view tests/test-releasenotes-formatting.t @ 35569:964212780daf

rust: implementation of `hg`

This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.

If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.

Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.

It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.

Now onto the implementation.

We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.

The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.

There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):

* Validates that the Python interpreter that was detected by the
  python27-sys crate provides a shared library (we only support
  shared library linking at this time - although this restriction
  could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
  maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
  find the path to the Python interpreter.

The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.

Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.

In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.

Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:

* test-run-tests.t -- Warnings emitted about using an unexpected
  Mercurial library. This is due to the hacky nature of setting the
  Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
  (This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
  assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
  Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
  line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.

It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.

Differential Revision: https://phab.mercurial-scm.org/D1581

#require fuzzywuzzy

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > releasenotes=
  > EOF

  $ hg init simple-repo
  $ cd simple-repo

A fix with a single line results in a bullet point in the appropriate section

  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > single line fix
  > 
  > .. fix::
  > 
  >    Simple fix with a single line content entry.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-single-line

  $ cat $TESTTMP/relnotes-single-line
  Bug Fixes
  =========
  
  * Simple fix with a single line content entry.

A fix with multiple lines is handled correctly

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > multi line fix
  > 
  > .. fix::
  > 
  >    First line of fix entry.
  >    A line after it without a space.
  > 
  >    A new paragraph in the fix entry. And this is a really long line. It goes on for a while.
  >    And it wraps around to a new paragraph.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-multi-line
  $ cat $TESTTMP/relnotes-multi-line
  Bug Fixes
  =========
  
  * First line of fix entry. A line after it without a space.
  
    A new paragraph in the fix entry. And this is a really long line. It goes on
    for a while. And it wraps around to a new paragraph.

A release note with a title results in a sub-section being written

  $ touch fix3
  $ hg -q commit -A -l - << EOF
  > fix with title
  > 
  > .. fix:: Fix Title
  > 
  >    First line of fix with title.
  > 
  >    Another paragraph of fix with title. But this is a paragraph
  >    with multiple lines.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-fix-with-title
  $ cat $TESTTMP/relnotes-fix-with-title
  Bug Fixes
  =========
  
  Fix Title
  ---------
  
  First line of fix with title.
  
  Another paragraph of fix with title. But this is a paragraph with multiple
  lines.

  $ cd ..

Formatting of multiple bullet points works

  $ hg init multiple-bullets
  $ cd multiple-bullets
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    first fix
  > EOF

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. fix::
  > 
  >    second fix
  > 
  >    Second paragraph of second fix.
  > EOF

  $ touch fix3
  $ hg -q commit -A -l - << EOF
  > commit 3
  > 
  > .. fix::
  > 
  >    third fix
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-multiple-bullets
  $ cat $TESTTMP/relnotes-multiple-bullets
  Bug Fixes
  =========
  
  * first fix
  
  * second fix
  
    Second paragraph of second fix.
  
  * third fix

  $ cd ..

Formatting of multiple sections works

  $ hg init multiple-sections
  $ cd multiple-sections
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    first fix
  > EOF

  $ touch feature1
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. feature::
  > 
  >    description of the new feature
  > EOF

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > commit 3
  > 
  > .. fix::
  > 
  >    second fix
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-multiple-sections
  $ cat $TESTTMP/relnotes-multiple-sections
  New Features
  ============
  
  * description of the new feature
  
  Bug Fixes
  =========
  
  * first fix
  
  * second fix

  $ cd ..

Section with subsections and bullets

  $ hg init multiple-subsections
  $ cd multiple-subsections

  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix:: Title of First Fix
  > 
  >    First paragraph of first fix.
  > 
  >    Second paragraph of first fix.
  > EOF

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. fix:: Title of Second Fix
  > 
  >    First paragraph of second fix.
  > 
  >    Second paragraph of second fix.
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-multiple-subsections
  $ cat $TESTTMP/relnotes-multiple-subsections
  Bug Fixes
  =========
  
  Title of First Fix
  ------------------
  
  First paragraph of first fix.
  
  Second paragraph of first fix.
  
  Title of Second Fix
  -------------------
  
  First paragraph of second fix.
  
  Second paragraph of second fix.

