* Add Externally Findable section to info command
* Use comma delimited detection attributes in addition to boolean value
* Unit test externally detectable part of spack info
* Force the Python interpreter with an env variable
This commit forces the Python interpreter with an
environment variable, to ensure that the Python set
by the "setup-python" action is the one being used.
Due to the policy adopted by Spack to prefer python3
over python we may end up picking a Python 3.X
interpreter where Python 2.7 was meant to be used.
* Revert "Update conftest.py (#24473)"
This reverts commit 477c8ce820.
* Make python-dateutil a soft dependency for unit tests
Before #23212 people could clone spack and run
```
spack unit-tests
```
while now this is not possible, since python-dateutil is
a required but not vendored dependency. This change makes
it not a hard requirement, i.e. it will be used if found
in the current interpreter.
* Workaround mypy complaint
This commit fixes a subtle bug that may occur when
a package is a "possible_provider" of a virtual but
no "provides_virtual" can be deduced. In that case
the cardinality constraint on "provides_virtual"
may arbitrarily assign a package the role of provider
even if the constraints for it to be one are not fulfilled.
The fix reworks the logic around three concepts:
- "possible_provider": a package may provide a virtual if some constraints are met
- "provides_virtual": a package meet the constraints to provide a virtual
- "provider": a package selected to provide a virtual
Spack packages can now fetch versions from CVS repositories. Note
this fetch mechanism is unsafe unless using :extssh:. Most public
CVS repositories use an insecure protocol implemented as part of CVS.
Here we are adding an install_times.json into the spack install metadata folder.
We record a total, global time, along with the times for each phase. The type
of phase or install start / end is included (e.g., build or fail)
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
Add a new "spack audit" command. This command can check for issues
with configuration or with packages and is intended to help a
user debug a failed Spack build.
In some cases the reported issues are always errors but are too
costly to check for (e.g. packages that specify missing variants on
dependencies). In other cases the issues may be legitimate but
uncommon usage of Spack and we want to be sure the user intended the
behavior (e.g. duplicate compiler definitions).
Audits are grouped by theme, and for now the two themes are packages
and configuration. For example you can run all available audits
on packages with "spack audit packages". It is intended that in
the future users will be able to define their own audits.
The package audits are good candidates for running in package_sanity
(i.e. they could catch bugs in user-submitted packages before they
are merged) but that is left for a later PR.
This should get us most of the way there to support using monitor during a spack container build, for both Singularity and Docker. Some quick notes:
### Docker
Docker works by way of BUILDKIT and being able to specify --secret. What this means is that you can prefix a line with a mount of type secret as follows:
```bash
# Install the software, remove unnecessary deps
RUN --mount=type=secret,id=su --mount=type=secret,id=st cd /opt/spack-environment && spack env activate . && export SPACKMON_USER=$(cat /run/secrets/su) && export SPACKMON_TOKEN=$(cat /run/secrets/st) && spack install --monitor --fail-fast && spack gc -y
```
Where the id for one or more secrets corresponds to the file mounted at `/run/secrets/<name>`. So, for example, to build this container with su (spackmon user) and sv (spackmon token) defined I would export them on my host and do:
```bash
$ DOCKER_BUILDKIT=1 docker build --network="host" --secret id=st,env=SPACKMON_TOKEN --secret id=su,env=SPACKMON_USER -t spack/container .
```
And when we add `env` to the secret definition that tells the build to look for the secret with id "st" in the environment variable `SPACKMON_TOKEN` for example.
If the user is building locally with a local spack monitor, we also need to set the `--network` to be the host, otherwise you can't connect to it (a la isolation of course.)
## Singularity
Singularity doesn't have as nice an ability to clearly specify secrets, so (hoping this eventually gets implemented) what I'm doing now is providing the user instructions to write the credentials to a file, add it to the container to source, and remove when done.
## Tags
Note that the tags PR https://github.com/spack/spack/pull/23712 will need to be merged before `--monitor-tags` will actually work because I'm checking for the attribute (that doesn't exist yet):
```bash
"tags": getattr(args, "monitor_tags", None)
```
So when that PR is merged to update the argument group, it will work here, and I can either update the PR here to not check if the attribute is there (it will be) or open another one in the case this PR is already merged.
