Big 1213: add regression unit test.

test/CMakeLists.txt

@@ -259,6 +259,8 @@ ei_add_test(dense_storage)
 ei_add_test(ctorleak)
 ei_add_test(mpl2only)
 
+add_executable(bug1213 bug1213.cpp bug1213_main.cpp)
+
 check_cxx_compiler_flag("-ffast-math" COMPILER_SUPPORT_FASTMATH)
 if(COMPILER_SUPPORT_FASTMATH)
   set(EIGEN_FASTMATH_FLAGS "-ffast-math")

test/bug1213.cpp

@@ -0,0 +1,13 @@
+
+// This anonymous enum is essential to trigger the linking issue
+enum {
+  Foo
+};
+
+#include "bug1213.h"
+
+bool bug1213_1(const Eigen::Vector3f& x)
+{
+  return bug1213_2(x);
+}
+

test/bug1213.h

@@ -0,0 +1,8 @@
+
+#include <Eigen/Core>
+
+template<typename T, int dim>
+bool bug1213_2(const Eigen::Matrix<T,dim,1>& x);
+
+bool bug1213_1(const Eigen::Vector3f& x);
+

test/bug1213_main.cpp

@@ -0,0 +1,18 @@
+
+// This is a regression unit regarding a weird linking issue with gcc.
+
+#include "bug1213.h"
+
+int main()
+{
+  return 0;
+}
+
+
+template<typename T, int dim>
+bool bug1213_2(const Eigen::Matrix<T,dim,1>& )
+{
+  return true;
+}
+
+template bool bug1213_2<float,3>(const Eigen::Vector3f&);