This makes it easier to differentiate between cases where certain
functionality is not implemented vs. cases where a code location
should really be unreachable.
Previously we would just print "ASSERTION FAILED: false", which was
kinda cryptic and also didn't make it clear whether this was a TODO or
an unreachable condition. Now, we actually print "ASSERTION FAILED:
TODO", making it crystal clear.
This optimization has already been done in LibC's `assert.h`, which
Userland `VERIFY()` calls resolve to. We now use it in the kernel, but
with the nicer C++ *unlikely* attribute instead of `__builtin_expect`.
This tells the compiler to arrange the generated machine code so that
the error-free branches execute faster (e.g. fewer jumps, better cache
locality).
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
Problem:
- `(void)` simply casts the expression to void. This is understood to
indicate that it is ignored, but this is really a compiler trick to
get the compiler to not generate a warning.
Solution:
- Use the `[[maybe_unused]]` attribute to indicate the value is unused.
Note:
- Functions taking a `(void)` argument list have also been changed to
`()` because this is not needed and shows up in the same grep
command.
I've been using this in the new HTML parser and it makes it much easier
to understand the state of unfinished code branches.
TODO() is for places where it's okay to end up but we need to implement
something there.
ASSERT_NOT_REACHED() is for places where it's not okay to end up, and
something has gone wrong.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
