[Bug libstdc++/120465] std::erase_if for std::flat_map calls predicate with incorrect type

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120465

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Eligor Kadaf from comment #0)
> However, it seems that in libstdc++ implementation of std::flat_map it's
> value_type is std::tuple.

No, the predicate is just called on the elements of a zip_view, and *that* has
a tuple as its value_type. The actual flat_map::value_type is correct, but is
not used by erase_if.