view tests/test-revset-legacy-lookup.t @ 46667:93e9f448273c

rhg: Add support for automatic fallback to Python

`rhg` is a command-line application that can do a small subset of what
`hg` can. It is written entirely in Rust, which avoids the cost of starting
a Python interpreter and importing many Python modules.
In a script that runs many `hg` commands, this cost can add up.

However making users decide when to use `rhg` instead of `hg` is
not practical as we want the subset of supported functionality
to grow over time.

Instead we introduce "fallback" behavior where, when `rhg` encounters
something (a sub-command, a repository format, …) that is not implemented
in Rust-only, it does nothing but silently start a subprocess of
Python-based `hg` running the same command.
That way `rhg` becomes a drop-in replacement for `hg` that sometimes
goes faster. Whether Python is used should be an implementation detail
not apparent to users (other than through speed).

A new `fallback` value is added to the previously introduced
`rhg.on-unsupported` configuration key. When in this mode, the new
`rhg.fallback-executable` config is determine what command to use
to run a Python-based `hg`.

The previous `rhg.on-unsupported = abort-silent` configuration was designed
to let a wrapper script call `rhg` and then fall back to `hg` based on the
exit code. This is still available, but having fallback behavior built-in
in rhg might be easier for users instead of leaving that script "as an
exercise for the reader".

Using a subprocess like this is not idea, especially when `rhg` is to be
installed in `$PATH` as `hg`, since the other `hg.py` executable needs
to still be available… somewhere. Eventually this could be replaced
by using PyOxidizer to a have a single executable that embeds a Python
interpreter, but only starts it when needed.

Differential Revision: https://phab.mercurial-scm.org/D10093

  $ cat >> $HGRCPATH << EOF
  > [command-templates]
  > log="{rev}:{node|short} {desc} [{tags}]\n"
  > EOF

  $ hg init legacy-lookup
  $ cd legacy-lookup
  $ echo a > a
  $ hg add a
  $ hg commit -m 'first'
  $ echo aa > a
  $ hg commit -m 'second'
  $ hg log -G
  @  1:43114e71eddd second [tip]
  |
  o  0:a87874c6ec31 first []
  

Create a tag that looks like a revset

  $ hg tag 'rev(0)'
  $ hg log -G
  @  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]
  |
  o  1:43114e71eddd second [rev(0)]
  |
  o  0:a87874c6ec31 first []
  

See how various things are resolved
-----------------------------------

Revision numbers

  $ hg log -r '0'
  0:a87874c6ec31 first []
  $ hg log -r '1'
  1:43114e71eddd second [rev(0)]

"rev(x)" form (the one conflicting with the tags)
(resolved as a label)

  $ hg log -r 'rev(0)'
  1:43114e71eddd second [rev(0)]
  $ hg log -r 'rev(1)'
  1:43114e71eddd second [rev(0)]

same within a simple revspec
(still resolved as the label)

  $ hg log -r ':rev(0)'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  $ hg log -r 'rev(0):'
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]

within a more advances revset
(still resolved as the label)

  $ hg log -r 'rev(0) and branch(default)'
  0:a87874c6ec31 first []

with explicit revset resolution
(still resolved as the label)

  $ hg log -r 'revset(rev(0))'
  0:a87874c6ec31 first []

some of the above with quote to force its resolution as a label

  $ hg log -r ':"rev(0)"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  $ hg log -r '"rev(0)":'
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]
  $ hg log -r '"rev(0)" and branch(default)'
  1:43114e71eddd second [rev(0)]

confusing bits within parents

  $ hg log -r '(rev(0))'
  0:a87874c6ec31 first []
  $ hg log -r '( rev(0))'
  0:a87874c6ec31 first []
  $ hg log -r '("rev(0)")'
  1:43114e71eddd second [rev(0)]

Test label with quote in them.

  $ hg tag '"foo"'

  $ hg log -r '"foo"'
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  $ hg log -r '("foo")'
  abort: unknown revision 'foo'
  [255]
  $ hg log -r 'revset("foo")'
  abort: unknown revision 'foo'
  [255]
  $ hg log -r '("\"foo\"")'
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  $ hg log -r 'revset("\"foo\"")'
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]

Test label with dash in them.

