Assert when Rust side of rule is missing (#88)

Author: lucic71

cpp2rust/converter/translation_rule.cpp

@@ -189,14 +189,18 @@ void LoadIrSrc(ExprRules &exprs, TypeRules &types,
     auto val = entry_val.getAsString();
     if (name[0] == 'f') {
       auto it = exprs.find(name);
-      if (it != exprs.end()) {
-        it->second.src = val->str();
+      if (it == exprs.end()) {
+        llvm::errs() << name << '\n';
+        assert(0 && "ir_src.json expr entry has no matching IR target rule");
       }
+      it->second.src = val->str();
     } else if (name[0] == 't') {
       auto it = types.find(name);
-      if (it != types.end()) {
-        it->second.src = val->str();
+      if (it == types.end()) {
+        llvm::errs() << name << '\n';
+        assert(0 && "ir_src.json type entry has no matching IR target rule");
       }
+      it->second.src = val->str();
     }
   }
 }