Generate wrapper aliases only if requested and not by default

Defining the aliases by default results in conflicts when including
headers from multiple modules as e.g. SWIG_PendingException_get() is
defined in all of them, and could also easily result in other unwanted
clashes, so make this opt-in and update the examples and tests relying
on using the wrappers without the module prefix to define
SWIG_DEFINE_WRAPPER_ALIASES explicitly.

Doc/Manual/C.html

@@ -192,7 +192,7 @@ Wrapping C functions and variables is obviously performed in a straightforward w
 
 
 <p>
-For each C function declared in the interface file a wrapper function with a prefix, required to make its name different from the original one, is created. The prefix for the global functions is <tt>module_</tt>, i.e. the name of the SWIG module followed by underscore. If <tt>nspace</tt> feature is used, the prefix for a function defined in a namespace is <tt>namespace_</tt> -- note that it does <em>not</em> contain the module prefix, as it's not necessary to make a unique function name in this case. The wrapper function performs a call to the original function, and returns its result. For convenience, a <tt>#define func prefix_func</tt> is also provided in the generated header file to make it possible to call the function under its original name. If this is undesirable, <tt>SWIG_NO_WRAPPER_ALIASES</tt> can be predefined before including the wrapper header to disable these defines.
+For each C function declared in the interface file a wrapper function with a prefix, required to make its name different from the original one, is created. The prefix for the global functions is <tt>module_</tt>, i.e. the name of the SWIG module followed by underscore. If <tt>nspace</tt> feature is used, the prefix for a function defined in a namespace is <tt>namespace_</tt> -- note that it does <em>not</em> contain the module prefix, as it's not necessary to make a unique function name in this case. The wrapper function performs a call to the original function, and returns its result. For convenience, a <tt>#define func prefix_func</tt> can be provided in the generated header file to make it possible to call the function under its original name: predefine <tt>SWIG_DEFINE_WRAPPER_ALIASES</tt> before including the wrapper header to enable these defines, which are disabled by default to avoid accidental name clashes.
 </p>
 
 <p>

Examples/c/exception/runme.c

@@ -5,6 +5,7 @@
 #include <stdio.h>
 #include <assert.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "example_wrap.h"
 
 static void show_exception(const char* prefix) {

Examples/c/simple/runme.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "example_wrap.h"
 
 int main(int argc, char **argv) {

Examples/test-suite/c/c_backend_cpp_exception_runme.c

@@ -1,4 +1,6 @@
 #include <assert.h>
+
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "c_backend_cpp_exception/c_backend_cpp_exception_wrap.h"
 
 int main()

Examples/test-suite/c/c_backend_cpp_natural_std_string_runme.c

@@ -1,6 +1,8 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <string.h>
+
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "c_backend_cpp_natural_std_string/c_backend_cpp_natural_std_string_wrap.h"
 
 int main()

Examples/test-suite/c/char_strings_runme.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "char_strings/char_strings_wrap.h"
 
 int main() {

Examples/test-suite/c/cpp_basic_runme.c

@@ -1,3 +1,4 @@
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "cpp_basic/cpp_basic_wrap.h"
 #include <assert.h>
 #include <stdio.h>

Examples/test-suite/c/cpp_basic_template_function_runme.c

@@ -1,4 +1,6 @@
 #include <assert.h>
+
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "cpp_basic_template_function/cpp_basic_template_function_wrap.h"
 
 int main() {

Examples/test-suite/c/enums_runme.c

@@ -1,6 +1,7 @@
 #include <assert.h>
 #include <stdlib.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "enums/enums_wrap.h"
 
 int main() {

Examples/test-suite/c/exception_order_runme.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "exception_order/exception_order_wrap.h"
 
 int main() {

Examples/test-suite/c/global_vars_runme.c

@@ -4,7 +4,7 @@
 
 int main(int argc, const char *argv[])
 {
-    init();
+    global_vars_init();
 
     assert(strcmp(b_get(), "string b") == 0);
     assert(x == 1234);

Examples/test-suite/c/li_std_pair_runme.c

@@ -1,3 +1,4 @@
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "li_std_pair/li_std_pair_wrap.h"
 #include <assert.h>
 

Examples/test-suite/c/operator_overload_runme.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#define SWIG_DEFINE_WRAPPER_ALIASES
 #include "operator_overload/operator_overload_wrap.h"
 
 #define assert(x,msg) if (!x) { printf("%d: %s\n", x, msg); exit(1); }

Source/Modules/c.cxx

@@ -476,9 +476,8 @@ public:
       f_wrappers_types = NewString("");
       f_wrappers_decl = NewString("");
 
-      // We also define aliases for the global wrapper functions to allow calling them using their original names, but as this can result in problems (as usual
-      // when using the preprocessor), we provide a way to disable this by defining SWIG_NO_WRAPPER_ALIASES when compiling the generated code and so we use a
-      // separate section for this too.
+      // We may also define aliases for the global wrapper functions to allow calling them using their original names, but as this can result in problems (as
+      // usual when using the preprocessor), this is only done when SWIG_DEFINE_WRAPPER_ALIASES is defined, so use a separate section for this.
       f_wrappers_aliases = NIL;
 
       {
@@ -504,7 +503,7 @@ public:
 	Dump(f_wrappers_aliases, f_wrappers_h);
 	Delete(f_wrappers_aliases);
 
-	Printv(f_wrappers_h, "#endif /* SWIG_NO_WRAPPER_ALIASES */\n", NIL);
+	Printv(f_wrappers_h, "#endif /* SWIG_DEFINE_WRAPPER_ALIASES */\n", NIL);
       }
     } // close wrapper header guard
 
@@ -903,7 +902,7 @@ public:
 	 if (!f_wrappers_aliases) {
 	   // Allocate it on demand.
 	   f_wrappers_aliases = NewStringEmpty();
-	   Printv(f_wrappers_aliases, "#ifndef SWIG_NO_WRAPPER_ALIASES\n", NIL);
+	   Printv(f_wrappers_aliases, "#ifdef SWIG_DEFINE_WRAPPER_ALIASES\n", NIL);
 	 }
 
 	 Printf(f_wrappers_aliases, "#define %s %s\n", name, wname);