  $ hg tag 'foo-bar'

  $ hg log -r 'foo-bar'
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  $ hg log -r '(foo-bar)'
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  $ hg log -r '"foo-bar"'
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  $ hg log -r '("foo-bar")'
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]

Test label with + in them.

  $ hg tag 'foo+bar'

  $ hg log -r 'foo+bar'
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  $ hg log -r '(foo+bar)'
  abort: unknown revision 'foo'
  [255]
  $ hg log -r 'revset(foo+bar)'
  abort: unknown revision 'foo'
  [255]
  $ hg log -r '"foo+bar"'
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  $ hg log -r '("foo+bar")'
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]

Test tag with numeric version number.

  $ hg tag '1.2'

  $ hg log -r '1.2'
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r '(1.2)'
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r 'revset(1.2)'
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r '"1.2"'
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r '("1.2")'
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r '::"1.2"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  $ hg log -r '::1.2'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]

Test tag with parenthesis (but not a valid revset)

  $ hg tag 'release_4.1(candidate1)'

  $ hg log -r 'release_4.1(candidate1)'
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  $ hg log -r '(release_4.1(candidate1))'
  hg: parse error: unknown identifier: release_4.1
  [10]
  $ hg log -r 'revset(release_4.1(candidate1))'
  hg: parse error: unknown identifier: release_4.1
  [10]
  $ hg log -r '"release_4.1(candidate1)"'
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  $ hg log -r '("release_4.1(candidate1)")'
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  $ hg log -r '::"release_4.1(candidate1)"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  $ hg log -r '::release_4.1(candidate1)'
  hg: parse error: unknown identifier: release_4.1
  [10]

Test tag with parenthesis and other function like char

  $ hg tag 'release_4.1(arch=x86,arm)'

  $ hg log -r 'release_4.1(arch=x86,arm)'
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  $ hg log -r '(release_4.1(arch=x86,arm))'
  hg: parse error: unknown identifier: release_4.1
  [10]
  $ hg log -r 'revset(release_4.1(arch=x86,arm))'
  hg: parse error: unknown identifier: release_4.1
  [10]
  $ hg log -r '"release_4.1(arch=x86,arm)"'
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  $ hg log -r '("release_4.1(arch=x86,arm)")'
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  $ hg log -r '::"release_4.1(arch=x86,arm)"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  $ hg log -r '::release_4.1(arch=x86,arm)'
  hg: parse error: unknown identifier: release_4.1
  [10]

Test tag conflicting with revset function

  $ hg tag 'secret(team=foo,project=bar)'

  $ hg log -r 'secret(team=foo,project=bar)'
  8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
  $ hg log -r '(secret(team=foo,project=bar))'
  hg: parse error: secret takes no arguments
  [10]
  $ hg log -r 'revset(secret(team=foo,project=bar))'
  hg: parse error: secret takes no arguments
  [10]
  $ hg log -r '"secret(team=foo,project=bar)"'
  8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
  $ hg log -r '("secret(team=foo,project=bar)")'
  8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
  $ hg log -r '::"secret(team=foo,project=bar)"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
  $ hg log -r '::secret(team=foo,project=bar)'
  hg: parse error: secret takes no arguments
  [10]

Test tag with space

  $ hg tag 'my little version'

  $ hg log -r 'my little version'
  9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
  $ hg log -r '(my little version)'
  hg: parse error at 4: unexpected token: symbol
  ((my little version)
       ^ here)
  [10]
  $ hg log -r 'revset(my little version)'
  hg: parse error at 10: unexpected token: symbol
  (revset(my little version)
             ^ here)
  [10]
  $ hg log -r '"my little version"'
  9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
  $ hg log -r '("my little version")'
  9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
  $ hg log -r '::"my little version"'
  0:a87874c6ec31 first []
  1:43114e71eddd second [rev(0)]
  2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
  3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
  4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
  5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
  6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
  7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
  8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
  9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
  $ hg log -r '::my little version'
  hg: parse error at 5: invalid token
  (::my little version
        ^ here)
  [10]