yamllint version 1.32.0

Inspired be ESLint's search, it looks for configuration files in all
parent directories up until it reaches the user's home or root.

closes #571

.flake8

@@ -0,0 +1,4 @@
+[flake8]
+import-order-style = pep8
+application-import-names = yamllint
+ignore = W503,W504

.github/workflows/ci.yaml

@@ -21,14 +21,15 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
       - run:
-          python -m pip install flake8 flake8-import-order sphinx
-            rstcheck[sphinx] doc8
-      - run: python -m pip install .
+          pip install flake8 flake8-import-order sphinx rstcheck[sphinx] doc8
+      - run: pip install .
       - run: flake8 .
       - run: doc8 $(git ls-files '*.rst')
       - run: rstcheck --ignore-directives automodule $(git ls-files '*.rst')
       - run: yamllint --strict $(git ls-files '*.yaml' '*.yml')
-      - run: python setup.py build_sphinx
+      - run: make -C docs html
+      - name: Check for broken links in documentation
+        run: make -C docs linkcheck
 
   test:
     name: Tests
@@ -51,8 +52,10 @@ jobs:
           python-version: ${{ matrix.python-version }}
       - name: Append GitHub Actions system path
         run: echo "$HOME/.local/bin" >> $GITHUB_PATH
-      - run: pip install coveralls
+      - run: pip install coverage
       - run: pip install .
-      - run: coverage run --source=yamllint -m unittest discover
+      # https://github.com/AndreMiras/coveralls-python-action/issues/18
+      - run: echo -e "[run]\nrelative_files = True" > .coveragerc
+      - run: coverage run -m unittest discover
       - name: Coveralls
         uses: AndreMiras/coveralls-python-action@develop

CHANGELOG.rst

@@ -1,6 +1,19 @@
 Changelog
 =========
 
+1.32.0 (2023-05-22)
+-------------------
+
+- Look for configuration file in parent directories
+- Rule ``anchors``: add new option ``forbid-unused-anchors``
+
+1.31.0 (2023-04-21)
+-------------------
+
+- Build: migrate from ``setup.py`` to ``pyproject.toml``
+- Docs: update some outdated URLs
+- Rule ``colons``: prevent error when space before is mandatory
+
 1.30.0 (2023-03-22)
 -------------------
 

MANIFEST.in

@@ -1,4 +0,0 @@
-include LICENSE
-include README.rst
-include docs/*
-include tests/*.py tests/rules/*.py tests/yaml-1.2-spec-examples/*

README.rst

@@ -8,8 +8,8 @@ repetition and cosmetic problems such as lines length, trailing spaces,
 indentation, etc.
 
 .. image::
-   https://travis-ci.org/adrienverge/yamllint.svg?branch=master
-   :target: https://travis-ci.org/adrienverge/yamllint
+   https://github.com/adrienverge/yamllint/actions/workflows/ci.yaml/badge.svg?branch=master
+   :target: https://github.com/adrienverge/yamllint/actions/workflows/ci.yaml?query=branch%3Amaster
    :alt: CI tests status
 .. image::
    https://coveralls.io/repos/github/adrienverge/yamllint/badge.svg?branch=master

docs/Makefile

@@ -2,7 +2,7 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
+SPHINXOPTS    = -W
 SPHINXBUILD   = sphinx-build
 PAPER         =
 BUILDDIR      = _build

docs/configuration.rst

@@ -15,7 +15,8 @@ If ``-c`` is not provided, yamllint will look for a configuration file in the
 following locations (by order of preference):
 
 - a file named ``.yamllint``, ``.yamllint.yaml``, or ``.yamllint.yml`` in the
-  current working directory
+  current working directory, or a parent directory (the search for this file is
+  terminated at the user's home or filesystem root)
 - a filename referenced by ``$YAMLLINT_CONFIG_FILE``, if set
 - a file named ``$XDG_CONFIG_HOME/yamllint/config`` or
   ``~/.config/yamllint/config``, if present
@@ -190,8 +191,8 @@ or ignore paths only for specific rules:
 
 Note that this ``.gitignore``-style path pattern allows complex path
 exclusion/inclusion, see the `pathspec README file
-<https://pypi.python.org/pypi/pathspec>`_ for more details.
-Here is a more complex example:
+<https://pypi.org/project/pathspec/>`_ for more details. Here is a more complex
+example:
 
 .. code-block:: yaml
 

docs/index.rst

@@ -11,7 +11,7 @@ Screenshot
 
 .. note::
 
-   The default output format is inspired by `eslint <http://eslint.org/>`_, a
+   The default output format is inspired by `eslint <https://eslint.org/>`_, a
    great linting tool for Javascript.
 
