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gh-142349: Implement PEP 810 - Explicit lazy imports (#142351)

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Co-authored-by: T. Wouters <twouters@meta.com >
Co-authored-by: Brittany Reynoso <breynoso@meta.com>
Co-authored-by: Dino Viehland <dinoviehland@meta.com>
This commit is contained in:
Pablo Galindo Salgado 2026-02-12 00:15:33 +00:00 • committed by GitHub
parent cac0c98450
commit 46d5106cfa
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GPG key ID: B5690EEEBB952194
138 changed files with 5126 additions and 197 deletions
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89
Python/codegen.c
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@ -357,8 +357,8 @@ codegen_addop_o(compiler *c, location loc,
#define LOAD_ZERO_SUPER_METHOD -4
static int
codegen_addop_name(compiler *c, location loc,
int opcode, PyObject *dict, PyObject *o)
codegen_addop_name_custom(compiler *c, location loc, int opcode,
PyObject *dict, PyObject *o, int shift, int low)
{
PyObject *mangled = _PyCompile_MaybeMangle(c, o);
if (!mangled) {
@ -369,40 +369,51 @@ codegen_addop_name(compiler *c, location loc,
if (arg < 0) {
return ERROR;
}
ADDOP_I(c, loc, opcode, (arg << shift) | low);
return SUCCESS;
}
static int
codegen_addop_name(compiler *c, location loc,
int opcode, PyObject *dict, PyObject *o)
{
int shift = 0, low = 0;
if (opcode == LOAD_ATTR) {
arg <<= 1;
shift = 1;
}
if (opcode == LOAD_METHOD) {
opcode = LOAD_ATTR;
arg <<= 1;
arg |= 1;
shift = 1;
low = 1;
}
if (opcode == LOAD_SUPER_ATTR) {
arg <<= 2;
arg |= 2;
shift = 2;
low = 2;
}
if (opcode == LOAD_SUPER_METHOD) {
opcode = LOAD_SUPER_ATTR;
arg <<= 2;
arg |= 3;
shift = 2;
low = 3;
}
if (opcode == LOAD_ZERO_SUPER_ATTR) {
opcode = LOAD_SUPER_ATTR;
arg <<= 2;
shift = 2;
}
if (opcode == LOAD_ZERO_SUPER_METHOD) {
opcode = LOAD_SUPER_ATTR;
arg <<= 2;
arg |= 1;
shift = 2;
low = 1;
}
ADDOP_I(c, loc, opcode, arg);
return SUCCESS;
return codegen_addop_name_custom(c, loc, opcode, dict, o, shift, low);
}
#define ADDOP_NAME(C, LOC, OP, O, TYPE) \
RETURN_IF_ERROR(codegen_addop_name((C), (LOC), (OP), METADATA(C)->u_ ## TYPE, (O)))
static int
#define ADDOP_NAME_CUSTOM(C, LOC, OP, O, TYPE, SHIFT, LOW) \
RETURN_IF_ERROR(codegen_addop_name_custom((C), (LOC), (OP), METADATA(C)->u_ ## TYPE, (O), SHIFT, LOW))
static int
codegen_addop_j(instr_sequence *seq, location loc,
int opcode, jump_target_label target)
{
@ -2864,6 +2875,17 @@ codegen_import_as(compiler *c, location loc,
return codegen_nameop(c, loc, asname, Store);
}
static int
codegen_validate_lazy_import(compiler *c, location loc)
{
if (_PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE) {
return _PyCompile_Error(
c, loc, "lazy imports only allowed in module scope");
}
return SUCCESS;
}
static int
codegen_import(compiler *c, stmt_ty s)
{
@ -2884,7 +2906,18 @@ codegen_import(compiler *c, stmt_ty s)
ADDOP_LOAD_CONST(c, loc, zero);
ADDOP_LOAD_CONST(c, loc, Py_None);
ADDOP_NAME(c, loc, IMPORT_NAME, alias->name, names);
if (s->v.Import.is_lazy) {
RETURN_IF_ERROR(codegen_validate_lazy_import(c, loc));
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 1);
} else {
if (_PyCompile_InExceptionHandler(c) ||
_PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE) {
// force eager import in try/except block
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 2);
} else {
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 0);
}
}
if (alias->asname) {
r = codegen_import_as(c, loc, alias->name, alias->asname);
@ -2930,13 +2963,29 @@ codegen_from_import(compiler *c, stmt_ty s)
ADDOP_LOAD_CONST_NEW(c, LOC(s), names);
identifier from = &_Py_STR(empty);
if (s->v.ImportFrom.module) {
ADDOP_NAME(c, LOC(s), IMPORT_NAME, s->v.ImportFrom.module, names);
from = s->v.ImportFrom.module;
}
else {
_Py_DECLARE_STR(empty, "");
ADDOP_NAME(c, LOC(s), IMPORT_NAME, &_Py_STR(empty), names);
if (s->v.ImportFrom.is_lazy) {
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, 0);
if (PyUnicode_READ_CHAR(alias->name, 0) == '*') {
return _PyCompile_Error(c, LOC(s), "cannot lazy import *");
}
RETURN_IF_ERROR(codegen_validate_lazy_import(c, LOC(s)));
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 1);
} else {
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, 0);
if (_PyCompile_InExceptionHandler(c) ||
_PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE ||
PyUnicode_READ_CHAR(alias->name, 0) == '*') {
// forced non-lazy import due to try/except or import *
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 2);
} else {
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 0);
}
}
for (Py_ssize_t i = 0; i < n; i++) {
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, i);
identifier store_name;