From 02e30b53ccee18d136352781c906102c030faaee Mon Sep 17 00:00:00 2001
From: Adam Greig <adam@adamgreig.com>
Date: Sat, 6 Jun 2020 12:43:25 +0100
Subject: [PATCH] hdl.xfrm: preserve allow_reset_less when transforming
 ResetSignal.

Fixes #400.
---
 nmigen/hdl/xfrm.py           |  3 ++-
 nmigen/test/test_hdl_xfrm.py | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/nmigen/hdl/xfrm.py b/nmigen/hdl/xfrm.py
index 4d83eb7..6e0c209 100644
--- a/nmigen/hdl/xfrm.py
+++ b/nmigen/hdl/xfrm.py
@@ -453,7 +453,8 @@ class DomainRenamer(FragmentTransformer, ValueTransformer, StatementTransformer)
 
     def on_ResetSignal(self, value):
         if value.domain in self.domain_map:
-            return ResetSignal(self.domain_map[value.domain])
+            return ResetSignal(self.domain_map[value.domain],
+                               allow_reset_less=value.allow_reset_less)
         return value
 
     def map_domains(self, fragment, new_fragment):
diff --git a/nmigen/test/test_hdl_xfrm.py b/nmigen/test/test_hdl_xfrm.py
index 121c87f..394d349 100644
--- a/nmigen/test/test_hdl_xfrm.py
+++ b/nmigen/test/test_hdl_xfrm.py
@@ -74,6 +74,24 @@ class DomainRenamerTestCase(FHDLTestCase):
             "pix": cd_pix,
         })
 
+    def test_rename_cd_preserves_allow_reset_less(self):
+        cd_pix  = ClockDomain(reset_less=True)
+
+        f = Fragment()
+        f.add_domains(cd_pix)
+        f.add_statements(
+            self.s1.eq(ResetSignal(allow_reset_less=True)),
+        )
+
+        f = DomainRenamer("pix")(f)
+        f = DomainLowerer()(f)
+        self.assertRepr(f.statements, """
+        (
+            (eq (sig s1) (const 1'd0))
+        )
+        """)
+
+
     def test_rename_cd_subfragment(self):
         cd_sync = ClockDomain()
         cd_pix  = ClockDomain()
-- 
2.30.2