compiler wrapper: parse Wl and Xlinker properly (#35912)

Two fixes:

1. `-Wl,a,b,c,d` is a comma separated list of linker arguments, we
   incorrectly assume key/value pairs, which runs into issues with for
   example `-Wl,--enable-new-dtags,-rpath,/x`
2. `-Xlinker,xxx` is not a think, so it shouldn't be parsed.

lib/spack/env/cc

@@ -427,6 +427,48 @@ isystem_include_dirs_list=""
 libs_list=""
 other_args_list=""
 
+# Global state for keeping track of -Wl,-rpath -Wl,/path
+wl_expect_rpath=no
+
+parse_Wl() {
+    # drop -Wl
+    shift
+    while [ $# -ne 0 ]; do
+    if [ "$wl_expect_rpath" = yes ]; then
+        rp="$1"
+        wl_expect_rpath=no
+    else
+        rp=""
+        case "$1" in
+            -rpath=*)
+                rp="${1#-rpath=}"
+                ;;
+            --rpath=*)
+                rp="${1#--rpath=}"
+                ;;
+            -rpath|--rpath)
+                wl_expect_rpath=yes
+                ;;
+            "$dtags_to_strip")
+                ;;
+            *)
+                append other_args_list "-Wl,$1"
+                ;;
+        esac
+    fi
+    if [ -n "$rp" ]; then
+        if system_dir "$rp"; then
+            append system_rpath_dirs_list "$rp"
+        else
+            append rpath_dirs_list "$rp"
+        fi
+    fi
+    shift
+    done
+    # By lack of local variables, always set this to empty string.
+    rp=""
+}
+
 
 while [ $# -ne 0 ]; do
 
@@ -526,54 +568,9 @@ while [ $# -ne 0 ]; do
             append other_args_list "-l$arg"
             ;;
         -Wl,*)
-            arg="${1#-Wl,}"
-            if [ -z "$arg" ]; then shift; arg="$1"; fi
-            case "$arg" in
-                -rpath=*)  rp="${arg#-rpath=}"  ;;
-                --rpath=*) rp="${arg#--rpath=}" ;;
-                -rpath,*)  rp="${arg#-rpath,}"  ;;
-                --rpath,*) rp="${arg#--rpath,}" ;;
-                -rpath|--rpath)
-                    shift; arg="$1"
-                    case "$arg" in
-                        -Wl,*)
-                            rp="${arg#-Wl,}"
-                            ;;
-                        *)
-                            die "-Wl,-rpath was not followed by -Wl,*"
-                            ;;
-                    esac
-                    ;;
-                "$dtags_to_strip")
-                    :  # We want to remove explicitly this flag
-                    ;;
-                *)
-                    append other_args_list "-Wl,$arg"
-                    ;;
-            esac
-            ;;
-        -Xlinker,*)
-            arg="${1#-Xlinker,}"
-            if [ -z "$arg" ]; then shift; arg="$1"; fi
-
-            case "$arg" in
-                -rpath=*)  rp="${arg#-rpath=}"  ;;
-                --rpath=*) rp="${arg#--rpath=}" ;;
-                -rpath|--rpath)
-                    shift; arg="$1"
-                    case "$arg" in
-                        -Xlinker,*)
-                            rp="${arg#-Xlinker,}"
-                        ;;
-                        *)
-                            die "-Xlinker,-rpath was not followed by -Xlinker,*"
-                            ;;
-                    esac
-                    ;;
-                *)
-                    append other_args_list "-Xlinker,$arg"
-                    ;;
-            esac
+            IFS=,
+            parse_Wl $1
+            unset IFS
             ;;
         -Xlinker)
             if [ "$2" = "-rpath" ]; then

lib/spack/spack/test/build_environment.py

@@ -127,13 +127,13 @@ def test_static_to_shared_library(build_environment):
         "linux": (
             "/bin/mycc -shared"
             " -Wl,--disable-new-dtags"
-            " -Wl,-soname,{2} -Wl,--whole-archive {0}"
+            " -Wl,-soname -Wl,{2} -Wl,--whole-archive {0}"
             " -Wl,--no-whole-archive -o {1}"
         ),
         "darwin": (
             "/bin/mycc -dynamiclib"
             " -Wl,--disable-new-dtags"
-            " -install_name {1} -Wl,-force_load,{0} -o {1}"
+            " -install_name {1} -Wl,-force_load -Wl,{0} -o {1}"
         ),
     }
 

lib/spack/spack/test/cc.py

@@ -342,6 +342,16 @@ def test_fc_flags(wrapper_environment, wrapper_flags):
     )
 
 
+def test_Wl_parsing(wrapper_environment):
+    check_args(
+        cc,
+        ["-Wl,-rpath,/a,--enable-new-dtags,-rpath=/b,--rpath", "-Wl,/c"],
+        [real_cc]
+        + target_args
+        + ["-Wl,--disable-new-dtags", "-Wl,-rpath,/a", "-Wl,-rpath,/b", "-Wl,-rpath,/c"],
+    )
+
+
 def test_dep_rpath(wrapper_environment):
     """Ensure RPATHs for root package are added."""
     check_args(cc, test_args, [real_cc] + target_args + common_compile_args)