Use --allow-empty when git amending to HEAD

Summary: ... in case the head commit is empty. Empty commits are useful for
injecting an Arcanist commit message in a branch then sending the whole thing
off for review. As far as I know there is no situation in which an empty commit
would exist unintentionally and using ##--allow-empty## would suppress an error.

Test Plan: works fine for a branch I just sent for review

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: 1241
Parse full URIs for "Differential Revision" in Arcanist

Summary:
  - Allow Arcanist to parse either "123", "D123" (existing behaviors) or
"http://phabricator.example.com/D123" (new behavior) values.
  - Drop support for labeling this field "DiffCamp". This should only impact
people trying to update revisions that are more than ~a year old, which should
be very very few.

Test Plan:   - Ran "arc diff" with values "74", "D74", "x74",
"http://local.aphront.com/D74", "http://local.aphront.com/x74". Got the expected
behaviors.

Reviewers: jungejason, btrahan

Reviewed By: jungejason

CC: aran, jungejason

Maniphest Tasks: T54, T692

Differential Revision: 1249
Improve detection of invalid unit and lint engines

Summary: We fatal confusingly if you specify a valid class that isn't of the
right subclass (like a linter rather than a lint engine). Improve the error
message.

Test Plan:
  - Ran "arc lint --engine PhutilSymbolLoader", "arc unit --engine
PhutilSymbolLoader", got expected failures.
  - Ran "arc diff" normally without errors.

Reviewers: btrahan, jungejason, aran

Reviewed By: aran

CC: aran

Differential Revision: https://secure.phabricator.com/D1259
Bump Arcanist client version to 3

Summary:
Thinking about this, I think it's worthwhile to bump versions for T1249/T1250.
The problem is that if you have an old Arcanist, trying to update diffs against
a new Phabricator will create new diffs instead, and it probably won't be
obvious what's wrong.

Bump the versions so users will get a message like "oh, hey, you should
upgrade".

Test Plan:
  - Tried to diff against a mismatched version.
  - Diffed against a matching version.

Reviewers: btrahan, jungejason, aran

Reviewed By: aran

CC: aran

Differential Revision: https://secure.phabricator.com/D1257
arc cover doesn't support against_commit

Summary: Blame Rev:

Test Plan: arc help cover

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1272
Add some version/env sanity checks to 'arc'

Summary:
A user filed an issue on GitHub about not having 'json_decode()':

  https://github.com/facebook/arcanist/issues/10

Detect this issue and raise a detailed error message.

Test Plan:
  - Set minimum version to 6.0.0, arc told me to upgrade.
  - Changed function/flag configuration and hit the flag and no-flag error
pathways.

Reviewers: btrahan, jungejason, rm

Reviewed By: rm

CC: aran, rm, epriestley

Differential Revision: https://secure.phabricator.com/D1267
Decompose TYPE_MULTICOPY changes into a MOVE_HERE plus one or more COPY_HERE

Summary:
See T419 for some philosophical musing on this. The "ideal" way to represent
these changes is two or more COPY_HERE plus a DELETE, but we can't build the
DELETE patch yet.

Just turn one of the COPY_HERE changes into a MOVE_HERE. While less idealistic,
I think this should always work.

Test Plan: This seemed to cleanly apply TenXer D265. TenXer guys, can you
confirm that this makes it actually patch correctly?

Reviewers: jonathanhester, bizrad6, kdeggelman, jungejason, btrahan

Reviewed By: jungejason

CC: aran, jonathanhester, jungejason, epriestley

Maniphest Tasks: T419

Differential Revision: https://secure.phabricator.com/D1270
Use getcwd() which is more reliable than $_SERVER['PWD']

Summary:
in arcanist we are using $_SERVER['PWD'], but in some cases it
is not returning the correct result. For example, when I'm using
PhpStorm (an php IDE) to launch the script, $_SERVER['PWD'] returns the
path of the binary of the IDE:
/home/jungejason/tools/PhpStorm-107.658/bin, not the path where arcanist
is at. getcwd() returns the correct value.

One difference between getcwd() and $_SERVER['PWD'] is that getcwd()
resolves symlink where $_SERVER['PWD'] does not. From what I can see,
using realpath should work.

Test Plan:
* ran arcanist as normal and it worked;
* run arcanist in PhpStorm and it worked.
* created a symlink pointing to the repository inside which
I ran the arc command, and it worked.
* created a symlink pointing to arcanist project, run `.
* resources/shell/bash-completion`  and it worked

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1285
Replace preg_quote() lint error by warning

Summary: See http://php.net/regexp.reference.delimiters

Test Plan: arc lint on a file with preg_quote() with one parameter

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley, vrana

Differential Revision: https://secure.phabricator.com/D1163
[arc svn-hook-pre-commit] Access working copy

Summary:
Creates a new hook API that can be used to interface with
SVN/Git/Mercurial in the context of a commit hook. Currently only adds a
function to read the modified file data in a Subversion commit hook.

