Rid all targets of sources_rel_path parameters. [API]

These paramaters were largely unused or else redundantly used/
misused.  The existing external users of this parameter agreed
they can adjust during the next pants upgrade cycle they have
so this change kills the parameters outright.

Fixup GoLocalSource globbing to be lazy and relative to the
spec_path so that it can employ a standard call to
`self.create_sources_field` when setting up its sources payload field.

Testing Done:
CI went green here:
  https://travis-ci.org/pantsbuild/pants/builds/78098070

Bugs closed: 2101

Reviewed at https://rbcommons.com/s/twitter/r/2738/

contrib/cpp/src/python/pants/contrib/cpp/targets/cpp_target.py

@@ -12,23 +12,16 @@
 class CppTarget(Target):
   """A base class for all cpp targets."""
 
-  def __init__(self,
-               address=None,
-               payload=None,
-               sources_rel_path=None,
-               sources=None,
-               **kwargs):
+  def __init__(self, address=None, payload=None, sources=None, **kwargs):
     """
     :param sources: Source code files to build. Paths are relative to the BUILD
       file's directory.
     :type sources: ``Fileset`` (from globs or rglobs) or list of strings
     """
-    if sources_rel_path is None:
-      sources_rel_path = address.spec_path
     payload = payload or Payload()
     payload.add_fields({
       'sources': self.create_sources_field(sources=sources,
-                                           sources_rel_path=sources_rel_path,
+                                           sources_rel_path=address.spec_path,
                                            key_arg='sources'),
     })
     super(CppTarget, self).__init__(address=address, payload=payload, **kwargs)

contrib/go/src/python/pants/contrib/go/targets/BUILD

@@ -28,7 +28,9 @@ python_library(
   name='go_local_source',
   sources=['go_local_source.py'],
   dependencies=[
+    '3rdparty/python/twitter/commons:twitter.common.dirutil',
     ':go_target',
+    'src/python/pants/base:build_environment',
     'src/python/pants/base:payload',
   ],
 )

contrib/go/src/python/pants/contrib/go/targets/go_local_source.py

@@ -6,9 +6,10 @@
                         unicode_literals, with_statement)
 
 import os
-from glob import glob
 
+from pants.base.build_environment import get_buildroot
 from pants.base.payload import Payload
+from twitter.common.dirutil.fileset import Fileset
 
 from pants.contrib.go.targets.go_target import GoTarget
 
@@ -32,11 +33,19 @@ def local_import_path(cls, source_root, address):
     return cls.package_path(source_root, address.spec_path)
 
   def __init__(self, address=None, payload=None, **kwargs):
-    sources = glob(os.path.join(address.spec_path, '*.go'))
+    # TODO(John Sirois): Make pants.backend.core.wrapped_globs.Globs in the core backend
+    # constructable with just a rel_path. Right now it violates the Law of Demeter and
+    # fundamentally takes a ParseContext, which it doesn't actually need and which other backend
+    # consumers should not need to know about or create.
+    # Here we depend on twitter/commons which is less than ideal in core pants and even worse in a
+    # plugin.  We depend on it here to ensure the globbing is lazy and skipped if the target is
+    # never fingerprinted (eg: when running `./pants list`).
+    sources = Fileset.globs('*.go', root=os.path.join(get_buildroot(), address.spec_path))
+
     payload = payload or Payload()
     payload.add_fields({
       'sources': self.create_sources_field(sources=sources,
-                                           sources_rel_path='',
+                                           sources_rel_path=address.spec_path,
                                            key_arg='sources'),
     })
     super(GoLocalSource, self).__init__(address=address, payload=payload, **kwargs)

