[XM] Add support for disabling lldb attach on crash (#670)

- https://bugzilla.xamarin.com/show_bug.cgi?id=23482

runtime/launcher.m

@@ -352,6 +352,11 @@ update_environment (xamarin_initialize_data *data)
 		}
 	}
 #endif
+	if (xamarin_disable_lldb_attach) {
+		// Unfortunately the only place to set debug_options.no_gdb_backtrace is in mini_parse_debug_option
+		// So route through MONO_DEBUG
+		setenv ("MONO_DEBUG", "no-gdb-backtrace", 0);
+	}
 }
 
 static void

runtime/runtime.m

@@ -46,6 +46,7 @@ bool xamarin_debug_mode = true;
 #else
 bool xamarin_debug_mode = false;
 #endif
+bool xamarin_disable_lldb_attach = false;
 // true if either OldDynamic or OldStatic (since the static registrar still needs
 // a dynamic registrar available too).
 bool xamarin_use_old_dynamic_registrar = false;

runtime/xamarin/main.h

@@ -42,6 +42,7 @@ extern bool mono_use_llvm; // this is defined inside mono
 extern bool xamarin_use_new_assemblies;
 extern bool xamarin_gc_pump;
 extern bool xamarin_debug_mode;
+extern bool xamarin_disable_lldb_attach;
 extern bool xamarin_use_old_dynamic_registrar;
 extern bool xamarin_use_il_registrar;
 extern bool xamarin_init_mono_debug;

tools/mmp/driver.cs

@@ -81,6 +81,7 @@ namespace Xamarin.Bundler {
 		static bool? thread_check = null;
 		static string link_flags = null;
 		static LinkerOptions linker_options;
+		static bool disable_lldb_attach = false;
 
 		static bool arch_set = false;
 		static string arch = "i386";
@@ -287,6 +288,7 @@ namespace Xamarin.Bundler {
 				{ "http-message-handler=", "Specify the default HTTP Message Handler", v => { http_message_provider = v; }},
 				{ "extension", "Specifies an app extension", v => is_extension = true },
 				{ "allow-unsafe-gac-resolution", "Allow MSBuild to resolve from the System GAC", v => {} , true }, // Used in Xamarin.Mac.XM45.targets and must be ignored here. Hidden since it is a total hack. If you can use it, you don't need support
+				{ "disable-lldb-attach=", "Disable automatic lldb attach on crash", v => disable_lldb_attach = ParseBool (v, "disable_lldb_attach")},
 			};
 
 			AddSharedOptions (os);
@@ -908,6 +910,8 @@ namespace Xamarin.Bundler {
 				sw.WriteLine ("\txamarin_use_il_registrar = {0};", registrar == RegistrarMode.IL ? "true" : "false");
 				sw.WriteLine ("\txamarin_marshal_managed_exception_mode = MarshalManagedExceptionMode{0};", App.MarshalManagedExceptions);
 				sw.WriteLine ("\txamarin_marshal_objectivec_exception_mode = MarshalObjectiveCExceptionMode{0};", App.MarshalObjectiveCExceptions);
+				if (disable_lldb_attach)
+					sw.WriteLine ("\txamarin_disable_lldb_attach = true;");
 				sw.WriteLine ();
 				if (Driver.registrar == RegistrarMode.Static)
 					sw.WriteLine ("\txamarin_create_classes ();");