Fix cocotb with verilator

When building the verilated model, the linker complains about missing python
symbols in some cases. We get around this by telling the linker to ignore
unknown symbols.

edalize/flows/sim.py

@@ -42,7 +42,7 @@ def configure_tools(self, flow):
                     [
                         "--vpi",
                         "--public-flat-rw --prefix Vtop",
-                        '-LDFLAGS "-Wl,-rpath,`cocotb-config --lib-dir` -L`cocotb-config --lib-dir` -lcocotbvpi_verilator -lgpi -lcocotb -lgpilog -lcocotbutils"',
+                        '-LDFLAGS "-Wl,-rpath,`cocotb-config --lib-dir` -L`cocotb-config --lib-dir` -lcocotbvpi_verilator -lgpi -lcocotb -lgpilog -lcocotbutils  -Wl,--unresolved-symbols=ignore-in-shared-libs"',
                     ],
                 ),
             }

tests/flows/sim/with_cocotb/Makefile

@@ -0,0 +1,19 @@
+#Auto generated by Edalize
+
+all: post_build
+
+pre_build: 
+
+Vtop.mk: design.vc sv_file.sv vlog_file.v vlog05_file.v vlog_incfile another_sv_file.sv | pre_build
+	$(EDALIZE_LAUNCHER) verilator -f design.vc `cocotb-config --share`/lib/verilator/verilator.cpp
+
+Vtop: Vtop.mk c_file.c cpp_file.cpp
+	$(EDALIZE_LAUNCHER) make -f Vtop.mk
+
+post_build: Vtop
+
+pre_run: 
+
+run: pre_run
+
+post_run: run

tests/flows/sim/with_cocotb/design.vc

@@ -0,0 +1,22 @@
+--Mdir .
+--cc
+--vpi
+--public-flat-rw --prefix Vtop
+-LDFLAGS "-Wl,-rpath,`cocotb-config --lib-dir` -L`cocotb-config --lib-dir` -lcocotbvpi_verilator -lgpi -lcocotb -lgpilog -lcocotbutils  -Wl,--unresolved-symbols=ignore-in-shared-libs"
++incdir+.
+-CFLAGS -I.
+sv_file.sv
+vlog_file.v
+vlog05_file.v
+another_sv_file.sv
+--top-module top_module
+
+--exe
+c_file.c
+cpp_file.cpp
+-Gvlogparam_bool=1
+-Gvlogparam_int=42
+-Gvlogparam_str=\"hello\"
+-Dvlogdefine_bool=1
+-Dvlogdefine_int=42
+-Dvlogdefine_str=hello

tests/test_flow_sim.py

@@ -20,3 +20,16 @@ def test_sim(flow_fixture):
             "Makefile",
         ]
     )
+
+
+def test_sim_cocotb(flow_fixture):
+    flow_options = {"tool": "verilator", "cocotb_module": "some_cocotb_module"}
+    ff = flow_fixture("sim", flow_options=flow_options, ref_subdir="with_cocotb")
+
+    ff.flow.configure()
+    ff.compare_config_files(
+        [
+            "design.vc",
+            "Makefile",
+        ]
+    )