[export-dep-as-jar] Respect strict_deps in libraries field (#9145)

### Problem
The libraries field of a target didn't respect the strict_deps of the target, making it not correct.

### Solution
Precalculate a set of "things we want in the classpath", which takes strict_deps into account.
Predicate including something in the libraries field, so that we only include things from this set.

### Result
The test introduced in the third commit failed before the change, succeeds after.

examples/src/scala/org/pantsbuild/example/strict_deps/A.scala

@@ -0,0 +1,3 @@
+package a
+
+class Foo

examples/src/scala/org/pantsbuild/example/strict_deps/B.scala

@@ -0,0 +1,3 @@
+package b
+
+class Foo

examples/src/scala/org/pantsbuild/example/strict_deps/BUILD

@@ -0,0 +1,32 @@
+# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+scala_library(
+  name = "a",
+  sources = ["A.scala"],
+)
+
+scala_library(
+  name = "b",
+  sources = ["B.scala"],
+)
+
+scala_library(
+  name = "c",
+  sources = ["C.scala"],
+  dependencies = [":a"],
+)
+
+scala_library(
+  name = "d",
+  sources = ["D.scala"],
+  dependencies = [":b", ":c"],
+  strict_deps = True,
+)
+
+scala_library(
+  name = "e",
+  sources = ["E.scala"],
+  dependencies = [":b", ":c"],
+  strict_deps = False,
+)

examples/src/scala/org/pantsbuild/example/strict_deps/C.scala

@@ -0,0 +1,5 @@
+package a
+
+class C {
+  val implementationDetail: Any = new a.Foo()
+}

examples/src/scala/org/pantsbuild/example/strict_deps/D.scala

@@ -0,0 +1,8 @@
+package d
+
+import a._
+import b._
+
+class App {
+  val foo: Foo = new Foo()
+}

examples/src/scala/org/pantsbuild/example/strict_deps/E.scala

@@ -0,0 +1,7 @@
+package e
+
+import a.Foo
+
+class App {
+  val foo: Foo = new Foo()
+}

src/python/pants/backend/project_info/tasks/export_dep_as_jar.py

@@ -169,14 +169,19 @@ def _zip_sources(target, location, suffix='.jar'):
           zip_file.write(os.path.join(get_buildroot(), src_from_build_root), src_from_source_root)
     return f
 
-  def _dependencies_to_include_in_libraries(self, t, modulizable_target_set):
-    dependencies_to_include = set([])
+  def _dependencies_to_include_in_libraries(self, t, modulizable_target_set, dependencies_needed_in_classpath):
+    """
+    NB: We need to pass dependencies_needed_in_classpath here to make sure we're being strict_deps-aware
+        when computing the dependencies.
+    """
+
+    dependencies_to_include = []
     self.context.build_graph.walk_transitive_dependency_graph(
       [direct_dep.address for direct_dep in t.dependencies],
       # NB: Dependency graph between modulizable targets is represented with modules,
       #     so we don't need to expand those branches of the dep graph.
-      predicate=lambda dep: dep not in modulizable_target_set,
-      work=lambda dep: dependencies_to_include.add(dep),
+      predicate=lambda dep: (dep not in modulizable_target_set) and (dep in dependencies_needed_in_classpath),
+      work=lambda dep: dependencies_to_include.append(dep),
     )
     return list(sorted(dependencies_to_include))
 
@@ -206,9 +211,6 @@ def _process_target(
       'extra_jvm_options': current_target.payload.get_field_value('extra_jvm_options', [])
     }
 
-    if not current_target.is_synthetic:
-      info['globs'] = current_target.globs_relative_to_buildroot()
-
     def iter_transitive_jars(jar_lib):
       """
       :type jar_lib: :class:`pants.backend.jvm.targets.jar_library.JarLibrary`
@@ -239,8 +241,19 @@ def _full_library_set_for_target(target):
         libraries.add(target.id)
       return libraries
 
+    if not current_target.is_synthetic:
+      info['globs'] = current_target.globs_relative_to_buildroot()
+
+    def _dependencies_needed_in_classpath(target):
+      if isinstance(target, JvmTarget):
+        return [dep for dep in DependencyContext.global_instance().dependencies_respecting_strict_deps(target)]
+      else:
+        return [dep for dep in target.closure()]
+
+    dependencies_needed_in_classpath = _dependencies_needed_in_classpath(current_target)
+
     libraries_for_target = set([self._jar_id(jar) for jar in iter_transitive_jars(current_target)])
-    for dep in self._dependencies_to_include_in_libraries(current_target, modulizable_target_set):
+    for dep in self._dependencies_to_include_in_libraries(current_target, modulizable_target_set, dependencies_needed_in_classpath):
       libraries_for_target.update(_full_library_set_for_target(dep))
     info['libraries'].extend(libraries_for_target)
 

tests/python/pants_test/backend/project_info/tasks/test_export_dep_as_jar.py

@@ -250,6 +250,20 @@ def setUp(self):
 
     self.linear_build_graph = self.make_linear_graph(['a', 'b', 'c', 'd', 'e'], target_type=ScalaLibrary)
 
+    self.strict_deps_enabled = self.make_target(
+      'strict_deps:enabled',
+      target_type=JvmTarget,
+      dependencies=[self.scala_with_source_dep],
+      strict_deps=True
+    )
+
+    self.strict_deps_disabled = self.make_target(
+      'strict_deps:disabled',
+      target_type=JvmTarget,
+      dependencies=[self.scala_with_source_dep],
+      strict_deps=False
+    )
+
   def create_runtime_classpath_for_targets(self, target):
     def path_to_zjar_with_workdir(address: Address):
       return os.path.join(self.pants_workdir, address.path_safe_spec, "z.jar")
@@ -613,3 +627,16 @@ def test_imports_3rdparty_jars_from_transitive_dependencies(self):
       'org.apache:apache-jar:12.12.2012',
       result['targets'][spec]['libraries']
     )
+
+  def test_libraries_respect_strict_deps(self):
+    enabled_spec = self.strict_deps_enabled.address.spec
+    enabled_result = self.execute_export_json(enabled_spec)['targets'][enabled_spec]
+    disabled_spec = self.strict_deps_disabled.address.spec
+    disabled_result = self.execute_export_json(disabled_spec)['targets'][disabled_spec]
+
+    # Both the targets under test transitively depend on this target
+    # but it shouldn't be included in the strict deps case.
+    transitive_dependency_library_entry = self.jvm_target_with_sources.id
+
+    assert transitive_dependency_library_entry in disabled_result['libraries']
+    assert transitive_dependency_library_entry not in enabled_result['libraries']