Fix duplicate const in generated code wrapping templates

Fix duplicate const in generated code when template instantiation type is const
and use of template parameter is also explicitly const, such as:

  template <typename T> struct Conster {
    void cccc1(T const& t) {}
  };
  %template(ConsterInt) Conster<const int>;

Above previously led to generated code:
  (arg1)->cccc1((int const const &)*arg2);
instead of
  (arg1)->cccc1((int const &)*arg2);

1 files changed, 14 insertions, 1 deletions

diff --git a/Source/Swig/stype.c b/Source/Swig/stype.c
index e9cbf7b43..7a7b727a2 100644
--- a/Source/Swig/stype.c
+++ b/Source/Swig/stype.c
@@ -1275,6 +1275,11 @@ String *SwigType_manglestr(const SwigType *s) {
  * SwigType_typename_replace()
  *
  * Replaces a typename in a type with something else.  Needed for templates.
+ * Collapses duplicate const into a single const.
+ * Reference collapsing probably should be implemented here.
+ * Example:
+ *   t=r.q(const).T pat=T rep=int           =>  r.q(const).int
+ *   t=r.q(const).T pat=T rep=q(const).int  =>  r.q(const).int  (duplicate const removed)
  * ----------------------------------------------------------------------------- */
 
 void SwigType_typename_replace(SwigType *t, String *pat, String *rep) {
@@ -1297,7 +1302,15 @@ void SwigType_typename_replace(SwigType *t, String *pat, String *rep) {
     if (SwigType_issimple(e)) {
       if (Equal(e, pat)) {
 	/* Replaces a type of the form 'pat' with 'rep<args>' */
-	Replace(e, pat, rep, DOH_REPLACE_ANY);
+	if (SwigType_isconst(rep) && i > 0 && SwigType_isconst(Getitem(elem, i - 1))) {
+	  /* Collapse duplicate const into a single const */
+	  SwigType *rep_without_const = Copy(rep);
+	  Delete(SwigType_pop(rep_without_const));
+	  Replace(e, pat, rep_without_const, DOH_REPLACE_ANY);
+	  Delete(rep_without_const);
+	} else {
+	  Replace(e, pat, rep, DOH_REPLACE_ANY);
+	}
       } else if (SwigType_istemplate(e)) {
 	/* Replaces a type of the form 'pat<args>' with 'rep' */
 	{