OS X still uses clang-14, which lacks sufficient std::ranges support for
recent Rebirth changes.
- Rewrite uses of std::ranges::SYMBOL to ranges::SYMBOL
- Add a stub header that, on gcc, provides for each SYMBOL a statement
`using std::ranges::SYMBOL;`, to delegate back to the standard library
implementation.
- On clang, define a minimal implementation of the required symbols,
without constraint enforcement. Compile-testing with gcc will catch
constraint violations.
Once OS X clang ships a standard library with the required features,
this stub header will be removed and the uses changed back to their full
names.
std::ranges::find_if permits use of a sentinel instead of a full
iterator, and supports std::ranges::find as an alternative to certain
simple uses of std::find_if.
Where possible, use the form that takes a range, rather than the form
that takes two iterators.
Add a declared, but not defined, default constructor for
self_return_iterator to satisfy the standard library's concept
`semiregular`, which insists that sentinels be default-constructible,
even for those functions that never need to do so.
Add a defined, but unused, operator++(postfix) for zip_iterator to
satisfy a standard library concept for `forward_iterator`.
Iterating over it returns each side number in turn. This allows
converting many loops of the form:
```
for (int i = 0; i < MAX_SIDES_PER_SEGMENT; ++i)
```
to the compact form:
```
for (const auto i : MAX_SIDES_PER_SEGMENT)
```
The compact form brings the usual benefit of range-based for: delegating
iteration to the compiler prevents the loop body from skipping a step,
and makes clear in the code that this is the case.
Some flags merit a type other than int8_t. Begin moving flags out to
distinct variables with their own type.
Add static_assert checks that the ABI relevant structures do not change.
gcc-7 warns if a structured binding defines a variable, and then does
not use it. Suppress the warning, since the binding is needed in the
non-editor build.