updated the assert macro to send SIGINT to the process (to break into the debugger) and also to be used on macos

Jamfile

@@ -106,12 +106,12 @@ rule building ( properties * )
 {
 	local result ;
 
-	if <toolset>gcc in $(properties)
+	if <variant>debug in $(properties)
-		&& <target-os>linux in $(properties)
+		&& ( <target-os>linux in $(properties)
-		&& <variant>debug in $(properties)
+		|| <target-os>darwin in $(properties) )
+		&& ( <toolset>gcc in $(properties)
+		|| <toolset>darwin in $(properties) )
 	{
-		# for backtraces in assertion failures
-		# which only works on ELF targets with gcc
 		result += <source>src/assert.cpp ;
 	}
 

include/libtorrent/assert.hpp

@@ -33,7 +33,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <cassert>
 
 #ifndef NDEBUG
-#if defined __linux__ && defined __GNUC__
+#if (defined __linux__ || defined __MACH__) && defined __GNUC__
 #ifdef assert
 #undef assert
 #endif

src/assert.cpp

@@ -34,7 +34,10 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <signal.h>
+#if defined __linux__ && defined __GNUC__
 #include <execinfo.h>
+#endif
 
 void assert_fail(char const* expr, int line, char const* file, char const* function)
 {
@@ -48,6 +51,7 @@ void assert_fail(char const* expr, int line, char const* file, char const* funct
 		"expression: %s\n"
 		"stack:\n", file, line, function, expr);
 
+#if defined __linux__ && defined __GNUC__
 	void* stack[50];
 	int size = backtrace(stack, 50);
 	char** symbols = backtrace_symbols(stack, size);
@@ -58,7 +62,11 @@ void assert_fail(char const* expr, int line, char const* file, char const* funct
 	}
 
 	free(symbols);
-	exit(1);
+#endif
+ 	// send SIGINT to the current process
+ 	// to break into the debugger
+ 	raise(SIGINT);
+ 	abort();
 }
 
 #endif