bpo-35975: Support parsing earlier minor versions of Python 3 (GH-12086)
This adds a `feature_version` flag to `ast.parse()` (documented) and `compile()` (hidden) that allow tweaking the parser to support older versions of the grammar. In particular if `feature_version` is 5 or 6, the hacks for the `async` and `await` keyword from PEP 492 are reinstated. (For 7 or higher, these are unconditionally treated as keywords, but they are still special tokens rather than `NAME` tokens that the parser driver recognizes.)
https://bugs.python.org/issue35975
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 906877a..199ea82 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -105,6 +105,7 @@
if (flags == NULL) {
flags = &local_flags;
local_flags.cf_flags = 0;
+ local_flags.cf_feature_version = PY_MINOR_VERSION;
}
v = _PySys_GetObjectId(&PyId_ps1);
if (v == NULL) {
@@ -1165,6 +1166,7 @@
return NULL;
flags.cf_flags = 0;
+ flags.cf_feature_version = PY_MINOR_VERSION;
mod = PyParser_ASTFromStringObject(str, filename, start, &flags, arena);
if (mod == NULL) {
PyArena_Free(arena);
@@ -1198,12 +1200,15 @@
PyCompilerFlags localflags;
perrdetail err;
int iflags = PARSER_FLAGS(flags);
+ if (flags && flags->cf_feature_version < 7)
+ iflags |= PyPARSE_ASYNC_HACKS;
node *n = PyParser_ParseStringObject(s, filename,
&_PyParser_Grammar, start, &err,
&iflags);
if (flags == NULL) {
localflags.cf_flags = 0;
+ localflags.cf_feature_version = PY_MINOR_VERSION;
flags = &localflags;
}
if (n) {
@@ -1249,6 +1254,7 @@
start, ps1, ps2, &err, &iflags);
if (flags == NULL) {
localflags.cf_flags = 0;
+ localflags.cf_feature_version = PY_MINOR_VERSION;
flags = &localflags;
}
if (n) {