Use internal extern "C" { ... } for C++

- removes warnings compiling swig engine
...
[ 10%] Generating swig-engine.cpp
.../libgnucash/engine/engine-helpers.h:31: Warning 313: Unrecognized extern type "C++".
.../libgnucash/engine/gnc-date.h:83: Warning 313: Unrecognized extern type "C++".
.../libgnucash/engine/qofquery.h:90: Warning 302: Identifier 'QofQuery' redefined (ignored),
.../libgnucash/engine/gnc-option.hpp:55: Warning 302: previous definition of 'QofQuery'.
.../libgnucash/engine/gnc-commodity.h:56: Warning 313: Unrecognized extern type "C++".
.../libgnucash/engine/gncBusiness.h:40: Warning 313: Unrecognized extern type "C++".
.../libgnucash/engine/gncEntry.h:37: Warning 313: Unrecognized extern type "C++".

bindings/app-utils.i

@@ -22,10 +22,6 @@
 %{
 /* Includes the header in the wrapper code */
 #include <glib.h>
-#ifdef __cplusplus
-extern "C"
-{
-#endif
 #include <config.h>
 #include <gnc-euro.h>
 #include <gnc-ui-util.h>
@@ -36,18 +32,14 @@ extern "C"
 #endif
 #include <gnc-accounting-period.h>
 #include <gnc-session.h>
-
-#ifdef __cplusplus
-}
-#endif
 %}
 
 #if defined(SWIGGUILE) //Always C++
 %{
-extern "C"
-{
 #include "guile-mappings.h"
 
+extern "C"
+{
 SCM scm_init_sw_app_utils_module (void);
 }
 %}

bindings/engine.i

@@ -23,11 +23,6 @@
 /* Includes the header in the wrapper code */
 #include <glib.h>
 
-#ifdef __cplusplus
-extern "C"
-{
-#endif
-
 #include <config.h>
 #include "qof.h"
 #include "qoflog.h"
@@ -58,9 +53,6 @@ extern "C"
 #include "gncTaxTable.h"
 #include "gncVendor.h"
 
-#ifdef __cplusplus
-}
-#endif
 %}
 #if defined(SWIGGUILE) //Always C++
 %{

bindings/guile/glib-guile.h

@@ -28,6 +28,10 @@
 #include <glib.h>
 #include <libguile.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 SCM gnc_glist_to_scm_list(GList *glist, const gchar *wct);
 GList* gnc_scm_list_to_glist(SCM wcp_list);
 
@@ -37,4 +41,8 @@ int     gnc_glist_string_p(SCM list);
 
 GSList * gnc_scm_to_gslist_string(SCM list);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

bindings/guile/gnc-engine-guile.cpp

@@ -27,8 +27,7 @@
 #include "swig-runtime.h"
 #include <libguile.h>
 #include <cstring>
-extern "C"
-{
+
 #include "Account.h"
 #include "engine-helpers.h"
 #include "gnc-engine-guile.h"
@@ -43,7 +42,6 @@ extern "C"
 #ifndef HAVE_STRPTIME
 #    include "strptime.h"
 #endif
-}
 
 /** \todo Code dependent on the private query headers
 qofquery-p.h and qofquerycore-p.h may need to be modified.

bindings/guile/gnc-engine-guile.h

@@ -27,15 +27,15 @@
 
 #include <glib.h>
 #include <libguile.h>
-#ifdef __cplusplus
-extern "C"
-{
-#endif
 
 #include "gnc-engine.h"
 #include <gncTaxTable.h>    /* for GncAccountValue */
 #include "gnc-hooks.h"
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
 /* Helpers for various conversions to and from guile */
 
 GDate gnc_time64_to_GDate(SCM x);

bindings/guile/gnc-guile-utils.h

@@ -27,6 +27,10 @@
 #include <glib.h>
 #include <libguile.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Helper function to get the string representation of
  *  a guile string.
  *
@@ -74,4 +78,8 @@ SCM    gnc_scm_call_1_to_vector(SCM func, SCM arg);
  *  comments. */
 gchar *gnc_scm_strip_comments (SCM scm_text);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

bindings/guile/gnc-helpers.h

@@ -28,7 +28,15 @@
 
 #include "gnc-ui-util.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 SCM  gnc_printinfo2scm(GNCPrintAmountInfo info);
 GNCPrintAmountInfo gnc_scm2printinfo(SCM info_scm);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

bindings/guile/gnc-kvp-guile.cpp

@@ -3,8 +3,6 @@
 #include <libguile.h>
 #include <numeric>
 
-extern "C"
-{
 #include <config.h>
 
 #include <qof.h>
@@ -13,7 +11,6 @@ extern "C"
 #include "gnc-engine-guile.h"
 #include "gnc-guile-utils.h"
 #include "gnc-kvp-guile.h"
-}
 
 /* NOTE: There are some problems with this approach. Currently,
  *       guids are stored simply as strings in scheme, so some

bindings/guile/gnc-kvp-guile.h

@@ -21,12 +21,13 @@
 #ifndef KVP_SCM_H
 #define KVP_SCM_H
 
+#include <qof.h>
+#include <libguile.h>
+
 #ifdef __cplusplus
 extern "C"
 {
 #endif
-#include <qof.h>
-#include <libguile.h>
 
 KvpValue* gnc_scm_to_kvp_value_ptr(SCM kvpval);
 SCM gnc_kvp_value_ptr_to_scm(KvpValue* val);

bindings/guile/test/test-print-queries.cpp

@@ -23,15 +23,11 @@
 #include <libguile.h>
 #include "guile-mappings.h"
 
-extern "C"
-{
-
 #include "gnc-engine-guile.h"
 #include "test-engine-stuff.h"
 #include "test-stuff.h"
 #include "Query.h"
 #include "TransLog.h"
-}
 
 static void
 test_query (Query *q, SCM val2str)

bindings/guile/test/test-scm-query-string.cpp

@@ -23,15 +23,12 @@
 #include "guile-mappings.h"
 #include <libguile.h>
 
-extern "C"
-{
 #include "gnc-engine-guile.h"
 #include "gnc-guile-utils.h"
 #include "test-engine-stuff.h"
 #include "test-stuff.h"
 #include "Query.h"
 #include "TransLog.h"
-}
 
 static void
 test_query (Query *q, SCM val2str)

bindings/guile/test/test-scm-query.cpp

@@ -22,15 +22,12 @@
 #include <libguile.h>
 #include <glib.h>
 
-extern "C"
-{
 
 #include "gnc-engine-guile.h"
 #include "test-engine-stuff.h"
 #include "test-stuff.h"
 #include "Query.h"
 #include "TransLog.h"
-}
 
 static void
 test_query (QofQuery *q)