Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
The interval template member functions mostly accept
tri-comparators but a few functions accept less-comparators.
To reduce the chance of error, and to provide better error
messages, constrain comparator parameters to the expected
signature.
In one case (db/size_estimates_virtual_reader.cc) the caller
had to be adjusted. The comparator supported comparisons
of the interval value type against other types, but not
against itself. To simplify things, we add that signature too,
even though it will never be called.
Closes#9291
If x is of type std::strong_ordering, then "x <=> 0" is equivalent to
x. These no-ops were inserted during #1449 fixes, but are now unnecessary.
They have potential for harm, since they can hide an accidental of the
type of x to an arithmetic type, so remove them.
Ref #1449.
Instead of working only for std::vector, deoverlap is now capable
of using other structures - including chunked_vector, which will
help split large allocations into smaller ones.
Allow the tri-comparator input to range functions to return
std::strong_ordering, e.g. the result of operator<=>. An int
input is still allowed, and coerced to std::strong_ordering by
tri-comparing it against zero. Once all users are converted, this
will be disallowed.
The clever code that performs boundary comparisons unfortunately
has to be dumbed down to conditionals. A helper
require_ordering_and_on_equal_return() is introduced that accepts
a comparison result between bound values, an expected comparison
result, and what to return if the bound value matches (this depends
on whether individual bounds are exclusive or inclusive, on
whether the bounds are start bounds or end bounds, and on the
sense of the comparison).
Unfortunately, the code is somewhat pessimized, and there is no
way to pessimize it as the enum underlying std::strong_ordering
is hidden.
nonwrapping_range<T> and related templates represent mathematical
intervals, and are different from C++ ranges. This causes confusion,
especially when C++ ranges and the range templates are used together.
As the first step to disentable this, introduce a new interval.hh
header with the contents of the old range.hh header, renaming as
follows:
range_bound -> interval_bound
nonwrapping_range -> nonwrapping_interval
wrapping_range -> wrapping_interval
Range -> Interval (concepts)
The range alias, which previously aliased wrapping_range, did
not get renamed - instead the interval alias now aliases
nonwrapping_interval, which is the natural interval type. I plan
to follow up making interval the template, and nonwrapping_interval
the alias (or perhaps even remove it).
To avoid churn, a new range.hh header is provided with the old names
as aliases (range, nonwrapping_range, wrapping_range, range_bound,
and Range) with the same meaning as their former selves.
Tests: unit (dev)
