How best to fix filelist backend about edalize HOT 3 CLOSED

diff --git a/fusesoc/capi2/core.py b/fusesoc/capi2/core.py
index ce17725..745cded 100644
--- a/fusesoc/capi2/core.py
+++ b/fusesoc/capi2/core.py
@@ -79,6 +79,21 @@ class String(str):
         )
 
 
+class StringWithVars(str):
+    """A string containing environment variables to expand and/or the special
+    __CORE_PATH__ variable that should be expanded to the dirname of the parent
+    core file. """
+    
+    def __init__(self, string):
+        self.string = os.path.expandvars(string)
+
+    def parse(self, core_root):
+        self.string = self.string.replace('__CORE_PATH__', core_root)
+
+    def __str__(self):
+        return self.string
+
+
 class Integer(int):
     pass
 
@@ -396,6 +411,8 @@ class Core:
                 if hasattr(section, member):
                     _member = getattr(section, member)
                     if _member:
+                        if isinstance(_member, StringWithVars):
+                            _member.parse(os.path.abspath(self.core_root))
                         options[member] = StringWithUseFlags(_member).parse(flags)
             for member in section.lists:
                 if hasattr(section, member):