cc-wrapper: support --

Fixes #228136.

pkgs/build-support/cc-wrapper/cc-wrapper.sh

@@ -33,6 +33,7 @@ cInclude=1
 expandResponseParams "$@"
 linkType=$(checkLinkType "${params[@]}")
 
+declare -ag positionalArgs=()
 declare -i n=0
 nParams=${#params[@]}
 while (( "$n" < "$nParams" )); do
@@ -54,6 +55,17 @@ while (( "$n" < "$nParams" )); do
                 c++*) isCxx=1 ;;
             esac
             ;;
+        --) # Everything else is positional args!
+            # See: https://github.com/llvm/llvm-project/commit/ed1d07282cc9d8e4c25d585e03e5c8a1b6f63a74
+
+            # Any positional arg (i.e. any argument after `--`) will be
+            # interpreted as a "non flag" arg:
+            if [[ -v "params[$n]" ]]; then nonFlagArgs=1; fi
+
+            positionalArgs=("${params[@]:$n}")
+            params=("${params[@]:0:$((n - 1))}")
+            break;
+            ;;
         -?*) ;;
         *) nonFlagArgs=1 ;; # Includes a solitary dash (`-`) which signifies standard input; it is not a flag
     esac
@@ -207,6 +219,12 @@ if [ "$cc1" = 1 ]; then
   extraBefore=()
 fi
 
+# Finally, if we got any positional args, append them to `extraAfter`
+# now:
+if [[ "${#positionalArgs[@]}" -gt 0 ]]; then
+    extraAfter+=(-- "${positionalArgs[@]}")
+fi
+
 # Optionally print debug info.
 if (( "${NIX_DEBUG:-0}" >= 1 )); then
     # Old bash workaround, see ld-wrapper for explanation.