fix: migrate py_pex_binary to use providers

Author: jbedard

e2e/cases/pex-interpreter-exclusion/BUILD.bazel

@@ -27,6 +27,13 @@ py_pex_binary(
     python_interpreter_constraints = [],
 )
 
+# Default constraints are stamped from the binary's version (3.13), not the pex
+# rule's toolchain (workspace default 3.11).
+py_pex_binary(
+    name = "app_mismatch_constrained_pex",
+    binary = ":app_mismatch",
+)
+
 py_test(
     name = "test_pex_excludes_interpreter",
     srcs = ["test_pex_excludes_interpreter.py"],
@@ -36,3 +43,10 @@ py_test(
     ],
     main = "test_pex_excludes_interpreter.py",
 )
+
+py_test(
+    name = "test_pex_constraint_version",
+    srcs = ["test_pex_constraint_version.py"],
+    data = [":app_mismatch_constrained_pex"],
+    main = "test_pex_constraint_version.py",
+)

e2e/cases/pex-interpreter-exclusion/test_pex_constraint_version.py

@@ -0,0 +1,24 @@
+"""The default python_interpreter_constraints must be stamped from the binary's
+own interpreter version, not the pex rule's toolchain.
+
+app_mismatch pins python_version 3.13 while this workspace's default is 3.11.
+With the default constraint (`CPython=={major}.{minor}.*`) the PEX must advertise
+3.13 — the interpreter it was actually built for — otherwise it would refuse to
+run on its own target interpreter.
+"""
+
+import json
+import os
+import zipfile
+from pathlib import Path
+
+pex = (
+    Path(os.environ["RUNFILES_DIR"])
+    / "_main/pex-interpreter-exclusion/app_mismatch_constrained_pex.pex"
+)
+with zipfile.ZipFile(pex) as zf:
+    info = json.loads(zf.read("PEX-INFO"))
+
+assert info["interpreter_constraints"] == ["CPython==3.13.*"], info[
+    "interpreter_constraints"
+]

py/private/BUILD.bazel

@@ -47,8 +47,11 @@ bzl_library(
     name = "py_image_layer",
     srcs = ["py_image_layer.bzl"],
     deps = [
+        ":providers",
         ":py_info",
         ":py_info_interop",
+        "//py/private/py_venv:types",
+        "//py/private/toolchain:types",
         "@bazel_lib//lib:transitions",
         "@tar.bzl//tar:mtree",
         "@tar.bzl//tar:tar",
@@ -120,8 +123,9 @@ bzl_library(
     name = "py_pex_binary",
     srcs = ["py_pex_binary.bzl"],
     deps = [
+        ":providers",
         ":py_info",
-        ":py_semantics",
+        "//py/private/py_venv:types",
         "//py/private/toolchain:types",
     ],
 )

py/private/py_image_layer.bzl

@@ -35,7 +35,8 @@ Sharing model:
 load("//py/private:providers.bzl", "PyWheelsInfo")
 load("//py/private:py_info.bzl", "PyInfo")
 load("//py/private:py_info_interop.bzl", "has_py_info")
-load("//py/private/toolchain:types.bzl", "PY_TOOLCHAIN")
+load("//py/private/py_venv:types.bzl", "PY_VENV_KINDS")
+load("//py/private/toolchain:types.bzl", "PY_TOOLCHAIN", "interpreter_files_and_version")
 
 _TAR_TOOLCHAIN = "@tar.bzl//tar/toolchain:type"
 
@@ -182,8 +183,6 @@ _LayerInfo = provider(
     },
 )
 
-_PY_VENV_KINDS = ("py_venv", "_py_venv", "_py_venv_lib")
-
 def _collect_from_deps(ctx, provider):
     """Walk deps/data/actual/venv and return a list of provider values from each matching dep."""
     results = []
@@ -307,11 +306,9 @@ def _layer_aspect_impl(target, ctx):
     # (NOT ctx.toolchains) is how the binary reads it back, which correctly
     # follows the binary's target-platform transition.
     if platform_common.ToolchainInfo in target:
-        py3 = getattr(target[platform_common.ToolchainInfo], "py3_runtime", None)
-        if py3 == None or py3.files == None:
+        interp_depset, _ = interpreter_files_and_version(target)
+        if interp_depset == None:
             return []
-        direct = [py3.interpreter] if getattr(py3, "interpreter", None) != None else []
-        interp_depset = depset(direct = direct, transitive = [py3.files])
         plan = ctx.attr._layer_tier[PyLayerTierInfo]
         interp_group = plan.interpreter_group
         interp_layer = None
@@ -399,7 +396,7 @@ def _layer_aspect_impl(target, ctx):
 
     # Skip PyInfo deps (including wheel-leaf targets, which also emit PyInfo) —
     # they self-capture via the aspect.
-    if kind not in _PY_VENV_KINDS and has_py_info(target) and not is_binary:
+    if kind not in PY_VENV_KINDS and has_py_info(target) and not is_binary:
         own_parts = [target[DefaultInfo].files]
         for attr_name in ("data", "deps"):
             attr_val = getattr(ctx.rule.attr, attr_name, None)
@@ -424,7 +421,7 @@ def _layer_aspect_impl(target, ctx):
         else:
             own_source.append(own_depset)
 
-    if kind in _PY_VENV_KINDS:
+    if kind in PY_VENV_KINDS:
         if PY_TOOLCHAIN in ctx.rule.toolchains:
             py_tc = ctx.rule.toolchains[PY_TOOLCHAIN]
             if _LayerInfo in py_tc: