             fi
-        done | awk -F'] ' '!seen[$2]++'
+        done | awk -F'\t' '
+            {
+                label = $1
+                text = substr($0, length(label) + 2)
+                if (!seen[text]++) print "[" label "] " text
+            }
+        '
     )
 
     chosen=""

contrib/fx/sources.d/30-selfdiag.sh

@@ -21,8 +21,19 @@ cmd="$1"
 prog=$(printf '%s' "$cmd" | awk '{print $1}')
 [ -n "$prog" ] || exit 0
 [ -n "$FX_OUTPUT" ] || exit 0
-printf '%s\n' "$FX_OUTPUT" | grep -qE "^[[:space:]]*${prog}[[:space:]]" || exit 0
+
+# Literal prefix comparison (substr/index), never a regex built from
+# $prog: proven broken live for program names containing ERE
+# metacharacters -- e.g. "g++ foo.cpp" produced the pattern
+# "^[[:space:]]*g++[[:space:]]", a malformed stacked-quantifier regex,
+# and this source silently found nothing even when $FX_OUTPUT clearly
+# started a line with "g++ ". Same fix applied to the emitted function
+# below, since it runs the identical check on every future call.
+printf '%s\n' "$FX_OUTPUT" | awk -v p="$prog" '
+    { line = $0; sub(/^[ \t]*/, "", line); if (substr(line, 1, length(p) + 1) == p " ") { found = 1; exit } }
+    END { exit !found }
+' || exit 0
 
 cat <<FIX
-${prog}(){ out=\$(command ${prog} "\$@" 2>&1); ec=\$?; if [ \$ec -ne 0 ]; then sug=\$(printf '%s\\n' "\$out" | awk '/^[ \\t]*${prog}[ \\t]/{sub(/^[ \\t]*/,""); s=\$0} END{print s}'); if [ -n "\$sug" ]; then eval "command \$sug"; return \$?; fi; fi; printf '%s\\n' "\$out"; return \$ec; }
+${prog}(){ out=\$(command ${prog} "\$@" 2>&1); ec=\$?; if [ \$ec -ne 0 ]; then sug=\$(printf '%s\\n' "\$out" | awk -v p="${prog}" '{ line=\$0; sub(/^[ \\t]*/,"",line); if (substr(line,1,length(p)+1)==p" ") s=line } END{print s}'); if [ -n "\$sug" ]; then eval "command \$sug"; return \$?; fi; fi; printf '%s\\n' "\$out"; return \$ec; }
 FIX