An object of this API is created in the SvnHookPreCommitWorkflow and
passed on the Lint Engine which then uses it to access current file
data, of the way the APIs seem to be structured); linters use the
getData function which is essentially a wrapper around the engine's
call, with another layer of caching.

Task ID: #770556

Blame Rev:

Test Plan:
- Create a local svn repository and add a minimal hook to run the local
  version of arc to test commits

(http://phabricator.com/docs/arcanist/article/Installing_Arcanist_SVN_Hooks.html)
- Create a temporary repository that can trigger any of the linters
  available, and test against a temporary linter by committing against
  the test repository: the linter should be able to access all required
  files by using loadData/getData in the LintEngine and Linter.

Revert Plan:

Tags: lint, svn-hook-pre-commit

Reviewers: jungejason, asukhachev, epriestley, aran

Reviewed By: epriestley

CC: aran, jungejason, epriestley, kunalb, asukhachev

Differential Revision: https://secure.phabricator.com/D1256
Slightly improve Arcanist unit test output messages

Summary:
  - Show file/line so you can tell which assertion failed if there's a block
with a zillion of them and they don't have messages.
  - Try to format stuff a little better.

Test Plan:   - Ran some failing unit tests.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, btrahan

Differential Revision: https://secure.phabricator.com/D1304
Make XHPAST linter correct too much space after control keywords like "if"

Summary: Previously, we would not correct excessive space after "if", etc.

Test Plan: Ran test case.

Reviewers: btrahan, jungejason, kiyoto

Reviewed By: jungejason

CC: aran, jungejason, epriestley

Differential Revision: https://secure.phabricator.com/D1311
Make XHPASTLinter correct too little space before opening braces

Summary: Previously, we would not correct missing space before "{".

Test Plan: Ran unit tests.

Reviewers: btrahan, jungejason, kiyoto

Reviewed By: jungejason

CC: aran, jungejason

Differential Revision: https://secure.phabricator.com/D1313
Ignore non-plaintext changes in cover

Test Plan:
Run ##arc lint## after changing a binary file
"Warning:  Invalid argument supplied for foreach() in
src/workflow/cover/ArcanistCoverWorkflow.php on line 88" should not be displayed

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1314
Remove all XHP lint tests from Arcanist

Summary:
  - Remove XHP tests so I can remove XHP support from XHPAST.
  - Update license tests so they don't break every year.

Test Plan:   - Ran all unit tests.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, pad, jungejason, btrahan

Maniphest Tasks: T635

Differential Revision: https://secure.phabricator.com/D1318
Refactor ArcanistDiffWorkflow to be a little more manageable

Summary:
I want to make some changes to this workflow but it a huge mess right now. Try
to refactor a bit to make it a little more manageable.

Broadly:

  - Moved lint/unit constant mapping into separate methods.
  - Moved lint/unit/local properties into separate methods.
  - Moved diff spec construction into a separate method.
  - Moved some message stuff into separate methods and reorganized related
methods near to one another.
  - Removed an unused findRevisionInformation() method.

I fixed a couple of small bugs, too:

  - --create now conflicts with --only and --preview.
  - --create now probably works in Mercurial.
  - --create messages now have basic reviewer validation.

This should have not have any significant behavioral changes.

Test Plan:
  - Created this revision.
  - Ran "arc diff --create".

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, btrahan, epriestley

Differential Revision: https://secure.phabricator.com/D1320
Add a "--raw" flag to "arc diff"

Summary:
Some Mercurial users at Dropbox have very specific diff preparation
needs. Allow "arc" to read an arbitrary diff off stdin. This disables most
features.

Test Plan:
Ran "git diff HEAD | arc diff --raw", "git show | arc diff --raw",
"hg diff --rev 8 | arc diff --raw".

Reviewers: btrahan, jungejason, Makinde

Reviewed By: btrahan

CC: aran, btrahan

Maniphest Tasks: T617

Differential Revision: https://secure.phabricator.com/D1323
Approximate "git merge-base" in Mercurial

Summary: Find the relative commit by finding the first non-outgoing commit, so
we don't show changes caused by merges we've performed since the last time we
pushed.

Test Plan: Checked out two hg working copies, A and B. Made a change in A. Made
a change in B. Pushed B. Merged in A. Made another change in A. Ran "arc diff"
in A. Got only changes I made in A in the diff, not the change from B.

Reviewers: Makinde, btrahan, jungejason

Reviewed By: btrahan

CC: aran, btrahan

Differential Revision: https://secure.phabricator.com/D1339
Add an "--update <revision>" flag to Arcanist

Summary:
See T614. This flag explicitly tells Arcanist to use the message for an existing
revision, and attach the change to it directly.

Next step is to have "arc diff" automatically choose "--create" or "--update" in
the absence of "--create", "--update", "--only", "--preview" or a template
commit message.

Test Plan:
Ran "arc diff --update <n>" for various revisions. Got updates or
errors as expected.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, btrahan, jungejason

Maniphest Tasks: T614

Differential Revision: https://secure.phabricator.com/D1346
Add support for zsh completion to bash-completion