v panic debug information

compiler/fn.v

@@ -752,6 +752,16 @@ fn (p mut Parser) fn_call_args(f mut Fn) *Fn {
 		p.check(.rpar)
 		return f
 	}
+	// add debug information to panic when -debug arg is passed
+	if p.v.pref.is_debug && f.name == 'panic' {
+		mod_name := p.mod.replace('_dot_', '.')
+		fn_name := p.cur_fn.name.replace('${p.mod}__', '')
+		file_path := p.file_path.replace('\\', '\\\\') // escape \
+		p.cgen.resetln(p.cgen.cur_line.replace(
+			'v_panic (',
+			'_panic_debug ($p.scanner.line_nr, tos2("$file_path"), tos2("$mod_name"), tos2("$fn_name"), '
+		))
+	}
 	// Receiver - first arg
 	for i, arg in f.args {
 		// println('$i) arg=$arg.name')

vlib/builtin/builtin.v

@@ -26,6 +26,19 @@ pub fn print_backtrace() {
 	}
 }
 
+// replaces panic when -debug arg is passed
+fn _panic_debug(line_no int, file,  mod, fn_name, s string) {
+	println('================ V panic ================')
+	println('   module: $mod')
+	println(' function: ${fn_name}()')
+	println('     file: $file')
+	println('     line: ' + line_no.str())
+	println('  message: $s')
+	println('=========================================')
+	print_backtrace()
+	C.exit(1)
+}
+
 pub fn panic(s string) {
 	println('V panic: $s')
 	print_backtrace()