Not all context accessor methods are generated when an alternative rule label is used for multiple alternatives

[ronangel]

When I reuse the same alternative rule label for multiple alternatives, ANTLR only generates accessor methods for the last alternative with the given label.

For example, with the following rule:

expression : '(' expression ')'                                 # ParenthesizedExpression
           | expression Caret<assoc=right> expression           # BinaryNumericExpression
           | expression (Times|DividedBy|ModuloDiv) expression  # BinaryNumericExpression
           | expression (Plus|Minus) expression                 # BinaryNumericExpression
           ;

The generated BinaryNumericExpressionContext class will only have Plus() and Minus() accessors, but not Caret(), Times(), DividedBy(), or ModuloDiv().

[parrt]

Interesting. I wonder if it should have all accessors or should it be an error?

[sharwell]

As mentioned in response to my deleted answer to this StackOverflow question, the ANTLR 4 documentation clearly states that multiple outer alternatives in the same rule can share a context class. I was not aware of this when I wrote the analysis in getDeclsForAllElements as part of this optimization, hence the bug.