build: switch to tomli for TOML v1 compliant parser

CHANGELOG.rst

@@ -10,6 +10,7 @@ Unreleased
 - The CLI now honnors `NO_COLOR`_ (`PR #333`_)
 - The CLI can now be forced to colorize the output by setting the ``FORCE_COLOR`` environment variable (`PR #335`_)
 - Added logging to ``build`` and ``build.env`` (`PR #333`_)
+- Switch to a TOML v1 compliant parser (`PR #336`_, Fixes `#308`_)
 
 
 Breaking Changes
@@ -19,7 +20,9 @@ Breaking Changes
 
 .. _PR #333: https://github.com/pypa/build/pull/333
 .. _PR #335: https://github.com/pypa/build/pull/335
+.. _PR #336: https://github.com/pypa/build/pull/336
 .. _#142: https://github.com/pypa/build/issues/142
+.. _#308: https://github.com/pypa/build/issues/308
 .. _NO_COLOR: https://no-color.org
 
 

docs/installation.rst

@@ -37,6 +37,9 @@ This package can build itself with only the ``toml`` and ``pep517``
 dependencies. The ``--skip-dependency-check`` flag should be used in this
 case.
 
+We have a dependency on tomli_, but toml_ can be used instead, which may make
+bootstraping easier.
+
 
 Compatibility
 =============
@@ -66,6 +69,9 @@ versions:
 .. _git tag: https://github.com/pypa/build/tags
 .. _project page: https://pypi.org/project/build/
 
+.. _tomli: https://github.com/hukkin/tomli
+.. _toml: https://github.com/uiri/toml
+
 
 .. |3DCE51D60930EBA47858BA4146F633CBB0EB4BF2| replace:: ``3DCE51D60930EBA47858BA4146F633CBB0EB4BF2``
 .. _3DCE51D60930EBA47858BA4146F633CBB0EB4BF2: https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x3dce51d60930eba47858ba4146f633cbb0eb4bf2

setup.cfg

@@ -27,7 +27,7 @@ packages = find:
 install_requires =
     packaging>=19.0
     pep517>=0.9.1
-    toml>=0.10.0
+    tomli>=1.0.0 # toml can be used instead -- in case it makes bootstraping easier
     colorama;os_name == "nt" # not actually a runtime dependency, only supplied as there is not "recomended dependency" support
     importlib-metadata>=0.22;python_version < "3.8"
 python_requires = >=3.6
@@ -54,10 +54,10 @@ test =
     pytest-rerunfailures>=9.1
     pytest-xdist>=1.34
     setuptools>=42.0.0
+    toml>=0.10.0
     wheel>=0.36.0
 typing =
     mypy==0.910
-    types-toml
     typing-extensions>=3.7.4.3
 virtualenv =
     virtualenv>=20.0.35

src/build/__init__.py

@@ -17,10 +17,35 @@
 import zipfile
 
 from collections import OrderedDict
-from typing import AbstractSet, Any, Callable, Dict, Iterator, Mapping, Optional, Sequence, Set, Tuple, Type, Union
+from typing import (
+    AbstractSet,
+    Any,
+    Callable,
+    Dict,
+    Iterator,
+    Mapping,
+    MutableMapping,
+    Optional,
+    Sequence,
+    Set,
+    Tuple,
+    Type,
+    Union,
+)
 
 import pep517.wrappers
-import toml
+
+
+TOMLDecodeError: Type[Exception]
+toml_loads: Callable[[str], MutableMapping[str, Any]]
+
+
+try:
+    from tomli import TOMLDecodeError
+    from tomli import loads as toml_loads
+except ModuleNotFoundError:  # pragma: no cover
+    from toml import TomlDecodeError as TOMLDecodeError  # type: ignore
+    from toml import loads as toml_loads  # type: ignore
 
 
 RunnerType = Callable[[Sequence[str], Optional[str], Optional[Mapping[str, str]]], None]
@@ -185,13 +210,13 @@ def __init__(
         spec_file = os.path.join(srcdir, 'pyproject.toml')
 
         try:
-            with open(spec_file, encoding='UTF-8') as f:
-                spec = toml.load(f)
+            with open(spec_file, 'rb') as f:
+                spec = toml_loads(f.read().decode())
         except FileNotFoundError:
             spec = {}
         except PermissionError as e:
             raise BuildException(f"{e.strerror}: '{e.filename}' ")
-        except toml.TomlDecodeError as e:
+        except TOMLDecodeError as e:
             raise BuildException(f'Failed to parse {spec_file}: {e} ')
 
         build_system = spec.get('build-system')

tests/constraints.txt

@@ -2,6 +2,7 @@ importlib-metadata==0.22;python_version < "3.8"
 packaging==19.0
 pep517==0.9.1
 toml==0.10.0
+tomli==1.0.0
 typing==3.5.3.0;python_version < "3"
 virtualenv==20.0.35;python_version < "3"
 setuptools==42.0.0

tests/test_projectbuilder.py

@@ -2,6 +2,7 @@
 
 
 import copy
+import importlib
 import os
 import sys
 import textwrap
@@ -520,3 +521,27 @@ def test_metadata_invalid_wheel(tmp_dir, test_bad_wheel_path):
 
     with pytest.raises(ValueError, match='Invalid wheel'):
         builder.metadata_path(tmp_dir)
+
+
+@pytest.fixture
+def mock_tomli_not_available(mocker):
+    loads = mocker.patch('tomli.loads')
+    mocker.patch.dict(sys.modules, {'tomli': None})
+    importlib.reload(build)
+    try:
+        yield
+    finally:
+        loads.assert_not_called()
+        mocker.stopall()
+        importlib.reload(build)
+
+
+def test_toml_instead_of_tomli(mocker, mock_tomli_not_available, tmp_dir, test_flit_path):
+    mocker.patch('pep517.wrappers.Pep517HookCaller', autospec=True)
+
+    builder = build.ProjectBuilder(test_flit_path)
+    builder._hook.build_sdist.return_value = 'dist.tar.gz'
+
+    builder.build('sdist', '.')
+
+    builder._hook.build_sdist.assert_called_with(os.path.abspath('.'), None)