Add control flow directives

Cython/Compiler/CmdLine.py

@@ -39,6 +39,7 @@ Options:
   -3                             Compile based on Python-3 syntax and code semantics.
   --fast-fail                    Abort the compilation on the first error
   --warning-error, -Werror       Make all warnings into errors
+  --warning-extra, -Wextra       Enable extra warnings
   -X, --directive <name>=<value>[,<name=value,...] Overrides a compiler directive
 """
 
@@ -132,6 +133,8 @@ def parse_command_line(args):
                 Options.fast_fail = True
             elif option in ('-Werror', '--warning-errors'):
                 Options.warning_errors = True
+            elif option in ('-Wextra', '--warning-extra'):
+                options.compiler_directives.update(Options.extra_warnings)
             elif option == "--disable-function-redefinition":
                 Options.disable_function_redefinition = True
             elif option == "--directive" or option.startswith('-X'):

Cython/Compiler/Options.py

@@ -95,10 +95,19 @@ directive_defaults = {
     'warn': None,
     'warn.undeclared': False,
     'warn.unreachable': True,
+    'warn.maybe_uninitialized': False,
+    'warn.unreachable': True,
+    'warn.unused': False,
+    'warn.unused_arg': False,
+    'warn.unused_result': False,
 
 # remove unreachable code
     'remove_unreachable': True,
 
+# control flow debug directives
+    'control_flow.dot_output': "", # Graphviz output filename
+    'control_flow.dot_annotate_defs': False, # Annotate definitions
+
 # test support
     'test_assert_path_exists' : [],
     'test_fail_if_path_exists' : [],
@@ -107,6 +116,13 @@ directive_defaults = {
     'binding': False,
 }
 
+# Extra warning directives
+extra_warnings = {
+    'warn.maybe_uninitialized': True,
+    'warn.unreachable': True,
+    'warn.unused': True,
+}
+
 # Override types possibilities above, if needed
 directive_types = {
     'final' : bool,  # final cdef classes and methods