Introduce conditional wchar_t (and std::wstring) support

The support is turned on by default but the user might need to be able
to turn it off which is now possible by defining CATCH_CONFIG_NO_WCHAR.

docs/configuration.md

@@ -120,6 +120,7 @@ by using `_NO_` in the macro, e.g. `CATCH_CONFIG_NO_CPP17_UNCAUGHT_EXCEPTIONS`.
     CATCH_CONFIG_WINDOWS_CRTDBG             // Enable leak checking using Windows's CRT Debug Heap
     CATCH_CONFIG_DISABLE_STRINGIFICATION    // Disable stringifying the original expression
     CATCH_CONFIG_DISABLE                    // Disables assertions and test case registration
+    CATCH_CONFIG_WCHAR                      // Enables use of wchart_t
 
 Currently Catch enables `CATCH_CONFIG_WINDOWS_SEH` only when compiled with MSVC, because some versions of MinGW do not have the necessary Win32 API support.
 
@@ -127,6 +128,9 @@ Currently Catch enables `CATCH_CONFIG_WINDOWS_SEH` only when compiled with MSVC,
 
 `CATCH_CONFIG_WINDOWS_CRTDBG` is off by default. If enabled, Windows's CRT is used to check for memory leaks, and displays them after the tests finish running.
 
+`CATCH_CONFIG_WCHAR` is on by default, but can be disabled. Currently
+it is only used in support for DJGPP cross-compiler.
+
 These toggles can be disabled by using `_NO_` form of the toggle, e.g. `CATCH_CONFIG_NO_WINDOWS_SEH`.
 
 ### `CATCH_CONFIG_FAST_COMPILE`

include/internal/catch_compiler_capabilities.h

@@ -130,6 +130,10 @@
 #if defined(CATCH_INTERNAL_CONFIG_POSIX_SIGNALS) && !defined(CATCH_INTERNAL_CONFIG_NO_POSIX_SIGNALS) && !defined(CATCH_CONFIG_NO_POSIX_SIGNALS) && !defined(CATCH_CONFIG_POSIX_SIGNALS)
 #   define CATCH_CONFIG_POSIX_SIGNALS
 #endif
+// This is set by default, because we assume that compilers with no wchar_t support are just rare exceptions.
+#if !defined(CATCH_INTERNAL_CONFIG_NO_WCHAR) && !defined(CATCH_CONFIG_NO_WCHAR) && !defined(CATCH_CONFIG_WCHAR)
+#   define CATCH_CONFIG_WCHAR
+#endif
 
 #if defined(CATCH_INTERNAL_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS) && !defined(CATCH_CONFIG_NO_CPP17_UNCAUGHT_EXCEPTIONS) && !defined(CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS)
 #  define CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS

include/internal/catch_default_main.hpp

@@ -12,7 +12,7 @@
 
 #ifndef __OBJC__
 
-#if defined(WIN32) && defined(_UNICODE) && !defined(DO_NOT_USE_WMAIN)
+#if defined(CATCH_CONFIG_WCHAR) && defined(WIN32) && defined(_UNICODE) && !defined(DO_NOT_USE_WMAIN)
 // Standard C/C++ Win32 Unicode wmain entry point
 extern "C" int wmain (int argc, wchar_t * argv[], wchar_t * []) {
 #else

include/internal/catch_session.cpp

@@ -202,7 +202,7 @@ namespace Catch {
         return returnCode;
     }
 
-#if defined(WIN32) && defined(UNICODE)
+#if defined(CATCH_CONFIG_WCHAR) && defined(WIN32) && defined(UNICODE)
     int Session::run( int argc, wchar_t* const argv[] ) {
 
         char **utf8Argv = new char *[ argc ];

include/internal/catch_session.h

@@ -30,7 +30,7 @@ namespace Catch {
         void useConfigData( ConfigData const& configData );
 
         int run( int argc, char* argv[] );
-    #if defined(WIN32) && defined(UNICODE)
+    #if defined(CATCH_CONFIG_WCHAR) && defined(WIN32) && defined(UNICODE)
         int run( int argc, wchar_t* const argv[] );
     #endif
         int run();

include/internal/catch_tostring.cpp

@@ -116,6 +116,7 @@ std::string StringMaker<std::string>::convert(const std::string& str) {
     return s;
 }
 
+#ifdef CATCH_CONFIG_WCHAR
 std::string StringMaker<std::wstring>::convert(const std::wstring& wstr) {
     std::string s;
     s.reserve(wstr.size());
@@ -124,6 +125,7 @@ std::string StringMaker<std::wstring>::convert(const std::wstring& wstr) {
     }
     return ::Catch::Detail::stringify(s);
 }
+#endif
 
 std::string StringMaker<char const*>::convert(char const* str) {
     if (str) {
@@ -139,6 +141,7 @@ std::string StringMaker<char*>::convert(char* str) {
         return{ "{null string}" };
     }
 }
+#ifdef CATCH_CONFIG_WCHAR
 std::string StringMaker<wchar_t const*>::convert(wchar_t const * str) {
     if (str) {
         return ::Catch::Detail::stringify(std::wstring{ str });
@@ -153,6 +156,7 @@ std::string StringMaker<wchar_t *>::convert(wchar_t * str) {
         return{ "{null string}" };
     }
 }
+#endif
 
 
 std::string StringMaker<int>::convert(int value) {

include/internal/catch_tostring.h

@@ -13,6 +13,7 @@
 #include <cstddef>
 #include <type_traits>
 #include <string>
+#include "catch_compiler_capabilities.h"
 #include "catch_stream.h"
 
 #ifdef __OBJC__
@@ -119,10 +120,12 @@ namespace Catch {
     struct StringMaker<std::string> {
         static std::string convert(const std::string& str);
     };
+#ifdef CATCH_CONFIG_WCHAR
     template<>
     struct StringMaker<std::wstring> {
         static std::string convert(const std::wstring& wstr);
     };
+#endif
 
     template<>
     struct StringMaker<char const *> {
@@ -132,6 +135,7 @@ namespace Catch {
     struct StringMaker<char *> {
         static std::string convert(char * str);
     };
+#ifdef CATCH_CONFIG_WCHAR
     template<>
     struct StringMaker<wchar_t const *> {
         static std::string convert(wchar_t const * str);
@@ -140,6 +144,7 @@ namespace Catch {
     struct StringMaker<wchar_t *> {
         static std::string convert(wchar_t * str);
     };
+#endif
 
     template<int SZ>
     struct StringMaker<char[SZ]> {

projects/SelfTest/UsageTests/Misc.tests.cpp

@@ -290,6 +290,7 @@ TEST_CASE( "Tabs and newlines show in output", "[.][whitespace][failing]" ) {
 }
 
 
+#ifdef CATCH_CONFIG_WCHAR
 TEST_CASE( "toString on const wchar_t const pointer returns the string contents", "[toString]" ) {
         const wchar_t * const s = L"wide load";
         std::string result = ::Catch::Detail::stringify( s );
@@ -313,6 +314,7 @@ TEST_CASE( "toString on wchar_t returns the string contents", "[toString]" ) {
         std::string result = ::Catch::Detail::stringify( s );
         CHECK( result == "\"wide load\"" );
 }
+#endif
 
 TEST_CASE( "long long" ) {
     long long l = std::numeric_limits<long long>::max();