Finally, I added a bunch of documetation for how to use monitor with containerize. I say "mostly working" because I can't do a full test run with this new version until the container base is built with the updated spack (the request to the monitor server for an env install was missing so I had to add it here).
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
When running executables from build dependencies, we want to avoid that
`LD_PRELOAD` and `DYLD_INSERT_LIBRARIES` any of their shared libs build
by spack with system libraries.
this will first support uploads for spack monitor, and eventually could be
used for other kinds of spack uploads
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
* extending example for buildcaches
I was attempting to create a local build cache from a directory, and I found the
docs for both buildcaches and mirrors, but did not connect the docs that the
url variable could be the local filesystem variable. I am extending the docs for
buildcaches with an example of creating and interacting with one on the filesystem
because I suspect other users will run into this need and possibly not find what
they are looking for.
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
* adding as follows to spack mirror list
Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>
It is currently kind of confusing to the reader to distinguish spack buildcache install
and spack install, and it is not clear how to use a build cache once a mirror is added.
Hopefully this little big of description can help (and I hope I got it right!)
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
Use the 'version_yearlike' attribute instead of 'version' to
check if the SPACK_COMPILER_EXTRA_RPATHS should be set to include
the built-in 'libfabrics'.
When using the bare 'version', the comparison is wrong when
building with 'intel-parallel-studio', which has the version
format '<edition>.YYYY.Nupdate', due to the leading '<edition>'.
Extracting specs for the result of a solve has been factored
as a method into the asp.Result class. The method account for
virtual specs being passed as initial requests.
Minimizing compiler mismatches in the DAG and preferring newer
versions of packages are now higher priority than trying to use as
many default values as possible in multi-valued variants.
Since the module roots were removed from the config file,
`--print-shell-vars` cannot find the module roots anymore. Fix it by
using the new `root_path` function. Moreover, the roots for lmod and
modules seems to have been flipped by accident.
The VALID_VERSION regex didn't check that the version string was
completely valid, only that a prefix of it was. This version ensures
the entire string represents a valid version.
This makes a few related changes.
1. Make the SEGMENT_REGEX identify *which* arm it matches by what groups
are populated, including whether it's a string or int component or a
separator all at once.
2. Use the updated regex to parse the input once with a findall rather
than twice, once with findall and once with split, since the version
components and separators can be distinguished by their group status.
3. Rather than "convert to int, on exception stay string," if the int
group is set then convert to int, if not then construct an instance
of the VersionStrComponent class
4. VersionStrComponent now implements all of the special string
comparison logic as part of its __lt__ and __eq__ methods to deal
with infinity versions and also overloads comparison with integers.
5. Version now uses direct tuple comparison since it has no per-element
special logic outside the VersionStrComponent class.
Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>
Passing absolute paths from pipeline generate job to downstream rebuild jobs
causes problems when the CI_PROJECT_DIR is not the same for the generate and
rebuild jobs. This has happened, for example, when gitlab checks out the
project into a runner-specific directory and different runners are chosen
for the generate and rebuild jobs.
* ensure that the stage root exists for `spack stage -p <PATH>`
* add test to verify `spack stage -p <PATH>` works!
* move out shared tmp staging path setup to a fixture to fix the test
* Simplified the spack.util.gpg implementation
All the classes defined in this Python module,
which were previously used to construct singleton
instances, have been removed in favor of four
global variables. These variables are initialized
lazily, like before.
The API of the module has been unchanged for the
most part. A few tests have been modified to use
the new global names.
For me the buildcache force overwrite option does not work. It tries to
delete a file, but errors with a key error, apparently because the
leading / has to be removed.
* util.tty.log: read up to 100 lines if ready
Rework to read up to 100 lines from the captured stdin as long as data
is ready to be read immediately. Adds a helper function to poll with
`select` for ready data. This showed a roughly 5-10x perf improvement
for high-rate writes through the logger with relatively short lines.
* util.tty.log: Defer flushes to end of ready reads
Rather than flush per line, flush per set of reads. Since this is a
non-blocking loop, the total perceived wait is short.
