Fix segfault on failed VERILOG_FRONTEND::const2ast, closes #1131

Signed-off-by: Clifford Wolf <clifford@clifford.at>

diff --git a/frontends/verilog/const2ast.cc b/frontends/verilog/const2ast.cc
index 3a3634d34a09c1a660c79053235b945f57cb735c..f6a17b2427b95902ef072e279c0324ed02a692c9 100644 (file)
--- a/frontends/verilog/const2ast.cc
+++ b/frontends/verilog/const2ast.cc
@@ -153,7 +153,7 @@ AstNode *VERILOG_FRONTEND::const2ast(std::string code, char case_type, bool warn
 {
        if (warn_z) {
                AstNode *ret = const2ast(code, case_type);
-               if (std::find(ret->bits.begin(), ret->bits.end(), RTLIL::State::Sz) != ret->bits.end())
+               if (ret != nullptr && std::find(ret->bits.begin(), ret->bits.end(), RTLIL::State::Sz) != ret->bits.end())
                        log_warning("Yosys has only limited support for tri-state logic at the moment. (%s:%d)\n",
                                current_filename.c_str(), get_line_num());
                return ret;