 Table of contents

docs/quickstart.rst

@@ -4,7 +4,7 @@ Quickstart
 Installing yamllint
 -------------------
 
-On Fedora / CentOS (note: `EPEL <https://fedoraproject.org/wiki/EPEL>`_ is
+On Fedora / CentOS (note: `EPEL <https://docs.fedoraproject.org/en-US/epel/>`_ is
 required on CentOS):
 
 .. code:: bash
@@ -45,7 +45,7 @@ If you prefer installing from source, you can run, from the source directory:
 
 .. code:: bash
 
- python setup.py sdist
+ python -m build
  pip install --user dist/yamllint-*.tar.gz
 
 Running yamllint

docs/text_editors.rst

@@ -13,7 +13,7 @@ Assuming that the `ALE <https://github.com/dense-analysis/ale>`_ plugin is
 installed, yamllint is supported by default. It is automatically enabled when
 editing YAML files.
 
-If you instead use the `syntastic <https://github.com/scrooloose/syntastic>`_
+If you instead use the `syntastic <https://github.com/vim-syntastic/syntastic>`_
 plugin, add this to your ``.vimrc``:
 
 ::
@@ -23,7 +23,7 @@ plugin, add this to your ``.vimrc``:
 Neovim
 ------
 
-Assuming that the `neomake <https://github.com/benekastah/neomake>`_ plugin is
+Assuming that the `neomake <https://github.com/neomake/neomake>`_ plugin is
 installed, yamllint is supported by default. It is automatically enabled when
 editing YAML files.
 

pyproject.toml

@@ -0,0 +1,54 @@
+[project]
+name = "yamllint"
+description = "A linter for YAML files."
+readme = {file = "README.rst", content-type = "text/x-rst"}
+requires-python = ">=3.7"
+license = {text = "GPL-3.0-only"}
+authors = [{name = "Adrien Vergé"}]
+keywords = ["yaml", "lint", "linter", "syntax", "checker"]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "Environment :: Console",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
+    "Programming Language :: Python",
+    "Topic :: Software Development",
+    "Topic :: Software Development :: Debuggers",
+    "Topic :: Software Development :: Quality Assurance",
+    "Topic :: Software Development :: Testing",
+]
+dependencies = [
+    "pathspec >= 0.5.3",
+    "pyyaml",
+]
+dynamic = ["version"]
+
+[project.optional-dependencies]
+dev = [
+    "doc8",
+    "flake8",
+    "flake8-import-order",
+    "rstcheck[sphinx]",
+    "sphinx",
+]
+
+[project.scripts]
+yamllint = "yamllint.cli:run"
+
+[project.urls]
+homepage = "https://github.com/adrienverge/yamllint"
+repository = "https://github.com/adrienverge/yamllint"
+documentation = "https://yamllint.readthedocs.io"
+
+[build-system]
+build-backend = "setuptools.build_meta"
+requires = ["setuptools >= 61"]
+
+[tool.setuptools]
+packages = ["yamllint", "yamllint.conf", "yamllint.rules"]
+
+[tool.setuptools.package-data]
+yamllint = ["conf/*.yaml"]
+
+[tool.setuptools.dynamic]
+version = {attr = "yamllint.__version__"}

setup.cfg

@@ -1,69 +0,0 @@
-[flake8]
-import-order-style = pep8
-application-import-names = yamllint
-ignore = W503,W504
-
-[build_sphinx]
-all-files = 1
-source-dir = docs
-build-dir = docs/_build
-warning-is-error = 1
-
-[metadata]
-keywords =
-  yaml
-  lint
-  linter
-  syntax
-  checker
-
-url = https://github.com/adrienverge/yamllint
-classifiers =
-  Development Status :: 5 - Production/Stable
-  Environment :: Console
-  Intended Audience :: Developers
-  License :: OSI Approved :: GNU General Public License v3 (GPLv3)
-  Programming Language :: Python :: 3
-  Programming Language :: Python :: 3.7
-  Programming Language :: Python :: 3.8
-  Programming Language :: Python :: 3.9
-  Programming Language :: Python :: 3.10
-  Programming Language :: Python :: 3.11
-  Topic :: Software Development
-  Topic :: Software Development :: Debuggers
-  Topic :: Software Development :: Quality Assurance
-  Topic :: Software Development :: Testing
-
-project_urls =
-  Documentation = https://yamllint.readthedocs.io
-  Download = https://pypi.org/project/yamllint/#files
-  Bug Tracker = https://github.com/adrienverge/yamllint/issues
-  Source Code = https://github.com/adrienverge/yamllint
-
-[options]
-packages = find:
-
-python_requires = >=3.7
-
-include_package_data = True
-install_requires =
-  pathspec >= 0.5.3
-  pyyaml
-  setuptools
-
-test_suite = tests
-
-[options.packages.find]
-exclude =
-  tests
-  tests.*
-
-[options.package_data]
-yamllint = conf/*.yaml
-
-[options.entry_points]
-console_scripts =
-  yamllint = yamllint.cli:run
-
-[coverage:run]
-relative_files = True