* util.tty.log: only scan each line once, usually
Rather than always find all control characters then substitute them all,
use `subn` to count the number of control characters replaced. Only if
control characters exist find out what they are. This could be made
truly single pass with sub with a function, but it's a more intrusive
change and this got 99%ish of the performance improvement (roughly
another 2x in some cases).
* util.tty.log: remove check for `readable`
Python < 3 does not support a readable check on streams, should not be
necessary here since we control the only use and it's explicitly a
stream to be read.
This PR allows users to `--export`, `--export-secret`, or both to export GPG keys
from Spack. The docs are updated that include a warning that this usually does not
need to be done.
This addresses an issue brought up in slack, and also represented in #14721.
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
Currently, module configurations are inconsistent because modulefiles are generated with the configs for the active environment, but are shared among all environments (and spack outside any environment).
This PR fixes that by allowing Spack environments (or other spack config scopes) to define additional sets of modules to generate. Each set of modules can enable either lmod or tcl modules, and contains all of the previously available module configuration. The user defines the name of each module set -- the set configured in Spack by default is named "default", and is the one returned by module manipulation commands in the absence of user intervention.
As part of this change, the module roots configuration moved from the config section to inside each module configuration.
Additionally, it adds a feature that the modulefiles for an environment can be configured to be relative to an environment view rather than the underlying prefix. This will not be enabled by default, as it should only be enabled within an environment and for non-default views constructed with separate projections per-spec.
### Overview
The goal of this PR is to make gitlab pipeline builds (especially build failures) more reproducible outside of the pipeline environment. The two key changes here which aim to improve reproducibility are:
1. Produce a `spack.lock` during pipeline generation which is passed to child jobs via artifacts. This concretized environment is used both by generated child jobs as well as uploaded as an artifact to be used when reproducing the build locally.
2. In the `spack ci rebuild` command, if a spec needs to be rebuilt from source, do this by generating and running an `install.sh` shell script which is then also uploaded as a job artifact to be run during local reproduction.
To make it easier to take advantage of improved build reproducibility, this PR also adds a new subcommand, `spack ci reproduce-build`, which, given a url to job artifacts:
- fetches and unzips the job artifacts to a local directory
- looks for the generated pipeline yaml and parses it to find details about the job to reproduce
- attempts to provide a copy of the same version of spack used in the ci build
- if the ci build used a docker image, the command prints a `docker run` command you can run to get an interactive shell for reproducing the build
#### Some highlights
One consequence of this change will be much smaller pipeline yaml files. By encoding the concrete environment in a `spack.lock` and passing to child jobs via artifacts, we will no longer need to encode the concrete root of each spec and write it into the job variables, greatly reducing the size of the generated pipeline yaml.
Additionally `spack ci rebuild` output (stdout/stderr) is no longer internally redirected to a log file, so job output will appear directly in the gitlab job trace. With debug logging turned on, this often results in log files getting truncated because they exceed the maximum amount of log output gitlab allows. If this is a problem, you still have the option to `tee` command output to a file in the within the artifacts directory, as now each generated job exposes a `user_data` directory as an artifact, which you can fill with whatever you want in your custom job scripts.
There are some changes to be aware of in how pipelines should be set up after this PR:
#### Pipeline generation
Because the pipeline generation job now writes a `spack.lock` artifact to be consumed by generated downstream jobs, `spack ci generate` takes a new option `--artifacts-root`, inside which it creates a `concrete_env` directory to place the lockfile. This artifacts root directory is also where the `user_data` directory will live, in case you want to generate any custom artifacts. If you do not provide `--artifacts-root`, the default is for it to create a `jobs_scratch_dir` within your `CI_PROJECT_DIR` (a gitlab predefined environment variable) or whatever is your current working directory if that variable isn't set. Here's the diff of the PR testing `.gitlab-ci.yml` taking advantage of the new option:
```
$ git diff develop..pipelines-reproducible-builds share/spack/gitlab/cloud_pipelines/.gitlab-ci.yml
diff --git a/share/spack/gitlab/cloud_pipelines/.gitlab-ci.yml b/share/spack/gitlab/cloud_pipelines/.gitlab-ci.yml
index 579d7b56f3..0247803a30 100644
--- a/share/spack/gitlab/cloud_pipelines/.gitlab-ci.yml
+++ b/share/spack/gitlab/cloud_pipelines/.gitlab-ci.yml
@@ -28,10 +28,11 @@ default:
- cd share/spack/gitlab/cloud_pipelines/stacks/${SPACK_CI_STACK_NAME}
- spack env activate --without-view .
