view tests/test-diff-issue2761.t @ 25996:b12e00a05d57 stable

revset: prevent crash caused by empty group expression while optimizing "or"

An empty group expression "()" generates None in AST, so it should be tested
before destructuring a tuple.

"A | ()" is still evaluated to an error because I'm not sure whether "()"
represents an empty set or an empty expression (= a unit value). They are
identical in "or" operation, but they should be evaluated differently in
"and" operation.

  expression  empty set  unit value
  ----------  ---------  ----------
  ()          {}         A
  A & ()      {}         A
  A | ()      A          A

Test issue2761

  $ hg init

  $ touch to-be-deleted
  $ hg add
  adding to-be-deleted
  $ hg ci -m first
  $ echo a > to-be-deleted
  $ hg ci -m second
  $ rm to-be-deleted
  $ hg diff -r 0

Same issue, different code path

  $ hg up -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ touch does-not-exist-in-1
  $ hg add
  adding does-not-exist-in-1
  $ hg ci -m third
  $ rm does-not-exist-in-1
  $ hg diff -r 1