Enable old panic behavior for Citra

ctr-std/Cargo.toml

@@ -15,3 +15,6 @@ default-features = false
 
 [dependencies.ctru-sys]
 path = "../ctru-sys"
+
+[features]
+citra = []

ctr-std/src/panicking.rs

@@ -57,8 +57,37 @@ pub fn begin_panic_fmt(msg: &fmt::Arguments, file_line_col: &(&'static str, u32,
     begin_panic(s, file_line_col);
 }
 
-/// We don't have stack unwinding, so all we do is print the panic message
-/// and then crash or hang the application
+// Citra doesn't support the Error applet yet
+#[cfg(feature = "citra")]
+#[unstable(feature = "libstd_sys_internals",
+           reason = "used by the panic! macro",
+           issue = "0")]
+#[inline(never)] #[cold]
+pub fn begin_panic<M: Any + Send + Display>(msg: M, file_line_col: &(&'static str, u32, u32)) -> ! {
+    let msg = Box::new(msg);
+    let (file, line, col) = *file_line_col;
+
+    // 3DS-specific code begins here
+    use libctru::{consoleInit, gfxScreen_t};
+
+    unsafe {
+        // set up a new console, overwriting whatever was on the top screen
+        // before we started panicking
+        let _console = consoleInit(gfxScreen_t::GFX_TOP, ptr::null_mut());
+
+        println!("thread '{}' panicked at '{}', {}:{}:{}",
+                 "<unnamed>", msg, file, line, col);
+
+        // Citra seems to ignore calls to svcExitProcess, and libc::abort()
+        // causes it to lock up and fill the console with endless debug statements.
+        // So instead of terminating the program, we just let it spin in the following
+        // loop. This means that any background threads might continue to run after
+        // this thread panics, but there's not a lot we can do about that currently.
+        loop { }
+    }
+}
+
+#[cfg(not(feature = "citra"))]
 #[unstable(feature = "libstd_sys_internals",
            reason = "used by the panic! macro",
            issue = "0")]
@@ -82,7 +111,7 @@ pub fn begin_panic<M: Any + Send + Display>(msg: M, file_line_col: &(&'static st
                   CFG_Language::CFG_LANGUAGE_EN);
         errorText(&mut error_conf, error_text.as_ptr() as *const libc::c_char);
 
-        // Display error via Error applet
+        // Display error
         errorDisp(&mut error_conf);
 
         // Now that we're all done printing, it's time to exit the program.