Do not use a repository-PEX if a PEX has platforms specified (cherrypick of #15031)

src/python/pants/backend/python/target_types.py

@@ -1025,8 +1025,9 @@ def parse_requirements_file(content: str, *, rel_path: str) -> Iterator[PipRequi
     VCS requirements will fail, with a helpful error message describing how to use PEP 440.
     """
     for i, line in enumerate(content.splitlines()):
-        line = line.strip()
-        if not line or line.startswith("#") or line.startswith("-"):
+        line, _, _ = line.partition("--")
+        line = line.strip().rstrip("\\")
+        if not line or line.startswith("#"):
             continue
         try:
             yield PipRequirement.parse(line)

src/python/pants/backend/python/target_types_test.py

@@ -358,20 +358,26 @@ def test_requirements_field() -> None:
 
 def test_parse_requirements_file() -> None:
     content = dedent(
-        """\
+        r"""\
         # Comment.
         --find-links=https://duckduckgo.com
         ansicolors>=1.18.0
         Django==3.2 ; python_version>'3'
         Un-Normalized-PROJECT  # Inline comment.
         pip@ git+https://github.com/pypa/pip.git
+        setuptools==54.1.2; python_version >= "3.6" \
+            --hash=sha256:dd20743f36b93cbb8724f4d2ccd970dce8b6e6e823a13aa7e5751bb4e674c20b \
+            --hash=sha256:ebd0148faf627b569c8d2a1b20f5d3b09c873f12739d71c7ee88f037d5be82ff
+        wheel==1.2.3 --hash=sha256:dd20743f36b93cbb8724f4d2ccd970dce8b6e6e823a13aa7e5751bb4e674c20b
         """
     )
     assert set(parse_requirements_file(content, rel_path="foo.txt")) == {
         PipRequirement.parse("ansicolors>=1.18.0"),
         PipRequirement.parse("Django==3.2 ; python_version>'3'"),
         PipRequirement.parse("Un-Normalized-PROJECT"),
         PipRequirement.parse("pip@ git+https://github.com/pypa/pip.git"),
+        PipRequirement.parse("setuptools==54.1.2; python_version >= '3.6'"),
+        PipRequirement.parse("wheel==1.2.3"),
     }
 
 

src/python/pants/backend/python/util_rules/pex_from_targets.py

@@ -393,13 +393,20 @@ async def create_pex_from_targets(
 
         pex_native_subsetting_supported = False
         if python_setup.enable_resolves:
+            # TODO: Once `requirement_constraints` is removed in favor of `enable_resolves`,
+            # `ChosenPythonResolveRequest` and `_PexRequirementsRequest` should merge and
+            # do a single transitive walk to replace this method.
             chosen_resolve = await Get(
                 ChosenPythonResolve, ChosenPythonResolveRequest(request.addresses)
             )
             loaded_lockfile = await Get(
                 LoadedLockfile, LoadedLockfileRequest(chosen_resolve.lockfile)
             )
             pex_native_subsetting_supported = loaded_lockfile.is_pex_native
+            if loaded_lockfile.constraints_strings:
+                requirements = dataclasses.replace(
+                    requirements, constraints_strings=loaded_lockfile.constraints_strings
+                )
 
         should_return_entire_lockfile = (
             python_setup.run_against_entire_lockfile and request.internal_only
@@ -520,6 +527,10 @@ async def create_pex_from_targets(
 async def get_repository_pex(
     request: _RepositoryPexRequest, python_setup: PythonSetup
 ) -> OptionalPexRequest:
+    # NB: It isn't safe to resolve against an entire lockfile or constraints file if
+    # platforms are in use. See https://github.com/pantsbuild/pants/issues/12222.
+    if request.platforms or request.complete_platforms:
+        return OptionalPexRequest(None)
 
     interpreter_constraints = await Get(
         InterpreterConstraints,
@@ -570,9 +581,7 @@ async def _setup_constraints_repository_pex(
     global_requirement_constraints: GlobalRequirementConstraints,
 ) -> OptionalPexRequest:
     request = constraints_request.repository_pex_request
-    # NB: it isn't safe to resolve against the whole constraints file if
-    # platforms are in use. See https://github.com/pantsbuild/pants/issues/12222.
-    if not python_setup.resolve_all_constraints or request.platforms or request.complete_platforms:
+    if not python_setup.resolve_all_constraints:
         return OptionalPexRequest(None)
 
     constraints_path = python_setup.requirement_constraints

src/python/pants/backend/python/util_rules/pex_from_targets_test.py

@@ -175,7 +175,7 @@ class Project:
 build_deps = ["setuptools==54.1.2", "wheel==0.36.2"]
 
