use future flags constants from cpython

from_cpython/Include/Python.h

@@ -111,6 +111,8 @@
 
 #include "pyfpe.h"
 
+#include "code.h"
+
 #define Py_single_input 256
 #define Py_file_input 257
 #define Py_eval_input 258

src/codegen/irgen/future.cpp

@@ -16,6 +16,8 @@
 
 #include <map>
 
+#include "Python.h"
+
 #include "core/ast.h"
 
 namespace pyston {
@@ -27,13 +29,15 @@ struct FutureOption {
 };
 
 const std::map<std::string, FutureOption> future_options
-    = { { "absolute_import", { version_hex(2, 5, 0), version_hex(3, 0, 0), FF_ABSOLUTE_IMPORT } },
-        { "division", { version_hex(2, 2, 0), version_hex(3, 0, 0), FF_DIVISION } },
-        { "generators", { version_hex(2, 2, 0), version_hex(3, 0, 0), FF_GENERATOR } },
-        { "unicode_literals", { version_hex(2, 6, 0), version_hex(3, 0, 0), FF_UNICODE_LITERALS } },
-        { "print_function", { version_hex(2, 6, 0), version_hex(3, 0, 0), FF_PRINT_FUNCTION } },
-        { "nested_scopes", { version_hex(2, 1, 0), version_hex(2, 2, 0), FF_NESTED_SCOPES } },
-        { "with_statement", { version_hex(2, 5, 0), version_hex(3, 6, 0), FF_WITH_STATEMENT } } };
+    = { { "absolute_import", { version_hex(2, 5, 0), version_hex(3, 0, 0), CO_FUTURE_ABSOLUTE_IMPORT } },
+        { "division", { version_hex(2, 2, 0), version_hex(3, 0, 0), CO_FUTURE_DIVISION } },
+        { "unicode_literals", { version_hex(2, 6, 0), version_hex(3, 0, 0), CO_FUTURE_UNICODE_LITERALS } },
+        { "print_function", { version_hex(2, 6, 0), version_hex(3, 0, 0), CO_FUTURE_PRINT_FUNCTION } },
+        { "with_statement", { version_hex(2, 5, 0), version_hex(3, 6, 0), CO_FUTURE_WITH_STATEMENT } },
+
+        // These are mandatory in all versions we care about (>= 2.3)
+        { "generators", { version_hex(2, 2, 0), version_hex(3, 0, 0), CO_GENERATOR } },
+        { "nested_scopes", { version_hex(2, 1, 0), version_hex(2, 2, 0), CO_NESTED } } };
 
 void raiseFutureImportErrorNotFound(const char* file, AST* node, const char* name) {
     raiseSyntaxErrorHelper(file, "", node, "future feature %s is not defined", name);

src/codegen/irgen/future.h

@@ -21,14 +21,6 @@
 
 namespace pyston {
 
-#define FF_ABSOLUTE_IMPORT 0x01
-#define FF_DIVISION 0x02
-#define FF_GENERATOR 0x04
-#define FF_UNICODE_LITERALS 0x08
-#define FF_PRINT_FUNCTION 0x10
-#define FF_NESTED_SCOPES 0x20
-#define FF_WITH_STATEMENT 0x40
-
 // Loop through import statements to find __future__ imports throwing errors for
 // bad __future__ imports. Returns the futures that are turned on. This is used
 // for irgeneration; the parser still has to handle some futures on its own,

src/core/cfg.cpp

@@ -19,6 +19,8 @@
 #include <cstdio>
 #include <cstdlib>
 
+#include "Python.h"
+
 #include "analysis/scoping_analysis.h"
 #include "core/ast.h"
 #include "core/options.h"
@@ -1481,7 +1483,7 @@ public:
             // level == -1 means check both sys path and relative for imports.
             // so if `from __future__ import absolute_import` was used in the file, set level to 0
             int level;
-            if (!(future_flags & FF_ABSOLUTE_IMPORT))
+            if (!(future_flags & CO_FUTURE_ABSOLUTE_IMPORT))
                 level = -1;
             else
                 level = 0;
@@ -1532,7 +1534,7 @@ public:
         // level == -1 means check both sys path and relative for imports.
         // so if `from __future__ import absolute_import` was used in the file, set level to 0
         int level;
-        if (node->level == 0 && !(future_flags & FF_ABSOLUTE_IMPORT))
+        if (node->level == 0 && !(future_flags & CO_FUTURE_ABSOLUTE_IMPORT))
             level = -1;
         else
             level = node->level;
@@ -1729,7 +1731,7 @@ public:
     }
 
     AST_TYPE::AST_TYPE remapBinOpType(AST_TYPE::AST_TYPE op_type) {
-        if (op_type == AST_TYPE::Div && (future_flags & (FF_DIVISION))) {
+        if (op_type == AST_TYPE::Div && (future_flags & (CO_FUTURE_DIVISION))) {
             return AST_TYPE::TrueDiv;
         } else {
             return op_type;