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Propagate global interpreter constraints when building PEXes with int…

…erpreter constraints requested (#7285)

### Problem
When running `./pants binary`, we do not consider the global interpreter constraints in passing them to the Pex builder.

This resulted in a bug where the interpreter used to build a PEX in CI differed from the Python used to run the PEX. See pantsbuild/pex#676. To resolve this issue, we need some way to specify the Pex builder must use the specific Python version 2.7.13 (UCS4). This blocks 

### Solution
Modify `PexBuilderWrapper` to use `compatibility_or_constrains()`. This will first try to get the compatibility constraints from the target itself, and then resort to using the PythonSetup subsystem's constraints (for the global instance, resolved from `pants.ini`, `PANTS_PYTHON_SETUP_INTERPRETER_CONSTRAINTS`, and `--interpreter-constraints`).

### Result
Users of the function `add_interpreter_constraints_from()` will now add the global `--interpreter-constraints` to the Pex builder if the targets do not themselves specify a constraint. At the moment, this only impacts `./pants binary`, as `` is the only file which uses this function.

Note this is still not a great solution. It would be better to kill `add_interpreter_constraint()` and `add_interpreter_constraints_from()` to instead automatically set the interpreter constraints from the targets' graph. This PR does not make that change to avoid scope creep.

#### Skipped tests
Due to pantsbuild/pex#655, we must now skip several tests that now fail. PEX does not correctly OR interpreter constraints, so these tests complain that they cannot find an appropriate interpreter to satisfy `['CPython>=3.6,<4', 'CPython>=2.7,<3']`.

Because this PR blocks #7235, which blocks #7197, we skip these tests until the upstream fix pantsbuild/pex#678 is merged into PEX and Pants upgrades its PEX to the new version #7186.
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Eric-Arellano committed Mar 7, 2019
1 parent 06028a6 commit 4d63f8ac3bfab48b5b78f3bef3b7e06a1e65616e
@@ -286,8 +286,9 @@ def add_interpreter_constraints_from(self, constraint_tgts):
# TODO this would be a great place to validate the constraints and present a good error message
# if they are incompatible because all the sources of the constraints are available.
# See:
for tgt in constraint_tgts:
for constraint in tgt.compatibility:
constraint_tuples = {self._python_setup_subsystem.compatibility_or_constraints(tgt) for tgt in constraint_tgts}
for constraint_tuple in constraint_tuples:
for constraint in constraint_tuple:

def add_direct_requirements(self, reqs):
@@ -140,7 +140,8 @@ def _create_binary(self, binary_tgt, results_dir):
if is_python_target(tgt):

# Add target's interpreter compatibility constraints to pex info.
# Add interpreter compatibility constraints to pex info. This will first check the targets for any
# constraints, and if they do not have any will resort to the global constraints.

# Dump everything into the builder's chroot.
@@ -6,6 +6,7 @@

import os
import time
import unittest

from pants.util.contextutil import temporary_dir
from pants_test.backend.python.interpreter_selection_utils import (PY_3, PY_27,
@@ -99,6 +100,9 @@ def test_pytest_run_killed_by_signal(self):
# Ensure that we get a message indicating the abnormal exit.
self.assertIn("FAILURE: Test was killed by signal", pants_run.stdout_data)

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_pytest_explicit_coverage(self):
with temporary_dir() as coverage_dir:
pants_run = self.run_pants(['clean-all',
@@ -109,6 +113,9 @@ def test_pytest_explicit_coverage(self):
self.assertTrue(os.path.exists(os.path.join(coverage_dir, 'coverage.xml')))

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_pytest_with_profile(self):
with temporary_dir() as profile_dir:
prof = os.path.join(profile_dir, '')
@@ -122,6 +129,9 @@ def test_pytest_with_profile(self):
# current process started.

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_pants_test_interpreter_selection_with_pexrc(self):
"""Test the pants test goal with intepreters selected from a PEX_PYTHON_PATH
@@ -5,6 +5,7 @@
from __future__ import absolute_import, division, print_function, unicode_literals

import os
import unittest

from pex.pex_bootstrapper import get_pex_info

@@ -115,6 +116,9 @@ def test_get_env_var(self):
self.assertEqual(var_val, pants_run.stdout_data.strip())

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_pants_run_interpreter_selection_with_pexrc(self):
py27_path, py3_path = python_interpreter_path(PY_27), python_interpreter_path(PY_3)
@@ -136,6 +140,9 @@ def test_pants_run_interpreter_selection_with_pexrc(self):
self.assertIn(py3_path, pants_run_3.stdout_data)

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_pants_binary_interpreter_selection_with_pexrc(self):
py27_path, py3_path = python_interpreter_path(PY_27), python_interpreter_path(PY_3)
@@ -167,6 +174,9 @@ def test_pants_binary_interpreter_selection_with_pexrc(self):

"Upgrade PEX: \
NB: Ensure is merged into the PEX release.")
def test_target_constraints_with_no_sources(self):
with temporary_dir() as interpreters_cache:

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