Much improves the panic function, now prints a stack trace more often. (#86)

Co-authored-by: Felix "xq" Queißner <xq@random-projects.net>

src/core/microzig.zig

@@ -86,27 +86,27 @@ else
     };
 
 /// The microzig default panic handler. Will disable interrupts and loop endlessly.
-pub fn microzig_panic(message: []const u8, maybe_stack_trace: ?*std.builtin.StackTrace, _: ?usize) noreturn {
+pub fn microzig_panic(message: []const u8, _: ?*std.builtin.StackTrace, _: ?usize) noreturn {
 
     // utilize logging functions
     std.log.err("microzig PANIC: {s}", .{message});
 
     if (builtin.cpu.arch != .avr) {
-        var writer = debug.writer();
-        writer.print("microzig PANIC: {s}\r\n", .{message}) catch unreachable;
-
-        if (maybe_stack_trace) |stack_trace| {
-            var frame_index: usize = 0;
-            var frames_left: usize = std.math.min(stack_trace.index, stack_trace.instruction_addresses.len);
-            while (frames_left != 0) : ({
-                frames_left -= 1;
-                frame_index = (frame_index + 1) % stack_trace.instruction_addresses.len;
-            }) {
-                const return_address = stack_trace.instruction_addresses[frame_index];
-                writer.print("0x{X:0>8}\r\n", .{return_address}) catch unreachable;
+        var index: usize = 0;
+        var iter = std.debug.StackIterator.init(@returnAddress(), null);
+        while (iter.next()) |address| : (index += 1) {
+            if (index == 0) {
+                std.log.err("stack trace:", .{});
             }
+            std.log.err("{d: >3}: 0x{X:0>8}", .{ index, address });
         }
     }
+    if (@import("builtin").mode == .Debug) {
+        // attach a breakpoint, this might trigger another
+        // panic internally, so only do that in debug mode.
+        std.log.info("triggering breakpoint...", .{});
+        @breakpoint();
+    }
     hang();
 }