In Linux when interacting with the virtual file system when writing
in invalid value to a file the OS will return errno 22 (INVAL).
Instead of triggering an unreachable, this change now returns a
newly introduced error.InvalidArgument.
In Linux when writing to various files in the virtual file system,
for example /sys/fs/cgroup, if you write an invalid value to a file
you'll get errno 16.
This change allows for these specific cases to be caught instead of
being lumped together in UnexpectedError.
This introduces a new builtin function that compiles down to something that results in an illegal instruction exception/interrupt.
It can be used to exit a program abnormally.
This implements the builtin for all backends.
If I could mark a builtin function as cold, I would mark @setCold as cold.
We have run out of `Zir.Inst.Tag`s so I had to move a tag from Zir.Inst.Tag to
Zir.Inst.Extended. This is because a new noreturn builtin will be added and
noreturn builtins cannot be part of Inst.Tag:
```
/// `noreturn` instructions may not go here; they must be part of the main `Tag` enum.
pub const Extended = enum(u16) {
```
Here's another reason I went for @setCold:
```
$ git grep setRuntimeSafety | wc -l
322
$ git grep setCold | wc -l
79
$ git grep setEvalBranchQuota | wc -l
82
```
This also simply removes @setCold from Autodoc and the docs frontend because
as far as I could understand it, builtins represented using Zir extended
instructions are not yet supported because I couldn't find
@setStackAlign or @setFloatMode there, either.
Give +x to the .wasm file if it is an executable and the OS is WASI.
Some systems may be configured to execute such binaries directly. Even
if that is not the case, it means we will get "exec format error" when
trying to run it rather than "access denied", and then can react to that
in the same way as trying to run an ELF file from a foreign CPU
architecture.
This is part of the strategy to unify RunStep and EmulatableRunStep.
