Fix -s option not pulling in transitive dependencies, fixes #22.

Takes packages passed in via -s and builds source distributions out of them
and then feeds them through the standard requirement resolution pipeline.
This ensures that transitive requirements are pulled in.

Also adds some debugging information in the package translation step when
certain packages are untranslateable.

pex/bin/pex.py

@@ -9,14 +9,15 @@
 from __future__ import absolute_import, print_function
 
 import os
+import shutil
 import sys
 from optparse import OptionParser
 
 from pex.common import safe_delete, safe_mkdtemp
 from pex.fetcher import Fetcher, PyPIFetcher
-from pex.installer import EggInstaller, WheelInstaller
+from pex.installer import EggInstaller, Packager, WheelInstaller
 from pex.interpreter import PythonInterpreter
-from pex.package import EggPackage, SourcePackage, WheelPackage
+from pex.package import EggPackage, Package, SourcePackage, WheelPackage
 from pex.pex import PEX
 from pex.pex_builder import PEXBuilder
 from pex.platforms import Platform
@@ -269,9 +270,30 @@ def build_pex(args, options):
   else:
     precedence = (EggPackage, SourcePackage)
 
+  requirements = options.requirements[:]
+
+  if options.source_dirs:
+    temporary_package_root = safe_mkdtemp()
+
+    for source_dir in options.source_dirs:
+      try:
+        sdist = Packager(source_dir).sdist()
+      except installer.Error:
+        die('Failed to run installer for %s' % source_dir, CANNOT_DISTILL)
+
+      # record the requirement information
+      sdist_pkg = Package.from_href(sdist)
+      requirements.append('%s==%s' % (sdist_pkg.name, sdist_pkg.raw_version))
+
+      # copy the source distribution
+      shutil.copyfile(sdist, os.path.join(temporary_package_root, os.path.basename(sdist)))
+
+    # Tell pex where to find the packages
+    fetchers.append(Fetcher([temporary_package_root]))
+
   with TRACER.timed('Resolving distributions'):
     resolveds = requirement_resolver(
-        options.requirements,
+        requirements,
         fetchers=fetchers,
         translator=translator,
         interpreter=interpreter,
@@ -285,13 +307,6 @@ def build_pex(args, options):
     pex_builder.add_distribution(pkg)
     pex_builder.add_requirement(pkg.as_requirement())
 
-  for source_dir in options.source_dirs:
-    try:
-      bdist = installer(source_dir).bdist()
-    except installer.Error:
-      die('Failed to run installer for %s' % source_dir, CANNOT_DISTILL)
-    pex_builder.add_dist_location(bdist)
-
   if options.entry_point is not None:
     log('Setting entry point to %s' % options.entry_point, v=options.verbosity)
     pex_builder.info.entry_point = options.entry_point

pex/installer.py

@@ -55,7 +55,7 @@ def __init__(self, source_dir, strict=True, interpreter=None, install_dir=None):
     self._interpreter = interpreter or PythonInterpreter.get()
     if not self._interpreter.satisfies(self.capability) and strict:
       raise self.IncapableInterpreter('Interpreter %s not capable of running %s' % (
-          self._interpreter, self.__class__.__name__))
+          self._interpreter.binary, self.__class__.__name__))
 
   def mixins(self):
     """Return a map from import name to requirement to load into setup script prior to invocation.

pex/translator.py

@@ -96,14 +96,18 @@ def translate(self, package, into=None):
       with TRACER.timed('Packaging %s' % package.name):
         try:
           dist_path = installer.bdist()
-        except self._installer_impl.InstallFailure:
+        except self._installer_impl.InstallFailure as e:
+          TRACER.log('Failed to install package at %s: %s' % (unpack_path, e))
           return None
         target_path = os.path.join(into, os.path.basename(dist_path))
         safe_copy(dist_path, target_path)
         target_package = Package.from_href(target_path)
         if not target_package:
+          TRACER.log('Target path %s does not look like a Package.' % target_path)
           return None
         if not target_package.compatible(self._interpreter.identity, platform=self._platform):
+          TRACER.log('Target package %s is not compatible with %s / %s' % (
+              target_package, self._interpreter.identity, self._platform))
           return None
         return DistributionHelper.distribution_from_path(target_path)
     except Exception as e:
@@ -131,6 +135,8 @@ def translate(self, package, into=None):
     if not isinstance(package, self._package_type):
       return None
     if not package.compatible(identity=self._identity, platform=self._platform):
+      TRACER.log('Target package %s is not compatible with %s / %s' % (
+          package, self._identity, self._platform))
       return None
     into = into or safe_mkdtemp()
     target_path = os.path.join(into, package.filename)