The pragma around set_parents() is no longer needed: the base branch
(#5585) creates a value before setting its type. Before, the type of a new
string was stored first, so GCC had to assume that operator new could
change it again, kept the object branch of the inlined set_parents() alive,
and checked it against the string's allocation. Rewriting set_parents()
itself (if/else instead of switch) does not help.
Verified with Docker GCC 12.5, 13, 14, 15.3 and 16.2: the regression test
builds and passes without the pragma, and fails to build on develop.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>