- spack ci generate --check-index-only
+ --artifacts-root "${CI_PROJECT_DIR}/jobs_scratch_dir"
--output-file "${CI_PROJECT_DIR}/jobs_scratch_dir/cloud-ci-pipeline.yml"
artifacts:
paths:
- - "${CI_PROJECT_DIR}/jobs_scratch_dir/cloud-ci-pipeline.yml"
+ - "${CI_PROJECT_DIR}/jobs_scratch_dir"
tags: ["spack", "public", "medium", "x86_64"]
interruptible: true
```
Notice how we replaced the specific pointer to the generated pipeline file with its containing folder, the same folder we passed as `--artifacts-root`. This way anything in that directory (the generated pipeline yaml, as well as the concrete environment directory containing the `spack.lock`) will be uploaded as an artifact and available to the downstream jobs.
#### Rebuild jobs
Rebuild jobs now must activate the concrete environment created by `spack ci generate` and provided via artifacts. When the pipeline is generated, a directory called `concrete_environment` is created within the artifacts root directory, and this is where the `spack.lock` file is written to be passed to the generated rebuild jobs. The artifacts root directory can be specified using the `--artifacts-root` option to `spack ci generate`, otherwise, it is assumed to be `$CI_PROJECT_DIR`. The directory containing the concrete environment files (`spack.yaml` and `spack.lock`) is then passed to generated child jobs via the `SPACK_CONCRETE_ENV_DIR` variable in the generated pipeline yaml file.
When you don't provide custom `script` sections in your `mappings` within the `gitlab-ci` section of your `spack.yaml`, the default behavior of rebuild jobs is now to change into `SPACK_CONCRETE_ENV_DIR` and activate that environment. If you do provide custom rebuild scripts in your `spack.yaml`, be aware those scripts should do the same thing: assume `SPACK_CONCRETE_ENV_DIR` contains the concretized environment to activate. No other changes to existing custom rebuild scripts should be required as a result of this PR.
As mentioned above, one key change made in this PR is the generation of the `install.sh` script by the rebuild jobs, as that same script is both run by the CI rebuild job as well as exported as an artifact to aid in subsequent attempts to reproduce the build outside of CI. The generated `install.sh` script contains only a single `spack install` command with arguments computed by `spack ci rebuild`. If the install fails, the job trace in gitlab will contain instructions on how to reproduce the build locally:
```
To reproduce this build locally, run:
spack ci reproduce-build https://gitlab.next.spack.io/api/v4/projects/7/jobs/240607/artifacts [--working-dir <dir>]
If this project does not have public pipelines, you will need to first:
export GITLAB_PRIVATE_TOKEN=<generated_token>
... then follow the printed instructions.
```
When run locally, the `spack ci reproduce-build` command shown above will download and process the job artifacts from gitlab, then print out instructions you can copy-paste to run a local reproducer of the CI job.
This PR includes a few other changes to the way pipelines work, see the documentation on pipelines for more details.
This PR erelies on
~- [ ] #23194 to be able to refer to uninstalled specs by DAG hash~
EDIT: that is going to take longer to come to fruition, so for now, we will continue to install specs represented by a concrete `spec.yaml` file on disk.
- [x] #22657 to support install a single spec already present in the active, concrete environment
- [x] add `in_buildcache` field to DB records to indicate what parts of an index,
which includes roots and dependencies, are in the buildcache.
- [x] add `mark()` method to DB for setting values on single nodes of the DAG.
I would like to be able to export (and save and then load programatically)
spack blame metadata, so this commit adds a spack blame --json argument,
along with developer docs for it
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
This work will come in two phases. The first here is to allow saving of a local result
with spack monitor, and the second will add a spack monitor command so the user can
do spack monitor upload.