contrib/spindle/src/python/pants/contrib/spindle/tasks/spindle_gen.py

@@ -120,8 +120,7 @@ def execute(self):
       for target in targets:
         java_synthetic_name = '{0}-{1}'.format(target.id, 'java')
         java_sources_rel_path = os.path.relpath(self.namespace_out, get_buildroot())
-        java_spec_path = java_sources_rel_path
-        java_synthetic_address = Address(java_spec_path, java_synthetic_name)
+        java_synthetic_address = Address(java_sources_rel_path, java_synthetic_name)
         java_generated_sources = [
           os.path.join(os.path.dirname(source), 'java_{0}.java'.format(os.path.basename(source)))
           for source in self.sources_generated_by_target(target)
@@ -140,7 +139,6 @@ def execute(self):
           target_type=JavaLibrary,
           dependencies=[dep.address for dep in self.synthetic_target_extra_dependencies],
           derived_from=target,
-          sources_rel_path=java_sources_rel_path,
           sources=java_relative_generated_sources,
         )
         java_synthetic_target = build_graph.get_target(java_synthetic_address)
@@ -161,8 +159,7 @@ def execute(self):
 
         synthetic_name = '{0}-{1}'.format(target.id, 'scala')
         sources_rel_path = os.path.relpath(self.namespace_out, get_buildroot())
-        spec_path = sources_rel_path
-        synthetic_address = Address(spec_path, synthetic_name)
+        synthetic_address = Address(sources_rel_path, synthetic_name)
         generated_sources = [
           '{0}.{1}'.format(source, 'scala')
           for source in self.sources_generated_by_target(target)
@@ -173,7 +170,6 @@ def execute(self):
           address=synthetic_address,
           target_type=ScalaLibrary,
           dependencies=self.synthetic_target_extra_dependencies,
-          sources_rel_path=sources_rel_path,
           sources=relative_generated_sources,
           derived_from=target,
           java_sources=[java_synthetic_target.address.spec],

src/python/pants/backend/codegen/tasks/simple_codegen_task.py

@@ -236,9 +236,14 @@ def execute(self):
           address=synthetic_address,
           target_type=self.synthetic_target_type,
           dependencies=self.synthetic_target_extra_dependencies(target),
-          sources_rel_path=sources_rel_path,
           sources=relative_generated_sources,
           derived_from=target,
+
+          # TODO(John Sirois): This assumes - currently, a JvmTarget or PythonTarget which both
+          # happen to have this attribute for carrying publish metadata but share no interface
+          # that defines this canonical property.  Lift up an interface and check for it or else
+          # add a way for SimpleCodeGen subclasses to specify extra attribute names that should be
+          # copied over from the target to its derived target.
           provides=target.provides,
         )
         synthetic_target = self.target

src/python/pants/backend/jvm/targets/jvm_target.py

@@ -26,7 +26,6 @@ def subsystems(cls):
   def __init__(self,
                address=None,
                payload=None,
-               sources_rel_path=None,
                sources=None,
                provides=None,
                excludes=None,
@@ -59,13 +58,11 @@ def __init__(self,
       by DistributionLocator.cached().version.
     """
     self.address = address  # Set in case a TargetDefinitionException is thrown early
-    if sources_rel_path is None:
-      sources_rel_path = address.spec_path
     payload = payload or Payload()
     excludes = ExcludesField(self.assert_list(excludes, expected_type=Exclude, key_arg='excludes'))
     configurations = ConfigurationsField(self.assert_list(configurations, key_arg='configurations'))
     payload.add_fields({
-      'sources': self.create_sources_field(sources, sources_rel_path, address, key_arg='sources'),
+      'sources': self.create_sources_field(sources, address.spec_path, key_arg='sources'),
       'provides': provides,
       'excludes': excludes,
       'configurations': configurations,

src/python/pants/backend/python/targets/python_target.py

@@ -23,7 +23,6 @@ class PythonTarget(Target):
   def __init__(self,
                address=None,
                payload=None,
-               sources_rel_path=None,
                sources=None,
                resources=None,  # Old-style resources (file list, Fileset).
                resource_targets=None,  # New-style resources (Resources target specs).
@@ -53,11 +52,9 @@ def __init__(self,
       agnostic to interpreter class.
     """
     self.address = address
-    if sources_rel_path is None:
-      sources_rel_path = address.spec_path
     payload = payload or Payload()
     payload.add_fields({
-      'sources': self.create_sources_field(sources, sources_rel_path, address, key_arg='sources'),
+      'sources': self.create_sources_field(sources, address.spec_path, key_arg='sources'),
       'resources': self.create_sources_field(resources, address.spec_path, key_arg='resources'),
       'provides': provides,
       'compatibility': PrimitiveField(maybe_list(compatibility or ())),