idk look at the changes

test/test_error.c3

@@ -0,0 +1,72 @@
+import std::io;
+
+struct FaultStack {
+	usz elem;
+	anyfault[16] v;
+}
+
+fn void FaultStack.push(&fs, anyfault f)
+{
+	if (fs.elem < fs.v.len) {
+		fs.v[fs.elem++] = f;
+	}
+}
+
+fn anyfault FaultStack.pop(&fs)
+{
+	return fs.elem > 0 ? fs.v[fs.elem-- - 1] : anyfault{};
+}
+
+FaultStack fs;
+
+fn int! err1()
+{
+	return IoError.OUT_OF_SPACE?;
+}
+
+fn void! err2()
+{
+	return IoError.EOF?;
+}
+
+/*
+macro @unwrap(#f)
+{
+	$if ($typeof(#f).typeid == void!.typeid) {
+		if (catch err = #f) { fs.push(err); }
+		return;
+	} $else {
+		$typeof(#f) x = #f;
+		if (catch err = x) {
+			fs.push(err);
+			return $typeof(#f!!){};
+		} else {return x;}
+	}
+}
+*/
+
+<*
+@require @typekind(#func) == OPTIONAL : `@unwrap requires an optional value`
+*>
+macro @unwrap(#func)
+{
+	anyfault exc = @catch(#func);
+	if (exc != anyfault{}) {
+		fs.push(exc);
+		$if $typeof(#func!!).typeid != void.typeid:
+			return $typeof(#func!!){};
+		$else
+			return;
+		$endif
+	} else {
+		return #func!!;
+	}
+}
+
+fn void main()
+{
+	@unwrap(err1());
+	@unwrap(err2());
+
+	io::printfn("%s", fs.v);
+}