Define flags to turn on parsing type comments

Demo: `compile(sample, "<sample>", "exec", PyCF_ONLY_AST|0x1000)`
This will crash if type comments are present.

It doesn't *work* yet -- type comments cause crashes in ast.c and type
ignore comments aren't passed on to Module yet.

Author: gvanrossum

Include/compile.h

@@ -22,6 +22,7 @@ PyAPI_FUNC(PyCodeObject *) PyNode_Compile(struct _node *, const char *);
 #define PyCF_DONT_IMPLY_DEDENT 0x0200
 #define PyCF_ONLY_AST 0x0400
 #define PyCF_IGNORE_COOKIE 0x0800
+#define PyCF_TYPE_COMMENTS 0x1000
 
 #ifndef Py_LIMITED_API
 typedef struct {

Include/parsetok.h

@@ -37,6 +37,7 @@ typedef struct {
 
 #define PyPARSE_IGNORE_COOKIE 0x0010
 #define PyPARSE_BARRY_AS_BDFL 0x0020
+#define PyPARSE_TYPE_COMMENTS 0x0040
 
 PyAPI_FUNC(node *) PyParser_ParseString(const char *, grammar *, int,
                                               perrdetail *);

Parser/parsetok.c

@@ -91,6 +91,9 @@ PyParser_ParseStringObject(const char *s, PyObject *filename,
         err_ret->error = PyErr_Occurred() ? E_DECODE : E_NOMEM;
         return NULL;
     }
+    if (*flags & PyPARSE_TYPE_COMMENTS) {
+        tok->type_comments = 1;
+    }
 
 #ifndef PGEN
     Py_INCREF(err_ret->filename);
@@ -159,6 +162,9 @@ PyParser_ParseFileObject(FILE *fp, PyObject *filename,
         err_ret->error = E_NOMEM;
         return NULL;
     }
+    if (*flags & PyPARSE_TYPE_COMMENTS) {
+        tok->type_comments = 1;
+    }
 #ifndef PGEN
     Py_INCREF(err_ret->filename);
     tok->filename = err_ret->filename;

Python/bltinmodule.c

@@ -771,7 +771,7 @@ builtin_compile_impl(PyObject *module, PyObject *source, PyObject *filename,
     cf.cf_flags = flags | PyCF_SOURCE_IS_UTF8;
 
     if (flags &
-        ~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT | PyCF_ONLY_AST))
+        ~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT | PyCF_ONLY_AST | PyCF_TYPE_COMMENTS))
     {
         PyErr_SetString(PyExc_ValueError,
                         "compile(): unrecognised flags");

Python/pythonrun.c

@@ -158,6 +158,8 @@ static int PARSER_FLAGS(PyCompilerFlags *flags)
         parser_flags |= PyPARSE_IGNORE_COOKIE;
     if (flags->cf_flags & CO_FUTURE_BARRY_AS_BDFL)
         parser_flags |= PyPARSE_BARRY_AS_BDFL;
+    if (flags->cf_flags & PyCF_TYPE_COMMENTS)
+        parser_flags |= PyPARSE_TYPE_COMMENTS;
     return parser_flags;
 }