[Go] Make sure that arguments for which use memcpy when calling C are

still live after the call.  This ensures that they will not be
collected if the GC runs during the call.

Examples/test-suite/go_director_inout.i

@@ -44,14 +44,14 @@ type GoRetStruct struct {
   $result.str.assign($input.p, $input.n);
 %}
 
-%typemap(out) RetStruct
+%typemap(out,fragment="AllocateString") RetStruct
 %{
-  $result = _swig_makegostring($1.str.data(), $1.str.length());
+  $result = Swig_AllocateString($1.str.data(), $1.str.length());
 %}
 
-%typemap(goout) RetStruct
+%typemap(goout,fragment="CopyString") RetStruct
 %{
-	$result = GoRetStruct{Str: $input}
+	$result = GoRetStruct{Str: swigCopyString($input)}
 %}
 
 %typemap(godirectorout) RetStruct
@@ -81,23 +81,28 @@ type GoRetStruct struct {
 	}
 %}
 
-%typemap(directorin) MyStruct
+%typemap(directorin,fragment="AllocateString") MyStruct
 %{
-  $input = _swig_makegostring($1.str.data(), $1.str.length());
+  $input = Swig_AllocateString($1.str.data(), $1.str.length());
 %}
 
-%typemap(out) MyStruct
+%typemap(godirectorin,fragment="CopyString") MyStruct
 %{
-  $result = _swig_makegostring($1.str.data(), $1.str.length());
+	if err := json.Unmarshal([]byte(swigCopyString($input)), &$result); err != nil {
-%}
-
-%typemap(godirectorin) MyStruct
-%{
-	if err := json.Unmarshal([]byte($input), &$result); err != nil {
 		panic(err)
 	}
 %}
 
+%typemap(out,fragment="AllocateString") MyStruct
+%{
+  $result = Swig_AllocateString($1.str.data(), $1.str.length());
+%}
+
+%typemap(goout,fragment="CopyString") MyStruct
+%{
+	$result = swigCopyString($input)
+%}
+
 %typemap(in) MyStruct
 %{
   $1.str.assign($input.p, $input.n);

Examples/test-suite/go_inout.i

@@ -56,14 +56,14 @@ type In json.Marshaler
 
 %typemap(imtype) RetStruct "string"
 
-%typemap(out) RetStruct
+%typemap(out,fragment="AllocateString") RetStruct
 %{
-  $result = _swig_makegostring($1.str.data(), $1.str.length());
+  $result = Swig_AllocateString($1.str.data(), $1.str.length());
 %}
 
-%typemap(goout) RetStruct
+%typemap(goout,fragment="CopyString") RetStruct
 %{
-	if err := json.Unmarshal([]byte($1), &$result); err != nil {
+	if err := json.Unmarshal([]byte(swigCopyString($1)), &$result); err != nil {
 		panic(err)
 	}
 %}
@@ -146,7 +146,7 @@ static void putuint64(std::string *s, size_t off, uint64_t v) {
 %}
 
 // Pack the vector into a string.
-%typemap(argout) MyArray*
+%typemap(argout,fragment="AllocateString") MyArray*
 %{
   {
     size_t tot = 8;
@@ -164,15 +164,15 @@ static void putuint64(std::string *s, size_t off, uint64_t v) {
       str.replace(off, p->size(), *p);
       off += p->size();
     }
-    *$input = _swig_makegostring(str.data(), str.size());
+    *$input = Swig_AllocateString(str.data(), str.size());
   }
 %}
 
 // Unpack the string into a []string.
-%typemap(goargout) MyArray*
+%typemap(goargout,fragment="CopyString") MyArray*
 %{
 	{
-		str := *$input
+		str := swigCopyString(*$input)
 		bin := binary.LittleEndian
 		size := bin.Uint64([]byte(str[:8]))
 		str = str[8:]

Lib/go/goruntime.swg

@@ -113,8 +113,22 @@ static char *_swig_topofstack() {
   }
 }
 
+static void _swig_gopanic(const char *p) {
+  struct {
+    const char *p;
+  } a;
+  a.p = p;
+  crosscall2(_cgo_panic, &a, (int) sizeof a);
+}
+
+%}
+
+#if !SWIGGO_CGO
+
 /* This is here for backward compatibility, but it will not work
    with Go 1.5 or later.  Do not use it in new code.  */
+%insert(runtime) %{
+
 static void *_swig_goallocate(size_t len) {
   struct {
     size_t len;
@@ -125,16 +139,10 @@ static void *_swig_goallocate(size_t len) {
   return a.ret;
 }
 
