Allow bootstrap

This package buildrequires flit_core to build the wheel, but flit_core requires tomli.

This also allows us to use tomli instead of toml in %pyproject_buildrequires.

python-tomli.spec

@@ -1,6 +1,12 @@
+# This package buildrequires flit_core to build the wheel, but flit_core requires tomli.
+# To bootstrap, we copy the files to appropriate locations manually and create a minimal dist-info metadata.
+# Note that as a pure Python package, the wheel contains no pre-built binary stuff.
+# When bootstrap is enabled, we don't run tests either, just an import check.
+%bcond_with     bootstrap
+
 Name:           python-tomli
 Version:        1.2.2
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        A little TOML parser for Python
 
 License:        MIT
@@ -10,14 +16,17 @@ Source0:        https://github.com/hukkin/tomli/archive/refs/tags/%{version}.tar
 BuildArch:      noarch
 BuildRequires:  python3-devel
 
-%global _description %{expand:
-Tomli is a Python library for parsing TOML.
-Tomli is fully compatible with TOML v1.0.0.}
-
+%if %{without bootstrap}
 # Upstream test requirements are in tests/requirements.txt,
 # but they're mixed together with coverage ones. Tests only need:
 BuildRequires:  python3-pytest
 BuildRequires:  python3-dateutil
+%endif
+
+%global _description %{expand:
+Tomli is a Python library for parsing TOML.
+Tomli is fully compatible with TOML v1.0.0.}
+
 
 %description %_description
 
@@ -31,21 +40,47 @@ Summary:        %{summary}
 %autosetup -p1 -n tomli-%{version}
 
 
+%if %{without bootstrap}
 %generate_buildrequires
 %pyproject_buildrequires -r
+%endif
 
 
 %build
+%if %{without bootstrap}
 %pyproject_wheel
+%else
+%global distinfo tomli-%{version}+rpmbootstrap.dist-info
+mkdir %{distinfo}
+cat > %{distinfo}/METADATA << EOF
+Metadata-Version: 2.2
+Name: tomli
+Version: %{version}+rpmbootstrap
+EOF
+%endif
 
 
 %install
+%if %{without bootstrap}
 %pyproject_install
 %pyproject_save_files tomli
+%else
+mkdir -p %{buildroot}%{python3_sitelib}
+cp -a tomli %{distinfo} %{buildroot}%{python3_sitelib}
+echo '%{python3_sitelib}/tomli/' > %{pyproject_files}
+echo '%{python3_sitelib}/%{distinfo}/' >> %{pyproject_files}
+%endif
 
 
 %check
+%py3_check_import tomli
+%if %{without bootstrap}
+# assert the properly built package has no runtime requires
+# if it does, we need to change the bootstrap metadata
+test -f %{buildroot}%{python3_sitelib}/tomli-%{version}.dist-info/METADATA
+! grep '^Requires-Dist:' %{buildroot}%{python3_sitelib}/tomli-%{version}.dist-info/METADATA
 %pytest
+%endif
 
 
 %files -n python3-tomli -f %{pyproject_files}
@@ -55,6 +90,9 @@ Summary:        %{summary}
 
 
 %changelog
+* Fri Oct 29 2021 Miro Hrončok <mhroncok@redhat.com> - 1.2.2-2
+- Allow a bootstrap build without flit_core
+
 * Wed Oct 27 2021 Petr Viktorin <pviktori@redhat.com> - 1.2.2-1
 - Update to version 1.2.2