Implement PyRuntimeInfo in Starlark

This is a basic transcription of the PyRuntimeInfo class; it isn't enabled, used,
or tested yet. Subsequent changes will address test failures.

Work towards bazelbuild#15897

PiperOrigin-RevId: 485988691
Change-Id: Ic42b03bc6b82d04742273b6a7f331665dd91aee5

src/main/starlark/builtins_bzl/common/python/providers.bzl

@@ -12,5 +12,91 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """Providers for Python rules."""
-PyRuntimeInfo = _builtins.toplevel.PyRuntimeInfo
+
+DEFAULT_STUB_SHEBANG = "#!/usr/bin/env python3"
+_PYTHON_VERSION_VALUES = ["PY2", "PY3"]
+
+def _PyRuntimeInfo_init(
+ *,
+ interpreter_path = None,
+ interpreter = None,
+ files = None,
+ coverage_tool = None,
+ coverage_files = None,
+ python_version,
+ stub_shebang = None):
+ if (interpreter_path == None) == (interpreter == None):
+ fail("exactly one of interpreter_path or interpreter must be set")
+ if (interpreter == None) != (files == None):
+ fail("interpreter and files must both be set or neither must be set")
+ if (coverage_tool == None) == (coverage_files == None):
+ fail("coverage_tool and coverage_files must both be set or neither must be set")
+ if python_version not in _PYTHON_VERSION_VALUES:
+ fail("invalid python_version: '{}'; must be one of {}".format(
+ python_version,
+ _PYTHON_VERSION_VALUES,
+ ))
+ if not stub_shebang:
+ stub_shebang = DEFAULT_STUB_SHEBANG
+ return {
+ "interpreter_path": interpreter_path,
+ "interpreter": interpreter,
+ "files": files,
+ "coverage_tool": coverage_tool,
+ "coverage_files": coverage_files,
+ "python_version": python_version,
+ "stub_shebang": stub_shebang,
+ }
+
+PyRuntimeInfo, _unused_raw_py_runtime_info_ctor = provider(
+ doc = """Contains information about a Python runtime, as returned by the `py_runtime`
+rule.
+
+A Python runtime describes either a *platform runtime* or an *in-build runtime*.
+A platform runtime accesses a system-installed interpreter at a known path,
+whereas an in-build runtime points to a `File` that acts as the interpreter. In
+both cases, an "interpreter" is really any executable binary or wrapper script
+that is capable of running a Python script passed on the command line, following
+the same conventions as the standard CPython interpreter.
+""",
+ init = _PyRuntimeInfo_init,
+ fields = {
+ "interpreter_path": (
+ "If this is a platform runtime, this field is the absolute " +
+ "filesystem path to the interpreter on the target platform. " +
+ "Otherwise, this is `None`."
+ ),
+ "interpreter": (
+ "If this is an in-build runtime, this field is a `File` representing " +
+ "the interpreter. Otherwise, this is `None`. Note that an in-build " +
+ "runtime can use either a prebuilt, checked-in interpreter or an " +
+ "interpreter built from source."
+ ),
+ "files": (
+ "If this is an in-build runtime, this field is a `depset` of `File`s" +
+ "that need to be added to the runfiles of an executable target that " +
+ "uses this runtime (in particular, files needed by `interpreter`). " +
+ "The value of `interpreter` need not be included in this field. If " +
+ "this is a platform runtime then this field is `None`."
+ ),
+ "coverage_tool": (
+ "If set, this field is a `File` representing tool used for collecting code coverage information from python tests. Otherwise, this is `None`."
+ ),
+ "coverage_files": (
+ "The files required at runtime for using `coverage_tool`. " +
+ "Will be `None` if no `coverage_tool` was provided."
+ ),
+ "python_version": (
+ "Indicates whether this runtime uses Python major version 2 or 3. " +
+ "Valid values are (only) `\"PY2\"` and " +
+ "`\"PY3\"`."
+ ),
+ "stub_shebang": (
+ "\"Shebang\" expression prepended to the bootstrapping Python stub " +
+ "script used when executing `py_binary` targets. Does not " +
+ "apply to Windows."
+ ),
+ },
+)
+
 PyInfo = _builtins.toplevel.PyInfo

src/main/starlark/builtins_bzl/common/python/py_runtime_rule.bzl

@@ -14,6 +14,7 @@
 """Implementation of py_runtime rule."""
 
 load(":common/paths.bzl", "paths")
+load(":common/python/providers.bzl", "DEFAULT_STUB_SHEBANG")
 
 _PyRuntimeInfo = _builtins.toplevel.PyRuntimeInfo
 
@@ -169,9 +170,7 @@ value.
  """,
  ),
  "stub_shebang": attr.string(
- # TODO(b/254866025): Have PyRuntimeInfo and this use a shared
- # constant
- default = "#!/usr/bin/env python3",
+ default = DEFAULT_STUB_SHEBANG,
  doc = """
 "Shebang" expression prepended to the bootstrapping Python stub script
 used when executing `py_binary` targets.