back.verilog: make Yosys version check compatible with Verific.

diff --git a/nmigen/back/verilog.py b/nmigen/back/verilog.py
index eb98a34cf1dd42fa88d70ad832d81646526430a2..6e2185abcdbe8a0df63b12f23d60ed497ab22502 100644 (file)
--- a/nmigen/back/verilog.py
+++ b/nmigen/back/verilog.py
@@ -16,7 +16,8 @@ class YosysError(Exception):
 def _yosys_version():
     yosys_path = require_tool("yosys")
     version = subprocess.check_output([yosys_path, "-V"], encoding="utf-8")
-    m = re.match(r"^Yosys ([\d.]+)(?:\+(\d+))?", version)
+    # If Yosys is built with Verific, then Verific license information is printed first.
+    m = re.search(r"^Yosys ([\d.]+)(?:\+(\d+))?", version, flags=re.M)
     tag, offset = m[1], m[2] or 0
     return tuple(map(int, tag.split("."))), offset