setup.py

@@ -15,15 +15,6 @@
 
 from setuptools import setup
 
-from yamllint import (__author__, __license__,
-                      APP_NAME, APP_VERSION, APP_DESCRIPTION)
-
-
-setup(
-    name=APP_NAME,
-    version=APP_VERSION,
-    author=__author__,
-    description=APP_DESCRIPTION.split('\n')[0],
-    long_description=APP_DESCRIPTION,
-    license=__license__,
-)
+# This is only kept for backward-compatibility with older versions that don't
+# support new packaging standards (e.g. PEP 517 or PEP 660):
+setup()

tests/rules/test_anchors.py

@@ -46,7 +46,7 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &y 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &y 3, *x : 4, e: *y}\n'
                    '...\n', conf)
         self.check('---\n'
                    '- &i 42\n'
@@ -74,13 +74,14 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &x 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &x 3, *x : 4, e: *y}\n'
                    '...\n', conf)
 
     def test_forbid_undeclared_aliases(self):
         conf = ('anchors:\n'
                 '  forbid-undeclared-aliases: true\n'
-                '  forbid-duplicated-anchors: false\n')
+                '  forbid-duplicated-anchors: false\n'
+                '  forbid-unused-anchors: false\n')
         self.check('---\n'
                    '- &b true\n'
                    '- &i 42\n'
@@ -106,7 +107,7 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &y 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &y 3, *x : 4, e: *y}\n'
                    '...\n', conf)
         self.check('---\n'
                    '- &i 42\n'
@@ -122,6 +123,7 @@ class AnchorsTestCase(RuleTestCase):
                    '- *f_m\n'
                    '- *f_s\n'  # declared after
                    '- &f_s [1, 2]\n'
+                   '...\n'
                    '---\n'
                    'block mapping: &b_m\n'
                    '  key: value\n'
@@ -134,20 +136,21 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &x 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &x 3, *x : 4, e: *y}\n'
                    '...\n', conf,
                    problem1=(9, 3),
                    problem2=(10, 3),
                    problem3=(11, 3),
                    problem4=(12, 3),
                    problem5=(13, 3),
-                   problem6=(24, 7),
-                   problem7=(27, 36))
+                   problem6=(25, 7),
+                   problem7=(28, 37))
 