Signed-off-by: vsoch <vsoch@users.noreply.github.com>
Co-authored-by: vsoch <vsoch@users.noreply.github.com>
Currently if one package does `depends_on('pkg default_library=shared')`
and another does `depends_on('pkg default_library=both')`, you'd get a
concretization error.
With this PR one package can do `depends_on('pkg default_library=shared')`
and another depends_on('default_library=static'), and it would concretize to
`pkg default_library=shared,static`
Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>
Bash has a builtin `fc` that will override the compiler if you use "fc",
so it's better to use the full spack-supplied compiler path.
Additionally, the filter regex in the docs was wrong: it replaced the
entire assignment operation with the RHS.
* Modification to R environment
This PR modifies how the R environmnet is presented, and fixes
installing the standalone Rmath library.
- The Rmath build and install methods are combined into one
- Set parallel=False when installing Rmath
- remove the run environment that set up variables for libraries and
headers that are not really needed, and pollute the environment.
* Add setup_run_environment back
- Add back the setup_run_environment with LD_LIBRARY_PATH and
PKG_CONFIG_PATH.
- Adjust documentation to reflect the current code.
Spack uses curl to fetch URL resources. For locally-stored resources
it uses curl's file protocol; when using this protocol, curl expects
that the URL encoding conforms to RFC 3986 (which reserves characters
like '?' and '=' for special use).
We were not performing this encoding, and found a resource where
curl was interpreting this in an unfavorable way (succeeding, but
producing an empty file). This commit properly encodes URLs when
using curl's file protocol.
This error did not likely come up before because in most contexts
Spack was either fetching via http or it was using URLs without
offending characters (for example, the sha-based URLs in mirrors
never contain these characters).
Spack doesn't require users to manually index their repos; it reindexes the indexes automatically when things change. To determine when to do this, it has to `stat()` all package files in each repository to make sure that indexes up to date with packages. We currently index virtual providers, patches by sha256, and tags on packages.
When this was originally implemented, we ran the checker all the time, at startup, but that was slow (see #7587). But we didn't go far enough -- it still consults the checker and does all the stat operations just to see if a package exists (`Repo.exists()`). That might've been a wash in 2018, but as the number of packages has grown, it's gotten slower -- checking 5k packages is expensive and users see this for small operations. It's a win now to make `Repo.exists()` check files directly.
**Fix:**
This PR does a number of things to speed up `spack load`, `spack info`, and other commands:
- [x] Make `Repo.exists()` check files directly again with `os.path.exists()` (this is the big one)
- [x] Refactor `Spec.satisfies()` so that a checking for virtual packages only happens if needed
(avoids some calls to exists())
- [x] Avoid calling `Repo.exists(spec)` in `Repo.get()`. `Repo.get()` will ultimately try to load
a `package.py` file anyway; we can let the failure to load it indicate that the package doesn't
exist, and avoid another call to exists().
- [x] Fix up some comments in spec parsing
- [x] Call `UnknownPackageError` more consistently in `repo.py`
- [x] `analyze` isn't commonly used; move it to long help
(`spack -H` vs `spack -h`). Give it its own section.
- [x] make it clear from `spack -h` that `spack module` can generate
module files
- [x] shorten help for `spack style`
Currently, module configurations are inconsistent because modulefiles are generated with the configs for the active environment, but are shared among all environments (and spack outside any environment).
This PR fixes that by allowing Spack environments (or other spack config scopes) to define additional sets of modules to generate. Each set of modules can enable either lmod or tcl modules, and contains all of the previously available module configuration. The user defines the name of each module set -- the set configured in Spack by default is named "default", and is the one returned by module manipulation commands in the absence of user intervention.
As part of this change, the module roots configuration moved from the `config` section to inside each module configuration.
Additionally, it adds a feature that the modulefiles for an environment can be configured to be relative to an environment view rather than the underlying prefix. This will not be enabled by default, as it should only be enabled within an environment and for non-default views constructed with separate projections per-spec.
TODO:
- [x] code changes to support multiple module sets
- [x] code changes to support modules relative to a view
- [x] Tests for multiple module configurations
- [x] Tests for modules relative to a view
- [x] Backwards compatibility for module roots from config section
- [x] Backwards compatibility for default module set without the name specified
- [x] Tests for backwards compatibility
The implementation for __str__ has been simplified to traverse the spec directly,
and doesn't call anymore the flat_dependencies method. Dead code has been
removed.
