Snap packages for LDC 1.2.0
Joseph Rushton Wakeling via digitalmars-d-ldc
digitalmars-d-ldc at puremagic.com
Mon May 1 07:22:19 PDT 2017
Hello all :-)
Stable snap packages for LDC 1.2.0 have been available since
before the official 1.2.0 release announcement 1 week ago.
However, since there's more than just the availability of the
packages to announce, I thought I'd write up some notes for the
forums.
Please report any issues using the package here:
https://github.com/ldc-developers/ldc2.snap
Enjoy, and please do let me know how you get on if you try these
packages :-)
Thanks & best wishes,
-- Joe
What are snap packages?
-----------------------
Snaps are one of a number of next-gen packaging schemes that are
designed to provide secure, containerized applications in a
distro-neutral manner. A good general overview is provided on
the main project website: https://snapcraft.io/
In practice, this means that the LDC snap package provides a
reliable way to install LDC on multiple different distros.
The LDC snap package is a 'classic' snap, meaning that its
confinement rules allow access to the host system in order to
access e.g. the host compiler toolchain, and development
libraries installed using the regular host package manager. More
information on classic snaps is available here:
https://insights.ubuntu.com/2017/01/09/how-to-snap-introducing-classic-confinement/
https://snapcraft.io/docs/reference/confinement
Installing
----------
It should be possible to install snap packages on any distro with
a sufficiently up to date version of the `snapd` daemon (which
manages both installing and running these packages).
Installation instructions for different distros are available
here:
https://snapcraft.io/docs/core/install
Once snapd is installed, log off and back on again to make sure
that your PATH environment variable is set to include the
location of any installed snap applications. Then, to install
the LDC snap:
sudo snap install --classic ldc2
Alternatively, on systems not supporting `sudo`, just run the
`snap install ...` command as root.
The `--classic` flag is necessary in order to grant permission
for the classic confinement used by the snap (see above).
The `ldc2` snap package is currently available for i386 and amd64
architectures, with plans to add more supported architectures
over time.
The installed package will auto-update over time, but can be
manually updated by running:
sudo snap refresh ldc2
The snap package makes available not only the `ldc2` compiler
itself but also the DMD-alike `ldmd2` compiler interface, and the
`ldc-profdata` and `ldc-prune-cache` tools. By default these can
be run using the command `ldc2.command`, e.g. `ldc2.ldmd2`. This
namespacing helps to avoid clashes between snap commands.
However, the package also defines aliases that allow for use of
the regular commands. For example:
sudo snap alias ldc2 ldmd2
will enable the `ldmd2` alias, allowing the `ldmd2` command to be
used directly instead of `ldc2.ldmd2`. Type:
snap aliases
for a complete list of the available aliases, and which ones are
currently enabled.
The command
snap list
can be used to list all currently installed snap packages, while
snap info [name]
will give information on a specific snap package (whether
installed or not); so e.g. `snap info ldc2` will give you
information on the LDC snap package.
Running
-------
The compiler can be invoked using the normal `ldc2` and `ldmd2`
commands (although see above regarding aliases if you want to use
`ldmd2`). It uses the host system's C compiler for linking, so
on most Linux distros it will require GCC to be installed.
Tracks and channels
-------------------
The snap store allows multiple different versions of the snap
package to be made available on user demand:
https://snapcraft.io/docs/reference/channels
In brief, snap packages are distributed via channels, named
`edge`, `beta`, `candidate` and `stable`. By default packages
are installed from `stable`, but it is possible to request
installation (and updates) from one of the other channels, e.g.:
sudo snap refresh --candidate ldc2
will ensure that you have the latest version installed from the
`candidate` channel, and that updates will be installed from that
channel instead of `stable`.
In addition, the snap store also defines release _tracks_, which
are used to define long-term-support release versions. For
example, if you want to guarantee you are installing from the
1.2.x release series of LDC, you can type:
sudo snap install --classic --channel=1.2/stable ldc2
or, to switch to tracking that track and channel:
sudo snap refresh --channel=1.2/stable
New tracks will be defined for each new minor release series of
LDC: for example, a 1.3 track is already defined in preparation
for the upcoming 1.3.0 release.
Without any specific requirements, it is recommended to just
install from the `stable` channel (with no track specified), as
this will keep you up to date with the latest stable LDC
releases. However, you can use the choice of track to ensure
that you only receive updates for a given minor release series of
LDC. Alternatively, you can switch between tracks and channels
as needed, if you want to try out different versions of the
compiler.
Known issues
------------
Given the current state of `snapd` support in distros, the `ldc2`
snap package is expected to work on:
* Ubuntu 14.04, 16.04, 16.10 and 17.04 (and current development
versions)
* Debian Testing and Unstable
* OpenSUSE Leap
Link-time optimization (the `-flto=full` option) is not expected
to work on Ubuntu 14.04 or on OpenSUSE, but should work fine on
Debian and on later Ubuntu releases.
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