Update vendored ruamel.yaml to v0.17.21 (spack#37008)

* Vendor ruamel.yaml v0.17.21

* Add unit test for whitespace regression

* Add an abstraction layer in Spack to wrap ruamel.yaml

All YAML operations are routed through spack.util.spack_yaml

The custom classes have been adapted to the new ruamel.yaml
class hierarchy.

Fixed line annotation issue in "spack config blame"

Author: alalazo

lib/spack/external/__init__.py

@@ -101,10 +101,7 @@
 * Usage: Used for config files. Ruamel is based on PyYAML but is more
   actively maintained and has more features, including round-tripping
   comments read from config files.
-* Version: 0.11.15 (last version supporting Python 2.6)
-* Note: This package has been slightly modified to improve Python 2.6
-  compatibility -- some ``{}`` format strings were replaced, and the
-  import for ``OrderedDict`` was tweaked.
+* Version: 0.17.21
 
 six
 ---

lib/spack/external/_vendoring/ruamel.pyi

@@ -0,0 +1 @@
+from ruamel import *

lib/spack/external/ruamel/yaml/LICENSE renamed to lib/spack/external/_vendoring/ruamel.yaml.LICENSE

@@ -1,21 +1,21 @@
- 
  The MIT License (MIT)
 
+ Copyright (c) 2014-2022 Anthon van der Neut, Ruamel bvba
+
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
-     
+
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
- 
+
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
- THE SOFTWARE.
-
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ SOFTWARE.

lib/spack/external/_vendoring/ruamel/yaml/__init__.py

@@ -0,0 +1,57 @@
+# coding: utf-8
+
+if False:  # MYPY
+    from typing import Dict, Any  # NOQA
+
+_package_data = dict(
+    full_package_name='ruamel.yaml',
+    version_info=(0, 17, 21),
+    __version__='0.17.21',
+    version_timestamp='2022-02-12 09:49:22',
+    author='Anthon van der Neut',
+    author_email='[email protected]',
+    description='ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order',  # NOQA
+    entry_points=None,
+    since=2014,
+    extras_require={
+        ':platform_python_implementation=="CPython" and python_version<"3.11"': ['ruamel.yaml.clib>=0.2.6'],  # NOQA
+        'jinja2': ['ruamel.yaml.jinja2>=0.2'],
+        'docs': ['ryd'],
+    },
+    classifiers=[
+        'Programming Language :: Python :: 3 :: Only',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Topic :: Software Development :: Libraries :: Python Modules',
+        'Topic :: Text Processing :: Markup',
+        'Typing :: Typed',
+    ],
+    keywords='yaml 1.2 parser round-trip preserve quotes order config',
+    read_the_docs='yaml',
+    supported=[(3, 5)],  # minimum
+    tox=dict(
+        env='*f',  # f for 3.5
+        fl8excl='_test/lib',
+    ),
+    # universal=True,
+    python_requires='>=3',
+    rtfd='yaml',
+)  # type: Dict[Any, Any]
+
+
+version_info = _package_data['version_info']
+__version__ = _package_data['__version__']
+
+try:
+    from .cyaml import *  # NOQA
+
+    __with_libyaml__ = True
+except (ImportError, ValueError):  # for Jython
+    __with_libyaml__ = False
+
+from ruamel.yaml.main import *  # NOQA

lib/spack/external/_vendoring/ruamel/yaml/anchor.py

@@ -0,0 +1,20 @@
+# coding: utf-8
+if False:  # MYPY
+    from typing import Any, Dict, Optional, List, Union, Optional, Iterator  # NOQA
+
+anchor_attrib = '_yaml_anchor'
+
+
+class Anchor:
+    __slots__ = 'value', 'always_dump'
+    attrib = anchor_attrib
+
+    def __init__(self):
+        # type: () -> None
+        self.value = None
+        self.always_dump = False
+
+    def __repr__(self):
+        # type: () -> Any
+        ad = ', (always dump)' if self.always_dump else ""
+        return 'Anchor({!r}{})'.format(self.value, ad)