     def test_forbid_duplicated_anchors(self):
         conf = ('anchors:\n'
                 '  forbid-undeclared-aliases: false\n'
-                '  forbid-duplicated-anchors: true\n')
+                '  forbid-duplicated-anchors: true\n'
+                '  forbid-unused-anchors: false\n')
         self.check('---\n'
                    '- &b true\n'
                    '- &i 42\n'
@@ -173,7 +176,7 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &y 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &y 3, *x : 4, e: *y}\n'
                    '...\n', conf)
         self.check('---\n'
                    '- &i 42\n'
@@ -189,6 +192,7 @@ class AnchorsTestCase(RuleTestCase):
                    '- *f_m\n'
                    '- *f_s\n'  # declared after
                    '- &f_s [1, 2]\n'
+                   '...\n'
                    '---\n'
                    'block mapping: &b_m\n'
                    '  key: value\n'
@@ -201,9 +205,77 @@ class AnchorsTestCase(RuleTestCase):
                    '  <<: *b_m\n'
                    '  foo: bar\n'
                    '---\n'
-                   '{a: 1, &x b: 2, c: &x 3, *x: 4, e: *y}\n'
+                   '{a: 1, &x b: 2, c: &x 3, *x : 4, e: *y}\n'
                    '...\n', conf,
                    problem1=(5, 3),
                    problem2=(6, 3),
-                   problem3=(21, 18),
-                   problem4=(27, 20))
+                   problem3=(22, 18),
+                   problem4=(28, 20))
+
+    def test_forbid_unused_anchors(self):
+        conf = ('anchors:\n'
+                '  forbid-undeclared-aliases: false\n'
+                '  forbid-duplicated-anchors: false\n'
+                '  forbid-unused-anchors: true\n')
+
+        self.check('---\n'
+                   '- &b true\n'
+                   '- &i 42\n'
+                   '- &s hello\n'
+                   '- &f_m {k: v}\n'
+                   '- &f_s [1, 2]\n'
+                   '- *b\n'
+                   '- *i\n'
+                   '- *s\n'
+                   '- *f_m\n'
+                   '- *f_s\n'
+                   '---\n'  # redeclare anchors in a new document
+                   '- &b true\n'
+                   '- &i 42\n'
+                   '- &s hello\n'
+                   '- *b\n'
+                   '- *i\n'
+                   '- *s\n'
+                   '---\n'
+                   'block mapping: &b_m\n'
+                   '  key: value\n'
+                   'extended:\n'
+                   '  <<: *b_m\n'
+                   '  foo: bar\n'
+                   '---\n'
+                   '{a: 1, &x b: 2, c: &y 3, *x : 4, e: *y}\n'
+                   '...\n', conf)
+        self.check('---\n'
+                   '- &i 42\n'
+                   '---\n'
+                   '- &b true\n'
+                   '- &b true\n'
+                   '- &b true\n'
+                   '- &s hello\n'
+                   '- *b\n'
+                   '- *i\n'    # declared in a previous document
+                   '- *f_m\n'  # never declared
+                   '- *f_m\n'
+                   '- *f_m\n'
+                   '- *f_s\n'  # declared after
+                   '- &f_s [1, 2]\n'
+                   '...\n'
+                   '---\n'
+                   'block mapping: &b_m\n'
+                   '  key: value\n'
+                   '---\n'
+                   'block mapping 1: &b_m_bis\n'
+                   '  key: value\n'
+                   'block mapping 2: &b_m_bis\n'
+                   '  key: value\n'
+                   'extended:\n'
+                   '  <<: *b_m\n'
+                   '  foo: bar\n'
+                   '---\n'
+                   '{a: 1, &x b: 2, c: &x 3, *x : 4, e: *y}\n'
+                   '...\n', conf,
+                   problem1=(2, 3),
+                   problem2=(7, 3),
+                   problem3=(14, 3),
+                   problem4=(17, 16),
+                   problem5=(22, 18))

tests/rules/test_colons.py

@@ -256,3 +256,19 @@ class ColonTestCase(RuleTestCase):
                    '  property: {a: 1, b:  2, c : 3}\n', conf,
                    problem1=(3, 11), problem2=(4, 4),
                    problem3=(8, 23), problem4=(8, 28))
+
+    # Although accepted by PyYAML, `{*x: 4}` is not valid YAML: it should be
+    # noted `{*x : 4}`. The reason is that a colon can be part of an anchor
+    # name. See commit message for more details.
+    def test_with_alias_as_key(self):
+        conf = 'colons: {max-spaces-before: 0, max-spaces-after: 1}'
+        self.check('---\n'
+                   '- anchor: &a key\n'
+                   '- *a: 42\n'
+                   '- {*a: 42}\n'
+                   '- *a : 42\n'
+                   '- {*a : 42}\n'
+                   '- *a  : 42\n'
+                   '- {*a  : 42}\n',
+                   conf,
+                   problem1=(7, 6), problem2=(8, 7))

tests/test_cli.py

@@ -734,3 +734,64 @@ class CommandLineConfigTestCase(unittest.TestCase):
 
