Ensure -c++out is not used with -c++

Error checking for this combination implemented as well as correcting
Octave

Also refactor, replacing CPlusPlusOut variable with cparse_cplusplusout
for an implementation which more closely resembles cparse_cplusplus which
is also required in both .c and .cxx files.

Source/CParse/cparse.h

@@ -25,9 +25,11 @@ extern "C" {
   extern String *cparse_file;
   extern int cparse_line;
   extern int cparse_cplusplus;
+  extern int cparse_cplusplusout;
   extern int cparse_start_line;
 
   extern void Swig_cparse_cplusplus(int);
+  extern void Swig_cparse_cplusplusout(int);
   extern void scanner_file(File *);
   extern void scanner_next_token(int);
   extern void skip_balanced(int startchar, int endchar);

Source/CParse/cscanner.c

@@ -37,6 +37,9 @@ int     cparse_start_line = 0;
 /* C++ mode */
 int cparse_cplusplus = 0;
 
+/* Generate C++ compatible code when wrapping C code */
+int cparse_cplusplusout = 0;
+
 /* Private vars */
 static int scan_init = 0;
 static int num_brace = 0;
@@ -52,6 +55,14 @@ void Swig_cparse_cplusplus(int v) {
   cparse_cplusplus = v;
 }
 
+/* -----------------------------------------------------------------------------
+ * Swig_cparse_cplusplusout()
+ * ----------------------------------------------------------------------------- */
+
+void Swig_cparse_cplusplusout(int v) {
+  cparse_cplusplusout = v;
+}
+
 /* ----------------------------------------------------------------------------
  * scanner_init()
  *

Source/CParse/parser.y

@@ -59,7 +59,6 @@ static int      extendmode   = 0;
 static int      compact_default_args = 0;
 static int      template_reduce = 0;
 static int      cparse_externc = 0;
-extern int CPlusPlusOut;
 
 /* -----------------------------------------------------------------------------
  *                            Assist Functions
@@ -3446,7 +3445,7 @@ cpp_class_decl  : storage_class cpptype idcolon inherit LBRACE {
 		   Delete(prefix);
 		   inclass = 1;
 		   currentOuterClass = $<node>$;
-		   if (CPlusPlusOut) {
+		   if (cparse_cplusplusout) {
 		     /* save the structure declaration to declare it in global scope for C++ to see */
 		     code = get_raw_text_balanced('{', '}');
 		     Setattr($<node>$, "code", code);
@@ -3577,7 +3576,7 @@ cpp_class_decl  : storage_class cpptype idcolon inherit LBRACE {
 		       Namespaceprefix = Swig_symbol_qualifiedscopename(0);
 		       yyrename = Copy(Getattr($<node>$, "class_rename"));
 		       add_symbols($$);
-		       if (!CPlusPlusOut)
+		       if (!cparse_cplusplusout)
 			 Delattr($$, "nested:outer");
 		       Delattr($$, "class_rename");
 		       $$ = 0;

Source/Modules/main.cxx

@@ -29,10 +29,6 @@
 
 static Language *lang = 0;	// Language method
 int CPlusPlus = 0;
-extern "C"
-{
-  int CPlusPlusOut = 0;		// Generate C++ compatible code when wrapping C code
-}
 int Extend = 0;			// Extend flag
 int ForceExtern = 0;		// Force extern mode
 int GenerateDefault = 1;	// Generate default constructors
@@ -488,7 +484,8 @@ void SWIG_getoptions(int argc, char *argv[]) {
 	Swig_cparse_cplusplus(1);
 	Swig_mark_arg(i);
       } else if (strcmp(argv[i], "-c++out") == 0) {
-	CPlusPlusOut = 1;
+	// Undocumented
+	Swig_cparse_cplusplusout(1);
 	Swig_mark_arg(i);
       } else if (strcmp(argv[i], "-fcompact") == 0) {
 	Wrapper_compact_print_mode_set(1);
@@ -955,6 +952,11 @@ int SWIG_main(int argc, char *argv[], Language *l) {
   // Don't check for an input file if -external-runtime is passed
   Swig_check_options(external_runtime ? 0 : 1);
 
+  if (CPlusPlus && cparse_cplusplusout) {
+    Printf(stderr, "The -c++out option is for C input but C++ input has been requested via -c++\n");
+    SWIG_exit(EXIT_FAILURE);
+  }
+
   install_opts(argc, argv);
 
   // Add language dependent directory to the search path

Source/Modules/nested.cxx

@@ -400,7 +400,7 @@ void Swig_nested_name_unnamed_c_structs(Node *n) {
 	c = next;
 	continue;
       }
-    } else if (CPlusPlusOut) {
+    } else if (cparse_cplusplusout) {
       if (Getattr(c, "nested:outer")) {
 	Node *ins = create_insert(c, true);
 	insertNodeAfter(c, ins);

Source/Modules/octave.cxx

@@ -12,6 +12,7 @@
  * ----------------------------------------------------------------------------- */
 
 #include "swigmod.h"
+#include "cparse.h"
 
 static String *global_name = 0;
 static String *op_prefix   = 0;
@@ -86,7 +87,6 @@ public:
      director_multiple_inheritance = 1;
      director_language = 1;
      docs = NewHash();
-     CPlusPlusOut = 1;
    }
 
   virtual void main(int argc, char *argv[]) {
@@ -133,6 +133,10 @@ public:
     SWIG_config_file("octave.swg");
     SWIG_typemap_lang("octave");
     allow_overloading();
+
+    // Octave API is C++, so output must be C++ compatibile even when wrapping C code
+    if (!cparse_cplusplus)
+      Swig_cparse_cplusplusout(1);
   }
 
   virtual int top(Node *n) {

Source/Modules/swigmod.h

@@ -32,7 +32,6 @@ extern String *input_file;
 extern int line_number;
 extern int start_line;
 extern int CPlusPlus;		// C++ mode
-extern "C" int CPlusPlusOut;	// generate C++ declarations for C code (currently used for Octave)
 extern int Extend;		// Extend mode
 extern int Verbose;
 extern int IsVirtual;

Source/Swig/cwrap.c

@@ -13,9 +13,8 @@
  * ----------------------------------------------------------------------------- */
 
 #include "swig.h"
+#include "cparse.h"
 
-extern int cparse_cplusplus;
-extern int CPlusPlusOut;
 static const char *cresult_variable_name = "result";
 
 static Parm *nonvoid_parms(Parm *p) {
@@ -777,7 +776,7 @@ String *Swig_cmemberset_call(const_String_or_char_ptr name, SwigType *type, Stri
     if (!Strstr(type, "enum $unnamed")) {
       String *dref = Swig_wrapped_var_deref(type, pname1, varcref);
       int extra_cast = 0;
-      if (CPlusPlusOut) {
+      if (cparse_cplusplusout) {
 	/* Required for C nested structs compiled as C++ as a duplicate of the nested struct is put into the global namespace.
 	 * We could improve this by adding the extra casts just for nested structs rather than all structs. */
 	String *base = SwigType_base(type);