 
-setuptools_poetry_lockfile = """
+setuptools_poetry_lockfile = r"""
 # This lockfile was autogenerated by Pants. To regenerate, run:
 #
 #    ./pants generate-lockfiles --resolve=setuptools
@@ -430,11 +430,16 @@ def test_exclude_requirements(
     assert len(pex_request.requirements.req_strings) == (1 if include_requirements else 0)
 
 
-def test_issue_12222(rule_runner: RuleRunner) -> None:
+@pytest.mark.parametrize("enable_resolves", [False, True])
+def test_cross_platform_pex_disables_subsetting(
+    rule_runner: RuleRunner, enable_resolves: bool
+) -> None:
+    # See https://github.com/pantsbuild/pants/issues/12222.
+    lockfile = "3rdparty/python/default.lock"
     constraints = ["foo==1.0", "bar==1.0"]
     rule_runner.write_files(
         {
-            "constraints.txt": "\n".join(constraints),
+            lockfile: "\n".join(constraints),
             "a.py": "",
             "BUILD": dedent(
                 """
@@ -445,19 +450,26 @@ def test_issue_12222(rule_runner: RuleRunner) -> None:
             ),
         }
     )
+
+    if enable_resolves:
+        options = [
+            "--python-enable-resolves",
+            # NB: Because this is a synthetic lockfile without a header.
+            "--python-invalid-lockfile-behavior=ignore",
+        ]
+    else:
+        options = [
+            f"--python-requirement-constraints={lockfile}",
+            "--python-resolve-all-constraints",
+        ]
+    rule_runner.set_options(options, env_inherit={"PATH"})
+
     request = PexFromTargetsRequest(
         [Address("", target_name="lib")],
         output_filename="demo.pex",
         internal_only=False,
         platforms=PexPlatforms(["some-platform-x86_64"]),
     )
-    rule_runner.set_options(
-        [
-            "--python-requirement-constraints=constraints.txt",
-            "--python-resolve-all-constraints",
-        ],
-        env_inherit={"PATH"},
-    )
     result = rule_runner.request(PexRequest, [request])
 
     assert result.requirements == PexRequirements(["foo"], constraints_strings=constraints)

src/python/pants/backend/python/util_rules/pex_requirements.py

@@ -9,7 +9,7 @@
 
 from pants.backend.python.pip_requirement import PipRequirement
 from pants.backend.python.subsystems.setup import InvalidLockfileBehavior, PythonSetup
-from pants.backend.python.target_types import PythonRequirementsField
+from pants.backend.python.target_types import PythonRequirementsField, parse_requirements_file
 from pants.backend.python.util_rules.interpreter_constraints import InterpreterConstraints
 from pants.backend.python.util_rules.lockfile_metadata import (
     InvalidPythonLockfileReason,
@@ -87,8 +87,11 @@ class LoadedLockfile:
     requirement_estimate: int
     # True if the loaded lockfile is in PEX's native format.
     is_pex_native: bool
+    # If !is_pex_native, the lockfile parsed as constraints strings, for use when the lockfile
+    # needs to be subsetted (see #15031, ##12222).
+    constraints_strings: FrozenOrderedSet[str] | None
     # The original file or file content (which may not have identical content to the output
-    # `lockfile_digest).
+    # `lockfile_digest`).
     original_lockfile: Lockfile | LockfileContent
 
 
@@ -167,11 +170,16 @@ async def load_lockfile(
             ),
         )
         requirement_estimate = _pex_lockfile_requirement_count(lock_bytes)
+        constraints_strings = None
     else:
         header_delimiter = "#"
+        lock_string = lock_bytes.decode()
         # Note: this is a very naive heuristic. It will overcount because entries often
         # have >1 line due to `--hash`.
-        requirement_estimate = len(lock_bytes.decode().splitlines())
+        requirement_estimate = len(lock_string.splitlines())
+        constraints_strings = FrozenOrderedSet(
+            str(req) for req in parse_requirements_file(lock_string, rel_path=lockfile_path)
+        )
 
     metadata: PythonLockfileMetadata | None = None
     if should_validate_metadata(lockfile, python_setup):
@@ -188,6 +196,7 @@ async def load_lockfile(
         metadata,
         requirement_estimate,
         is_pex_native,
+        constraints_strings,
         original_lockfile=lockfile,
     )