This commit reworks how Sema handles arithmetic on comptime-known
values, fixing many bugs in the process.
The general pattern is that arithmetic on comptime-known values is now
handled by the new namespace `Sema.arith`. Functions handling comptime
arithmetic no longer live on `Value`; this is because some of them can
emit compile errors, so some *can't* go on `Value`. Only semantic
analysis should really be doing arithmetic on `Value`s anyway, so it
makes sense for it to integrate more tightly with `Sema`.
This commit also implements more coherent rules surrounding how
`undefined` interacts with comptime and mixed-comptime-runtime
arithmetic. The rules are as follows.
* If an operation cannot trigger Illegal Behavior, and any operand is
`undefined`, the result is `undefined`. This includes operations like
`0 *| undef`, where the LHS logically *could* be used to determine a
defined result. This is partly to simplify the language, but mostly to
permit codegen backends to represent `undefined` values as completely
invalid states.
* If an operation *can* trigger Illegal Behvaior, and any operand is
`undefined`, then Illegal Behavior results. This occurs even if the
operand in question isn't the one that "decides" illegal behavior; for
instance, `undef / 1` is undefined. This is for the same reasons as
described above.
* An operation which would trigger Illegal Behavior, when evaluated at
comptime, instead triggers a compile error. Additionally, if one
operand is comptime-known undef, such that the other (runtime-known)
operand isn't needed to determine that Illegal Behavior would occur,
the compile error is triggered.
* The only situation in which an operation with one comptime-known
operand has a comptime-known result is if that operand is undefined,
in which case the result is either undefined or a compile error per
the above rules. This could potentially be loosened in future (for
instance, `0 * rt` could be comptime-known 0 with a runtime assertion
that `rt` is not undefined), but at least for now, defining it more
conservatively simplifies the language and allows us to easily change
this in future if desired.
This commit fixes many bugs regarding the handling of `undefined`,
particularly in vectors. Along with a collection of smaller tests, two
very large test cases are added to check arithmetic on `undefined`.
The operations which have been rewritten in this PR are:
* `+`, `+%`, `+|`, `@addWithOverflow`
* `-`, `-%`, `-|`, `@subWithOverflow`
* `*`, `*%`, `*|`, `@mulWithOverflow`
* `/`, `@divFloor`, `@divTrunc`, `@divExact`
* `%`, `@rem`, `@mod`
Other arithmetic operations are currently unchanged.
Resolves: #22743Resolves: #22745Resolves: #22748Resolves: #22749Resolves: #22914
This commits adds the following distinct integer types to std.zig.Ast:
- OptionalTokenIndex
- TokenOffset
- OptionalTokenOffset
- Node.OptionalIndex
- Node.Offset
- Node.OptionalOffset
The `Node.Index` type has also been converted to a distinct type while
`TokenIndex` remains unchanged.
`Ast.Node.Data` has also been changed to a (untagged) union to provide
safety checks.
This reverts commit dea72d15da, reversing
changes made to ab381933c8.
The changeset does not work as advertised and does not have sufficient
test coverage.
Reopens#22822
Functions like isMinGW() and isGnuLibC() have a good reason to exist: They look
at multiple components of the target. But functions like isWasm(), isDarwin(),
isGnu(), etc only exist to save 4-8 characters. I don't think this is a good
enough reason to keep them, especially given that:
* It's not immediately obvious to a reader whether target.isDarwin() means the
same thing as target.os.tag.isDarwin() precisely because isMinGW() and similar
functions *do* look at multiple components.
* It's not clear where we would draw the line. The logical conclusion before
this commit would be to also wrap Arch.isX86(), Os.Tag.isSolarish(),
Abi.isOpenHarmony(), etc... this obviously quickly gets out of hand.
* It's nice to just have a single correct way of doing something.
* arm_apcs is the long dead "OABI" which we never had working support for.
* arm_aapcs16_vfp is for arm-watchos-none which is a dead target that we've
dropped support for.
This is all of the expected 0.14.0 progress on #21530, which can now be
postponed once this commit is merged.
