Close subprocess stdout stream once value has been read

Fixes the following warnings with python3:
Exception ignored in: <_io.FileIO name=4 mode='rb' closefd=True>
ResourceWarning: unclosed file <_io.BufferedReader name=4>

docs/history.rst

@@ -17,6 +17,9 @@ Version 1.7.4 (not yet released)
 1. Since this release, pyggcxml's version numbers do not contain the ``v``
    prefix anymore. This was breaking distribution on PyPI (pypi.python.org).
 
+2. Close subprocess stdout stream once value has been read.
+   Fixes some warnings under python3.
+
 Version 1.7.3
 -------------
 

pygccxml/parser/config.py

@@ -452,6 +452,7 @@ def create_compiler_path(xml_generator, compiler_path):
             p = subprocess.Popen(
                 ['which', 'clang++'], stdout=subprocess.PIPE)
             compiler_path = p.stdout.read().decode("utf-8").rstrip()
+            p.stdout.close()
             # No clang found; use gcc
             if compiler_path == '':
                 compiler_path = '/usr/bin/c++'

pygccxml/utils/utils.py

@@ -50,13 +50,16 @@ def find_xml_generator(name=None):
         name = "gccxml"
         p = subprocess.Popen([command, name], stdout=subprocess.PIPE)
         path = p.stdout.read().decode("utf-8")
+        p.stdout.close()
         if path == "":
             name = "castxml"
             p = subprocess.Popen([command, name], stdout=subprocess.PIPE)
             path = p.stdout.read().decode("utf-8")
+            p.stdout.close()
     else:
         p = subprocess.Popen([command, name], stdout=subprocess.PIPE)
         path = p.stdout.read().decode("utf-8")
+        p.stdout.close()
     if path == "":
         raise(Exception(
             "No c++ parser found. Please install castxml or gccxml."))

unittests/file_cache_tester.py

@@ -89,6 +89,7 @@ def test_reopen_cache(self):
             [sys.executable, "unittests/reopen_cache_tester.py"],
             stdout=subprocess.PIPE)
         print(p.stdout.read())
+        p.stdout.close()
 
 
 def create_suite():