Can an NNBD library catch dynamic? #916
Description
As I was migrating language_2/exception/try_catch_optimized5_test.dart, I ran into an interesting failure. Given:
main() {
try {
throw "ok";
} on dynamic catch (error) {
print(error);
}
}It runs fine in the VM:
$ dart --null-safety --enable-experiment=non-nullable temp.dart
ok
But analyzer does not like it:
$ dartanalyzer --enable-experiment=non-nullable temp.dart
Analyzing temp.dart...
error • A nullable type can't be used in an 'on' clause because it isn't valid to throw 'null'. • temp.dart:4:8 • nullable_type_in_catch_clause
1 error found.
I don't see anything in the NNBD spec related to catching non-nullable types so I don't know which tool is behavior correctly. My hunch is that we probably do want to treat dynamic specially and allow that in a catch clause even though it's technically nullable?
A related question is around type parameters:
main<T>() {
try {
throw "ok";
} on T catch (error) {
print(error);
}
}Analyzer currently considers that an error, but does allow:
main<T extends Object>() {
try {
throw "ok";
} on T catch (error) {
print(error);
}
}