Replace number stringification hack with custom YAML loader (#4183)

* Custom yaml Loader

Instead of monkeypatching the yaml Loader in an attempt to avoid parsing numbers make a custom Loader where the float/int tags are entirely removed.

* Test that all int/floats are parsed as str

conda_build/metadata.py

@@ -2,7 +2,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 from __future__ import annotations
 
-import contextlib
 import copy
 import hashlib
 import json
@@ -41,9 +40,37 @@
     )
 
 try:
-    loader = yaml.CLoader
-except:
-    loader = yaml.Loader
+    Loader = yaml.CLoader
+except AttributeError:
+    Loader = yaml.Loader
+
+
+class StringifyNumbersLoader(Loader):
+    @classmethod
+    def remove_implicit_resolver(cls, tag):
+        if "yaml_implicit_resolvers" not in cls.__dict__:
+            cls.yaml_implicit_resolvers = {
+                k: v[:] for k, v in cls.yaml_implicit_resolvers.items()
+            }
+        for ch in tuple(cls.yaml_implicit_resolvers):
+            resolvers = [(t, r) for t, r in cls.yaml_implicit_resolvers[ch] if t != tag]
+            if resolvers:
+                cls.yaml_implicit_resolvers[ch] = resolvers
+            else:
+                del cls.yaml_implicit_resolvers[ch]
+
+    @classmethod
+    def remove_constructor(cls, tag):
+        if "yaml_constructors" not in cls.__dict__:
+            cls.yaml_constructors = cls.yaml_constructors.copy()
+        if tag in cls.yaml_constructors:
+            del cls.yaml_constructors[tag]
+
+
+StringifyNumbersLoader.remove_implicit_resolver("tag:yaml.org,2002:float")
+StringifyNumbersLoader.remove_implicit_resolver("tag:yaml.org,2002:int")
+StringifyNumbersLoader.remove_constructor("tag:yaml.org,2002:float")
+StringifyNumbersLoader.remove_constructor("tag:yaml.org,2002:int")
 
 on_win = sys.platform == "win32"
 
@@ -261,9 +288,7 @@ def select_lines(data, namespace, variants_in_place):
 
 def yamlize(data):
     try:
-        with stringify_numbers():
-            loaded_data = yaml.load(data, Loader=loader)
-        return loaded_data
+        return yaml.load(data, Loader=StringifyNumbersLoader)
     except yaml.error.YAMLError as e:
         if "{{" in data:
             try:
@@ -1056,23 +1081,7 @@ def _hash_dependencies(hashing_dependencies, hash_length):
     return f"h{hash_.hexdigest()}"[: hash_length + 1]
 
 
-@contextlib.contextmanager
-def stringify_numbers():
-    # ensure that numbers are not interpreted as ints or floats.  That trips up versions
-    #     with trailing zeros.
-    implicit_resolver_backup = loader.yaml_implicit_resolvers.copy()
-    for ch in list("0123456789"):
-        if ch in loader.yaml_implicit_resolvers:
-            del loader.yaml_implicit_resolvers[ch]
-    yield
-    for ch in list("0123456789"):
-        if ch in implicit_resolver_backup:
-            loader.yaml_implicit_resolvers[ch] = implicit_resolver_backup[ch]
-
-
 class MetaData:
-    __hash__ = None  # declare as non-hashable to avoid its use with memoization
-
     def __init__(self, path, config=None, variant=None):
         self.undefined_jinja_vars = []
         self.config = get_or_merge_config(config, variant=variant)

tests/test_metadata.py

@@ -8,7 +8,7 @@
 import pytest
 
 from conda_build import api
-from conda_build.metadata import MetaData, _hash_dependencies, select_lines
+from conda_build.metadata import MetaData, _hash_dependencies, select_lines, yamlize
 from conda_build.utils import DEFAULT_SUBDIRS
 
 from .utils import metadata_dir, thisdir
@@ -260,3 +260,66 @@ def test_config_member_decoupling(testing_metadata):
     b = testing_metadata.copy()
     b.config.some_member = "123"
     assert b.config.some_member != testing_metadata.config.some_member
+
+
+# ensure that numbers are not interpreted as ints or floats, doing so trips up versions
+# with trailing zeros
+def test_yamlize_zero():
+    yml = yamlize(
+        """
+        - 0
+        - 0.
+        - 0.0
+        - .0
+        """
+    )
+
+    assert yml == ["0", "0.", "0.0", ".0"]
+
+
+def test_yamlize_positive():
+    yml = yamlize(
+        """
+        - +1
+        - +1.
+        - +1.2
+        - +.2
+        """
+    )
+
+    assert yml == ["+1", "+1.", "+1.2", "+.2"]
+
+
+def test_yamlize_negative():
+    yml = yamlize(
+        """
+        - -1
+        - -1.
+        - -1.2
+        - -.2
+        """
+    )
+
+    assert yml == ["-1", "-1.", "-1.2", "-.2"]
+
+
+def test_yamlize_numbers():
+    yml = yamlize(
+        """
+        - 1
+        - 1.2
+        """
+    )
+
+    assert yml == ["1", "1.2"]
+
+
+def test_yamlize_versions():
+    yml = yamlize(
+        """
+        - 1.2.3
+        - 1.2.3.4
+        """
+    )
+
+    assert yml == ["1.2.3", "1.2.3.4"]