Merge pull request #229754 from rrbutani/fix/cc-wrapper-extra-positional-args

Support `--` in `cc-wrapper`

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

···
 expandResponseParams "$@"
 linkType=$(checkLinkType "${params[@]}")
 
+declare -ag positionalArgs=()
 declare -i n=0
 nParams=${#params[@]}
 while (( "$n" < "$nParams" )); do
···
                 *-header) dontLink=1 ;;
                 c++*) isCxx=1 ;;
             esac
+            ;;
+        --) # Everything else is positional args!
+            # See: https://github.com/llvm/llvm-project/commit/ed1d07282cc9d8e4c25d585e03e5c8a1b6f63a74
+
+            # Any positional arg (i.e. any argument after `--`) will be
+            # interpreted as a "non flag" arg:
+            if [[ -v "params[$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
···
 if [ "$cc1" = 1 ]; then
   extraAfter=()
   extraBefore=()
+fi
+
+# Finally, if we got any positional args, append them to `extraAfter`
+# now:
+if [[ "${#positionalArgs[@]}" -gt 0 ]]; then
+    extraAfter+=(-- "${positionalArgs[@]}")
 fi
 
 # Optionally print debug info.

pkgs/test/cc-wrapper/default.nix

···
   name = "cc-wrapper-test";
 
   buildCommand = ''
+    set -o pipefail
+
     NIX_DEBUG=1 $CC -v
     NIX_DEBUG=1 $CXX -v
 
···
         $CC ${staticLibc} -static-pie -o cc-static-pie ${./cc-main.c}
         ${emulator} ./cc-static-pie
       ''}
+    ''}
+
+    ${# See: https://github.com/llvm/llvm-project/commit/ed1d07282cc9d8e4c25d585e03e5c8a1b6f63a74
+      # `gcc` does not support this so we gate the test on `clang`
+      lib.optionalString stdenv.cc.isClang ''
+        printf "checking whether cc-wrapper accepts -- followed by positional (file) args..." >&2
+        mkdir -p positional
+
+        # Make sure `--` is not parsed as a "non flag arg"; we should get an
+        # input file error here and *not* a linker error.
+        { ! $CC --; } |& grep -q "no input files"
+
+        # And that positional file args _must_ be files (this is just testing
+        # that we remembered to put the `--` back in the args to the compiler):
+        { ! $CC -c -- -o foo ${./foo.c}; } \
+          |& grep -q "no such file or directory: '-o'"
+
+        # Now check that we accept single and multiple positional file args:
+        $CC -c -DVALUE=42 -o positional/foo.o -- ${./foo.c}
+        $CC -o positional/main -- positional/foo.o ${./ldflags-main.c}
+        ${emulator} ./positional/main
     ''}
 
     printf "checking whether compiler uses NIX_CFLAGS_COMPILE... " >&2