Set port attributes on exported blackboxes

src/blackboxes.cc

@@ -224,7 +224,7 @@ void export_blackbox_to_rtlil(ast::Compilation &comp, const ast::InstanceSymbol
 	}
 
 	RTLIL::Module *mod = target->addModule(name);
-	transfer_attrs<ast::Symbol>((ast::Symbol&) inst.getDefinition(), mod);
+	transfer_attrs<const ast::Symbol>((ast::Symbol&) inst.getDefinition(), mod);
 
 	inst.body.visit(ast::makeVisitor([&](auto&, const ast::PortSymbol &port) {
 		if (!port.getSyntax() ||
@@ -299,6 +299,7 @@ void export_blackbox_to_rtlil(ast::Compilation &comp, const ast::InstanceSymbol
 
 		RTLIL::Wire *wire =
 			mod->addWire(RTLIL::escape_id(std::string{port.name}), port.getType().getBitstreamWidth());
+		transfer_attrs<const ast::Symbol>(port, wire);
 
 		switch (port.direction) {
 		case ast::ArgumentDirection::In:

src/slang_frontend.cc

@@ -239,7 +239,7 @@ void transfer_attrs(T &from, RTLIL::AttrObject *to)
 		}
 	}
 }
-template void transfer_attrs<ast::Symbol>(ast::Symbol &from, RTLIL::AttrObject *to);
+template void transfer_attrs<const ast::Symbol>(const ast::Symbol &from, RTLIL::AttrObject *to);
 
 #define assert_nonstatic_free(signal) \
 	for (auto bit : (signal)) \

tests/various/stringattrs.ys

@@ -0,0 +1,18 @@
+logger -expect log "attribute \\foo1 \"bar1\"" 1
+logger -expect log "attribute \\foo2 \"bar2\"" 1
+
+read_slang --keep-hierarchy <<EOF
+(* blackbox *)
+module sm(
+	(* foo1="bar1" *)
+	input w
+);
+endmodule
+module top(
+	(* foo2="bar2" *)
+	input y
+);
+	sm sm1();
+endmodule
+EOF
+dump