Allow member accesses to Never #40055
Description
Member accesses on Never should be allowed (cf. dart-lang/language#711 (comment)) and issues arising because the resulting code is likely to be a bug should be handled by detecting and flagging unreachable code with a warning.
So a receiver of type Never is treated as if it had all member signatures, just like a receiver of type dynamic, but n.foo() where n has type Never should be flagged with a warning indicating that the invocation of foo will not occur.
However, the log https://logs.chromium.org/logs/dart/buildbucket/cr-buildbucket.appspot.com/8891663887450837936/+/steps/test_results/0/logs/new_test_failures__logs_/0 shows that the analyzer reports an error for such a situation.
The situation occurs in static_errors_A11_t02:
main() {
Null a = null;
a?.toString();
a ?.. toString();
}where the receiver a is treated as having type NonNull(Null), which is Never. In the log, the analyzer reports that a receiver of type Never is an error per se:
ERROR|STATIC_WARNING|INVALID_USE_OF_NEVER_VALUE|/b/s/w/ir/cache/builder/sdk/tests/co19/src/LanguageFeatures/nnbd/static_errors_A11_t02.dart|25|3|1|This expression is invalid because its target is of type Never and will never complete with a value
It might be sufficient to change this response such that it is not an error but a warning (according to test.dart), and adjust the text to mention that there is dead code at this location.