                 self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
                                  (0, '', ''))
+
+    def test_parent_config_file(self):
+        workspace = {'a/b/c/d/e/f/g/a.yml': 'hello: world\n'}
+        conf = ('---\n'
+                'extends: relaxed\n')
+
+        for conf_file in ('.yamllint', '.yamllint.yml', '.yamllint.yaml'):
+            with self.subTest(conf_file):
+                with temp_workspace(workspace):
+                    with RunContext(self) as ctx:
+                        os.chdir('a/b/c/d/e/f')
+                        cli.run(('-f', 'parsable', '.'))
+
+                self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                                 (0, './g/a.yml:1:1: [warning] missing '
+                                     'document start "---" (document-start)\n',
+                                     ''))
+
+                with temp_workspace({**workspace, **{conf_file: conf}}):
+                    with RunContext(self) as ctx:
+                        os.chdir('a/b/c/d/e/f')
+                        cli.run(('-f', 'parsable', '.'))
+
+                self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                                 (0, '', ''))
+
+    def test_multiple_parent_config_file(self):
+        workspace = {'a/b/c/3spaces.yml': 'array:\n'
+                                          '   - item\n',
+                     'a/b/c/4spaces.yml': 'array:\n'
+                                          '    - item\n',
+                     'a/.yamllint': '---\n'
+                                    'extends: relaxed\n'
+                                    'rules:\n'
+                                    '  indentation:\n'
+                                    '    spaces: 4\n',
+                     }
+
+        conf3 = ('---\n'
+                 'extends: relaxed\n'
+                 'rules:\n'
+                 '  indentation:\n'
+                 '    spaces: 3\n')
+
+        with temp_workspace(workspace):
+            with RunContext(self) as ctx:
+                os.chdir('a/b/c')
+                cli.run(('-f', 'parsable', '.'))
+
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                         (0, './3spaces.yml:2:4: [warning] wrong indentation: '
+                         'expected 4 but found 3 (indentation)\n', ''))
+
+        with temp_workspace({**workspace, **{'a/b/.yamllint.yml': conf3}}):
+            with RunContext(self) as ctx:
+                os.chdir('a/b/c')
+                cli.run(('-f', 'parsable', '.'))
+
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                         (0, './4spaces.yml:2:5: [warning] wrong indentation: '
+                         'expected 3 but found 4 (indentation)\n', ''))

yamllint/__init__.py

@@ -21,7 +21,7 @@ indentation, etc."""
 
 
 APP_NAME = 'yamllint'
-APP_VERSION = '1.30.0'
+APP_VERSION = '1.32.0'
 APP_DESCRIPTION = __doc__
 
 __author__ = 'Adrien Vergé'

yamllint/cli.py

@@ -141,6 +141,19 @@ def show_problems(problems, file, args_format, no_warn):
     return max_level
 
 
+def find_project_config_filepath(path='.'):
+    for filename in ('.yamllint', '.yamllint.yaml', '.yamllint.yml'):
+        filepath = os.path.join(path, filename)
+        if os.path.isfile(filepath):
+            return filepath
+
+    if os.path.abspath(path) == os.path.abspath(os.path.expanduser('~')):
+        return None
+    if os.path.abspath(path) == os.path.abspath(os.path.join(path, '..')):
+        return None
+    return find_project_config_filepath(path=os.path.join(path, '..'))
+
+
 def run(argv=None):
     parser = argparse.ArgumentParser(prog=APP_NAME,
                                      description=APP_DESCRIPTION)
@@ -185,6 +198,7 @@ def run(argv=None):
     else:
         user_global_config = os.path.expanduser('~/.config/yamllint/config')
 
+    project_config_filepath = find_project_config_filepath()
     try:
         if args.config_data is not None:
             if args.config_data != '' and ':' not in args.config_data:
@@ -192,12 +206,8 @@ def run(argv=None):
             conf = YamlLintConfig(content=args.config_data)
         elif args.config_file is not None:
             conf = YamlLintConfig(file=args.config_file)
-        elif os.path.isfile('.yamllint'):
-            conf = YamlLintConfig(file='.yamllint')
-        elif os.path.isfile('.yamllint.yaml'):
-            conf = YamlLintConfig(file='.yamllint.yaml')
-        elif os.path.isfile('.yamllint.yml'):
-            conf = YamlLintConfig(file='.yamllint.yml')
+        elif project_config_filepath:
+            conf = YamlLintConfig(file=project_config_filepath)
         elif os.path.isfile(user_global_config):
             conf = YamlLintConfig(file=user_global_config)
         else:

yamllint/rules/anchors.py

@@ -24,6 +24,8 @@ anchors.
   later in the document).
 * Set ``forbid-duplicated-anchors`` to ``true`` to avoid duplications of a same
   anchor.
+* Set ``forbid-unused-anchors`` to ``true`` to avoid anchors being declared but
+  not used anywhere in the YAML document via alias.
 
