[antlr-interest] Lexical nondeterminism

[Sohail Somani]

Given this simple lexer:

class L extends Lexer;
options
{
        testLiterals = true;
        k=2;
        caseSensitive=true;
        caseSensitiveLiterals=true;
}

SOME_KEYWORD
        : "if"
        ;

protected
LETTER
        : 'a'..'z' | 'A'..'Z'
        ;

protected
DIGIT
        : '0'..'9'
        ;

IDENTIFIER
        : LETTER (LETTER | DIGIT)*
        ;

antlr 2.7.6 tells me:

test.g: warning:lexical nondeterminism between rules SOME_KEYWORD and
IDENTIFIER upon
test.g:     k==1:'i'
test.g:     k==2:'f'

Why is this? I thought testLiterals is supposed to get antlr to compare
matched tokens to my literals?

Thanks

Sohail