(extended_return_object_declaration): accept aspect_specification
In accordance with Ada 2022 RM 6.5(2.1/5); this was not allowed in Ada
2012, but was changed in AI12-0398-1/03.
add test.
The existing grammar was causing simple expressions to be incorrectly
parsed as a subtype indication. This change raises the precedence for
a discrete choice expression to address that issue.
Updated the test corpus to reflect the parsing correction. Additional
test cases were added for discrete choice.
This was copied from ada_mode, but results in
confusion when we have statements after the pragma
Fix allocates with if-expression, which no longer
needs double-parenthesis.