 .. rubric:: Default values (when enabled)
 
@@ -33,6 +35,7 @@ anchors.
    anchors:
      forbid-undeclared-aliases: true
      forbid-duplicated-anchors: false
+     forbid-unused-anchors: false
 
 .. rubric:: Examples
 
@@ -78,6 +81,26 @@ anchors.
     ---
     - &anchor Foo Bar
     - &anchor [item 1, item 2]
+
+#. With ``anchors: {forbid-unused-anchors: true}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    ---
+    - &anchor
+      foo: bar
+    - *anchor
+
+   the following code snippet would **FAIL**:
+   ::
+
+    ---
+    - &anchor
+      foo: bar
+    - items:
+      - item1
+      - item2
 """
 
 
@@ -89,15 +112,22 @@ from yamllint.linter import LintProblem
 ID = 'anchors'
 TYPE = 'token'
 CONF = {'forbid-undeclared-aliases': bool,
-        'forbid-duplicated-anchors': bool}
+        'forbid-duplicated-anchors': bool,
+        'forbid-unused-anchors': bool}
 DEFAULT = {'forbid-undeclared-aliases': True,
-           'forbid-duplicated-anchors': False}
+           'forbid-duplicated-anchors': False,
+           'forbid-unused-anchors': False}
 
 
 def check(conf, token, prev, next, nextnext, context):
-    if conf['forbid-undeclared-aliases'] or conf['forbid-duplicated-anchors']:
-        if isinstance(token, (yaml.StreamStartToken, yaml.DocumentStartToken)):
-            context['anchors'] = set()
+    if (conf['forbid-undeclared-aliases'] or
+            conf['forbid-duplicated-anchors'] or
+            conf['forbid-unused-anchors']):
+        if isinstance(token, (
+                yaml.StreamStartToken,
+                yaml.DocumentStartToken,
+                yaml.DocumentEndToken)):
+            context['anchors'] = {}
 
     if (conf['forbid-undeclared-aliases'] and
             isinstance(token, yaml.AliasToken) and
@@ -113,6 +143,32 @@ def check(conf, token, prev, next, nextnext, context):
             token.start_mark.line + 1, token.start_mark.column + 1,
             f'found duplicated anchor "{token.value}"')
 
-    if conf['forbid-undeclared-aliases'] or conf['forbid-duplicated-anchors']:
+    if conf['forbid-unused-anchors']:
+        # Unused anchors can only be detected at the end of Document.
+        # End of document can be either
+        #   - end of stream
+        #   - end of document sign '...'
+        #   - start of a new document sign '---'
+        # If next token indicates end of document,
+        # check if the anchors have been used or not.
+        # If they haven't been used, report problem on those anchors.
+        if isinstance(next, (yaml.StreamEndToken,
+                             yaml.DocumentStartToken,
+                             yaml.DocumentEndToken)):
+            for anchor, info in context['anchors'].items():
+                if not info['used']:
+                    yield LintProblem(info['line'] + 1,
+                                      info['column'] + 1,
+                                      f'found unused anchor "{anchor}"')
+        elif isinstance(token, yaml.AliasToken):
+            context['anchors'].get(token.value, {})['used'] = True
+
+    if (conf['forbid-undeclared-aliases'] or
+            conf['forbid-duplicated-anchors'] or
+            conf['forbid-unused-anchors']):
         if isinstance(token, yaml.AnchorToken):
-            context['anchors'].add(token.value)
+            context['anchors'][token.value] = {
+                'line': token.start_mark.line,
+                'column': token.start_mark.column,
+                'used': False
+            }

yamllint/rules/colons.py

@@ -92,7 +92,9 @@ DEFAULT = {'max-spaces-before': 0,
 
 
 def check(conf, token, prev, next, nextnext, context):
-    if isinstance(token, yaml.ValueToken):
+    if isinstance(token, yaml.ValueToken) and not (
+            isinstance(prev, yaml.AliasToken) and
+            token.start_mark.pointer - prev.end_mark.pointer == 1):
         problem = spaces_before(token, prev, next,
                                 max=conf['max-spaces-before'],
                                 max_desc='too many spaces before colon')

yamllint/rules/new_line_at_end_of_file.py

@@ -17,7 +17,7 @@
 Use this rule to require a new line character (``\\n``) at the end of files.
 
 The POSIX standard `requires the last line to end with a new line character
-<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206>`_.
+<https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206>`_.
 All UNIX tools expect a new line at the end of files. Most text editors use
 this convention too.
 """