diff --git a/src/mlir/cxx/mlir/codegen_units.cc b/src/mlir/cxx/mlir/codegen_units.cc
index f627219d..0a55ab3d 100644
--- a/src/mlir/cxx/mlir/codegen_units.cc
+++ b/src/mlir/cxx/mlir/codegen_units.cc
@@ -22,10 +22,28 @@
 
 // cxx
 #include <cxx/ast.h>
+#include <cxx/ast_visitor.h>
 #include <cxx/translation_unit.h>
 
 namespace cxx {
 
+namespace {
+struct ForEachExternalDefinition final : ASTVisitor {
+  std::function<void(FunctionDefinitionAST*)> functionCallback;
+
+  void visit(TemplateDeclarationAST*) override {
+    // Skip template declarations, we only want to visit function definitions.
+  }
+
+  void visit(FunctionDefinitionAST* ast) override {
+    if (functionCallback) functionCallback(ast);
+
+    ASTVisitor::visit(ast);
+  }
+};
+
+}  // namespace
+
 struct Codegen::UnitVisitor {
   Codegen& gen;
 
@@ -46,8 +64,15 @@ auto Codegen::UnitVisitor::operator()(TranslationUnitAST* ast) -> UnitResult {
 
   std::swap(gen.module_, module);
 
+  ForEachExternalDefinition forEachExternalDefinition;
+
+  forEachExternalDefinition.functionCallback =
+      [&](FunctionDefinitionAST* function) {
+        auto functionResult = gen.declaration(function);
+      };
+
   for (auto node : ListView{ast->declarationList}) {
-    auto value = gen.declaration(node);
+    forEachExternalDefinition.accept(node);
   }
 
   std::swap(gen.module_, module);
diff --git a/src/parser/cxx/binder.cc b/src/parser/cxx/binder.cc
index 7ec35e08..1874116e 100644
--- a/src/parser/cxx/binder.cc
+++ b/src/parser/cxx/binder.cc
@@ -320,6 +320,14 @@ void Binder::bind(ParameterDeclarationAST* ast, const Decl& decl,
                   bool inTemplateParameters) {
   ast->type = getDeclaratorType(unit_, ast->declarator, decl.specs.type());
 
+  // decay the type of the parameters
+  if (control()->is_array(ast->type))
+    ast->type = control()->add_pointer(control()->remove_extent(ast->type));
+  else if (control()->is_function(ast->type))
+    ast->type = control()->add_pointer(ast->type);
+  else if (control()->is_scalar(ast->type))
+    ast->type = control()->remove_cv(ast->type);
+
   if (auto declId = decl.declaratorId; declId && declId->unqualifiedId) {
     auto paramName = get_name(control(), declId->unqualifiedId);
     if (auto identifier = name_cast<Identifier>(paramName)) {
diff --git a/src/parser/cxx/external_name_encoder.cc b/src/parser/cxx/external_name_encoder.cc
index 4b3e0966..aa9ab398 100644
--- a/src/parser/cxx/external_name_encoder.cc
+++ b/src/parser/cxx/external_name_encoder.cc
@@ -236,7 +236,7 @@ struct ExternalNameEncoder::EncodeType {
     // todo: "Y" prefix for the bare function type encodes extern "C"
     encoder.out("F");
 
-    encoder.encodeBareFunctionType(type);
+    encoder.encodeBareFunctionType(type, /*includeReturnType=*/true);
 
     if (type->refQualifier() == RefQualifier::kLvalue)
       encoder.out("R");