For configure (e.g. for hdf5) to pass, this option needs to be pulled out when invoked in ccld mode.
I thought it had fixed the issue but I still saw it after that. After some digging, my guess is that I was able
to get hdf5 to build with ifort instead of ifx. Lot of overlapping changes occurring at the time, as it were.
There are still outstanding issues building hdf5 with ifx, and Intel is looking into what appears to be a
compiler bug, but this manifests during build and is likely a separate issue.
I have verified that the making the edit in 'ccld' mode removes the -loopopt=0 and enables hdf5 to pass
configure. It should be fine to make the edit in 'ld' mode as well, but I have not tested that and didn't
include an -or- condition for it.
Currently, environment views blink out of existence during the view regeneration, and are slowly built back up to their new and improved state. This is not good if other processes attempt to access the view -- they can see it in an inconsistent state.
This PR fixes makes environment view updates atomic. This requires a level of indirection (via symlink, similar to nix or guix) from the view root to the underlying implementation on the filesystem.
Now, an environment view at `/path/to/foo` is a symlink to `/path/to/._foo/<hash>`, where `<hash>` is a hash of the contents of the view. We construct the view in its content-keyed hash directory, create a new symlink to this directory, and atomically replace the symlink with one to the new view.
This PR has a couple of other benefits:
* It future-proofs environment views so that we can implement rollback.
* It ensures that we don't leave users in an inconsistent state if building a new view fails for some reason.
For background:
* there is no atomic operation in posix that allows for a non-empty directory to be replaced.
* There is an atomic `renameat2` in the linux kernel starting in version 3.15, but many filesystems don't support the system call, including NFS3 and NFS4, which makes it a poor implementation choice for an HPC tool, so we use the symlink approach that others tools like nix and guix have used successfully.
fixes#22351
The ASP-based solver now accounts for the presence
in the DAG of deprecated versions and tries to minimize
their number at highest priority.
Variants explicitly set in an abstract root spec are considered
as defaults for the package they refer to, and they override
what is in packages.yaml and in package.py. This is relevant
only for multi-valued variants, where a constraint may extend
an already default value.
The code for guessing cpu archtype based on craype modules names got confused,
at least on LLNL RZ prototype systems. In particular a (L) or (D) at the end of a craype-x86-xxx or other
cpu architecture module was geting the logic confused.
With this patch, any white space + remaining characters in the moduel name are removed.
Signed-off-by: Howard Pritchard <howardp@lanl.gov>
There have been a lot of questions and some confusion recently surrounding Spack installation test capabilities so this PR is intended to clean up and refine the documentation for "Checking an installation".
It aims to better distinguish between checks that are performed during an installation (i.e., build-time tests) and those that can be done days and weeks after the software has been installed (i.e., install (or smoke) tests).
When we first merged the ASP-based solver, unit-tests
were run in a Docker container with root permissions
and that was preventing a few tests to succeed.
Since some time though, clingo is tested as a regular
user within Github Actions VMs, so we should start to
run checks again.
In an active concretize environment, support installing one or more
cli specs only if they are already present in the environment. The
`--no-add` option is the default for root specs, but optional for
dependency specs. I.e. if you `spack install <depspec>` in an
environment, the dependency-only spec `depspec` will be added as a
root of the environment before being installed. In addition,
`spack install --no-add <spec>` fails if it does not find an
unambiguous match for `spec`.
Like compilers targets now try to minimize
mismatches, instead of maximizing matches.
Deduction of mismatches is reworked to be
the opposite of a match, since computing
that is faster.
The ASP-based solver can natively manage cases where more than one root spec is given, and is able to concretize all the roots together (ensuring one spec per package at most).
Modifications:
- [x] When concretising together an environment the ASP-based solver calls directly its `solve` method rather than constructing a temporary fake root package.
The loading protocol mandates that the the module we are going
to import needs to be already in sys.modules before its code is
executed, so to prevent unbounded recursions and multiple loading.
Loading a module from file exits early if the module is already
in sys.modules