-static void _swig_gopanic(const char *p) {
-  struct {
-    const char *p;
-  } a;
-  a.p = p;
-  crosscall2(_cgo_panic, &a, (int) sizeof a);
-}
-
 %}
 
+#endif
+
 #if !SWIGGO_CGO
 
 /* Boilerplate for C code when using 6g/8g.  This code is compiled
@@ -246,6 +254,8 @@ void SwigCgocallBackDone() {
 
 #endif
 
+#if !SWIGGO_CGO
+
 %insert(runtime) %{
 
 /* This is here for backward compatibility, but it will not work
@@ -258,6 +268,12 @@ static _gostring_ _swig_makegostring(const char *p, size_t l) {
   return ret;
 }
 
+%}
+
+#endif
+
+%insert(runtime) %{
+
 #define SWIG_contract_assert(expr, msg) \
   if (!(expr)) { _swig_gopanic(msg); } else
 %}
@@ -290,8 +306,6 @@ type _ unsafe.Pointer
 
 %}
 
-#if !SWIGGO_CGO
-
 /* Swig_always_false is used to conditionally assign parameters to
    Swig_escape_val so that the compiler thinks that they escape.  We
    only assign them if Swig_always_false is true, which it never is.
@@ -302,8 +316,6 @@ var Swig_escape_always_false bool
 var Swig_escape_val interface{}
 %}
 
-#endif
-
 /* Function pointers are translated by the code in go.cxx into
    _swig_fnptr.  Member pointers are translated to _swig_memberptr.  */
 

Source/Modules/go.cxx

@@ -2035,7 +2035,7 @@ private:
    * needs to explicitly escape.  This is true if the parameter has a
    * non-empty argout or freearg typemap, because in those cases the
    * Go argument might be or contain a pointer.  We need to ensure
-   * that that pointer does not oint into the stack, which means that
+   * that that pointer does not point into the stack, which means that
    * it needs to escape.
    * ---------------------------------------------------------------------- */
   bool paramNeedsEscape(Parm *p) {
@@ -2502,6 +2502,28 @@ private:
 	p = Getattr(p, "tmap:goargout:next");
       }
     }
+
+    // When using cgo, if we need to memcpy a parameter to pass it to
+    // the C code, the compiler may think that the parameter is not
+    // live during the function call.  If the garbage collector runs
+    // while the C/C++ function is running, the parameter may be
+    // freed.  Force the compiler to see the parameter as live across
+    // the C/C++ function.
+    if (cgo_flag) {
+      int parm_count = emit_num_arguments(parms);
+      p = parms;
+      for (int i = 0; i < parm_count; ++i) {
+	p = getParm(p);
+	bool c_struct_type;
+	Delete(cgoTypeForGoValue(p, Getattr(p, "type"), &c_struct_type));
+	if (c_struct_type) {
+	  Printv(f_go_wrappers, "\tif Swig_escape_always_false {\n", NULL);
+	  Printv(f_go_wrappers, "\t\tSwig_escape_val = ", Getattr(p, "emit:goinput"), "\n", NULL);
+	  Printv(f_go_wrappers, "\t}\n", NULL);
+	}
+	p = nextParm(p);
+      }
+    }
   }
 
   /* -----------------------------------------------------------------------
@@ -3537,6 +3559,8 @@ private:
     DelWrapper(dummy);
 
     Swig_typemap_attach_parms("gotype", parms, NULL);
+    Swig_typemap_attach_parms("goin", parms, NULL);
+    Swig_typemap_attach_parms("goargout", parms, NULL);
     Swig_typemap_attach_parms("imtype", parms, NULL);
     int parm_count = emit_num_arguments(parms);
 
@@ -3689,6 +3713,8 @@ private:
 
       Printv(f_go_wrappers, call, "\n", NULL);
 
+      goargout(parms);
+
       Printv(f_go_wrappers, "\treturn p\n", NULL);
       Printv(f_go_wrappers, "}\n\n", NULL);