Allow taking address of skForVar variables (#8632)

Fixes #8630

compiler/parampatterns.nim

@@ -217,7 +217,7 @@ proc isAssignable*(owner: PSym, n: PNode; isUnsafeAddr=false): TAssignableResult
     if n.typ != nil and n.typ.kind == tyVar:
       result = arLValue
   of nkSym:
-    let kinds = if isUnsafeAddr: {skVar, skResult, skTemp, skParam, skLet}
+    let kinds = if isUnsafeAddr: {skVar, skResult, skTemp, skParam, skLet, skForVar}
                 else: {skVar, skResult, skTemp}
     if n.sym.kind in kinds:
       if owner != nil and owner == n.sym.owner and

tests/compiles/t8630.nim

@@ -0,0 +1,13 @@
+discard """
+  output: '''
+foo
+bar
+'''
+"""
+
+proc test(strings: seq[string]) =
+  for s in strings:
+    var p3 = unsafeAddr(s)
+    echo p3[]
+
+test(@["foo", "bar"])