It seems to be a problem in the parser.
For the query 'true[false()]', I get the following AST
<ParseNodeTree> <MainModule pos='/home/mbrantner/zorba/build/../build/tmp.jq:1.2-15' ptr='0x1ba4a20'> <QueryBody pos='/home/mbrantner/zorba/build/../build/tmp.jq:1.2-15' ptr='0x1b693d0'> <BooleanLiteral pos='/home/mbrantner/zorba/build/../build/tmp.jq:1.2-15' ptr='0x1b7e220'> </BooleanLiteral> </QueryBody> </MainModule> </ParseNodeTree
which seems to completely miss the predicate.
For the query 'true()[false()] it works.
It seems to be a problem in the parser.
For the query 'true[false()]', I get the following AST
<ParseNodeTree> mbrantner/ zorba/build/ ../build/ tmp.jq: 1.2-15' ptr='0x1ba4a20'> mbrantner/ zorba/build/ ../build/ tmp.jq: 1.2-15' ptr='0x1b693d0'> mbrantner/ zorba/build/ ../build/ tmp.jq: 1.2-15' ptr='0x1b7e220'> teral>
<MainModule pos='/home/
<QueryBody pos='/home/
<BooleanLiteral pos='/home/
</BooleanLi
</QueryBody>
</MainModule>
</ParseNodeTree
which seems to completely miss the predicate.
For the query 'true()[false()] it works.