Don't use exception specification with C++ compiler in example

Support for the exception specifications using types was removed in
C++17 (and "throw ()" in C++20), so don't use them when using the C++
compiler any longer, as this broke the example with recent g++ versions
that use C++17 by default.

We still need them for SWIG, however, so use SWIG_THROW macro, defined
differently for SWIG and the compiler, to preserve the existing
behaviour.

Using %except might be a better idea, but would require more changes.

Examples/c/exception/example.h

@@ -3,6 +3,7 @@
 #ifndef SWIG
 struct A {
 };
+#define SWIG_THROW(...)
 #endif
 
 class Exc {
@@ -15,38 +16,29 @@ public:
   char msg[256];
 };
 
-#if defined(_MSC_VER)
-  #pragma warning(disable: 4290) // C++ exception specification ignored except to indicate a function is not __declspec(nothrow)
-#endif
-
 class Test {
 public:
-  int simple() throw(int&) {
+  int simple() SWIG_THROW(int&) {
       throw(37);
       return 1;
   }
-  int message() throw(const char *) {
+  int message() SWIG_THROW(const char *) {
       throw("I died.");
       return 1;
   }
-  int hosed() throw(Exc) {
+  int hosed() SWIG_THROW(Exc) {
       throw(Exc(42,"Hosed"));
       return 1;
   } 
-  int unknown() throw(A*) {
+  int unknown() SWIG_THROW(A*) {
       static A a;
       throw &a;
       return 1;
   }
-  int multi(int x) throw(int, const char *, Exc) {
+  int multi(int x) SWIG_THROW(int, const char *, Exc) {
      if (x == 1) throw(37);
      if (x == 2) throw("Bleah!");
      if (x == 3) throw(Exc(42,"No-go-diggy-die"));
      return 1;
   }
 };
-
-#if defined(_MSC_VER)
-  #pragma warning(default: 4290) // C++ exception specification ignored except to indicate a function is not __declspec(nothrow)
-#endif
-

Examples/c/exception/example.i

@@ -9,6 +9,9 @@
   SWIG_exception(SWIG_RuntimeError, $1.msg);
 }
 
+/* This needs to be defined for SWIG, even though it can't be used in C++ any more. */
+#define SWIG_THROW(...) throw(__VA_ARGS__)
+
 /* Let's just grab the original header file here */
 %include "example.h"