Include the opening brace's line in multiline f-string errors

An unclosed f-string replacement field can report an error on a later line, making the opening brace hard to find:

var = "abc"
a = f""" {var} extern "C" { """
b = """ string """

  File "script.py", line 3
    b = """ string """
                   ^
SyntaxError: f-string: expecting '}'

The quotes after the second { start a string inside the replacement field. That string ends on line 3, and the final quotes start another string that is never closed.

The error should include the line number of the opening brace:

SyntaxError: f-string: expecting '}' to close '{' on line 2

The same problem affects t-strings. Valid strings inside replacement fields should continue to work.

Linked PRs

• gh-157779

Comece com o reprodutor de f-string multilinha fornecido e compare seu diagnóstico com a mensagem esperada. Verifique o caso correspondente de t-string e confirme que strings válidas dentro dos campos de substituição continuam funcionando. Considera-se concluído quando ambas as mensagens de erro afetadas identificarem a linha da chave de abertura sem causar regressões nas strings válidas; um pull request vinculado já está listado.