Parse user code to AST using compiler flags.

Closes ipythongh-777.

IPython/core/compilerop.py

@@ -28,6 +28,7 @@
 from __future__ import print_function
 
 # Stdlib imports
+from ast import PyCF_ONLY_AST
 import codeop
 import hashlib
 import linecache
@@ -77,6 +78,16 @@ def __init__(self):
         # stdlib that call it outside our control go through our codepath
         # (otherwise we'd lose our tracebacks).
         linecache.checkcache = self.check_cache
+
+    def ast_parse(self, source, filename='<unknown>', symbol='exec'):
+        """Parse code to an AST with the current compiler flags active."""
+        return compile(source, filename, symbol, self.flags | PyCF_ONLY_AST, 1)
+
+    def reset_compiler_flags(self):
+        """Reset compiler flags to default state."""
+        # This value is copied from codeop.Compile.__init__, so if that ever
+        # changes, it will need to be updated.
+        self.flags = codeop.PyCF_DONT_IMPLY_DEDENT
 
     @property
     def compiler_flags(self):

IPython/core/interactiveshell.py

@@ -2281,7 +2281,7 @@ def run_cell(self, raw_cell, store_history=True):
 
                 with self.display_trap:
                     try:
-                        code_ast = ast.parse(cell, filename=cell_name)
+                        code_ast = self.compile.ast_parse(cell, filename=cell_name)
                     except IndentationError:
                         self.showindentationerror()
                         self.execution_count += 1

IPython/core/tests/test_interactiveshell.py

@@ -122,3 +122,14 @@ def __repr__(self):
         import IPython.core.formatters
         f = IPython.core.formatters.PlainTextFormatter()
         f([Spam(),Spam()])
+
+    def test_future_flags(self):
+        """Check that future flags are used for parsing code (gh-777)"""
+        ip = get_ipython()
+        ip.run_cell('from __future__ import print_function')
+        try:
+            ip.run_cell('prfunc_return_val = print(1,2, sep=" ")')
+            assert 'prfunc_return_val' in ip.user_ns
+        finally:
+            # Reset compiler flags so we don't mess up other tests.
+            ip.compile.reset_compiler_flags()