This commit changes how we represent comptime-mutable memory
(`comptime var`) in the compiler in order to implement the intended
behavior that references to such memory can only exist at comptime.
It does *not* clean up the representation of mutable values, improve the
representation of comptime-known pointers, or fix the many bugs in the
comptime pointer access code. These will be future enhancements.
Comptime memory lives for the duration of a single Sema, and is not
permitted to escape that one analysis, either by becoming runtime-known
or by becoming comptime-known to other analyses. These restrictions mean
that we can represent comptime allocations not via Decl, but with state
local to Sema - specifically, the new `Sema.comptime_allocs` field. All
comptime-mutable allocations, as well as any comptime-known const allocs
containing references to such memory, live in here. This allows for
relatively fast checking of whether a value references any
comptime-mtuable memory, since we need only traverse values up to
pointers: pointers to Decls can never reference comptime-mutable memory,
and pointers into `Sema.comptime_allocs` always do.
This change exposed some faulty pointer access logic in `Value.zig`.
I've fixed the important cases, but there are some TODOs I've put in
which are definitely possible to hit with sufficiently esoteric code. I
plan to resolve these by auditing all direct accesses to pointers (most
of them ought to use Sema to perform the pointer access!), but for now
this is sufficient for all realistic code and to get tests passing.
This change eliminates `Zcu.tmp_hack_arena`, instead using the Sema
arena for comptime memory mutations, which is possible since comptime
memory is now local to the current Sema.
This change should allow `Decl` to store only an `InternPool.Index`
rather than a full-blown `ty: Type, val: Value`. This commit does not
perform this refactor.
Some users are hitting this limit. I think it's primarily due to not
deduplicating (solved in the previous commit) but this seems like a
better limit regardless.
The zig way is to let the compiler provide errors, rather than trying to
implement the compiler in the standard library.
I played around with this and found the compile errors to be easier to
comprehend without this logic.
1. Entirely rewrote frexp with generics, reducing the implementation to a single function and enabling parameters of types f80 and f16
2. Expanded upon the tests, making them more descriptive and comprehensive, and automatically generating the test bodies for each floating point type
3. Added a doctest for frexp
Symmetry with parse_float and to hide the implementation from the user.
Additionally, we expose the entire namespace and provide some aliases so
everything is available to a user.
Closes#19366
netbsd fix:
- `Futex.zig:542:56: error: expected error union type, found 'c_int'`
openbsd fix:
- `emutls.zig:10:21: error: root struct of file 'os' has no member named 'abort'`
- `Thread.zig:627:22: error: expected 6 argument(s), found 5`
This was a mistake from day one. This is the wrong abstraction layer to
do this in.
My alternate plan for this is to make all I/O operations require an IO
interface parameter, similar to how allocations require an Allocator
interface parameter today.
