fix yosys version import

diff --git a/nmigen/back/verilog.py b/nmigen/back/verilog.py
index 367488dc31ecc99def993487fbb9196b2ea204b7..19a91e41dd9fb35883c56b634c4fc91c1343b29b 100644 (file)
--- a/nmigen/back/verilog.py
+++ b/nmigen/back/verilog.py
@@ -1,3 +1,4 @@
+from .._yosys import *
 from . import rtlil
 
 
@@ -5,9 +6,9 @@ __all__ = ["YosysError", "convert", "convert_fragment"]
 
 
 def _convert_rtlil_text(rtlil_text, *, strip_internal_attrs=False, write_verilog_opts=()):
-    version, offset = _yosys_version()
-    if version < (0, 9):
-        raise YosysError("Yosys {}.{} is not supported".format(*version))
+    # this version requirement needs to be synchronized with the one in setup.py!
+    yosys = find_yosys(lambda ver: ver >= (0, 9))
+    yosys_version = yosys.version()
 
     attr_map = []
     if strip_internal_attrs: