conan-io / hooks

Official Conan client hooks

Conan Hooks

Repository to develop experimental Conan hooks for Conan >= 1.8.

• Conan Center
• Attribute checker
• Binary linter
• Github updater
• Member typo checker
• SPDX checker
• Recipe linter
• Non ASCII
• YAML linter
• Reduce conandata.yml

Hook setup

Place your hook Python files under ~/.conan/hooks. The name of the hook would be the same one as the file name.

*~/.conan/hooks/conan-center.py

Only copying hook files will not activate them.

Conan config as installer

To install all hooks from Conan repository in Github:

$ conan config install https://github.com/conan-io/hooks.git

If you are using Conan >=1.14 you can specify the source and destination folder to avoid copying undesired files to your local cache:

$ conan config install https://github.com/conan-io/hooks.git -sf hooks -tf hooks

Conan config install does not activate any hook.

Hook activation

You can activate any hook with:

$ conan config set hooks.conan-center

If you handle multiple dependencies in your project is better to add a conan.conf:

    [hooks]
    attribute_checker
    conan-center_reviewer

Hooks

These are the hooks currently available in this repository

Conan Center

This hook does checks for the inclusion guidelines of third-party libraries in Conan Center.

It is mostly intended for users who want to contribute packages to Conan Center. With this hook they will test some of the requirements in the guidelines, as this hook will check for recipe metadata, binary matching... during the conan create step and will output the result of each check as OK, WARNING or ERROR:

[HOOK - conan-center_reviewer.py] pre_export(): [RECIPE METADATA] OK
[HOOK - conan-center_reviewer.py] pre_export(): [HEADER ONLY] OK
[HOOK - conan-center_reviewer.py] pre_export(): [NO COPY SOURCE] OK
[HOOK - conan-center_reviewer.py] pre_export(): [FPIC OPTION] OK
[HOOK - conan-center_reviewer.py] pre_export(): [FPIC MANAGEMENT] 'fPIC' option not found
[HOOK - conan-center_reviewer.py] pre_export(): [VERSION RANGES] OK
[HOOK - conan-center_reviewer.py] post_package(): ERROR: [PACKAGE LICENSE] No package licenses found in: ~/
.conan/data/name/version/jgsogo/test/package/3475bd55b91ae904ac96fde0f106a136ab951a5e. Please
 package the library license to a 'licenses' folder
[HOOK - conan-center_reviewer.py] post_package(): [DEFAULT PACKAGE LAYOUT] OK
[HOOK - conan-center_reviewer.py] post_package(): [MATCHING CONFIGURATION] OK
[HOOK - conan-center_reviewer.py] post_package(): [SHARED ARTIFACTS] OK

If you want the hook to fail the execution, if an error is reported, you can adjust the environment variable CONAN_HOOK_ERROR_LEVEL:

• CONAN_HOOK_ERROR_LEVEL=40 it will raise if any error happen.
• CONAN_HOOK_ERROR_LEVEL=30 it will raise if any error or warning happen.

Conan 2.x support

The Conan Center hook is NOT supported by Conan v2 yet. Do not try to run this file with Conan v2.

There is an effort on the disabled-hook_conan-center-v2.py, but is not updated and should be broken by now.

The support for Conan 2.x should be rethinked first, because others items like linter and extensions should be considered too.

Attribute checker

This hook checks that some important attributes are present in the ConanFile: url, license and description, and will output a warning for the missing ones.

Binary Linter

This Conan hook validates produced binary artifacts of the given package.

Binaries stored in the package folder are checked for compatibility with package settings and options.

Currently, the following checks are performed:

• Binary format (Mach-O, ELF or PE)
• Architecture
• No shared libraries are produced for shared=False
• Visual Studio runtime library in use

The hook uses LIEF library in order to perform its checks.

The hook is automatically called when package command is executed.

GitHub Updater

This Conan hook reads your recipe and updates its GitHub repository properties using the attributes.

The following attributes are updated:

• homepage

• description

• topics

It's necessary to pass GitHub token by environment variable: GITHUB_TOKEN.

Members Typo checker

This pre_export() hook checks ConanFile's members for potential typos, for example:

from conans import ConanFile

class ConanRecipe(ConanFile):
    name = "name"
    version = "version"

    export_sources = "OH_NO"

Will produce the next warning:

pre_export(): WARN: The 'export_sources' member looks like a typo. Similar to:
pre_export(): WARN:     exports_sources

SPDX checker

This Conan hook validates that conanfile's license attribute specifies valid license identifier(s) from the SPDX license list.

The hook uses spdx_lookup python module in order to perform its checks.

Use pip install spdx_lookup in order to install required dependency.

The hook is automatically called when export command is executed.

Recipe linter

This hook runs Pylint over the recipes before exporting them (it runs in the pre_export hook), it can be really useful to check for typos, code flaws or company standards.

There several environment variables you can use to configure it:

• CONAN_PYLINTRC: path to a configuration file to fully customize Pylint behavior.
• CONAN_PYLINT_WERR: if set, linting errors will trigger a ConanException.
• CONAN_PYLINT_RECIPE_PLUGINS: list of modules (comma separated list) to load. They are used to register additional checker or dynamic fields before running the linter. By default it points to the conans.pylint_plugin module distributed together with Conan, this file contains the declaration of some extra fields that are valid in the ConanFile class.

This hook requires additional dependencies to work: pip install pylint astroid.

Non ASCII

Separate KB-H047 from Conan Center, which is no longer required due Python 2.7 deprecation.

Validates if conanfile.py and test_package/conanfile.py contain a non-ascii present, when there is a character, it logs an error.

YAML linter

This hook runs yamllint over the yaml files in a recipe before exporting them (it runs in the pre_export hook), it can be really useful to check for typos.

This hook requires additional dependencies to work: pip install yamllint.

Reduce conandata.yml

Same as KB-H031, but for conan 2.0. Reduces conandata.yml files, keeping only entry for the current package version. It only helps to avoid generation of extra recipe revisions in case of adding new versions.

License

MIT License

hooks's Issues

[suggestion] Move the check for mixed settings into hooks

conan-io/conan#4602

There is no need to scare consumers of the recipe by these warnings.

[conan center] check URL points to the https://github.com/conan-io/conan-center-index

check that URL attribute of conanfile.py points to the https://github.com/conan-io/conan-center-index (not to the bincrafters or conan-community, for instance)

How to test plugins?

Hi!

It would be nice add some tests for new plugins but using conan config to install, all tests will be copied also.

Is there some way to ignore those files using conan config install ?

Credentials of bintray plugin env vars

About these variables:

CONAN_LOGIN_USERNAME: Bintray login username
CONAN_PASSWORD: Bintray API KEY

I know that these variables are used in CPT, but even these I would like to rename them.
I think would make more sense to name them as "BINTRAY_XXX" even check if there are some "standard" variables maybe in the jfrog cli?

SPDX license check hook

hook to verify license attribute of conanfile matches SPDX identifier
from:
conan-io/conan#3498
conan-io/conan#2342

/cc @liberforce @weatherhead99

Hook to test conans.tools import

We should check that tools are imported conans. Related to: https://github.com/conan-community/community/issues/116 and conan-io/conan#4068

make hook from readme generator

it would be nice to automatically update README to synchronize it with conanfile, so README always points to the correct name, version, description, etc.
could be made from: https://github.com/bincrafters/conan-readme-generator

[bintray-update] Wont work with conan_server

Hi!

When running conan_server, the hooks bintray-update shown:

[HOOK - bintray_update.py] post_upload_recipe(): ERROR: Could not extract subject and repo from http://0.0.0.0:9300: Invalid pattern

We need to check before to extract the information if the endpoint is Bintray.

[Conan Center] fPIC pre-export check is weak

Coming from conan-io/conan-center-index#123 (comment) cc/ @ericLemanissier

In conan-io/conan-center-index#82, the PR passed without the conan center hook erroring on fPIC not managed correctly (KB-H007).

I suspect this was because the hook checks literally for "fpic" and the recipe has 'fpic' as showed here:

hooks/hooks/conan-center.py

Line 150 in cb81c49

if '"fpic"' in low:

This check should be improved.

[bug] Conan Center hook is not able to deal with shell script recipe

conan-io/conan-center-index#156 (comment)

[github-updater] Increase output information

The github-updater hook works silently and in my case it only outputs:

[HOOK - conanio/hooks/github-updater.py] pre_export(): no topics to update

I don't know if it is done on purpose, but it should say what this it is updating in github.

[conan center] check homepage attribute is specified

binary sign hook

add hook to sign conan libraries
should invoke signtool for Windows/WindowsStore, and codesign for Macos/iOS/watchOS/tvOS.
probably, should be no-op for other platforms (like Linux).
some environment variables should specify path to the sign keys.

[binary linter] verify OSX/iOS minimal version

[conan center] check recipe doesn't export LICENSE.md / LICENSE

check that recipe doesn't export the LICENSE.md (or just LICENSE) file
the following shouldn't be in conanfile.py:

export = ["LICENSE.md"]

Handle configurations of hooks

As soon as hooks start to proliferate there will be more and more environment variables to configure them, I think we should consider that risk and think about alternatives, there could be a better approach. It is time for brainstorming:

• Do nothing, hooks will start to introduce env variables (there are already some of them), I think it could be a mess in the long term

• Use a json file to handle the configuration of all the hooks (shareable with a conan config install), the HookManager could pass those variables in every function call:

  hooks_config.json

  {
      "hook_name_1": {
          "key1": "value",
          "key2": "value"
      },
      "hook_name_2": {
          "...": "..."
      }
  }

  hooks/hook_name_1.py

  ...
  def pre_export(..., config):
      assert config == {"key1": "value", "key2": "value"}
      ...
  
  def post_package(..., config):
      ...

• add them to conan.conf file inside the cache

• ...more ideas?

[conan-center_reviewer] Should we consider fPIC for installer and header-only?

Hi!

Question about the hook conan-center_reviewer. It checks the fPIC, but some recipes does not have options, like installers and header-only. Maybe we could skip fPIC check (including log) if there is no option attribute computed.

Regards!

[conan center] check that test_package uses run_environment instead of RunEnvironment

check that test_package/conanfile.py uses run_environment=True instead of RunEnvironment helper

Document 'export_metadata' hook

There is no mention to it in the README.

[binary-linter] Reduce verbosity of output

Outputing 2 lines for every file in package folder is too much for a reasonable output:

[HOOK - conanio/hooks/binary-linter.py] post_package(): conan binary linter plug-in
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\conaninfo.txt" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\conanmanifest.txt" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): checking file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr110.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr110d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr100.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr100d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr130.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr130d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr120.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr120d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" imports library "vcruntime140.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "vcruntime140d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" imports library "vcruntime140.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "vcruntime140d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr90.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr90d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr80.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msvcr80d.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "cygwin1.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msys-1.0.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\bin\docopt.dll" doesn't import library "msys-2.0.dll"
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\include\docopt.h" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\include\docopt_util.h" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\include\docopt_value.h" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\lib\docopt.lib" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\licenses\LICENSE-Boost-1.0" is not a executable, skipping...
[HOOK - conanio/hooks/binary-linter.py] post_package(): file "C:\Users\danimtb\.conan\data\docopt\0.6.2\danitmb\testing\package\970e773c5651dc2560f86200a4ea56c23f568ff9\licenses\LICENSE-MIT" is not a executable, skipping...

All those is not a executable, skipping... could be omitted

[conan-center hook] Add .cc to the list of C++ extensions

@uilianries said in #45:

could you please add ".cc". It's the Google's C++ extension. Also, ".c++" is a valid extension, according CMake.

[suggestion] A hook to check for Recipe's typos

Hi, friends.
Moved from conan-io/conan#5747

Users do typos from time to time, especially with exports_sources. Would be cool to catch that.

[conan center] check there is topics attribute

[bintray-update] Map SPDX licenses

Hi!

There is a lack between Bintray and SPDX licenses, where Bintray only supports a limited number of licenses, but any Conan recipe could have one or multiple licenses, following the SPDX format.

