Fix #71

peglib.h

@@ -2486,18 +2486,23 @@ inline void ReferenceChecker::visit(Reference& ope) {
 }
 
 inline void LinkReferences::visit(Reference& ope) {
-    if (grammar_.count(ope.name_)) {
+    // Check if the reference is a macro parameter
+    auto found_param = false;
+    for (size_t i = 0; i < params_.size(); i++) {
+        const auto& param = params_[i];
+        if (param == ope.name_) {
+            ope.iarg_ = i;
+            found_param = true;
+            break;
+        }
+    }
+
+    // Check if the reference is a definition rule
+    if (!found_param && grammar_.count(ope.name_)) {
         auto& rule = grammar_.at(ope.name_);
         ope.rule_ = &rule;
-    } else {
-        for (size_t i = 0; i < params_.size(); i++) {
-            const auto& param = params_[i];
-            if (param == ope.name_) {
-                ope.iarg_ = i;
-                break;
-            }
-        }
     }
+
     for (auto arg: ope.args_) {
         arg->accept(*this);
     }

test/test.cc

@@ -1453,6 +1453,18 @@ TEST_CASE("Macro token check test", "[macro]")
     REQUIRE(parser["T"].is_token() == true);
 }
 
+TEST_CASE("Macro rule-parameter collision", "[macro]")
+{
+    parser parser(R"(
+        A    <- B(C)
+        B(D) <- D
+        C    <- 'c'
+        D    <- 'd'
+	)");
+
+    REQUIRE(parser.parse("c"));
+}
+
 TEST_CASE("Line information test", "[line information]")
 {
     parser parser(R"(