swig -go: treat non-const references as pointers

Also clean up the handling of int* and int& to convert between the C
type int and the Go type int, which are often different sizes.

Fixes #2210

Examples/test-suite/go/go_director_inout_runme.go

@@ -14,6 +14,26 @@ func (p *GoMyClass) Adjust(m map[string]interface{}) wrap.GoRetStruct {
 	return wrap.GoRetStruct{s}
 }
 
+func (p *GoMyClass) S1(s string) {
+	if s != "S1" {
+		panic(s)
+	}
+}
+
+func (p *GoMyClass) S2(s *string) {
+	if *s != "S2" {
+		panic(s)
+	}
+	*s = "R2"
+}
+
+func (p *GoMyClass) S3(s *string) {
+	if *s != "S3" {
+		panic(s)
+	}
+	*s = "R3"
+}
+
 func main() {
 	a := wrap.NewDirectorMyClass(&GoMyClass{})
 	m := map[string]interface{}{
@@ -24,6 +44,18 @@ func main() {
 		panic(s)
 	}
 
+	a.S1("S1")
+	str := "S2"
+	a.S2(&str)
+	if str != "R2" {
+		panic(str)
+	}
+	str = "S3"
+	a.S3(&str)
+	if str != "R3" {
+		panic(str)
+	}
+
 	a = wrap.NewDirectorMyClass(nil)
 	s = a.Adjust(m)
 	if s.Str != `{"first":"second"}` {

Examples/test-suite/go_director_inout.i

@@ -2,6 +2,8 @@
 
 %module(directors="1") go_director_inout
 
+%include <std_string.i>
+
 %{
 #include <string>
 %}
@@ -108,6 +110,25 @@ type GoRetStruct struct {
   $1.str.assign($input.p, $input.n);
 %}
 
+%typemap(directorin) std::string & (_gostring_ temp) {
+    $input = &temp;
+    temp.p = (char *) $1.data();
+    temp.n = $1.size();
+}
+%typemap(directorargout) std::string & {
+    _gostring_ *tmp = $input;
+    $1.assign(tmp->p, tmp->p + tmp->n);
+}
+
+%typemap(directorin) std::string * (_gostring_ temp) {
+    $input = &temp;
+    $input->p = (char *) $1->data();
+    $input->n = $1->size();
+}
+%typemap(directorargout) std::string * {
+    $1->assign($input->p, $input->p + $input->n);
+}
+
 %feature("director") MyClass;
 
 %inline
@@ -121,6 +142,10 @@ class MyClass {
     r.str = s.str;
     return r;
   }
+
+  virtual void S1(std::string s) = 0;
+  virtual void S2(std::string& s) = 0;
+  virtual void S3(std::string* s) = 0;
 };
 
 %}

Lib/go/go.swg

@@ -453,9 +453,12 @@
 %}
 
 %typemap(freearg)
-	char *, char *&, char[ANY], char[]
+	char *, char[ANY], char[]
 %{ free($1); %}
 
+%typemap(freearg) char *&
+%{ free(*$1); %}
+
 %typemap(out,fragment="AllocateString")
 	char *, char *&, char[ANY], char[]
 %{ $result = Swig_AllocateString((char*)$1, $1 ? strlen((char*)$1) : 0); %}
@@ -520,6 +523,44 @@
   $2 = ($2_ltype)$input.n;
 %}
 
+/* The int & type needs to convert to intgo.  */
+
+%typemap(gotype) int & "*int"
+
+%typemap(in) int & (int e)
+%{
+  e = (int)*$input;
+  $1 = &e;
+%}
+
+%typemap(out) int &
+%{ $result = new intgo(*$1); %}
+
+%typemap(argout) int &
+%{ *$input = (intgo)e$argnum; %}
+
+%typemap(goout) int & ""
+
+%typemap(directorin) int & (intgo e)
+%{
+  e = (intgo)$1;
+  $input = &e;
+%}
+
+%typemap(godirectorin) int & ""
+
+%typemap(directorout) int &
+%{
+  $*1_ltype f = ($*1_ltype)*$input;
+  $result = ($1_ltype)&f;
+%}
+
+%typemap(directorargout) int &
+%{ $1 = (int)*$input; %}
+
+%typemap(argout) const int & ""
+%typemap(directorargout) const int & ""
+
 /* Enums.  We can't do the right thing for enums in typemap(gotype) so
    we deliberately don't define them.  The right thing would be to
    capitalize the name.  This is instead done in go.cxx.  */
@@ -552,10 +593,7 @@
 %typemap(godirectorin) enum SWIGTYPE & ""
 
 %typemap(directorout) enum SWIGTYPE &
-%{
-  $*1_ltype f = ($*1_ltype)*$input;
-  $result = ($1_ltype)&f;
-%}
+%{ $result = $input; %}
 
 /* Arbitrary type.  This is a type passed by value in the C/C++ code.
    We convert it to a pointer for the Go code.  Note that all basic

Source/Modules/go.cxx

@@ -377,7 +377,7 @@ private:
   /* ---------------------------------------------------------------------
    * top()
    *
-   * For 6g/8g, we are going to create the following files:
+   * For gc, we are going to create the following files:
    *
    * 1) A .c or .cxx file compiled with gcc.  This file will contain
    *    function wrappers.  Each wrapper will take a pointer to a
@@ -5284,7 +5284,7 @@ private:
    * gcCTypeForGoValue()
    *
    * Given a type, return the C/C++ type which will be used to catch
-   * the value in Go.  This is the 6g/8g version.
+   * the value in Go.  This is the gc version.
    * ---------------------------------------------------------------------- */
 
   String *gcCTypeForGoValue(Node *n, SwigType *type, String *name) {
@@ -5293,7 +5293,19 @@ private:
 
     String *tail = NewString("");
     SwigType *t = SwigType_typedef_resolve_all(type);
-    if (!SwigType_isreference(t)) {
+    bool is_const_ref = false;
+    if (SwigType_isreference(t)) {
+      SwigType* tt = Copy(t);
+      SwigType_del_reference(tt);
+      if (SwigType_isqualifier(tt)) {
+	String* q = SwigType_parm(tt);
+	if (Strcmp(q, "const") == 0) {
+	  is_const_ref = true;
+	}
+      }
+      Delete(tt);
+    }
+    if (!is_const_ref) {
       while (Strncmp(gt, "*", 1) == 0) {
 	Replace(gt, "*", "", DOH_REPLACE_FIRST);
 	Printv(tail, "*", NULL);
@@ -5436,17 +5448,6 @@ private:
     return ret;
   }
 
-  /* ----------------------------------------------------------------------
-   * gccgoCTypeForGoValue()
-   *
-   * Given a type, return the C/C++ type which will be used to catch
-   * the value in Go.  This is the gccgo version.
-   * ---------------------------------------------------------------------- */
-
-  String *gccgoCTypeForGoValue(Node *n, SwigType *type, String *name) {
-    return gcCTypeForGoValue(n, type, name);
-  }
-
   /* ----------------------------------------------------------------------
    * goTypeIsInterface
    *