Fix R memory leak on exception

There is a possible memory leak in case the SWIG_exception_fail macro
is called. The problem is related to its definition that call the
function Rf_warning. This function (as well as Rf_error) involves
a longjmp over C++ destructors on the stack. Thus, all the objects
allocated on the heap are not freed.

Closes #914

Examples/test-suite/r/Makefile.in

@@ -18,6 +18,7 @@ C_TEST_CASES += \
 
 CPP_TEST_CASES += \
 	r_double_delete \
+	r_memory_leak \
 	r_overload_array \
 	r_sexp \
         r_overload_comma \

Examples/test-suite/r/r_memory_leak_runme.R

@@ -0,0 +1,26 @@
+clargs <- commandArgs(trailing=TRUE)
+source(file.path(clargs[1], "unittest.R"))
+
+dyn.load(paste("r_memory_leak", .Platform$dynlib.ext, sep=""))
+source("r_memory_leak.R")
+cacheMetaData(1)
+
+a <- Foo();
+unittest(Foo_get_count(), 1);
+b <- Foo();
+unittest(Foo_get_count(), 2);
+
+# Normal behaviour
+invisible(trigger_internal_swig_exception("no problem", a));
+unittest(Foo_get_count(), 2);
+# SWIG exception introduced
+result <- tryCatch({
+  trigger_internal_swig_exception("null", b);
+}, warning = function(w) {
+  # print("        Hum... We received a warning, but this should be an error");
+  unittest(1,0);
+}, error = function(e) {
+  # print("        Gotcha!");
+  unittest(1,1);
+})
+unittest(Foo_get_count(), 2);

Examples/test-suite/r_memory_leak.i

@@ -0,0 +1,40 @@
+%module r_memory_leak
+
+%include <std_string.i>
+
+%typemap(in) Foo* foo
+{
+  $1 = new Foo;
+}
+%typemap(freearg) Foo* foo
+{
+  printf("    \"        Object deleted\"\n");
+  delete $1;
+}
+%typemap(out) Foo* verify_no_memory_leak
+{
+  if ($1 == NULL)
+    SWIG_exception_fail(SWIG_RuntimeError, "Let's see how the bindings manage this exception!");
+}
+%typemap(scoerceout) Foo*
+  %{ if (!is.null($result) && !is.logical($result)) {$result <- new("$R_class", ref=$result) ;} %}
+
+%inline %{
+  #include <string>
+
+  class Foo {
+      static unsigned count;
+    public:
+      Foo() { ++count; }
+      ~Foo() { --count; }
+      static unsigned get_count() { return count; }
+  };
+
+  unsigned Foo::count = 0;
+
+  static Foo* trigger_internal_swig_exception(const std::string& message, Foo* foo)
+  {
+    return (message == "null") ? NULL : foo;
+  };
+
+%}