This required rewriting the (un)wrap operations since the original
implementations were extremely buggy.
Also adds an easy way to retrigger Sema OPV bugs so that I don't have to
keep updating #22419 all the time.
Sometimes we emit runtime instructions in comptime scopes. These
instructions will be discarded, but they allow comptime blocks to
contain intermediate runtime-known values, which is necessary for
expressions like `runtime_array.len` to work.
Since we will always throw away these runtime instructions, including
safety checks is a time waste at best and trips an assertion at worst!
Resolves: #20064
The changes from a few commits earlier, where semantic analysis no
longer occurs if any Zig files failed to lower to ZIR, mean `file`
dependencies are no longer necessary! However, we now need them for ZON
files, to be invalidated whenever a ZON file changes.
This came with a big cleanup to `Zcu.PerThread.updateFile` (formerly
`astGenFile`).
Also, change how the cache manifest works for files in the import table.
Instead of being added to the manifest when we call `semaFile` on them,
we iterate the import table after running the AstGen workers and add all
the files to the cache manifest then.
The downside is that this is a bit more eager to include files in the
manifest; in particular, files which are imported but not actually
referenced are now included in analysis. So, for instance, modifying any
standard library file will invalidate all Zig compilations using that
standard library, even if they don't use that file.
The original motivation here was simply that the old logic in `semaFile`
didn't translate nicely to ZON. However, it turns out to actually be
necessary for correctness. Because `@import("foo.zig")` is an
AstGen-level error if `foo.zig` does not exist, we need to invalidate
the cache when an imported but unreferenced file is removed to make sure
this error is triggered when it needs to be.
Resolves: #22746
This is mainly in preparation for integrating ZonGen into the pipeline
properly, although these names are better because `astGenFile` isn't
*necessarily* running AstGen; it may determine that the current ZIR is
up-to-date, or load cached ZIR.
Instead, `source`, `tree`, and `zir` should all be optional. This is
precisely what we're actually trying to model here; and `File` isn't
optimized for memory consumption or serializability anyway, so it's fine
to use a couple of extra bytes on actual optionals here.
This commit allows using ZON (Zig Object Notation) in a few ways.
* `@import` can be used to load ZON at comptime and convert it to a
normal Zig value. In this case, `@import` must have a result type.
* `std.zon.parse` can be used to parse ZON at runtime, akin to the
parsing logic in `std.json`.
* `std.zon.stringify` can be used to convert arbitrary data structures
to ZON at runtime, again akin to `std.json`.
This commit effectively reverts 9e683f0, and hence un-accepts #19777.
While nice in theory, this proposal turned out to have a few problems.
Firstly, supplying a result type implicitly coerces the operand to this
type -- that's the main point of result types! But for `try`, this is
actually a bad idea; we want a redundant `try` to be a compile error,
not to silently coerce the non-error value to an error union. In
practice, this didn't always happen, because the implementation was
buggy anyway; but when it did, it was really quite silly. For instance,
`try try ... try .{ ... }` was an accepted expression, with the inner
initializer being initially coerced to `E!E!...E!T`.
Secondly, the result type inference here didn't play nicely with
`return`. If you write `return try`, the operand would actually receive
a result type of `E!E!T`, since the `return` gave a result type of `E!T`
and the `try` wrapped it in *another* error union. More generally, the
problem here is that `try` doesn't know when it should or shouldn't
nest error unions. This occasionally broke code which looked like it
should work.
So, this commit prevents `try` from propagating result types through to
its operand. A key motivation for the original proposal here was decl
literals; so, as a special case, `try .foo(...)` is still an allowed
syntax form, caught by AstGen and specially lowered. This does open the
doors to allowing other special cases for decl literals in future, such
as `.foo(...) catch ...`, but those proposals are for another time.
Resolves: #21991Resolves: #22633
This check isn't valid in such cases, because the source and destination
pointers both refer to zero bits of memory, meaning they effectively
never alias.
Resolves: #21655