This feature intents to map SPDX licenses to Bintray format, fixing possible lacks.
For example:

SPDX GPL-2.0-or-later -> Bintray GPL-2.0

Regards!

[binary linter] verify shared library exports

conan-center hook fails on symlinks

ERROR: [HOOK - conan-center.py] pre_export(): [Errno 62] Too many levels of symbolic links: '/Users/sse4/bincrafters/test-symlinks/test'
Traceback (most recent call last):
  File "/Users/sse4/bincrafters/conan/conans/client/hook_manager.py", line 58, in execute
    method(output=output, **kwargs)
  File "/Users/sse4/.conan/hooks/conan-center.py", line 58, in wrapper
    ret = func(output, *args, **kwargs)
  File "/Users/sse4/.conan/hooks/conan-center.py", line 142, in pre_export
    @run_test("RECIPE FOLDER SIZE", output)
  File "/Users/sse4/.conan/hooks/conan-center.py", line 67, in tmp
    ret = func(out)
  File "/Users/sse4/.conan/hooks/conan-center.py", line 151, in test
    total_size += os.path.getsize(file_path)
  File "/usr/local/Cellar/python@2/2.7.16/Frameworks/Python.framework/Versions/2.7/lib/python2.7/genericpath.py", line 57, in getsize
    return os.stat(filename).st_size
OSError: [Errno 62] Too many levels of symbolic links: '/Users/sse4/bincrafters/test-symlinks/test'

repro:

mkdir test-symlinks
cd test-symlinks
conan new test/1.0@user/testing
ln -s test test
conan create . user/testing

Create a post package hooks that checks for external "broken" links

Checks for link files that point to files outside of the package folder

Link to original issue: conan-io/conan#4147

Documentation about hooks

It may be too early in the process for this, but in artifactory plugins, we've given each plugin its own directory so that its test and readme functions can be clearly defined on an individual plugin-by-plugin basis. This allows us to test one plugin at a time etc.
Also this mandates an individual readme per plugin which tries to summarize what each plugin does, so a user can decide whether or not they want an individual plugin. Given how early we are in building plugins, that may be premature. On the other hand, having been responsible for the effort of creating those readmes a few years later in a repository without that documentation, it is definitely easier for everyone to do it up-front, so I figured I'd mention it now.

[conan center] check for self.settings.compiler.cppstd

setting self.settings.compiler.cppstd should be removed, same check as self.settings.compiler.libcxx

[conan center] check there is no imports in test_package/conanfile.py

seems like imports method is not needed in test_package/conanfile.py, if we use run_environment?

[binary linter] verify Android API level

[conan center] check meta lines

check the following meta lines are not in conanfile.py and test_package/conanfile.py:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

• shebang
• vim
• coding header

clarify requirements

this topic actually has multiple questions to clarify

• can plug-in depend on other python libraries (e.g. lief, requests)? if so, how to specify them (e.g. requirements.txt)?
• can plug-in have build_requirements? (e.g. if it depend on external tool like git, ninja or whatever)
• can plug-in have system_requirements? (as above, to install system tools, like git)
• can plug-in have python_requirements? (to share code between plug-ins)
• can plug-in have requirements?

UPDATE: it turns out, hooks cannot use any of conan dependencies, like requirements, system_requirements, python_requirements or build_requerements, as they invoke conan methods, which has to be hooked, and it goes into infinite vicious circle.
moreover, hooks should be very careful choosing which conan API to use, in order to avoid such infinite recursion.

/cc @solvingj @Croydon @uilianries @lasote @memsharded @danimtb @jgsogo

[conan-center hook] Include check about recipe license being exported

There is check about package license but no one for the recipe license that should be exported with the conanfile.py

[conan center] check CMakeLists.txt file starts with cmake_minimum_required

if there is CMakeLists.txt file near to the conanfile.py, it should start from the cmake_minimum_required at very beginning
same for test_package/CMakeLists.txt (if exists)

[binary linter] verify debug information available for Debug and RelWithDebInfo

Create tests for Bintray plugin

Related issue: #2

Use same approach from #17 to design the tests.

[binary linter] verify ELF ABI

Should we rename hooks?

