From 2496de85a9469f4e528c81a487433c51ee75fbbe Mon Sep 17 00:00:00 2001
From: Duy-Nguyen Ta <dta-huynh@irobot.com>
Date: Sat, 10 Sep 2016 19:44:53 -0400
Subject: [PATCH] check if default constructor exists. Autogenerate copy
 constructor by default

---
 wrap/Constructor.cpp | 19 +++++++++++++++++++
 wrap/Constructor.h   |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/wrap/Constructor.cpp b/wrap/Constructor.cpp
index 53fe31e5b..17c708cda 100644
--- a/wrap/Constructor.cpp
+++ b/wrap/Constructor.cpp
@@ -121,10 +121,29 @@ void Constructor::python_wrapper(FileWriter& wrapperFile, Str className) const {
       << ");\n";
 }
 
+/* ************************************************************************* */
+bool Constructor::hasDefaultConstructor() const {
+  for (size_t i = 0; i < nrOverloads(); i++) {
+    if (argumentList(i).size() == 0) return true;
+  }  
+  return false;
+}
+
 /* ************************************************************************* */
 void Constructor::emit_cython_pxd(FileWriter& pxdFile, Str className) const {
+  // if it can ever be constructed, add the default copy constructor by default
+  if (nrOverloads() > 0) {
+      pxdFile.oss << "\t\t" << className << "(const " << className
+                  << "&) except +\n";
+  }
+
   for (size_t i = 0; i < nrOverloads(); i++) {
     ArgumentList args = argumentList(i);
+    // ignore copy constructor, it's generated by default above
+    if (args.size() == 1 && args[0].is_const && args[0].is_ref &&
+        !args[0].is_ptr && args[0].type.cythonClassName() == className)
+        continue;
+    // generate the constructor
     pxdFile.oss << "\t\t" << className << "(";
     args.emit_cython_pxd(pxdFile);
     pxdFile.oss << ") " << "except +\n";
diff --git a/wrap/Constructor.h b/wrap/Constructor.h
index aca6abb9d..8a4259a09 100644
--- a/wrap/Constructor.h
+++ b/wrap/Constructor.h
@@ -45,6 +45,9 @@ struct Constructor: public OverloadedFunction {
     return inst;
   }
 
+  /// return true if the default constructor exists
+  bool hasDefaultConstructor() const;
+
   // MATLAB code generation
   // toolboxPath is main toolbox directory, e.g., ../matlab
   // classFile is class proxy file, e.g., ../matlab/@Point2/Point2.m