bpo-38605: Make 'from __future__ import annotations' the default (GH-20434)

The hard part was making all the tests pass; there are some subtle issues here, because apparently the future import wasn't tested very thoroughly in previous Python versions.

For example, `inspect.signature()` returned type objects normally (except for forward references), but strings with the future import. We changed it to try and return type objects by calling `typing.get_type_hints()`, but fall back on returning strings if that function fails (which it may do if there are future references in the annotations that require passing in a specific namespace to resolve).
This commit is contained in:
Batuhan Taskaya 2020-10-06 23:03:02 +03:00 committed by GitHub
parent bef7d299eb
commit 044a1048ca
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GPG key ID: 4AEE18F83AFDEB23
27 changed files with 403 additions and 299 deletions

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@ -392,7 +392,6 @@ static int astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state
static int astfold_arguments(arguments_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_comprehension(comprehension_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_keyword(keyword_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_arg(arg_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_withitem(withitem_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_excepthandler(excepthandler_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
#define CALL(FUNC, TYPE, ARG) \
@ -595,25 +594,11 @@ astfold_comprehension(comprehension_ty node_, PyArena *ctx_, _PyASTOptimizeState
static int
astfold_arguments(arguments_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
CALL_SEQ(astfold_arg, arg, node_->posonlyargs);
CALL_SEQ(astfold_arg, arg, node_->args);
CALL_OPT(astfold_arg, arg_ty, node_->vararg);
CALL_SEQ(astfold_arg, arg, node_->kwonlyargs);
CALL_SEQ(astfold_expr, expr, node_->kw_defaults);
CALL_OPT(astfold_arg, arg_ty, node_->kwarg);
CALL_SEQ(astfold_expr, expr, node_->defaults);
return 1;
}
static int
astfold_arg(arg_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
if (!(state->ff_features & CO_FUTURE_ANNOTATIONS)) {
CALL_OPT(astfold_expr, expr_ty, node_->annotation);
}
return 1;
}
static int
astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
@ -622,17 +607,11 @@ astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
CALL(astfold_arguments, arguments_ty, node_->v.FunctionDef.args);
CALL(astfold_body, asdl_seq, node_->v.FunctionDef.body);
CALL_SEQ(astfold_expr, expr, node_->v.FunctionDef.decorator_list);
if (!(state->ff_features & CO_FUTURE_ANNOTATIONS)) {
CALL_OPT(astfold_expr, expr_ty, node_->v.FunctionDef.returns);
}
break;
case AsyncFunctionDef_kind:
CALL(astfold_arguments, arguments_ty, node_->v.AsyncFunctionDef.args);
CALL(astfold_body, asdl_seq, node_->v.AsyncFunctionDef.body);
CALL_SEQ(astfold_expr, expr, node_->v.AsyncFunctionDef.decorator_list);
if (!(state->ff_features & CO_FUTURE_ANNOTATIONS)) {
CALL_OPT(astfold_expr, expr_ty, node_->v.AsyncFunctionDef.returns);
}
break;
case ClassDef_kind:
CALL_SEQ(astfold_expr, expr, node_->v.ClassDef.bases);
@ -656,9 +635,6 @@ astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
break;
case AnnAssign_kind:
CALL(astfold_expr, expr_ty, node_->v.AnnAssign.target);
if (!(state->ff_features & CO_FUTURE_ANNOTATIONS)) {
CALL(astfold_expr, expr_ty, node_->v.AnnAssign.annotation);
}
CALL_OPT(astfold_expr, expr_ty, node_->v.AnnAssign.value);
break;
case For_kind:

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@ -2026,12 +2026,7 @@ compiler_visit_argannotation(struct compiler *c, identifier id,
{
if (annotation) {
PyObject *mangled;
if (c->c_future->ff_features & CO_FUTURE_ANNOTATIONS) {
VISIT(c, annexpr, annotation)
}
else {
VISIT(c, expr, annotation);
}
VISIT(c, annexpr, annotation);
mangled = _Py_Mangle(c->u->u_private, id);
if (!mangled)
return 0;
@ -5261,12 +5256,7 @@ compiler_annassign(struct compiler *c, stmt_ty s)
if (s->v.AnnAssign.simple &&
(c->u->u_scope_type == COMPILER_SCOPE_MODULE ||
c->u->u_scope_type == COMPILER_SCOPE_CLASS)) {
if (c->c_future->ff_features & CO_FUTURE_ANNOTATIONS) {
VISIT(c, annexpr, s->v.AnnAssign.annotation)
}
else {
VISIT(c, expr, s->v.AnnAssign.annotation);
}
VISIT(c, annexpr, s->v.AnnAssign.annotation);
ADDOP_NAME(c, LOAD_NAME, __annotations__, names);
mangled = _Py_Mangle(c->u->u_private, targ->v.Name.id);
ADDOP_LOAD_CONST_NEW(c, mangled);

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@ -41,7 +41,7 @@ future_check_features(PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
} else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
continue;
} else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
ff->ff_features |= CO_FUTURE_ANNOTATIONS;
continue;
} else if (strcmp(feature, "braces") == 0) {
PyErr_SetString(PyExc_SyntaxError,
"not a chance");