When I started the conan-center hook I thought it would make sense to call it the same way as the remote conan-center.

Having a look at the existing hooks I would like to have the naming "somehow" unified.

This is my proposal:

• binary-linter.py --> binary_linter.py
• bintray_update.py --> bintray_updater.py
• github-updater.py --> github_updater.py

Should we rename conan-center.py to something like conan-center_reviewer.py or conan-center_checker.py ?

cc/ @conan-io/community-leaders

Centrally installed hooks vs. build reproducibility

Continuing discussion from #21 (comment)

In my opinion, hooks, as they are currently, should be akin to git hooks: not necessary for functioning, but allow complementing functionality. They should never affect the resulting build.

If I relied on a hook for capturing some build-time information in my package (as suggested on Slack, see my earlier comment, I would need a specific hook installed to be able to reproduce that package. And that requirement is not apparent from the conanfile (nor is it enforced by conan). My recipe is no longer portable, I need to take specific steps (installing a hook) before I can rebuild it.

Furthermore, it seems to me that once a hook is installed it affects all builds? (I might be wrong about this). This would make it impossible to perform functionality on just a couple of recipes.

I would propose a different, simpler model, based on function overrides. So hook functions like pre_export, post_export etc. would be simply member functions in Conanfile. That would make using the hooks very visible and environment-independent (if I clone the repo on a different machine, I don't need to perform additional hidden steps, it's there in the conanfile). This model also allows global overrides, by relying on python_requires and an intermediary base class:

class MyConanfile(Conanfile):
  def post_source(self):
    print("I'm in all recipes derived from MyConanfile")

Again, this preserves the build reproducibility.

[conan center] check there is no version if all is used

if recipe is in all directory, it shouldn't specify any version

Tox should run the latest Conan version

Instead of keep updating manually, we could define "latest":

https://github.com/conan-io/conan-package-tools/blob/develop/tox.ini#L5

Add Appveyor CI

We need to run tests against Conan versions in Windows too.

[binary linter] verify fPIC

[binary linter] verify standard library used (libc++ vs libstdc++)

[conan-center] Validate conandata.yml keys and fail if unknown

• For the conan-center one
• Validate the structure failing if unknown one:
  • "sources" (already documented)
  • "paches" (look latest proposal conan-io/conan-center-index#90)

[conan-center] settings.os should not be mandatory

Hi!

When building an installer package (bincrafters/pkg-config_installer), only the settings os_build and arch_build are available. However, the hook conan-center requires settings.os as well:

ERROR: [HOOK - conan-center.py] post_build(): 'settings.os' doesn't exist
'settings' possible configurations are ['arch_build', 'compiler', 'os_build']
Traceback (most recent call last):
  File "/opt/python/pyenv/versions/3.6.0/lib/python3.6/site-packages/conans/client/hook_manager.py", line 56, in execute
    method(output, **kwargs)
  File "/home/uilian/.conan/hooks/conan-center.py", line 121, in post_build
    if not _files_match_settings(conanfile, conanfile.build_folder):
  File "/home/uilian/.conan/hooks/conan-center.py", line 209, in _files_match_settings
    os = _get_os(conanfile)
  File "/home/uilian/.conan/hooks/conan-center.py", line 243, in _get_os
    if hasattr(conanfile.settings, attrib):
  File "/opt/python/pyenv/versions/3.6.0/lib/python3.6/site-packages/conans/model/settings.py", line 257, in __getattr__
    self._check_field(field)
  File "/opt/python/pyenv/versions/3.6.0/lib/python3.6/site-packages/conans/model/settings.py", line 253, in _check_field
    raise undefined_field(self._name, field, self.fields, self._parent_value)
conans.errors.ConanException: 'settings.os' doesn't exist
'settings' possible configurations are ['arch_build', 'compiler', 'os_build']

We should check if os or os_build are available.

Regards!

[conan center] check there is no author attribute

[conan center] check there is no system_requirements

I think we have previously agreed to disallow system_requirements in conan-center-index
so, it would be nice to check in hook there are no system_requirements methods
all exceptions will be white-listed in hook I guess

[binary linter] verify endianess