diff --git a/Lib/test/test_fstring.py b/Lib/test/test_fstring.py index da0160d2382cc6b..27c7f70cef32e39 100644 --- a/Lib/test/test_fstring.py +++ b/Lib/test/test_fstring.py @@ -8,6 +8,7 @@ # Unicode identifiers in tests is allowed by PEP 3131. import ast +import dis import os import re import types @@ -1738,5 +1739,14 @@ def test_syntax_warning_infinite_recursion_in_file(self): self.assertIn(rb'\1', stdout) self.assertEqual(len(stderr.strip().splitlines()), 2) + def test_fstring_without_formatting_bytecode(self): + # f-string without any formatting should emit the same bytecode + # as a normal string. See gh-99606. + def get_code(s): + return [(i.opname, i.oparg) for i in dis.get_instructions(s)] + + for s in ["", "some string"]: + self.assertEqual(get_code(f"'{s}'"), get_code(f"f'{s}'")) + if __name__ == '__main__': unittest.main() diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-11-25-20-36-38.gh-issue-99606.fDY5hK.rst b/Misc/NEWS.d/next/Core and Builtins/2023-11-25-20-36-38.gh-issue-99606.fDY5hK.rst new file mode 100644 index 000000000000000..adc0e3a6bbc89a5 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2023-11-25-20-36-38.gh-issue-99606.fDY5hK.rst @@ -0,0 +1,2 @@ +Make code generated for an empty f-string identical to the code of an empty +normal string. diff --git a/Python/compile.c b/Python/compile.c index 8b1eef79a79eaea..8b9e2f02048f111 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -5042,8 +5042,12 @@ compiler_joined_str(struct compiler *c, expr_ty e) } else { VISIT_SEQ(c, expr, e->v.JoinedStr.values); - if (asdl_seq_LEN(e->v.JoinedStr.values) != 1) { - ADDOP_I(c, loc, BUILD_STRING, asdl_seq_LEN(e->v.JoinedStr.values)); + if (value_count > 1) { + ADDOP_I(c, loc, BUILD_STRING, value_count); + } + else if (value_count == 0) { + _Py_DECLARE_STR(empty, ""); + ADDOP_LOAD_CONST_NEW(c, loc, Py_NewRef(&_Py_STR(empty))); } } return SUCCESS;