This changeset fixes the handling of alignment in several places. The
new rules are:
* `@alignOf(T)` where `T` is a runtime zero-bit type is at least 1,
maybe greater.
* Zero-bit fields in `extern` structs *do* force alignment, potentially
offsetting following fields.
* Zero-bit fields *do* have addresses within structs which can be
observed and are consistent with `@offsetOf`.
These are not necessarily all implemented correctly yet (see disabled
test), but this commit fixes all regressions compared to master, and
makes one new test pass.
Previously it would canonicalize or not depending on some volatile
internal state of the compiler, now it forces resolution of the element
type to determine the alignment if it needs to.
All of the logic in `Value.elemValue` is quite questionable, but
printing an error is definitely better than crashing. Notably, this
should stop us from hitting crashes when dumping AIR.
This also modifies AstGen so that struct types use 1 bit each from the
flags to communicate if there are nonzero inits, alignments, or comptime
fields. This allows adding a struct type to the InternPool without
looking ahead in memory to find out the answers to these questions,
which is easier for CPUs as well as for me, coding this logic right now.
Structs were previously using `SegmentedList` to be given indexes, but
were not actually backed by the InternPool arrays.
After this, the only remaining uses of `SegmentedList` in the compiler
are `Module.Decl` and `Module.Namespace`. Once those last two are
migrated to become backed by InternPool arrays as well, we can introduce
state serialization via writing these arrays to disk all at once.
Unfortunately there are a lot of source code locations that touch the
struct type API, so this commit is still work-in-progress. Once I get it
compiling and passing the test suite, I can provide some interesting
data points such as how it affected the InternPool memory size and
performance comparison against master branch.
I also couldn't resist migrating over a bunch of alignment API over to
use the log2 Alignment type rather than a mismash of u32 and u64 byte
units with 0 meaning something implicitly different and special at every
location. Turns out you can do all the math you need directly on the
log2 representation of alignments.
The new CI images provided by GitHub no longer provide ninja.exe, so
this commit installs it explicitly, using the suggested method from
GitHub.
See https://github.com/actions/runner-images/issues/8343 for more
details.
Simplify wording and add some formatting in several locations.
Expand sentinel array tests to highlight (non-)handling of internal
sentinels.
Fix format of symbol names in function pointers example.
Clarify wording a bit on the builin atomic* documentation.
Remove the (second) builtin compileLog example that demonstrated a lack of
compileLog entries.
* langref: address comments from rohlem
Use "0-terminated" instead of "null-terminated".
Undo some changes that were not as clear an improvement as I though.
* langref: remove stray ""
Thanks to rohlem for spotting this typo.
previously, in the container view (the type of view that you see when
you look at `std` for example), when listing types and namespaces, we
would only show doc comments places on the direct child decl, which in
the case of the `std` namespace, for example, it's just a bunch of
re-exports.
now, if we don't find a direct doc comment, we chase indirection and
display doc comments placed directly on the definition, if any.
this is the precise priority order:
```
/// 1
pub const Foo = _Foo;
/// 2
const _Foo = struct {
//! 3
};
```
The numbers show the priority order for autodoc.
It is very common, and well-defined, for a pointer on one side of a C ABI
to have a different but compatible element type. Examples include:
- `char*` vs `uint8_t*` on a system with 8-bit bytes
- `const char*` vs `char*`
- `char*` vs `unsigned char*`
Without this flag, Clang would invoke UBSAN when such an extern
function was called.
Might be nice to file an upstream issue and find out if there is a more
precise way to disable the problematic check.
`-fsanitize-cfi-icall-generalize-pointers` looks promising according to
the documentation, but empirically it does not work.
