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gh-144261: SyntaxWarning when await an unawaitable constant #144271

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gh-144261: SyntaxWarning when await an unawaitable constant #144271

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warning when await an unawaitable constant
Locked-chess-official Jan 27, 2026
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add new
Locked-chess-official Jan 27, 2026
c0ade96
add missing type
Locked-chess-official Jan 27, 2026
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-01-27-19-06-08.gh-issue-144261.iQANFZ.rst
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@@ -0,0 +1 @@
SyntaxWarning when await an unawaitable constant.
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@picnixz picnixz Jan 27, 2026

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This requires better phrasing. This does not explain anything.

28 changes: 28 additions & 0 deletions Python/codegen.c
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Expand Up @@ -3748,6 +3748,33 @@ check_index(compiler *c, expr_ty e, expr_ty s)
}
}

static int
check_awaitable(compiler* c, expr_ty e)
{
/* Emit a warning when awaiting obvious non-awaitable literal objects. */
switch (e->kind) {
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@picnixz picnixz Jan 27, 2026

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It's better to swap the kinds and only consider kinds that are awaitable. Otherwise, we need to update that list whenever we add a new kind that is not awaitable.

case Constant_kind:
case Tuple_kind:
case List_kind:
case ListComp_kind:
case Dict_kind:
case DictComp_kind:
case Set_kind:
case SetComp_kind:
case GeneratorExp_kind:
case JoinedStr_kind:
case TemplateStr_kind:
case FormattedValue_kind:
case Interpolation_kind: {
location loc = LOC(e);
return _PyCompile_Warn(c, loc, "'%.200s' object can't be awaited",
infer_type(e)->tp_name);
}
default:
return SUCCESS;
}
}

static int
is_import_originated(compiler *c, expr_ty e)
{
Expand Down Expand Up @@ -5295,6 +5322,7 @@ codegen_visit_expr(compiler *c, expr_ty e)
ADD_YIELD_FROM(c, loc, 0);
break;
case Await_kind:
RETURN_IF_ERROR(check_awaitable(c, e->v.Await.value));
VISIT(c, expr, e->v.Await.value);
ADDOP_I(c, loc, GET_AWAITABLE, 0);
ADDOP_LOAD_CONST(c, loc, Py_None);
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