This function is a hotspot, but it has inefficient codegen:
1. For whatever reason, the chars() iterator of wstr is slower
than that of a slice. Use the slice.
2. Unnecessary overflow checks were preventing vectorization.
Switch to a more optimized implementation.
This improves aliases benchmark time by about 9%.
This was used in CMake to detect invalid mbrtowc implementations. The only known
case was on SnowLeopard, which is no longer supported. Remove this file.
Since none of the compiles(xxx) calls are to particularly complex code, we can
just use `rsconf` directly to test for the presence of the symbols or headers as
needed.
Note that it seems at least some of the previous detection was not working
correctly; in particular HAVE_PIPE2 was evaluating to false on my WSL install
where pipe2(2) was available (caught because it revealed some compilation errors
in that conditional compilation path after porting).
I kept the cfg names and the tests themselves mostly as-is, though we might want
to change that to conform with the rust convention of lowercase cfg names and
decide whether we want to prefix all these with have_, fish_, or nothing at all.
Also the posix_spawn() test should probably check for the symbol `posix_spawn()`
rather than the header `spawn.h` since we don't use it via the header but rather
via the symbol (but in reality they're almost certainly going to give the same
result).
NB: I only encountered this when rewriting the cfg detection, which means that
the previous detection wasn't correct since I have pipe2 on Linux but didn't run
into this build error before.
I had originally created a safe `set_locale()` wrapper and clippy-disallowed
`libc::setlocale()` but almost all our uses of `libc::setlocale()` are in a loop
where it makes much more sense to just obtain the lock outright then call
`setlocale()` repeatedly rather than lock it in the wrapper function each time.
No need to use cfg_attr and have to worry about syncing the preconditions for
the cfg_attr with the preconditions for where `slice_contains_slice()` is used
in the codebase, just mark it as `allow(unused)` with a comment.
pcre2-sys includes a vendored copy of PCRE2, which allows for
statically-linked PCRE2. Hook this up to the CMake build variable, and
remove the C++ integration for PCRE2.
They are probably not terribly useful for us but let's see what happens.
Unfortunately cargo does not properly forward the combination of "RUSTFLAGS"
and "--target" that is currently required to build with ASan [1]. Hence doctests
will fail to link on ASan builds. Let's disable doctests when ASan is active.
[1]: https://github.com/rust-lang/cargo/issues/10666 et al
