503 relation-subscript operator has the highest binding strength (as function call):

   504 

   505   $ hg debugrevspec -p parsed 'tip:tip^#generations[-1]'

   506   * parsed:

   507   (range

   508     ('symbol', 'tip')

   509     (relsubscript

   510       (parentpost

   511         ('symbol', 'tip'))

   512       ('symbol', 'generations')

   513       (negate

   514         ('symbol', '1'))))

   515   hg: parse error: can't use a relation in this context

   516   [255]

   517 

   518   $ hg debugrevspec -p parsed --no-show-revs 'not public()#generations[0]'

   519   * parsed:

   520   (not

   521     (relsubscript

   522       (func

   523         ('symbol', 'public')

   524         None)

   525       ('symbol', 'generations')

   526       ('symbol', '0')))

   527   hg: parse error: can't use a relation in this context

   528   [255]

   529 

   530 left-hand side of relation-subscript operator should be optimized recursively:

   531 

   532   $ hg debugrevspec -p analyzed -p optimized --no-show-revs \

   533   > '(not public())#generations[0]'

   534   * analyzed:

   535   (relsubscript

   536     (not

   537       (func

   538         ('symbol', 'public')

   539         None

   540         any)

   541       define)

   542     ('symbol', 'generations')

   543     ('symbol', '0')

   544     define)

   545   * optimized:

   546   (relsubscript

   547     (func

   548       ('symbol', '_notpublic')

   549       None

   550       any)

   551     ('symbol', 'generations')

   552     ('symbol', '0')

   553     define)

   554   hg: parse error: can't use a relation in this context

   555   [255]

   556 

   557 resolution of subscript and relation-subscript ternary operators:

   558 

   559   $ hg debugrevspec -p analyzed 'tip[0]'

   560   * analyzed:

   561   (subscript

   562     ('symbol', 'tip')

   563     ('symbol', '0')

   564     define)

   565   hg: parse error: can't use a subscript in this context

   566   [255]

   567 

   568   $ hg debugrevspec -p analyzed 'tip#rel[0]'

   569   * analyzed:

   570   (relsubscript

   571     ('symbol', 'tip')

   572     ('symbol', 'rel')

   573     ('symbol', '0')

   574     define)

   575   hg: parse error: can't use a relation in this context

   576   [255]

   577 

   578   $ hg debugrevspec -p analyzed '(tip#rel)[0]'

   579   * analyzed:

   580   (subscript

   581     (relation

   582       ('symbol', 'tip')

   583       ('symbol', 'rel')

   584       define)

   585     ('symbol', '0')

   586     define)

   587   hg: parse error: can't use a subscript in this context

   588   [255]

   589 

   590   $ hg debugrevspec -p analyzed 'tip#rel[0][1]'

   591   * analyzed:

   592   (subscript

   593     (relsubscript

   594       ('symbol', 'tip')

   595       ('symbol', 'rel')

   596       ('symbol', '0')

   597       define)

   598     ('symbol', '1')

   599     define)

   600   hg: parse error: can't use a subscript in this context

   601   [255]

   602 

   603   $ hg debugrevspec -p analyzed 'tip#rel0#rel1[1]'

   604   * analyzed:

   605   (relsubscript

   606     (relation

   607       ('symbol', 'tip')

   608       ('symbol', 'rel0')

   609       define)

   610     ('symbol', 'rel1')

   611     ('symbol', '1')

   612     define)

   613   hg: parse error: can't use a relation in this context

   614   [255]

   615 

   616   $ hg debugrevspec -p analyzed 'tip#rel0[0]#rel1[1]'

   617   * analyzed:

   618   (relsubscript

   619     (relsubscript

   620       ('symbol', 'tip')

   621       ('symbol', 'rel0')

   622       ('symbol', '0')

   623       define)

   624     ('symbol', 'rel1')

   625     ('symbol', '1')

   626     define)

   627   hg: parse error: can't use a relation in this context

   628   [255]

   629 

   630 parse errors of relation, subscript and relation-subscript operators:

   631 

   632   $ hg debugrevspec '[0]'

   633   hg: parse error at 0: not a prefix: [

   634   [255]

   635   $ hg debugrevspec '.#'

   636   hg: parse error at 2: not a prefix: end

   637   [255]

   638   $ hg debugrevspec '#rel'

   639   hg: parse error at 0: not a prefix: #

   640   [255]

   641   $ hg debugrevspec '.#rel[0'

   642   hg: parse error at 7: unexpected token: end

   643   [255]

   644   $ hg debugrevspec '.]'

   645   hg: parse error at 1: invalid token

   646   [255]

   647