Now add bullet points to sections having sub-sections

  $ touch fix3
  $ hg -q commit -A -l - << EOF
  > commit 3
  > 
  > .. fix::
  > 
  >    Short summary of fix 3
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-multiple-subsections-with-bullets
  $ cat $TESTTMP/relnotes-multiple-subsections-with-bullets
  Bug Fixes
  =========
  
  Title of First Fix
  ------------------
  
  First paragraph of first fix.
  
  Second paragraph of first fix.
  
  Title of Second Fix
  -------------------
  
  First paragraph of second fix.
  
  Second paragraph of second fix.
  
  Other Changes
  -------------
  
  * Short summary of fix 3

  $ cd ..

Multiple 'Other Changes' sub-sections for every section

  $ hg init multiple-otherchanges
  $ cd multiple-otherchanges

  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix:: Title of First Fix
  > 
  >    First paragraph of fix 1.
  > EOF

  $ touch feature1
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. feature:: Title of First Feature
  > 
  >    First paragraph of feature 1.
  > EOF

  $ touch feature2
  $ hg -q commit -A -l - << EOF
  > commit 3
  > 
  > .. feature::
  > 
  >    Short summary of feature 2.
  > EOF

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > commit 4
  > 
  > .. fix::
  > 
  >    Short summary of fix 2
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-multiple-otherchanges
  $ cat $TESTTMP/relnotes-multiple-otherchanges
  New Features
  ============
  
  Title of First Feature
  ----------------------
  
  First paragraph of feature 1.
  
  Other Changes
  -------------
  
  * Short summary of feature 2.
  
  Bug Fixes
  =========
  
  Title of First Fix
  ------------------
  
  First paragraph of fix 1.
  
  Other Changes
  -------------
  
  * Short summary of fix 2

  $ cd ..

Using custom sections in notes

  $ hg init custom-section
  $ cd custom-section
  $ cat >> .hgreleasenotes << EOF
  > [sections]
  > testsection=Name of Section
  > EOF

  $ touch a
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. testsection::
  > 
  >    First paragraph under this admonition.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-custom-section
  $ cat $TESTTMP/relnotes-custom-section
  Name of Section
  ===============
  
  * First paragraph under this admonition.

Overriding default sections (For eg. by default feature = New Features)

  $ cat >> .hgreleasenotes << EOF
  > [sections]
  > feature=Feature Additions
  > EOF

  $ touch b
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. feature::
  > 
  >    Adds a new feature.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-override-section
  $ cat $TESTTMP/relnotes-override-section
  Feature Additions
  =================
  
  * Adds a new feature.

  $ cd ..

Testing output for the --check (-c) flag

  $ hg init check-flag
  $ cd check-flag

  $ touch a
  $ hg -q commit -A -l - << EOF
  > .. asf::
  > 
  >    First paragraph under this admonition.
  > EOF

Suggest similar admonition in place of the invalid one.

  $ hg releasenotes -r . -c
  Invalid admonition 'asf' present in changeset 4026fe9e1c20

  $ touch b
  $ hg -q commit -A -l - << EOF
  > .. fixes::
  > 
  >    First paragraph under this admonition.
  > EOF

  $ hg releasenotes -r . -c
  Invalid admonition 'fixes' present in changeset 0e7130d2705c
  (did you mean fix?)

  $ cd ..

Usage of --list flag

  $ hg init relnotes-list
  $ cd relnotes-list
  $ hg releasenotes -l
  feature: New Features
  bc: Backwards Compatibility Changes
  fix: Bug Fixes
  perf: Performance Improvements
  api: API Changes

  $ cd ..

Raise error on simultaneous usage of flags

  $ hg init relnotes-raise-error
  $ cd relnotes-raise-error
  $ hg releasenotes -r . -l
  abort: cannot use both '--list' and '--rev'
  [255]

  $ hg releasenotes -l -c
  abort: cannot use both '--list' and '--check'
  [255]

Display release notes for specified revs if no file is mentioned

  $ hg init relnotes-nofile
  $ cd relnotes-nofile

  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix:: Title of First Fix
  > 
  >    First paragraph of fix 1.
  > EOF

  $ hg releasenote -r .
  Bug Fixes
  =========
  
  Title of First Fix
  ------------------
  
  First paragraph of fix 1.